Littérature scientifique sur le sujet « Antibiotic resistance bacteria (ARB) »
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Articles de revues sur le sujet "Antibiotic resistance bacteria (ARB)"
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Xi, Chuanwu, Yongli Zhang, Carl F. Marrs, Wen Ye, Carl Simon, Betsy Foxman et Jerome Nriagu. « Prevalence of Antibiotic Resistance in Drinking Water Treatment and Distribution Systems ». Applied and Environmental Microbiology 75, no 17 (6 juillet 2009) : 5714–18. http://dx.doi.org/10.1128/aem.00382-09.
Texte intégralRésumé :
ABSTRACT The occurrence and spread of antibiotic-resistant bacteria (ARB) are pressing public health problems worldwide, and aquatic ecosystems are a recognized reservoir for ARB. We used culture-dependent methods and quantitative molecular techniques to detect and quantify ARB and antibiotic resistance genes (ARGs) in source waters, drinking water treatment plants, and tap water from several cities in Michigan and Ohio. We found ARGs and heterotrophic ARB in all finished water and tap water tested, although the amounts were small. The quantities of most ARGs were greater in tap water than in finished water and source water. In general, the levels of bacteria were higher in source water than in tap water, and the levels of ARB were higher in tap water than in finished water, indicating that there was regrowth of bacteria in drinking water distribution systems. Elevated resistance to some antibiotics was observed during water treatment and in tap water. Water treatment might increase the antibiotic resistance of surviving bacteria, and water distribution systems may serve as an important reservoir for the spread of antibiotic resistance to opportunistic pathogens.
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Zhang, Minglu, Mengyao Xu, Shaofeng Xu, Lingyue Zhang, Kaizong Lin, Lei Zhang, Miao Bai, Can Zhang et He Zhou. « Response of the Bacterial Community and Antibiotic Resistance in Overnight Stagnant Water from a Municipal Pipeline ». International Journal of Environmental Research and Public Health 17, no 6 (18 mars 2020) : 1995. http://dx.doi.org/10.3390/ijerph17061995.
Texte intégralRésumé :
Although drinking water safety has raised considerable concern, to date, the hidden health risks in newly released overnight water from a municipal pipeline have seldom received attention. In this study, bacterial community composition and the response of antibiotic-resistant bacteria (ARB) to ciprofloxacin, azithromycin, tetracycline, penicillin, and cephalosporin in overnight stagnant water were analyzed. With increases in heterotrophic bacteria plate count (HPC) during water stagnation, the numbers of ARB and the ARB/HPC ratios for the five antibiotics in resident water were observed to increase, which illustrated that the prevalence of ARB rose in the pipe network water during stagnation time (ST). Furthermore, during water stagnation for 12 h, an increase in bacteria related to fermentation was also observed. When the ST rose to 48 h, the fermentation bacteria become non-significant, and this was related to the exchange of pipe network water during daytime stagnation within the 48-h period. The antibiotic resistance index (ARI) showed that tetracycline had the highest resistance level in fresh water, and then decreased during water stagnation. When ST increased to 12 h, all ARI values of the five antibiotics were low, which was associated with changes in parameters during water retention and reduced resistance during short-term stagnation. When the ST increased to 24 and 48 h, the resistance to most antibiotics (except for tetracycline) increased, which showed that increasing antibiotic resistance is caused by the formation of biofilms in the pipeline during water stagnation.
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SIEDLECKA, AGATA, MIRELA WOLF-BACA et KATARZYNA PIEKARSKA. « Antibiotic and Disinfectant Resistance in Tap Water Strains – Insight into the Resistance of Environmental Bacteria ». Polish Journal of Microbiology 70, no 1 (mars 2021) : 57–67. http://dx.doi.org/10.33073/pjm-2021-004.
Texte intégralRésumé :
Although antibiotic-resistant bacteria (ARB) have been isolated from tap water worldwide, the knowledge of their resistance patterns is still scarce. Both horizontal and vertical gene transfer has been suggested to contribute to the resistance spread among tap water bacteria. In this study, ARB were isolated from finished water collected at two independent water treatment plants (WTPs) and tap water collected at several point-of-use taps during summer and winter sampling campaigns. A total of 24 strains were identified to genus or species level and subjected to antibiotic and disinfectant susceptibility testing. The investigated tap water ARB belonged to phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. The majority of the isolates proved multidrug resistant and resistant to chemical disinfectant. Neither seasonal nor WTP-dependent variabilities in antibiotic or disinfectant resistance were found. Antibiotics most effective against the investigated isolates included imipenem, tetracyclines, erythromycin, and least effective – aztreonam, cefotaxime, amoxicillin, and ceftazidime. The most resistant strains originate from Afipia sp. and Methylobacterium sp. Comparing resistance patterns of isolated tap water ARB with literature reports concerning the same genera or species confirms intra-genus or even intra-specific variabilities of environmental bacteria. Neither species-specific nor acquired resistance can be excluded.
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Courti, Ibtissam, Cristina Muja, Thomas Maho, Florent P. Sainct et Philippe Guillot. « Degradation of Bacterial Antibiotic Resistance Genes during Exposure to Non-Thermal Atmospheric Pressure Plasma ». Antibiotics 11, no 6 (31 mai 2022) : 747. http://dx.doi.org/10.3390/antibiotics11060747.
Texte intégralRésumé :
Bacterial resistance to antibiotics has become a major public health problem in recent years. The occurrence of antibiotics in the environment, especially in wastewater treatment plants, has contributed to the development of antibiotic-resistant bacteria (ARB) and the spread of antibiotic resistance genes (ARGs). Despite the potential of some conventional processes used in wastewater treatment plants, the removal of ARB and ARGs remains a challenge that requires further research and development of new technologies to avoid the release of emerging contaminants into aquatic environments. Non-thermal atmospheric pressure plasmas (NTAPPs) have gained a significant amount of interest for wastewater treatment due to their oxidizing potential. They have shown their effectiveness in the inactivation of a wide range of bacteria in several fields. In this review, we discuss the application of NTAPPs for the degradation of antibiotic resistance genes in wastewater treatment.
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Yang, Fang, Yu Wang, Qianwen Liu, Bo Xu, Huan Chen, Yaomen Li, Kun Wang et al. « High Prevalence and Varied Distribution of Antibiotic-Resistant Bacteria in the Rhizosphere and Rhizoplane of Citrus medica ». Microorganisms 10, no 9 (25 août 2022) : 1708. http://dx.doi.org/10.3390/microorganisms10091708.
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The plant-associated bacteria, including that in the rhizosphere and rhizoplane, play important roles in human exposure to antibiotic-resistant bacteria (ARB). The rhizosphere and rhizoplane represent two distinct environments with different selective pressures for bacterial colonization. However, whether the difference in characteristics between the rhizosphere and rhizoplane can affect the abundance and antibiotic resistance profiles of ARB colonizing, the two environments remain largely unknown. In this study, we obtained 174 bacterial isolates from the rhizosphere (113 isolates) and rhizoplane (61 isolates) of Citrus medica trees grown in a park, where humans could easily and frequently contact the trees. A very high proportion of isolates exhibited resistance to several clinically important antibiotics, including β-lactam class antibiotics and polymyxin, with several known antibiotic-resistant opportunistic pathogens, such as Micrococcus luteus, being identified. The prevalence of ARB in the rhizoplane was higher than that in the rhizosphere. While the prevalence of polymyxin-resistant isolates was higher in the rhizoplane, the prevalence of amphenicol-resistant isolates was significantly higher in the rhizosphere. In summary, our findings suggest that the rhizosphere and rhizoplane are important media for the spread of ARB, and the different characteristics between the two environments can affect the distribution of ARB.
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Li, Yongqiang, Chongmiao Zhang, Xiao Mou, Peipei Zhang, Jie Liang et Zhen Wang. « Distribution characteristics of antibiotic resistance bacteria and related genes in urban recreational lakes replenished by different supplementary water source ». Water Science and Technology 85, no 4 (22 janvier 2022) : 1176–90. http://dx.doi.org/10.2166/wst.2022.018.
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Abstract The distribution characteristics of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in urban recreational water from different water-supply sources might be different. In this study, water samples were collected to detect the antibiotic resistance of heterotrophic bacteria to five antibiotics, and the content, phenotype, gene type and species distribution of resistant bacteria were analyzed. The results showed that the changes of bacteria resistance rate in two lakes to five kinds of antibiotics were synchronous with time, and it would reach its maximum in autumn. The detection of ARGs and int I in 80 resistance strains showed that the detection rate of tetG, tetA and int I was high. Here, 51.25% of the bacteria were doubly resistant to AMP-CTX. The 80 isolate strains were of nine genera and 19 species, among which Bacillus cereus, Escherichia coli, Aeromonas veronii, Aeromonas caviae and Raoultella ornithinolytica were the common ARB species in two lakes. Correlation analysis showed that the water temperature was significantly correlated with the content of ARB in sulfamethoxazole (SMZ) and cefotaxime (CTX) (p < 0.05), and the total phosphorus (TP) in FQ lake was significantly correlated with the content of AMP-resistant bacteria (p < 0.05), while there were no other correlations between the changes of other water quality indexes and the content of ARB (p > 0.05).
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Ye, Jinzhou, et Xinhai Chen. « Current Promising Strategies against Antibiotic-Resistant Bacterial Infections ». Antibiotics 12, no 1 (30 décembre 2022) : 67. http://dx.doi.org/10.3390/antibiotics12010067.
Texte intégralRésumé :
Infections caused by antibiotic-resistant bacteria (ARB) are one of the major global health challenges of our time. In addition to developing new antibiotics to combat ARB, sensitizing ARB, or pursuing alternatives to existing antibiotics are promising options to counter antibiotic resistance. This review compiles the most promising anti-ARB strategies currently under development. These strategies include the following: (i) discovery of novel antibiotics by modification of existing antibiotics, screening of small-molecule libraries, or exploration of peculiar places; (ii) improvement in the efficacy of existing antibiotics through metabolic stimulation or by loading a novel, more efficient delivery systems; (iii) development of alternatives to conventional antibiotics such as bacteriophages and their encoded endolysins, anti-biofilm drugs, probiotics, nanomaterials, vaccines, and antibody therapies. Clinical or preclinical studies show that these treatments possess great potential against ARB. Some anti-ARB products are expected to become commercially available in the near future.
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Kwok, Annie, Michael C. Davis et Sanghoon Kang. « Antibiotic resistant bacteria in an urban freshwater ecosystem in central Texas ». Fine Focus 3, no 2 (1 août 2017) : 113–26. http://dx.doi.org/10.33043/ff.3.2.113-126.
Texte intégralRésumé :
Antibiotic resistance is a growing concern for the human population and is becoming prevalent in many environments. For example, increasing occurrences of antibiotic resistance genes (ARGs) in aquatic ecosystems elevates the risk of pathogenic microbes acquiring those resistance genes. There is an urgent need to more closely examine the relationship between antibiotic resistant bacteria (ARB) and antibiotic residues in urban freshwater environments. Thus, our main objective was to investigate the presence of antibiotic resistance in wastewater treatment plant (WWTP) influent and effluent leading into the Brazos River using several commonly used antibiotics: penicillin, ciprofloxacin, erythromycin, trimethoprim, tetracycline, sulfamethoxazole, and gentamicin. An additional aim was to explore possible mechanisms of resistance emergence to these antibiotics using techniques such as replica plating, the Luria-Delbrück Fluctuation Test, the Newcombe Test, and 16S rRNA sequencing. Four samples of influent and treated effluent wastewater were collected from the WWTP to enumerate resistant bacteria in the community and to investigate whether mutations causing resistance in ARB might be induced or spontaneous. We found that penicillin had the highest rate of resistance in all samples and that a similar trend of resistance appeared across all four samples. According to the Luria–Delbrück Fluctuation Test and the Newcombe Test, different antibiotics appear to be associated with different tendencies of resistance emergence, with certain groups of antibiotics producing different results, which raises evolutionary questions about the roles of random mutation and induction. Most ARB detected from the Luria–Delbrück Fluctuation Test belong to the Klebsiella, Enterobacter, and Aeromonas genera. This study provides a baseline understanding of the urban freshwater ecosystem status in central Texas and quantitatively examines the degree of resistance emergence.
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Potorski, Jacek, Izabela Koniuszewska, Małgorzata Czatzkowska et Monika Harnisz. « Drug resistance in airborne bacteria isolated from waste management and wastewater treatment plants in Olsztyn ». E3S Web of Conferences 100 (2019) : 00066. http://dx.doi.org/10.1051/e3sconf/201910000066.
Texte intégralRésumé :
Wastewater treatment plants (WWTPs) and municipal waste management plants (MWMPs) emit bioaerosols containing potentially pathogenic biological components which post a threat for human health. Microbiological monitoring supports evaluations of the antibiotic resistance (AR) of airborne microorganisms and the relevant health risks. The aim of this study was to analyze the microbiological quality of air sampled in a WWTP and MWMP in Olsztyn based on total bacterial counts, the presence of bacteria resistant to three antibiotic classes (beta-lactams, tetracyclines and chloramphenicol) and genes encoding resistance to these antibiotics (blaTEM, blaSHV, blaCMY-2, blaAmpC, tet(M), tet(A), tet(X), tet(B), cmlA, floR, fexA, fexB and catA1 ). Bacterial counts were higher in air samples collected from the MWMP (~104 CFU/m3) than from the WWTP (101–103 CFU/m3). A similar trend was noted in the counts of antibiotic resistant bacteria (ARB). The abundance of ARB did not exceed 1.7 x 102 CFU/m3 in WWTP samples, but was higher at up to 4.2 x 103 CFU/m3 in MWMP samples. Bacteria resistant to doxycycline were least prevalent in the analyzed ARB. In the group of 49 tested bacterial strains, 44 harbored at least one of the analyzed antibiotic resistance genes (ARGs). A comparison of ARGs in all bacterial strains isolated from WWTP and MWMP air samples revealed the highest diversity and prevalence of ARGs in the samples collected in the mechanical segment of the waste processing line in MWMP and the biological segment of the wastewater processing line in WWTP. The results of this study point to high microbiological contamination of air in MWMPs and WWTPs which are reservoirs of ARB and ARGs and potential sources of AR.
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Scott, Laura C., Nicholas Lee et Tiong Gim Aw. « Antibiotic Resistance in Minimally Human-Impacted Environments ». International Journal of Environmental Research and Public Health 17, no 11 (2 juin 2020) : 3939. http://dx.doi.org/10.3390/ijerph17113939.
Texte intégralRésumé :
Antibiotic resistant bacteria (ARB) have become contaminants of concern in environmental systems. Studies investigating environmental ARB have primarily focused on environments that are greatly impacted by anthropogenic activity. Background concentrations of ARB in natural environments is not well understood. This review summarizes the current literature on the monitoring of ARB and antibiotic resistance genes (ARGs) in environments less impacted by human activity. Both ARB and ARGs have been detected on the Antarctic continent, on isolated glaciers, and in remote alpine environments. The methods for detecting and quantifying ARB and ARGs from the environment are not standardized and warrant optimization. Further research should be focused on the detection and quantification of ARB and ARGs along human gradients to better characterize the factors leading to their dissemination in remote environments.
Thèses sur le sujet "Antibiotic resistance bacteria (ARB)"
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Wind, Lauren Lee. « Persistence of Culturable Antibiotic Resistant Fecal Coliforms From Manure Amended Vegetable Fields ». Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/86262.
Texte intégralRésumé :
The reduced efficacy of antibiotics in treating common infections is one of the most pressing health concerns of the 21st Century. Increasing evidence links the widespread use of antibiotics in livestock production to the transfer of bacteria carrying antibiotic resistance genes to the broader environment. It is therefore critical to understand the persistence and dissemination of resistance in agricultural soils to understand potential threats to consumers. The goal of this large-scale agricultural field experiment was to identify the effects of crop (lettuce, radish) and fertilizer type (inorganic, compost, raw manure) on the incidence and persistence of antibiotic-resistant fecal coliforms, a common family of fecal indicator bacteria used to track the environmental spread of antibiotic resistance. Soil samples were collected eight times over a 120-day period and analyzed for fecal coliforms utlizing a suite of MacConkey agars supplemented with different antibiotics (ceftazidime, clindamycin, erythromycin, sulfamethoxazole, and tetracycline). Given the number of samples with resistant fecal coliform concentrations below the limit of detection, analyses to identify the effects of soil treatment and crop relied on Zero-inflated Poisson Regressions. Antibiotic-resistant culturable fecal coliforms were recoverable from soils across all treatments immediately following application, though persistence throughout the experiment varied by antibiotic. Sulfamethoxazole- and tetracycline-resistant fecal coliforms were nondetectable after Day 1; this was expected, as the cattle supplying the manure amendments were not treated with these antibiotics or similar analogs. Clindamycin- and erythromycin-resistant fecal coliforms were nondetectable after 42 days but rebounded on Day 90 in the soil; both of these drugs were of the same antibiotic class as the ones used to treat the dairy cattle during the manure collection period. Ceftazidime-resistant fecal coliform levels were consistently high throughout the duration of the growing season. No statistical differences were observed between root and aboveground crops. Results suggest that soils amended with raw or composted dairy manure are at risk of contamination with antibiotic resistant fecal coliforms; however, composting decreased the antibiotic resistant fecal coliform levels of the macrolide (erythromycin) and lincosamide (clindamycin) antibiotic classes administered to the dairy cattle (cephapirin and pirlimycin).Master of Science
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Riquelme, Breazeal Maria Virginia. « Improved monitoring of emerging environmental biocontaminants through (nano)biosensors and molecular analyses ». Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/83419.
Texte intégralRésumé :
Outputs of human-derived chemicals and constituents to the environment, and shifts in these outputs, can result in unintended consequences to human and ecological health. One such shift is the advent of the modern antibiotic era, in which mass production and outputs of antibiotics, which are mostly naturally-derived microbial defense compounds and include a few synthetic antimicrobials, has profound implications for contributing to the spread of antibiotic resistance. Antibiotic resistance arises from mutations and/or sharing of antibiotic resistance genes (ARGs) among bacteria via horizontal gene transfer, with carriage of ARGs by pathogenic bacteria of particular concern to human health. While most attention to stopping the spread of antibiotic resistance has been devoted to the clinic, it is critical to consider the environmental origin, ecology and pathways by which antibiotic resistance spreads in order to develop comprehensive strategies to combat antibiotic resistance. In particular, wastewater treatment plants (WWTPs) represent a potentially key critical control point given that they receive antibiotic resistant bacteria (ARB) and ARGs from the population, which are then routed to activated sludge biological treatment, consisting of high density, highly active microbial populations. The research projects described in this dissertation aimed to explore the occurrence of ARGs in WWTPs, particularly WWTPs in developing countries representing the extremes of what is expected to be encountered in terms of potential to spread antibiotic resistance, and to improve and apply novel technologies for monitoring key markers of antibiotic resistance in WWTPs and affected environments. The pathogen Staphylococcus aureus and a corresponding ARG (methicillin resistance mecA gene) were chosen as model biocontaminants of concern due to their environmental and public health relevance. The results reported in Chapters 3-5 advance the knowledge of bio(nano)sensing techniques and highlight areas of promise and challenge. The results reported in Chapter 2 provided insight into the baseline levels of ARGs expected in a highly impacted WWTP in India, thereby highlighting the magnitude and global scale of the problem of antibiotic resistance as well as the need for innovative solutions.Ph. D.
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Williams, Robert Kyle. « Effect of Composting on the Prevalence of Antibiotic Resistant Bacteria and Resistance Genes in Cattle Manure ». Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/74952.
Texte intégralRésumé :
Antibiotic resistance is a growing human health threat, making infections more difficult to treat and increasing fatalities from and cost of treatment of associated diseases. The rise of multidrug resistant pathogens threatens a return to the pre-antibiotic era where even the most common infections may be impossible to treat. It is estimated that the majority of global antibiotic use, and use in the U.S., is dedicated towards livestock, where they are used to promote growth, treat, or prevent disease. Given that exposure to antibiotics selects for antibiotic resistant bacteria (ARBs) and can stimulate the horizontal transfer of their associated antibiotic resistance genes (ARGs), it is important to examine livestock operations as a reservoir of resistance. Correspondingly, there is growing interest in identifying how agricultural practices can limit the potential for spread of antibiotic resistance through the "farm to fork continuum," starting with antibiotic use practices, manure management and land application and ending with the spread of ARBs and ARGs present onto edible crops and serving as a route of exposure to consumers. This study focused specifically on the effect of composting on the prevalence of ARBs and ARGs in cattle manure. Three composting trials were performed: small-scale, heat-controlled, and large-scale. The small-scale composting trial compared dairy and beef manures, with or without antibiotic treatment (treated beef cattle received chlortetracycline, sulfamethazine, and tylosin while treated dairy cattle received cephapirin and pirlimycin), subject to either static or turned composting. The heat-controlled composting trial examined only dairy manure, with or without antibiotic treatment, subject to static composting, but using external heat tape applied to the composting tumblers to extend the duration of the thermophilic (>55°C) temperature range. The large-scale composting trial examined dairy manure, with or without antibiotic treatment, subject to static composting at a much larger scale that is more realistic to typical farm practices. Samples were analyzed to assess phenotypic resistance using the Kirby Bauer disk diffusion method and by diluting and plating onto antibiotic-supplemented agar. Genetic markers of resistance were also assessed using quantitative polymerase chain reaction (qPCR) to quantify sul1 and tet(W) ARGs; metagenomic DNA sequencing and analysis were also performed to assess and compare total ARG abundance and types across all samples. Results indicate that composting can enrich indicators of phenotypic and genetic resistance traits to certain antibiotics, but that most ARGs are successfully attenuated during composting, as evidenced by the metagenomic sequencing. Maintaining thermophilic composting temperatures for adequate time is necessary for the effective elimination of enteric bacteria. This study suggests that indicator bacteria that survive composting tend to be more resistant than those in the original raw manure; however, extending the thermophilic stage of composting, as was done in the heat-controlled trial, can reduce target indicator bacteria below detection limits. Of the two ARGs specifically quantified via qPCR, prior administration of antibiotics to cattle only had a significant impact on tet(W). There was not an obvious difference in the final antibiotic resistance profiles in the finished beef versus dairy manure composts according to metagenomics analysis. Based on these results, composting is promising as a method of attenuating ARGs, but further research is necessary to examine in depth all of the complex interactions that occur during the composting process to maximize performance. If not applied appropriately, e.g., if time and temperature guidelines are not enforced, then there is potential that composting could exacerbate the spread of certain types of antibiotic resistance.Master of Science
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RIVA, FRANCESCO. « ANTIBIOTIC RESISTANCE SPREAD MEDIATED BY HORIZONTAL GENE TRANSFER IN THE AGRI-FOOD ECOSYSTEM ». Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/914666.
Texte intégralRésumé :
Antibiotic resistance (AR) is a public problem for human health and food safety. Globalization has contributed to create an intense connection among human and animal health and the environment, allowing bacteria and their genes to move among all these compartments, making a “one-health approach” necessary to counteract this phenomenon. Horizontal gene transfer (HGT), which contributes to AR determinants diffusion, is mediated by three main mechanisms: i) conjugation, ii) transduction, and ii) natural transformation. Several environments linked to the agri-food system are both sources of AR determinants and hot spots of HGT.
One of the main routes of AR spread in the agri-food system could be represented by the use of treated wastewater as irrigation source: the reuse of water is indeed a common practice in several countries, including Europe, to fight the water crisis exacerbated by global warming. Wastewater treatment plants (WWTPs) could be one of the main sources of free antibiotic resistance genes (ARGs) which could be released in freshwater bodies. AR determinants present in the treated wastewater would thus enter in the food production through irrigation and could be acquired by pathogenic strains, potentially posing a risk to human health. Even if the presence and the related issues about AR determinants in the environment are well known, there are many aspects which have to be understood e.g. the relative contributions of different sources of AR determinants in the environment, also considering HGT events.
Since information about the relationship between environmental HGT and spread of AR determinants is limited, the aim of this PhD thesis was to evaluate the diffusion of ARGs through natural transformation and conjugation in environment or in environmental-like conditions to describe several possible routes of AR spread in the agri-food system.
Zooplankton plays a crucial role in waterbodies, being closely linked to bacteria inhabiting aquatic environments in several ecological function, and it establishes a connection with bacterial communities that are inhabitant of the environment in which it lives. Due to the interaction between bacteria and zooplankton, together with the presence of Escherichia coli in waterbodies, derived from human and animal faecal waste, I first evaluated the relationship established between zooplankton, with the model Daphnia obtusa, and E. coli, isolated from it, suggesting that Daphnia could help the bacterium to adapt to the harsh condition that could be found in the freshwater bodies, highlighting the possible role of zooplankton in the diffusion of antibiotic resistant bacteria (ARB) in the agri-food system.
The interaction observed between Daphnia and E. coli in the first part of this thesis, together with the knowledge of the presence of ARGs in aquatic environment and the moderate ability to E. coli to acquire DNA through natural transformation, have thus led to the study of natural transformation in zooplankton-associated bacteria, also in terms to unveil the animal influence. Indeed, I studied the natural transformation of the environmental E. coli strain ED1, isolated from D. obtusa, mimicking environmental conditions which could be found in the agri-food system. ED1 ability to acquire exogenous DNA, with a higher frequency than the one of a laboratory strain, together with its ability to thrive in lettuce rhizosphere, underlined the importance to investigate the spread of AR determinants in the agri-food system, especially in the rhizosphere of plants which are usually raw-consumed. Moreover, the possible influence of the zooplankton on natural transformation was investigated through the use of D. obtusa and Acinetobacter baylyi BD413, known to be naturally competent to acquire DNA. A decrease of transformation frequency was observed in presence of Daphnia, due to the degradation of exogenous DNA, highlighting the need of further investigations on zooplankton involvement in ARGs diffusion in aquatic environments.
Considering possible routes of diffusion of AR determinants in the agri-food system, i.e. from WWTPs to freshwater bodies and their inhabitant community, to crops and plants, I then devoted my attention on HGT by conjugation in rhizosphere of lettuce, used as model of raw-eaten vegetables. The aim of this work was the construction of a donor strain belonging to the Enterobacteriaceae family and isolated from treated wastewater. Specifically, Klebsiella variicola subsp. variicola was genetically manipulated through the chromosomal tagging with a mCherry gene and a constitutively expressed LacIq gene, and the insertion of the broad host range plasmid pKJK5::gfp::KanR, carrying a green fluorescent protein gene (Gfp) under the control of laclq repressible promoter, and thus resulting in the absence of gfp expression in the donor. The gfp was expressed only in recipient strains, following the mobilization of the plasmid through conjugation. The strain ability to donate the plasmid within the bacterial community of lettuce rhizosphere and its ability to colonize the plant root system were verified, making K. variicola subsp. variicola EEF15::lacIq-pLppmCherry-GmR with plasmid pKJK5::gfp a perfect candidate for the study of conjugation in plants microniches.
Finally, I contributed to prepare a critical review on microbial assisted phytodepuration and the use of plant growth promoting bacteria in Constructed Wetland (CW) systems, with a focus on HGT events and the possible spread of AR determinants in the rhizosphere of plants used in phytodepuration.
Data collected in this PhD project underline the importance to study the diffusion of AR determinants trough HGT events in the agri-food system, in order to create a rank risk and a risk assessment map to mitigate the diffusion of AR.
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Hiliare, Sheldon. « Impact of Manure Land Management Practices on Manure Borne Antibiotic Resistant Elements (AREs) in Agroecosystems ». Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/102218.
Texte intégralRésumé :
Rising global antibiotic resistance has caused concerns over sources and pathways for the spread of contributing factors. Majority of the antimicrobials used in the U.S. are involved in veterinary medicine, primarily with livestock rearing. Animal manure land application integrates livestock farming and agroecosystems. This manure contains antibiotic resistant elements (AREs) (resistant bacteria, resistance genes, and veterinary antibiotics) that contribute towards antimicrobial resistance. Altering manure application techniques can reduce surface runoff of other contaminants such as excess N and P, pesticides, and hormones, that can impact water quality. Conventional tillage practices in the U.S. has reduced or stopped, making subsurface injection of manure a promising option when compared to surface application. Our research compared manure application methods, manure application seasons, cropping system, and manure-rainfall time gaps to gauge the impact on AREs in the environment. Two field-scale rainfall simulation studies were conducted along with one laboratory study. Using the injection method lowered concentrations of manure associated AREs entering surface runoff. When manure was surface applied and rainfall occurred 7 d after application, 9-30 times less resistant fecal coliform bacteria (FCB) entered surface runoff when compared to 1 d time gap for that broadcast method. Within a day of manure application, antibiotic resistance gene (ARG) profiles in soil began to differ from each other based on manure application and soil ARG richness in all manure-amended soil increased compared to the background. Runoff from injection plots contained 52 ARGs with higher abundance compared to runoff from surface applied plots. ARGs in the former were more correlated to soil and more correlated to manure in the latter. The highest antibiotic concentrations were in the injection slit soil of those plots. Antibiotic concentrations in samples corresponded positively to concentrations of resistant FCB and ARGs, and there was a positive correlation between resistant FCB and their associated ARGs (Spearman's ρ = 0.43-0.63). A CRIISPR-Cas12a assay for quantification of ARGs in environmental samples was just as precise as conventional methods. There is also potential for in-situ detection. These combined results can hopefully help farmers improve manure management practices that mitigate spread of AREs to surrounding water, crops, and soil.Doctor of Philosophy
Rising global antibiotic resistance cause concerns over sources and pathways for the spread of contributing factors. Most of the antimicrobials used in the U.S. are involved in veterinary medicine, especially with livestock rearing. Overuse of antibiotics that are medically important to human medicine compromises the effectiveness of our medicines. Animal manure contains antibiotic resistant elements (AREs) such as resistant bacteria, resistance genes, and antibiotics) that contribute towards resistance issues. Once these AREs enter the environment, they can be taken up by crops, runoff into surface water or leached into ground water, or even reside within the animal products we consume. Altering manure application techniques is beneficial for nutrient conservation but also potentially for reducing ARE spread. With our research, we compared manure application methods, manure application seasons, cropping systems, and manure-rainfall time gaps to find ways to balance the need for manure application and the spread of resistance. We used two field-scale rainfall simulation studies along with one laboratory study. Overall, using the injection method resulted in significantly lower concentrations of manure associated AREs entering surface runoff. When manure was surface applied and rainfall occurred 7 d after application, less resistant fecal coliform bacteria (FCB) entered surface runoff when compared to the 1 d time gap for broadcast methods. Within a day of manure application, antibiotic resistance gene (ARG) profiles in soil began to differ from each other and soil ARG totals in all manure applied soil increased compared to the background. Runoff from injection plots contained more soil ARGs and runoff from surface applied plots containing more manure associated ARGs. The subsurface injection method also caused highest antibiotic concentrations in the injection slit soil of those plots. High antibiotic concentrations in samples generally meant high concentrations of resistant FCB and ARGs, and resistant FCB were also found with their associated ARGs as well. A CRISPR-Cas12a assay for quantification of ARGs in environmental samples was just as precise as conventional methods. There is also potential for onsite detection. These combined results can hopefully help farmers improve manure management practices that mitigate spread of AREs to surrounding water, crops, and soil.
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Zhang, Lu. « Establishment and Development of Antibiotic Resistant Bacteria in Host Gastrointestinal Tract—Food, Drug, or Are We Born with It ? » The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316186957.
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Nagulapally, Sujatha Reddy. « Antibiotic resistance patterns in municipal wastewater bacteria ». Thesis, Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/331.
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Roe, Darcie Elizabeth. « Prevalence and mechanisms of antibiotic resistance in oral bacteria ». Thesis, Connect to this title online ; UW restricted, 1996. http://hdl.handle.net/1773/9310.
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Melnyk, Anita. « The Evolution of Antibiotic Resistance in Experimental Populations of Bacteria ». Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34556.
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Antibiotic resistance is a major threat to public health. Understanding how it evolves,
and the genes that underlie resistance, is the main goal of my Ph.D. research. After a resistance mutation arises, it’s fate within a pathogen population will be etermined in part by its fitness: mutations that suffer little or no fitness cost are more likely to persist in the absence of antibiotic treatment. My research centers on understanding this process better by gaining knowledge about the spectrum of fitness effects associated with antibiotic resistance mutations.
Using a meta-analysis framework I find that, across a range of antibiotics and pathogens, on average single resistance mutations exhibit fitness costs in the absence of drug, however, there are instances of cost-free mutations. To evaluate the conditions leading to the persistence of resistance in the absence of antibiotic, I use experimental evolution of the opportunistic pathogen Pseudomonas aeruginosa and the antibiotic ciprofloxacin to investigate the phenotypic and genetic differences associated with constant and fluctuating drug treatment. I find that fluctuating drug treatment leads to the evolution of cost-free resistance. At the genetic level, cost-free resistance is the result of second-site mutations that compensate for the fitness cost associated with ciprofloxacin-resistance mutations. Further examination of the resistance mutations shows a lack of epistatic interactions between co-occurring mutations that confer resistance within a single isolate. To investigate the repeatability of the genetic causes of resistance, I execute a second evolution experiment using multiple clinical strains of P. aeruginosa adapting to a constant ciprofloxacin selective pressure. I find a remarkable lack of parallel evolution at the genomic level both within and between different P. aeruginosa strains.
I have shown that antibiotic resistance is costly, and that these costs can be ameliorated by second-site mutations that readily arise over short time scales. Additionally, different strains of the same bacteria can gain resistance through a diverse set of genetic mutations. On an applied level these results are not positive; combating resistance evolution will be difficult because pathogens can easily compensate fitness costs of resistance, and resistance itself can be gained via a large number of genetic targets.
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Suarez, Rachel. « Chemical disinfectant resistance in multiple antibiotic resistant and susceptible bacteria ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ57585.pdf.
Texte intégralLivres sur le sujet "Antibiotic resistance bacteria (ARB)"
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P, Gilbert, Maillard J. -Y et Godfree A. F, dir. Antibiotic and biocide resistance in bacteria. Oxford : Blackwell Science, 2002.
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Amábile-Cuevas, Carlos F. Origin, evolution and spread of antibiotic resistance genes. Austin : R.G. Landes Co., 1993.
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Gravelle, Louise N. The antibiotic resistance of bacteria isolated from dental unit waterlines. Sudbury, Ont : Laurentian University, School of Graduate Studies, 2005.
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United States. Congress. Office of Technology Assessment., dir. Impacts of antibiotic-resistant bacteria : Thanks to penicillin-- He will come home ! Washington, DC : Office of Technology Assessment, Congress of the U.S., 1995.
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F, Amábile-Cuevas Carlos, dir. Antibiotic resistance : From molecular basics to therapeutic options. New York : Chapman & Hall, 1996.
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Levy, Stuart B. The antibiotic paradox : How miracle drugs are destroying themiracle. London : Plenum Press, 1992.
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The antibiotic paradox : How miracle drugs are destroying the miracle. New York : Plenum Press, 1992.
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The antibiotic paradox : How the misuse of antibiotics destroys their curative power. 2e éd. Cambridge, MA : Perseus Pub., 2002.
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R, Fogarty Lisa, Oakland County (Mich.). Health Division. et Geological Survey (U.S.), dir. Antibiotic-resistant fecal bacteria, antibiotics, and mercury in surface waters of Oakland County, Michigan, 2005-2006. Reston, Va : U.S. Dept. of the Interior, U.S. Geological Survey, 2007.
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R, Fogarty Lisa, Oakland County (Mich.). Health Division. et Geological Survey (U.S.), dir. Antibiotic-resistant fecal bacteria, antibiotics, and mercury in surface waters of Oakland County, Michigan, 2005-2006. Reston, Va : U.S. Dept. of the Interior, U.S. Geological Survey, 2007.
Trouver le texte intégralChapitres de livres sur le sujet "Antibiotic resistance bacteria (ARB)"
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Marathe, Nachiket P., et Michael S. Bank. « The Microplastic-Antibiotic Resistance Connection ». Dans Microplastic in the Environment : Pattern and Process, 311–22. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78627-4_9.
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AbstractMicroplastic pollution is a big and rapidly growing environmental problem. Although the direct effects of microplastic pollution are increasingly studied, the indirect effects are hardly investigated, especially in the context of spreading of disease and antibiotic resistance genes, posing an apparent hazard for human health. Microplastic particles provide a hydrophobic surface that provides substrate for attachment of microorganisms and readily supports formation of microbial biofilms. Pathogenic bacteria such as fish pathogens Aeromonas spp., Vibrio spp., and opportunistic human pathogens like Escherichia coli are present in these biofilms. Moreover, some of these pathogens are shown to be multidrug resistant. The presence of microplastics is known to enhance horizontal gene transfer in bacteria and thus, may contribute to dissemination of antibiotic resistance. Microplastics can also adsorb toxic chemicals like antibiotics and heavy metals, which are known to select for antibiotic resistance. Microplastics may, thus, serve as vectors for transport of pathogens and antibiotic resistance genes in the aquatic environment. In this book chapter, we provide background information on microplastic biofouling (“plastisphere concept”), discuss the relationship between microplastic and antibiotic resistance, and identify knowledge gaps and directions for future research.
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Ondon, Brim Stevy, Shengnan Li, Qixing Zhou et Fengxiang Li. « Sources of Antibiotic Resistant Bacteria (ARB) and Antibiotic Resistance Genes (ARGs) in the Soil : A Review of the Spreading Mechanism and Human Health Risks ». Dans Reviews of Environmental Contamination and Toxicology, 121–53. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/398_2020_60.
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Littmann, Jasper, A. M. Viens et Diego S. Silva. « The Super-Wicked Problem of Antimicrobial Resistance ». Dans Ethics and Drug Resistance : Collective Responsibility for Global Public Health, 421–43. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-27874-8_26.
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Abstract Antimicrobial resistance (AMR) – the progressive process by which microbes, such as bacteria, through evolutionary, environmental and social factors develop the ability to become resistant to drugs that were once effective at treating them – is a threat from which no one can escape. It is one of the largest threats to clinical and global health in the twenty-first century – inflicting monumental health, economic and social consequences. All persons locally and globally, and even all future persons yet to come into existence, all suffer the shared, interdependent vulnerability to this threat that will have a substantial impact on all aspects of our lives. For example, while reliable data are hard to find, the European Centre for Disease Prevention and Control (ECDC) has conservatively estimated that, in Europe alone, AMR causes additional annual cost to health care systems of at least €1.5 billion, and is responsible for around 25,000 deaths per year. Furthermore, AMR significantly increases the cost of treating bacterial infections with an increase in length of hospital stays and average number of re-consultations, as well as the resultant lost productivity from increased morbidity. With a combined cost of up to $100 trillion to the global economy – pushing a further 28 million people into extreme poverty – this is one of the most pressing challenges facing the world. Most troublingly, if we do not succeed in diminishing the progression of AMR, there is the very real potential for it to threaten common procedures and treatments of modern medicine, including the safety and efficacy of surgical procedures and immunosuppressing chemotherapy. Some experts are warning that we may soon be ushering in a post-antibiotic area.
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Liu, H. H. « Antibiotic Resistance in Bacteria ». Dans Rheumaderm, 387–96. Boston, MA : Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-4857-7_59.
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Brook, Itzhak. « Antibiotic Resistance of Anaerobic Bacteria ». Dans Antimicrobial Drug Resistance, 873–99. Totowa, NJ : Humana Press, 2009. http://dx.doi.org/10.1007/978-1-60327-595-8_15.
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Fatima, Syeda Sograh, et Eman Al Mussaed. « Antibiotic Resistance in UTI Bacteria ». Dans SpringerBriefs in Applied Sciences and Technology, 47–60. Singapore : Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-4750-3_3.
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Nishiyama, Masateru, Mith Hasika, Jian Pu, In Sokneang et Toru Watanabe. « Antibiotic Resistance of Intestinal Bacteria ». Dans Water and Life in Tonle Sap Lake, 307–16. Singapore : Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-6632-2_30.
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Srivastava, Anmol, Vivek Kumar et Vishnu Agarwal. « Antimicrobial Activity of Some Essential Oils Against Pseudomonas aeruginosa ». Dans Proceedings of the Conference BioSangam 2022 : Emerging Trends in Biotechnology (BIOSANGAM 2022), 27–34. Dordrecht : Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_4.
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AbstractThe emergence of multidrug resistance in bacteria due to overuse of antibiotics is becoming an important health concern in recent years, which requires development of novel alternatives to fight against these bacteria. Essential oils (EOs) are secondary metabolites that have different components and chemical compositions which may provide promising solution to the problem of rising number of drug resistant bacteria, as they can effectively kill bacteria. Here, in this study our aim is to determine the efficacy of lemongrass, rosemary, clary sage, geranium and tea tree essential oil against Pseudomonas aeruginosa, using agar well diffusion method. The minimum inhibitory concentration (MIC) of these EOs were also determined. The chemical composition of these essential oils were known by gas chromatography-mass spectrometry (GC-MS) analysis. It was revealed in this study that most of the essential oils show antimicrobial property against the test bacterium. The MIC of lemongrass is 0.25% (v/v), rosemary is 1% (v/v), clary sage is 2% (v/v), geranium is 0.5% (v/v) and for tea tree oil is 1% (v/v). We can infer from this data that lemongrass, rosemary, clary sage, geranium and tree oil can be utilized to treat infections caused by Pseudomonas aeruginosa, which is a gram-negative bacterium.
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Golz, Julia Carolin, et Kerstin Stingl. « Natural Competence and Horizontal Gene Transfer in Campylobacter ». Dans Current Topics in Microbiology and Immunology, 265–92. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65481-8_10.
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AbstractThermophilic Campylobacter, in particular Campylobacter jejuni, C. coli and C. lari are the main relevant Campylobacter species for human infections. Due to their high capacity of genetic exchange by horizontal gene transfer (HGT), rapid adaptation to changing environmental and host conditions contribute to successful spreading and persistence of these foodborne pathogens. However, extensive HGT can exert dangerous side effects for the bacterium, such as the incorporation of gene fragments leading to disturbed gene functions. Here we discuss mechanisms of HGT, notably natural transformation, conjugation and bacteriophage transduction and limiting regulatory strategies of gene transfer. In particular, we summarize the current knowledge on how the DNA macromolecule is exchanged between single cells. Mechanisms to stimulate and to limit HGT obviously coevolved and maintained an optimal balance. Chromosomal rearrangements and incorporation of harmful mutations are risk factors for survival and can result in drastic loss of fitness. In Campylobacter, the restricted recognition and preferential uptake of free DNA from relatives are mediated by a short methylated DNA pattern and not by a classical DNA uptake sequence as found in other bacteria. A class two CRISPR-Cas system is present but also other DNases and restriction–modification systems appear to be important for Campylobacter genome integrity. Several lytic and integrated bacteriophages have been identified, which contribute to genome diversity. Furthermore, we focus on the impact of gene transfer on the spread of antibiotic resistance genes (resistome) and persistence factors. We discuss remaining open questions in the HGT field, supposed to be answered in the future by current technologies like whole-genome sequencing and single-cell approaches.
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Sagar, Sadhana, Shilpa Kaistha, Amar Jyoti Das et Rajesh Kumar. « Intrinsic Antibiotic Resistance Mechanism in Bacteria ». Dans Antibiotic Resistant Bacteria : A Challenge to Modern Medicine, 69–85. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-9879-7_6.
Texte intégralActes de conférences sur le sujet "Antibiotic resistance bacteria (ARB)"
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Lutphy Ali, Noor, Mustafa D. Younus, Omar F. Bahjat, Lina Sordash Hassan, Mohamad Hawar Rahman, Kawa Kamal Kareem, Darya Emad et Hataw Ali. « Identification of Pharyngitis Bacteria in Patients with Sore Throat Features in Rizgary Teaching Hospital and Overuse of Antibiotics ». Dans 4th International Conference on Biological & Health Sciences (CIC-BIOHS’2022). Cihan University, 2022. http://dx.doi.org/10.24086/biohs2022/paper.745.
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This research is designed to study sore throat (pharyngitis) and its causes, which is considered to be one of the serious health problems that affect many individuals annually. The research included an infected study status of 81 cases suspected of pharyngitis attending Rzgary Hospital department of ENT, in Erbil city. Infection was diagnosed by culturing the throat swab and collecting data about individual gender, age, occupation and residency. Also, this study deals with acute and chronic pain of sore throat (pharyngitis) and describes their causes. As well as the diagnosis was also achieved. Streptococcus pneumonia, Streptococcus pyogenes, Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus sp., were isolated from the pharyngitis patients. The antibiotic susceptibility test was carried on the isolated bacteria using different types of antibiotics such as Ampicillin, Penicillin, Streptomycin, Ceftriaxone and Cefotaxime. The results indicated that most of the bacteria were resistant to the antibiotics. The highest sensitivity of pathogenic bacterial species was found towards streptomycin, while Ampicillin and Penicillin had the highest resistance; hence antimicrobial treatment should be recommended only after culturing and sensitivity testing. This would aid in the appropriate treatment, discourage the indiscriminate use of antibiotics, and avoid further development of drug resistance. It has been found that males are more vulnerable to getting pharyngitis than females. Age has a significant influence on increasing or decreasing the number of infected people. Also, the individuals living in Erbil city are more prone to be infected than those in the villages.
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Johar, Alreem, Najlaa Al-Thani, Sara Al-Hadidi, Elyes Dlissi, Mahmoud Mahoud et Nahla Eltai. « Antibiotic Resistance and Virulence Gene Patterns Associated with Avian Pathogenic Escherichia coli from Broiler Chickens in Qatar ». Dans Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2021. http://dx.doi.org/10.29117/quarfe.2021.0102.
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Introduction: Avian Pathogenic Escherichia coli (APEC) is the contributing agent behind the avian infectious disease colibacillosis, which causes substantial fatalities in poultry industries that significantly impact the economy and food safety. Several virulence genes have been shown to be concomitant with the extra-intestinal survival of APEC. This study investigates the antibiotic resistance patterns and APEC‐associated virulence genes content in Escherichia coli (E. coli) isolated from non‐healthy and healthy broiler chickens from a commercial poultry farm in Qatar. Material and Methods: 158 E. coli strains were isolated from 47 chickens from five different organs (air sac, cloacal, kidney, liver, and trachea). Genomic DNA was extracted from E. coli using the QIAamp Pathogen Mini Kit. Multiplex PCR was executed to detect tsh, iucD, ompT, hlyF, iroN, iss, vat, cvi/cva genes associated with PPEC. Antibiotic susceptibility testing was performed using the standard Kirby-Bauer disk and E-test. Amplified virulence genes detected were sequenced and analyzed. Graph Pad version 8 and PAST software version 4.03 were used for statistical and clustering analysis. The chi-square test was performed on all data to compare the antibiotic resistance and virulence gene patterns between non-healthy and healthy chicken samples Results: 65% of the isolated bacteria were APEC strains containing five or more virulence genes, and 34% were non‐pathogenic E. coli (NPEC) strains. The genes ompT, hlyF, iroN, tsh, vat, iss, cvi/cva, and iucD were significantly prevalent in all APEC strains. E. coli isolates showed 96% resistance to at least one of the 18 antibiotics, with high resistance to ampicillin, cephalothin, ciprofloxacin, tetracycline, and fosfomycin. Conclusions: Our findings indicate high antibiotic resistance prevalence in non-healthy and healthy chicken carcasses. Such resistant E. coli can spread to humans. Hence, special programs are required to monitor the use of antibiotics in chicken production in Qatar.
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Mekki, Yosra M., Mohamed M. Mekki, Mohamed Hamammi et Susu Zughaier. « Virtual Reality Module Depicting Catheter-Associated Urinary Tract Infection as Educational Tool to Reduce Antibiotic Resistant Hospital-Acquired Bacterial Infections ». Dans Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0250.
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Introduction: Virtual reality (VR) and augmented reality (AR) are used as simulation models in student-patient interactive medical education and shown to enhance learning outcomes. The rise in global burden of infectious diseases and antibiotic resistance world-wide prompt immediate action to combat this emerging threat. Catheter associated urinary infections (CAUTI) are the leading cause of hospital-acquired infections. The aim of this research is to develop a virtual reality (VR) based educational tool depicting the process of CAUTI caused by antibiotic resistant bacteria. The VR-CAUTI module is designed to provide insights to health care providers and community which help in reducing the burden of antibiotic resistant infections. Material and methods: The VRCAUTI module is designed using tools including Blender, Cinema4D and Unity to create a scientifically accurate first-person interactive movie. The users are launched inside a human bladder that needs to be drained. They can witness the insertion of a medical catheter into the bladder to drain the urine. Bacteria adhere to the catheter to establish colonization and infection. An interaction between antibiotic molecules and bacteria in the biofilm is observed later. After designing the 3D models, a highlight of the interaction between models, taken from the storyboard, is used to determine the necessary animation. Moreover, dialogue that facilitates the understanding of infections and antibiotic resistance is recorded. This is followed by the assembly of the module on Unity, and enrichments such as lights and orientation. Results and conclusion: This VRCAUTI module is the proof-of-concept for designing detailed VR based scientifically very accurate medical simulation that could be used in medical education to maximize learning outcomes. VR based modules that have the potential to transform and revolutionize learning experience and render medical education compatible with the IoT in the current 4th industrial revolution.
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Ilea, Mihai, Andrei Gheorghita et Marius Turnea. « DYNAMICS OF SALMONELLA TRANSMISSION USING COMPARTMENTAL MODELS ». Dans eLSE 2019. Carol I National Defence University Publishing House, 2019. http://dx.doi.org/10.12753/2066-026x-19-179.
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Salmonella is a zoonotic disease that is transmitted from animal products by contact with sick animals or the environments where these animals are living. The mathematical model of transmission disease improve the students' understanding of pathogen dynamics, the role of factors that influence the transmission and control of a specific pathogen and the trend of antimicrobial resistance for this pathogen. The tendency to increase of resistance of Salmonella to antibiotic and combination of antibiotics suggest that models are useful in simulation of different scenarios for dynamic of transmission of this disease. There are two main Salmonella types: Typhimurium serotype and Enteritidis serotype. Both types are included in the software toolbox in a tutorial and interactive manners. The three models of Salmonella compartmental are presented in friendly manner to user with possibility to automatically generation of system equations using built-in templates. Tools that calculate the R0 number and stability analysis are provided as modules in order to evaluate how the experimental data are fit to model or to evaluate the influence of constant coefficients over mathematical model. Because Salmonella typhi bacteria is responsible for a communicable disease, Typhoid fever, an optional module is append to main software in order to give to student the possibility to improve the knowledge with mathematical model of this disease as direct result of a particular bacteria from a larger group of bacteria. The educational software has a friendly GUI (Graphic User Interface) that help student to understand better the dynamic of a specific pathogen modeled by class of larger mathematical models, the compartmental models.
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Eglite, Sabine, Aija Ilgaza et Maksims Zolovs. « The probiotic mixture X feeding effect on the growth and development of broiler chicken digestive tract ». Dans Research for Rural Development 2022 : annual 28th international scientific conference proceedings. Latvia University of Life Sciences and Technologies, 2022. http://dx.doi.org/10.22616/rrd.28.2022.019.
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The issue of antibiotic resistance has become more pressing in the last decades. Therefore, substitutes for antibiotics are being sought. The aim of our study was to evaluate the effect of the mixture x of lactic acid bacteria on development of the broiler chicken digestive tract and the growth. The study was organised in three trials. In each trial, 260 one day old Ross 308 broiler chicks (males and females) were obtained from a commercial hatchery. They were randomly divided in two groups – the control group and the probiotic group. The dietary treatment was basal diet for the control group and basal diet + the mixture X of lactic acid bacteria 4 g 10 kg-1 for the probiotic group. Broilers were raised till day 35. All broilers were weighted on the day 1, 7, 14, 21, 28, 35 and 10 birds per treatment were randomly selected and killed by cervical dislocation. The gastrointestinal tract was excised (proventriculus, gizzard, intestines) and weighed with content. Overall, this study achieved significant results of the body weight results in the probiotic and the control groups, 2,835.7g ±161.74 and 2,828.02±115.64, respectively. The body weight of chickens and their gastrointestinal tract parts (proventriculus, gizzard, intestines) did not differ between the probiotic and control groups (p > 0.05).
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Khudadad, Hanan, et Lukman Thalib. « Antibiotics Prescription Patterns in Primary Health Care in Qatar – A Population based study from 2017 to 2018 ». Dans Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0169.
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Background: Antibiotics are antimicrobial drugs used in the treatment and prevention of bacterial infections. They played a pivotal role in achieving major advances in medicine and surgery (1). Yet, due to increased and inappropriate use of antibiotics, antibiotic resistance (AR) has become a growing public health problem. Information on antibiotic prescription patterns are vital in developing a constructive approach to deal with growing antibiotic resistance (2). The study aims to describe the population based antibiotic prescriptions among patients attending primary care centers in Qatar. Methodology: A population based observational study of all medications prescribed in the all Primary Health Care Centers during the period of 2017-2018 in Qatar. Records with all medication prescriptions were extracted and linked to medical diagnosis. Antibiotics prescriptions records were compared to non- antibiotics records using logistic regression model in identifying the potential predictors for antibiotic prescriptions. Results: A total of 11,069,439 medication prescriptions given over a period of two-years, we found about 12.1% (n= 726,667) antibiotics prescriptions were antibiotics, and 65% of antibiotics are prescribed and received by the patients at the first visits. Paracetamol (22.3%) was the first highest medication prescribed followed by antibiotics (12.1 %) and vitamin D2 (10.2 %). More than half of all antibiotics prescribed during the period of January 2017 to December 2018 were Penicillin (56.9%). We found that half of the antibiotics (49.3 %) have been prescribed for the respiratory system comparing to the other body system. We found that males were 29% more likely be given an antibiotic compared to females (OR=1.29, 95% CI= 1.24- 1.33). Implications: The study provides a baseline data to enable PHCC management to design effective intervention program to address the problem of antibiotics resistance. Furthermore, it will help the policymakers to comprehend the size of the issue and develop a system to manage the antibiotics therapy. Conclusion: Antibiotics was the second highest medication prescribed in the Primary Health Care Centers in Qatar after paracetamol and most of the patients received it at the first visit. Most of the prescriptions in Primary Health Care Centers in Qatar were for the respiratory system, and Penicillin was the highest class prescribed. Male visitors were prescribed antibiotics more than female visitors.
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Soares, Jennifer M., Vanderlei S. Bagnato et Kate C. Blanco. « Synergistic enhancement effects of antibiotic combination with photodynamic inactivation ». Dans Latin America Optics and Photonics Conference. Washington, D.C. : Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.w4a.29.
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Antimicrobial resistance is one of the most severe threats to global public health in this century. Photodynamic Inactivation (PDI) is an alternative to antibiotic therapy, a standard treatment for infections because the combination of a photosensitizer with light leads to the production of reactive oxygen species that promote eliminating undesirable cells without bacterial selection and with few side effects for the patient. This work investigates whether PDI can restore bacterial sensitivity to antibiotics. PDI protocols using curcumin and light at 450 nm are applied at regular intervals and new values of minimum inhibitory concentration of antibiotics are obtained. As a result, we observed that PDI treatments can decrease MIC. Thus, the combination of both antimicrobial therapies may result in synergistic effects.
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Liu, Miao, et Wenjun Wang. « Analysis of antibiotic purchasing service design based on SAPAD-AHP method ». Dans 13th International Conference on Applied Human Factors and Ergonomics (AHFE 2022). AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1002124.
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In the medical field, more than half of people will choose antibiotics for self-medication, they believe that antibiotics can be used for illnesses such as colds and fevers, or even for viral infections, which accelerates bacterial immunity to antibiotics. Misuse of antibiotics is not only unhelpful, but can damage the organism in a variety of ways that can lead to drug resistance, drug toxicity and allergic reactions. Worldwide, hundreds of thousands of people die each year due to bacterial resistance. In China, the use of antibiotics is even higher in outpatient and inpatient settings. The misuse of antibiotics poses a serious threat to the effectiveness of their use. In order to raise awareness of the dangers of antibiotic misuse, reduce people's choice of non-essential antibiotic medication, and expand and improve monitoring of health care institutions, this study introduces the SAPAD model and AHP to tap into users' real needs and complete a study of users' service design system for antibiotic drug purchase.The article uses observation method, user interview method and questionnaire method in the early stage to get the process of users' medicine purchase in common flu. Based on the SAPAD model framework, the user behavior is disassembled, and the people and things involved in the drug purchase process are listed to complete the mapping of behavior-object-meaning. The study obtained meaning clusters by clustering analysis of meaning layers, and combined with AHP to calculate the weight of each meaning cluster to derive core meaning clusters. The SAPAD model is a user-centered model framework for solving practical problems, which can start from the user's behavior, analyze, cluster and reorganize the meaning behind the behavior layer by layer, and finally dig into the user's real needs; the AHP method combines qualitative and quantitative analysis, and is highly logical and scientific, which can be applied to this topic The effective combination of SAPAD model and hierarchical analysis can gradually quantify the qualitative analysis and obtain more objective research results, which provides new ideas for the theoretical research framework of service design.This study completes the construction of meaning-based objects through the mapping of core meaning clusters to objects. The research process analyzes the key behaviors of users in purchasing drugs in common influenza, and obtains four semantic level meaning clusters through cluster analysis, namely "want to buy drugs quickly and correctly", "want to fully understand the effects of drugs", "want doctors to provide advice on appropriate medication" and "want to raise awareness of antibiotic medications". The study used AHP to analyze the meaning clusters and calculated the weights of each level to obtain the core meaning clusters of "buy the right medicine quickly", "get the right medication diagnosis", and "understand the effect of the medicine".The study reconstructed the service design system for users to purchase drugs in the process of common influenza through user requirements, summarized the key design elements, and improved the service function modules of online drug purchase and online consultation and advice.This study combines SAPAD model and AHP to design research on the user's antibiotic purchase process. Through the SAPAD model, we deeply study the user behavior, get the mapping of user behavior and meaning, and combine the quantitative research of AHP to get the core meaning cluster "quickly buy the right medicine", "get the right diagnosis of medication" and "understand the effect of medication", which guide the design of the service system of user's medication purchase process and the design of the APP for online medication purchase consultation. The SAPAD-AHP method in this study improved the function of the service system for antibiotic purchase process, and the designed output APP effectively improved the user's knowledge on the cautious use of antibiotics, strengthened the supervision of doctors' prescribing of antibiotics, and provided an effective solution to improve the problem of excessive use of antibacterial drugs in primary care institutions and rural areas.
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« Cytokine Profile as a Prognostic Parameter ». Dans 4th International Conference on Biological & Health Sciences (CIC-BIOHS’2022). Cihan University, 2022. http://dx.doi.org/10.24086/biohs2022/paper.633.
Texte intégralRésumé :
Burn injuries of the skin are one of the most common household injuries which vary depending on the way of induction and its severity. Common complications are sepsis of the wound and immunosuppression. A total of 44 burned patients were included in the study. Blood samples and a swab were taken from the location of burn from each patient. All cytokines (IL-5, IL-6, IL-10, G-CSF, TNF and IFN) were evaluated using the ELISA technique. Swabs were cultured and the bacterial growths were tested for sensitivity to 20 different antibiotic discs. Hematological tests were performed and compared to the healthy group control using the automated five parameter counter. The mean serum levels of the cytokines in both female and male patients were significantly higher when compared to the healthy control group. Hematological parameter level results showed an increase in WBC count in both female and male samples, eosinophil and lymphocyte levels decreased in both genders. Neutrophils have significantly increased in both female and male samples. Monocytes, basophils, and RBC count showed no significant difference in both female and male patient samples. The mean concentrations of Hb and platelets have significantly increased in males but no significant difference in female samples. In the bacteriological cultures, only 21 samples showed a bacterial growth. 14 were females and 7 were males. 7 Gram negative bacteria and 13 Gram positive bacteria were detected. 6 total bacterial species were identified (Enterococcus, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Enterobacter, and Pseudomonas). Antibiotic sensitivity results showed that the number of sensitive bacteria was significantly higher than the resistant bacteria. 14 of the patients had 3rd degree burns. 5 had 2nd degree burns, and 1 had 1st degree burn.Further immunological studies are required to interpret the high mortality rates in burned patients.
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Terzić, Jelena, Marina Stanković et Olgica Stefanović. « ANTIBIOFILM ACTIVITY OF SELECTED PLANT SPECIES ». Dans 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.280t.
Texte intégralRésumé :
Bacterial biofilm is a complex community of bacterial cells enclosed in a polymer matrix and attached to a biotic or abiotic substrate. In this living form the bacteria are more resistant to antimicrobial agents than in the form of planktonic cells. Biofilm is a common cause of chronic infections in humans, so due to the growing resistance to antibiotics, alternative methods for controlling infections using medicinal plants have been proposed. In this study, the antibiofilm activity of ethanol and acetone extracts of plants Lamium album, Achillea millefolium and Agrimonia eupatoria against eight clinical isolates of human pathogenic bacteria was examined. Inhibition of biofilm formation was demonstrated using the crystal violet test and the effect on metabolic activity was confirmed by the use of resazurin dye test. Ethanol extract of L. album showed the greatest activity against P. aeruginosa (PA9) at a concentration of 20 mg/ml (> 80% of inhibition), while acetone extract acted at a concentration of 5 mg/ml (≥ 18%) against Klebsiella sp. (K9). At a concentration of 10 mg/ml, the ethanol extract of A. millefolium was effective against E. coli (E16) and P. aeruginosa (PA8) (> 70%), while the acetone extract was effective at 2.5 mg/ml (> 80%) against E. coli (E16). Ethanol and acetone extracts of A. eupatoria were effective at a concentration of 10 mg/ml (> 50%) against E. coli (E16). The antibiofilm activity of the tested plant extracts on certain clinical isolates indicates their great potential in the treatment of infections caused by biofilm-producing bacteria.
Rapports d'organisations sur le sujet "Antibiotic resistance bacteria (ARB)"
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Cytryn, Eddie, Mark R. Liles et Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, janvier 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
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Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.
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Hutchinson, M. L., J. E. L. Corry et R. H. Madden. A review of the impact of food processing on antimicrobial-resistant bacteria in secondary processed meats and meat products. Food Standards Agency, octobre 2020. http://dx.doi.org/10.46756/sci.fsa.bxn990.
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For meat and meat products, secondary processes are those that relate to the downstream of the primary chilling of carcasses. Secondary processes include maturation chilling, deboning, portioning, mincing and other operations such as thermal processing (cooking) that create fresh meat, meat preparations and ready-to-eat meat products. This review systematically identified and summarised information relating to antimicrobial resistance (AMR) during the manufacture of secondary processed meatand meat products (SPMMP). Systematic searching of eight literature databases was undertaken and the resultantpapers were appraised for relevance to AMR and SPMMP. Consideration was made that the appraisal scores, undertaken by different reviewers, were consistent. Appraisal reduced the 11,000 initially identified documents to 74, which indicated that literature relating to AMR and SPMMP was not plentiful. A wide range of laboratory methods and breakpoint values (i.e. the concentration of antimicrobial used to assess sensitivity, tolerance or resistance) were used for the isolation of AMR bacteria.The identified papers provided evidence that AMR bacteria could be routinely isolated from SPMMP. There was no evidence that either confirmed or refuted that genetic materials capable of increasing AMR in non-AMR bacteria were present unprotected (i.e. outside of a cell or a capsid) in SPMMP. Statistical analyses were not straightforward because different authors used different laboratory methodologies.However, analyses using antibiotic organised into broadly-related groups indicated that Enterobacteriaceaeresistant to third generation cephalosporins might be an area of upcoming concern in SPMMP. The effective treatment of patients infected with Enterobacteriaceaeresistant to cephalosporins are a known clinical issue. No AMR associations with geography were observed and most of the publications identified tended to be from Europe and the far east.AMR Listeria monocytogenes and lactic acid bacteria could be tolerant to cleaning and disinfection in secondary processing environments. The basis of the tolerance could be genetic (e.g. efflux pumps) or environmental (e.g. biofilm growth). Persistent, plant resident, AMR L. monocytogenes were shown by one study to be the source of final product contamination. 4 AMR genes can be present in bacterial cultures used for the manufacture of fermented SPMMP. Furthermore, there was broad evidence that AMR loci could be transferred during meat fermentation, with refrigeration temperatures curtailing transfer rates. Given the potential for AMR transfer, it may be prudent to advise food business operators (FBOs) to use fermentation starter cultures that are AMR-free or not contained within easily mobilisable genetic elements. Thermal processing was seen to be the only secondary processing stage that served as a critical control point for numbers of AMR bacteria. There were significant linkages between some AMR genes in Salmonella. Quaternary ammonium compound (QAC) resistance genes were associated with copper, tetracycline and sulphonamide resistance by virtue of co-location on the same plasmid. No evidence was found that either supported or refuted that there was any association between AMR genes and genes that encoded an altered stress response or enhanced the survival of AMR bacteria exposed to harmful environmental conditions.
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Ciapponi, Agustín. What is the effectiveness of interventions to improve antibiotic prescribing practices for hospital inpatients ? SUPPORT, 2016. http://dx.doi.org/10.30846/1610132.
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In-hospital infections caused by antibiotic-resistant bacteria and Clostridium difficile are associated with higher rates of death, illness and prolonged hospital stay which is a serious problem for patients and healthcare systems. These infections occur because antibiotics are used too often and incorrectly.
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Soupir, Michelle L., Matthew J. Helmers et Thomas B. Moorman. Antibiotic Resistant Bacteria and Resistance Genes in Crop Fields. Ames : Iowa State University, Digital Repository, 2013. http://dx.doi.org/10.31274/farmprogressreports-180814-640.
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Soupir, Michelle, Matt Helmers et Thomas Moorman. Antibiotic Resistant Bacteria and Resistance Genes in Crop Fields. Ames : Iowa State University, Digital Repository, 2015. http://dx.doi.org/10.31274/farmprogressreports-180814-802.
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Haynes, Dr Edward, Chris Conyers, Dr Marc Kennedy, Roy Macarthur, Sam McGreig et Dr John Walshaw. What is the Burden of Antimicrobial Resistance Genes in Selected Ready-to-Eat Foods ? Food Standards Agency, novembre 2021. http://dx.doi.org/10.46756/sci.fsa.bsv485.
Texte intégralRésumé :
This study was designed to get a broad estimate of the presence and the types of antimicrobial resistance genes across 52 simple ready-to-eat foods. It was also carried out to understand the benefits and drawbacks of using metagenomic sequencing, a fairly new technology, to study AMR genes. An antimicrobial is any substance that kills or inhibits the growth of microorganisms. It includes antibiotics which are used to treat bacterial infections in both humans and animals. Given the relevant selective pressures, the bacteria itself can change and find ways to survive the effects of an antimicrobials. This results in the bacteria becoming resistant to the ‘killing’ effects of antimicrobials and is known as ‘antimicrobial resistance’. The more we use antimicrobials and antibiotics and the way that we use them can increase the chance that bacteria will become resistant to antimicrobials. This is important as it can lead to infections that become more difficult to treat with drugs and poses a risk to the public health. T Addressing AMR is a national strategic priority for the UK Government which has led to the development of a new 20-year Vision for AMR and the 5-year National Action Plan (NAP), which runs until 2024. The NAP lays out how the UK will address the AMR challenge and takes a ‘One-Health’ approach which spans people, animals, agriculture, food and the environment. The NAP includes a specific section on the importance of better food safety to limit the contamination of foods and spread of AMR. This section emphasises the need to strengthen the evidence base for AMR and food safety through research, surveillance and promoting good practice across the food chain. The FSA is playing its part by continuing to fill evidence gaps on the role that food plays in AMR through the commissioning of research and surveillance. We are also promoting and improving UK food hygiene (‘4Cs’ messages) across the food chain that will help reduce exposure to AMR bacteria.
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Rosa-Mangeret, Flavia, Otis Olela, Francisca Barcos-Munoz, Noemie Wagner, Olivier Duperrex, Marc Dupuis et Riccardo E. Pfister. Drug Resistant Bacterial Neonatal Early Onset Sepsis in Africa : A 20 year- prevalence review and metanalysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, janvier 2022. http://dx.doi.org/10.37766/inplasy2022.1.0112.
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Review question / Objective: What is the prevalence of drug-resistant pathogens associated with neonatal Early Onset Sepsis (NEOS) in the African continent and their likelihood of resistance to commonly used antibiotics in the NEOS, and what is the trend through time? Condition being studied: There is no consensus on the definition of neonatal sepsis. Two main categories of neonatal sepsis are widely accepted: early-onset sepsis (EOS) defined as occurring in the first 72 hours of life, hence representing perinatal vertical infection; and late-onset sepsis (LOS), which occurs between 72 hours to 28 days and can be hospital or community-acquired. Information sources: Pubmed, EMBASE, Web of Science. All authors from papers with missing information were contacted before article exclusion.
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Cahaner, Avigdor, Susan J. Lamont, E. Dan Heller et Jossi Hillel. Molecular Genetic Dissection of Complex Immunocompetence Traits in Broilers. United States Department of Agriculture, août 2003. http://dx.doi.org/10.32747/2003.7586461.bard.
Texte intégralRésumé :
Objectives: (1) Evaluate Immunocompetence-OTL-containing Chromosomal Regions (ICRs), marked by microsatellites or candidate genes, for magnitude of direct effect and for contribution to relationships among multiple immunocompetence, disease-resistance, and growth traits, in order to estimate epistatic and pleiotropic effects and to predict the potential breeding applications of such markers. (2) Evaluate the interaction of the ICRs with genetic backgrounds from multiple sources and of multiple levels of genetic variation, in order to predict the general applicability of molecular genetic markers across widely varied populations. Background: Diseases cause substantial economic losses to animal producers. Emerging pathogens, vaccine failures and intense management systems increase the impact of diseases on animal production. Moreover, zoonotic pathogens are a threat to human food safety when microbiological contamination of animal products occurs. Consumers are increasingly concerned about drug residues and antibiotic- resistant pathogens derived from animal products. The project used contemporary scientific technologies to investigate the genetics of chicken resistance to infectious disease. Genetic enhancement of the innate resistance of chicken populations provides a sustainable and ecologically sound approach to reduce microbial loads in agricultural populations. In turn, animals will be produced more efficiently with less need for drug treatment and will pose less of a potential food-safety hazard. Major achievements, conclusions and implications:. The PI and co-PIs had developed a refined research plan, aiming at the original but more focused objectives, that could be well-accomplished with the reduced awarded support. The successful conduct of that research over the past four years has yielded substantial new information about the genes and genetic markers that are associated with response to two important poultry pathogens, Salmonella enteritidis (SE) and Escherichia coli (EC), about variation of immunocompetence genes in poultry, about relationships of traits of immune response and production, and about interaction of genes with environment and with other genes and genetic background. The current BARD work has generated a base of knowledge and expertise regarding the genetic variation underlying the traits of immunocompetence and disease resistance. In addition, unique genetic resource populations of chickens have been established in the course of the current project, and they are essential for continued projects. The US laboratory has made considerable progress in studies of the genetics of resistance to SE. Microsatellite-marked chromosomal regions and several specific genes were linked to SE vaccine response or bacterial burden and the important phenomenon of gene interaction was identified in this system. In total, these studies demonstrate the role of genetics in SE response, the utility of the existing resource population, and the expertise of the research group in conducting such experiments. The Israeli laboratories had showed that the lines developed by selection for high or low level of antibody (Ab) response to EC differ similarly in Ab response to several other viral and bacterial pathogens, indicating the existence of a genetic control of general capacity of Ab response in young broilers. It was also found that the 10w-Ab line has developed, possibly via compensatory "natural" selection, higher cellular immune response. At the DNA levels, markers supposedly linked to immune response were identified, as well as SNP in the MHC, a candidate gene responsible for genetic differences in immunocompetence of chickens.
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Crowley, David E., Dror Minz et Yitzhak Hadar. Shaping Plant Beneficial Rhizosphere Communities. United States Department of Agriculture, juillet 2013. http://dx.doi.org/10.32747/2013.7594387.bard.
Texte intégralRésumé :
PGPR bacteria include taxonomically diverse bacterial species that function for improving plant mineral nutrition, stress tolerance, and disease suppression. A number of PGPR are being developed and commercialized as soil and seed inoculants, but to date, their interactions with resident bacterial populations are still poorly understood, and-almost nothing is known about the effects of soil management practices on their population size and activities. To this end, the original objectives of this research project were: 1) To examine microbial community interactions with plant-growth-promoting rhizobacteria (PGPR) and their plant hosts. 2) To explore the factors that affect PGPR population size and activity on plant root surfaces. In our original proposal, we initially prqposed the use oflow-resolution methods mainly involving the use of PCR-DGGE and PLFA profiles of community structure. However, early in the project we recognized that the methods for studying soil microbial communities were undergoing an exponential leap forward to much more high resolution methods using high-throughput sequencing. The application of these methods for studies on rhizosphere ecology thus became a central theme in these research project. Other related research by the US team focused on identifying PGPR bacterial strains and examining their effective population si~es that are required to enhance plant growth and on developing a simulation model that examines the process of root colonization. As summarized in the following report, we characterized the rhizosphere microbiome of four host plant species to determine the impact of the host (host signature effect) on resident versus active communities. Results of our studies showed a distinct plant host specific signature among wheat, maize, tomato and cucumber, based on the following three parameters: (I) each plant promoted the activity of a unique suite of soil bacterial populations; (2) significant variations were observed in the number and the degree of dominance of active populations; and (3)the level of contribution of active (rRNA-based) populations to the resident (DNA-based) community profiles. In the rhizoplane of all four plants a significant reduction of diversity was observed, relative to the bulk soil. Moreover, an increase in DNA-RNA correspondence indicated higher representation of active bacterial populations in the residing rhizoplane community. This research demonstrates that the host plant determines the bacterial community composition in its immediate vicinity, especially with respect to the active populations. Based on the studies from the US team, we suggest that the effective population size PGPR should be maintained at approximately 105 cells per gram of rhizosphere soil in the zone of elongation to obtain plant growth promotion effects, but emphasize that it is critical to also consider differences in the activity based on DNA-RNA correspondence. The results ofthis research provide fundamental new insight into the composition ofthe bacterial communities associated with plant roots, and the factors that affect their abundance and activity on root surfaces. Virtually all PGPR are multifunctional and may be expected to have diverse levels of activity with respect to production of plant growth hormones (regulation of root growth and architecture), suppression of stress ethylene (increased tolerance to drought and salinity), production of siderophores and antibiotics (disease suppression), and solubilization of phosphorus. The application of transcriptome methods pioneered in our research will ultimately lead to better understanding of how management practices such as use of compost and soil inoculants can be used to improve plant yields, stress tolerance, and disease resistance. As we look to the future, the use of metagenomic techniques combined with quantitative methods including microarrays, and quantitative peR methods that target specific genes should allow us to better classify, monitor, and manage the plant rhizosphere to improve crop yields in agricultural ecosystems. In addition, expression of several genes in rhizospheres of both cucumber and whet roots were identified, including mostly housekeeping genes. Denitrification, chemotaxis and motility genes were preferentially expressed in wheat while in cucumber roots bacterial genes involved in catalase, a large set of polysaccharide degradation and assimilatory sulfate reduction genes were preferentially expressed.
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Fluhr, Robert, et Maor Bar-Peled. Novel Lectin Controls Wound-responses in Arabidopsis. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7697123.bard.
Texte intégralRésumé :
Innate immune responses in animals and plants involve receptors that recognize microbe-associated molecules. In plants, one set of this defense system is characterized by large families of TIR–nucleotide binding site–leucine-rich repeat (TIR-NBS-LRR) resistance genes. The direct interaction between plant proteins harboring the TIR domain with proteins that transmit and facilitate a signaling pathway has yet to be shown. The Arabidopsis genome encodes TIR-domain containing genes that lack NBS and LRR whose functions are unknown. Here we investigated the functional role of such protein, TLW1 (TIR LECTIN WOUNDRESPONSIVE1). The TLW1 gene encodes a protein with two domains: a TIR domain linked to a lectin-containing domain. Our specific aim in this proposal was to examine the ramifications of the TL1-glycan interaction by; A) The functional characterization of TL1 activity in the context of plant wound response and B) Examine the hypothesis that wounding induced specific polysaccharides and examine them as candidates for TL-1 interactive glycan compounds. The Weizmann group showed TLW1 transcripts are rapidly induced by wounding in a JA-independent pathway and T-DNA-tagged tlw1 mutants that lack TLW1 transcripts, fail to initiate the full systemic wound response. Transcriptome methodology analysis was set up and transcriptome analyses indicates a two-fold reduced level of JA-responsive but not JA-independent transcripts. The TIR domain of TLW1 was found to interact directly with the KAT2/PED1 gene product responsible for the final b-oxidation steps in peroxisomal-basedJA biosynthesis. To identify potential binding target(s) of TL1 in plant wound response, the CCRC group first expressed recombinant TL1 in bacterial cells and optimized conditions for the protein expression. TL1 was most highly expressed in ArcticExpress cell line. Different types of extraction buffers and extraction methods were used to prepare plant extracts for TL1 binding assay. Optimized condition for glycan labeling was determined, and 2-aminobenzamide was used to label plant extracts. Sensitivity of MALDI and LC-MS using standard glycans. THAP (2,4,6- Trihydroxyacetophenone) showed minimal background peaks at positive mode of MALDI, however, it was insensitive with a minimum detection level of 100 ng. Using LC-MS, sensitivity was highly increased enough to detect 30 pmol concentration. However, patterns of total glycans displayed no significant difference between different extraction conditions when samples were separated with Dionex ICS-2000 ion chromatography system. Transgenic plants over-expressing lectin domains were generated to obtain active lectin domain in plant cells. Insertion of the overexpression construct into the plant genome was confirmed by antibiotic selection and genomic DNA PCR. However, RT-PCR analysis was not able to detect increased level of the transcripts. Binding ability of azelaic acid to recombinant TL1. Azelaic acid was detected in GST-TL1 elution fraction, however, DHB matrix has the same mass in background signals, which needs to be further tested on other matrices. The major findings showed the importance of TLW1 in regulating wound response. The findings demonstrate completely novel and unexpected TIR domain interactions and reveal a control nexus and mechanism that contributes to the propagation of wound responses in Arabidopsis. The implications are to our understanding of the function of TIR domains and to the notion that early molecular events occur systemically within minutes of a plant sustaining a wound. A WEB site (http://genome.weizmann.ac.il/hormonometer/) was set up that enables scientists to interact with a collated plant hormone database.