Letteratura scientifica selezionata sul tema "Human pathogenic bacterium"
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Articoli di riviste sul tema "Human pathogenic bacterium"
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Voropaev, E. V. "MOLECULAR AND GENETIC FACTORS FOR REALIZATION OF THE PATHOGENIC POTENTIAL OF <i>HELICOBACTER PYLORI:</i> PERSONIFIED TECHNIQUES FOR ASSESSMENT OF MANIFESTATIONS, LABORATORY DIAGNOSIS AND PROGNOSIS". Health and Ecology Issues, n. 1 (28 marzo 2018): 15–20. http://dx.doi.org/10.51523/2708-6011.2018-15-1-3.
Testo completoAbstract (sommario):
The work presents an analytical review of features of techniques for assessment of the pathogenetic potential of Helicobacter pylori bacterium, an etiological agent of a number of gastrointestinal diseases. The main emphasis is laid on modern molecular and genetic techniques that make it possible to assess not only the pathogenic potential of the bacterium, but also the characteristics of the stomach microbiota and the infected human host`s genotype.
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Johnsborg, Ola, e Leiv Sigve Håvarstein. "Pneumococcal LytR, a Protein from the LytR-CpsA-Psr Family, Is Essential for Normal Septum Formation in Streptococcus pneumoniae". Journal of Bacteriology 191, n. 18 (6 luglio 2009): 5859–64. http://dx.doi.org/10.1128/jb.00724-09.
Testo completoAbstract (sommario):
ABSTRACT Proliferation of the human-pathogenic bacterium Streptococcus pneumoniae is fundamentally linked to the bacterial proteins that function in cell division. Here, we show that LytR, a pneumococcal protein from the LytR-CpsA-Psr family, is essential to this process.
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Gerrard, John G., Nicholas R. Waterfield e Maria Sanchez-Contreeras. "Photorhabdus asymbiotica: Shedding Light on a Human Pathogenic Bioluminescent Bacterium". Clinical Microbiology Newsletter 33, n. 14 (luglio 2011): 103–9. http://dx.doi.org/10.1016/j.clinmicnews.2011.06.004.
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Kumar, Rajneesh, e Pooja Singh. "Characterization and Diagnostics of Listeria Monocytogenes: A Human Pathogen". Asian Pacific Journal of Health Sciences 9, n. 2 (1 aprile 2022): 102–8. http://dx.doi.org/10.21276/apjhs.2022.9.2.21.
Testo completoAbstract (sommario):
Listeria monocytogenes, Gram positive bacteria, rod-shaped, intracellular, opportunistic, invasive food borne bacterium, which is ubiquitous in nature. Soil, vegetation, sewage, water, and fecal materials are its primary source through which it reaches to our food system. It is one of the leading food borne bacteria which is pathogenic, causing Listeriosis in immunodeficient children, adult, pregnant women, central nervous system infection, bacteremia, and other clinical manifestation. Bacterium has arsenal of virulence factors Listeriolysin, phospholipases, internalins and Act A protein which help to enter, invade and infect the host cell, escape from autophagy and promote cell to cell spread. It can withstand diverse environmental parameters, that is, low temperatures, pH, osmotic and oxidative stress. Bacterium is deadly to humans and is food borne, causing economic losses and is a threat to food industry. Present review gives an overview of bacterial characteristics, etiology, isolation, distribution and pathogenicity of L. monocytogenes.
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Oliver, J. D., D. M. Roberts, V. K. White, M. A. Dry e L. M. Simpson. "Bioluminescence in a strain of the human pathogenic bacterium Vibrio vulnificus." Applied and Environmental Microbiology 52, n. 5 (1986): 1209–11. http://dx.doi.org/10.1128/aem.52.5.1209-1211.1986.
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Martins, Rodrigo, Cristiana Mateus, Fernanda Domingues, Roland Bücker, Mónica Oleastro e Susana Ferreira. "Effect of Atmospheric Conditions on Pathogenic Phenotypes of Arcobacter butzleri". Microorganisms 10, n. 12 (6 dicembre 2022): 2409. http://dx.doi.org/10.3390/microorganisms10122409.
Testo completoAbstract (sommario):
Arcobacter butzleri is an emergent gram-negative enteropathogenic bacterium widespread in different environments and hosts. During the colonization of the gastrointestinal tract, bacteria face a variety of environmental conditions to successfully establish infection in a new host. One of these challenges is the fluctuation of oxygen concentrations encountered not only throughout the host gastrointestinal tract and defences but also in the food industry. Oxygen fluctuations can lead to modulations in the virulence of the bacterium and possibly increase its pathogenic potential. In this sense, eight human isolates of A. butzleri were studied to evaluate the effects of microaerobic and aerobic atmospheric conditions in stressful host conditions, such as oxidative stress, acid survival, and human serum survival. In addition, the effects on the modulation of virulence traits, such as haemolytic activity, bacterial motility, biofilm formation ability, and adhesion and invasion of the Caco-2 cell line, were also investigated. Overall, aerobic conditions negatively affected the susceptibility to oxygen reactive species and biofilm formation ability but improved the isolates’ haemolytic ability and motility while other traits showed an isolate-dependent response. In summary, this work demonstrates for the first time that oxygen levels can modulate the potential pathogenicity of A. butzleri, although the response to stressful conditions was very heterogeneous among different strains.
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Tran, Tran Thi Ai, You Jung Kang, Hyun-Kyoung Kim, Hyung-Ryong Kim e Hansang Cho. "Oral Pathogenic Bacteria-Inducing Neurodegenerative Microgliosis in Human Neural Cell Platform". International Journal of Molecular Sciences 22, n. 13 (28 giugno 2021): 6925. http://dx.doi.org/10.3390/ijms22136925.
Testo completoAbstract (sommario):
Porphyromonas gingivalis is a gram-negative bacterium found in the human oral cavity and is responsible for the development of chronic periodontitis as well as neurological diseases, including Alzheimer’s disease (AD). Given the significance of the roles of P. gingivalis in AD pathogenesis, it is critical to understand the underlying mechanisms of P. gingivalis-driven neuroinflammation and their contribution to neurodegeneration. Herein, we hypothesize that P. gingivalis produces secondary metabolites that may cause neurodegeneration through direct or indirect pathways mediated by microglia. To test our hypothesis, we treated human neural cells with bacterial conditioned media on our brain platforms and assessed microgliosis, astrogliosis and neurodegeneration. We found that bacteria-mediated microgliosis induced the production of nitric oxide, which causes neurodegeneration assessed with high pTau level. Our study demonstrated the elevation of detrimental protein mediators, CD86 and iNOS and the production of several pro-inflammatory markers from stimulated microglia. Through inhibition of LPS and succinate dehydrogenase in a bacterial conditioned medium, we showed a decrease in neurodegenerative microgliosis. In addition, we demonstrated the bidirectional effect of microgliosis and astrogliosis on each other exacerbating neurodegeneration. Overall, our study suggests that the mouth-brain axis may contribute to the pathogenesis of AD.
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Spigaglia, Patrizia, Fabrizio Barbanti e Paola Mastrantonio. "Tetracycline Resistance Gene tet(W) in the Pathogenic Bacterium Clostridium difficile". Antimicrobial Agents and Chemotherapy 52, n. 2 (10 dicembre 2007): 770–73. http://dx.doi.org/10.1128/aac.00957-07.
Testo completoAbstract (sommario):
ABSTRACT In this study, the tet(W) gene region of a human clinical isolate of Clostridium difficile resistant to tetracycline was characterized. This gene was a new allele showing 99% sequence identity to the gene found in the human strain Bifidobacterium longum F8, and it is not transferable by “in vitro” mating experiments.
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Pozdeev, О. К., А. О. Pozdeeva, Yu V. Valeeva e P. E. Gulyaev. "MECHANISMS OF INTERRACTION OF HELICOBACTER PYLORI WITH EPITHELIUM OF GASTRIC MUCOSA. I. PATHOGENIC FACTORS PROMOTING SUCCESSFUL COLONIZATION". Russian Journal of Infection and Immunity 8, n. 3 (4 novembre 2018): 273–83. http://dx.doi.org/10.15789/2220-7619-2018-3-273-283.
Testo completoAbstract (sommario):
H. pylori is a Gram-negative, crimp and motile bacterium that colonizes the hostile microniche of the human stomach roughly one half of the human population. Then persists for the host’s entire life, but only causes overt gastric disease in a subset of infected hosts. To the reasons contributing to the development of diseases, usually include: concomitant infections of the gastrointestinal tract, improper sterilization of medical instruments, usually endoscopes, nonobservance of personal hygiene rules, prolonged contact with infected or carriers, including family members and a number of other factors. Clinically, H. pylori plays a causative role in the development of a wide spectrum of diseases including chronic active gastritis, peptic and duodenal ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Due to the global distribution of H. pylori, we are able to conclude that smart strategies are contributing to adaptation of the bacterium in an aggressive environment of a stomach and lifelong permanent circulation in its host. Thirty-four years after the discovery of this bacterium, there are still many unanswered questions. For example, which strategies help the bacterium to survive in this inhospitable conditions? Understanding the mechanisms governing H. pylori persistence will improve identification of the increased risk of different gastric diseases in persons infected with this bacterium. A well-defined and long-term equilibrium between the human host and H. pylori allows bacterial persistence in the gastric microniche; although this coexistence leads to a high risk of severe diseases the diseases which are listed above. In this review, we discuss the pathogenesis of this bacterium and the mechanisms it uses to promote persistent colonization of the gastric mucosa, with a focus on recent insights into the role of some virulence factors like urease, LPS, outer membrane proteins, cytotoxins, factors, promoting invasion. Information on the mechanisms related to H. pylori persistence can also provide the direction for future research concerning effective therapy and management of gastroduodenal disorders. The topics presented in the current review are important for elucidating the strategies used by H. pylori to help the bacterium persist in relation to the many unfavorable features of living in the gastric microniche.
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Kim, Kwang Kyu, Keun Chul Lee, Haeyoung Jeong, David A. Stevens e Jung-Sook Lee. "Draft Genome Sequence of the Human Pathogen Halomonas stevensii S18214T". Journal of Bacteriology 194, n. 18 (28 agosto 2012): 5143. http://dx.doi.org/10.1128/jb.01071-12.
Testo completoAbstract (sommario):
ABSTRACTHalomonas stevensiiis a Gram-negative, moderately halophilic bacterium causing environmental contamination and infections in a dialysis center. Here we present the 3.7-Mb draft genome sequence of the type strain (S18214T) ofH. stevensii, which will give insight into the pathogenic potential ofH. stevensii.
Tesi sul tema "Human pathogenic bacterium"
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Muraleedharan, Samada [Verfasser], e Simon [Akademischer Betreuer] Ringgaard. "Understanding cell division and its regulation in the human pathogenic bacterium, Vibrio parahaemolyticus / Samada Muraleedharan ; Betreuer: Simon Ringgaard". Marburg : Philipps-Universität Marburg, 2019. http://d-nb.info/1193177529/34.
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Habeeb, Fatema. "Bacteria-cytokines interactions : effect of normal bacterial flora of pathogenic bacteria on pro-inflammatory cytokines production in human blood". Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501921.
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Badilla, Lobo Adriana. "Characterization of a family of small proteins regulated by second messenger-binding riboswitches in Clostridioides difficile". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASL120.
Testo completoAbstract (sommario):
Clostridioides difficile est une cause majeure de diarrhée nosocomiale. La physiopathologie de C. difficile est régie par des réseaux de régulation complexes, incluant des mécanismes basés sur l'ARN tels que les riboswitches. Les riboswitches, situés dans la région 5' non traduite des ARNm, se lient à des ligands spécifiques, induisant des changements de conformation qui modulent l'expression du gène en aval. Chez C. difficile, 16 riboswitches répondent à la molécule de signalisation c-di-GMP. Le c-di-GMP est un régulateur contrôlant la transition d'un mode de vie planctonique libre à un mode de vie sessile associé à la régulation des facteurs de virulence. Plusieurs riboswitches à c-di-GMP régulent des gènes impliqués dans la formation des flagelles, l'assemblage des pili de type IV, le développement du biofilm, l'adhésion et la production de facteurs de virulence tels que les toxines chez C. difficile. De plus, le c-di-GMP inhibe la sporulation chez C. difficile, mais le mécanisme sous-jacent n'est pas connu.Nous avons caractérisé ici des riboswitches à c-di-GMP qui n'ont pas encore été étudiés. Nos analyses bioinformatiques ont révélé que 5 d'entre eux sont situés directement en amont de gènes codant des petites protéines (PPs) de 58 acides aminés (AA). De manière intéressante, un alignement de ces 5 protéines a montré qu'elles sont presque identiques en séquence. De plus, une recherche d'homologie a permis de découvrir 2 protéines supplémentaires de 60 AA, très similaires aux cinq premières, bien que leurs gènes ne soient pas précédés d'un riboswitch. Cette nouvelle famille de protéines est conservée dans toutes les souches de C. difficile, mais n'a pas d'homologues en dehors de l'espèce. Nous avons construit une version étiquetée d'une PP et l'avons détectée par immunoblotting de fractions cellulaires, confirmant sa nature protéique et révélant qu'elle est associée à la membrane.Des données de séquençage de l'ARN (RNA-seq) ont démontré que le c-di-GMP régule négativement l'expression des 5 gènes de PP en aval des riboswitches ainsi que des 2 gènes supplémentaires. Nous avons également observé que le c-di-AMP, un autre dinucléotide cyclique impliqué dans l'osmorégulation, réprime l'expression des 7 gènes. Des expériences de fusions transcriptionnelles entre la région promotrice d'une PP et un gène rapporteur ont confirmé que le c-di-GMP nécessite le riboswitch pour moduler l'expression des gènes en aval. En revanche, le c-di-AMP régule leur expression indépendamment du riboswitch en modulant l'activité du promoteur. Ainsi, le c-di-GMP et le c-di-AMP influencent l'expression des PP par des mécanismes distincts.Pour étudier le rôle des PP chez C. difficile, nous avons surexprimé l'une d'elles et comparé son transcriptome à celui de la souche sauvage. Cela a révélé l'induction de l'expression de plus de 100 gènes impliqués dans la sporulation dans la souche surexprimant la PP. Conformément à ces données, la surexpression de cette PP a conduit à un phénotype d'hypersporulation. En outre, la délétion des 7 gènes de PP (mutant Δ7) a entraîné une réduction de la sporulation, avec des phénotypes intermédiaires pour les souches où seuls certains gènes des PP ont été délétés. Le défaut de sporulation de Δ7 est similaire à celui d'une souche produisant des niveaux élevés de c-di-GMP, suggérant que l'impact du c-di-GMP sur la sporulation pourrait être médié par la régulation des PP. Pour tester cette hypothèse, nous avons créé un mutant Δ7 produisant de fortes concentrations de c-di-GMP. Le défaut de sporulation de cette souche était équivalent à celui du mutant Δ7 non affecté dans sa production de c-di-GMP, indiquant que les effets des délétions des PP et de la surproduction de c-di-GMP ne sont pas cumulatifs.Dans l'ensemble, nos résultats démontrent que cette nouvelle famille de petites protéines est régulée à la fois par le c-di-GMP et le c-di-AMP et joue un rôle clé dans le contrôle de la sporulation chez C. difficileClostridioides difficile is the leading cause of nosocomial diarrhea in adults in industrialized countries. The pathophysiology of C. difficile is governed by complex regulatory networks, including RNA-based mechanisms like riboswitches. Riboswitches, located in the 5' untranslated region of mRNAs, bind specific ligands, inducing conformational changes that either promote or inhibit the expression of the downstream gene. In C. difficile, 16 riboswitches respond to the signaling molecule cyclic di-GMP (c-di-GMP). C-di-GMP acts as a second messenger and is recognized as a central regulator controlling the transition from a free planktonic to a sessile lifestyle associated with biofilm formation and virulence factor regulation. Several of the c-di-GMP-responding riboswitches have been well-studied in C. difficile and shown to regulate genes involved in flagella formation, type IV pili assembly, biofilm development, adhesion, and the production of virulence factors such as toxins. Moreover, c-di-GMP inhibits sporulation in C. difficile, but the underlying mechanism remains unclear.In this PhD work, we sought to characterize c-di-GMP-responding riboswitches that have not yet been studied. Our bioinformatics analyses revealed that 5 of them are located directly upstream of predicted genes encoding small proteins (SPs) of 58 amino acids. Interestingly, an alignment of these 5 proteins showed that they are almost identical in sequence. Moreover, a homology search uncovered two additional proteins of 60 amino acids, highly similar to the first five, though their genes are not preceded by a c-di-GMP riboswitch. This novel family of proteins is conserved across C. difficile strains but lacks homologs outside the species. We built a tagged version of one SP and detected it by immunoblotting of cell fractions, confirming its protein nature and revealing that it is primarily localized to the cell membrane.RNA sequencing (RNA-seq) data demonstrated that c-di-GMP negatively regulates not only the expression of the 5 SP genes downstream of the riboswitches but also the 2 additional genes. Unexpectedly, we also observed that c-di-AMP, another cyclic dinucleotide primarily involved in osmoregulation, repressed the expression of all seven genes. We performed reporter assays in different strain backgrounds to explore how these small proteins are regulated by both c-di-GMP and c-di-AMP. These experiments indicated that c-di-GMP required the riboswitch for modulation of downstream gene expression. In contrast, c-di-AMP regulated their expression independently of the riboswitch by modulating the promoter activity. Thus, c-di-GMP and c-di-AMP influence SP expression through distinct mechanisms.To investigate the role of these small proteins in C. difficile physiology, we overexpressed one SP and compared its transcriptome to that of the wild-type strain using RNA-seq. This revealed the upregulation of more than 100 genes involved in sporulation in the overexpressing strain. Consistent with these data, overexpression of this SP led to a hypersporulation phenotype. Furthermore, deletion of all 7 SP genes (Δ7 mutant) resulted in a significant reduction in sporulation, with intermediate phenotypes in strains where only some of the SP genes were deleted. Interestingly, the sporulation defect in the Δ7 mutant was mirrored in a strain producing elevated levels of c-di-GMP, suggesting that the impact of c-di-GMP on sporulation could be mediated by SP regulation. To test this hypothesis, we created a Δ7 mutant producing high concentrations of c-di-GMP. The sporulation defect in this strain was equivalent to that of the Δ7 mutant unaffected in its c-di-GMP production, indicating that the effects of SP gene deletions and c-di-GMP overproduction were not cumulative.Overall, our findings demonstrate that this novel family of small proteins is regulated by both c-di-GMP and c-di-AMP and plays a key role in controlling sporulation in C. difficile
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Davids, Wagied. "Causes of Substitution Frequency Variation in Pathogenic Bacteria". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4838.
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Al-Attwani, Jasim Hussein. "The effect of probiotics on bacterial human skin pathogens". Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3087.
Testo completoAbstract (sommario):
Probiotic bacteria have been investigated in the prevention and treatment of various diseases and allergies. The current study was undertaken to determine the effect of eight probiotic Lactobacillus species against bacterial human skin pathogens using several techniques. Antimicrobial activity of lactobacilli against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Propionibacterium acnes was evaluated using lactobacilli broth cultures (BCB) and cell free supernatant (CFS). Antimicrobial activity was significantly greater with BCB compared with CFS especially for Lactobacillus plantarum and Lactobacillus acidophilus. Lactobacilli and pathogen aggregation, biofilm formation and adhesion to keratin were assessed. L. casei and L. plantarum were selected for further study as they showed the greatest co-aggregation (18.02 ± 1.34% with L. casei and 14.92 ± 1.45% with L. plantarum) with the pathogens (16.63 ± 1.65% with S. aureus 3761 and 14.58 ± 1.68% with P. aeruginosa) and prevention of biofilm formation by the pathogens. The antimicrobial activity of human beta defensin-2 (hBD-2) alone or with L. plantarum against pathogens was assessed. The results with hBD-2 showed that hBD-2 (10 μg / ml for 5 h) and L. plantarum together were significantly more inhibitory against S. aureus than hBD-2 alone. The presence of NaCl reduced the effectiveness of hBD-2 alone and with L. plantarum. In the presence of L. plantarum, inactivation of mprF and dlt genes led to increased binding of hBD-2 by the bacterial cell wall, and then inhibition growth of bacterial cell wall. Studies investigated the effect of exposure of methicillin resistant Staphylococcus aureus (MRSA) to the supernatant of L. plantarum the susceptibility of MRSA to β-lactams. MRSA became sensitive to β-lactams when treated with culture supernatant of L. plantarum. Gene expression studies demonstrated that the mecR1-mecI-mecA-PBP2 signalling pathway was impeded by exposure to culture supernatant of L. plantarum and β-lactams. The studies reported here demonstrate a possible alternative approach to dealing with skin pathogens, which may have clinical implications especially with regard to MRSA infections, and continued research is advised.
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Hernández, Jorge. "Human Pathogens and Antibiotic Resistant Bacteria in Polar Regions". Doctoral thesis, Uppsala universitet, Institutionen för medicinska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-230700.
Testo completoAbstract (sommario):
Coincident with human activity in recent decades, human-associated microorganisms have arrived to the Antarctic region, possibly linked to increasing presence of scientific bases and ship-borne tourists. In the Arctic, humans have been present for a very long time, and the few parts of the Arctic without human activities is decreasing with time. The studies in this thesis investigate the occurrence of different pathogens in Antarctic and Arctic wildlife, especially in birds. The first study shows the existence of Enteropatogenic Escherichia coli (EPEC) in Antarctic fur seals. The EPEC isolates were so called atypical EPECs, carrying the eae gene but lacking the bfp gene. This is the first record of a diarrheogenic E. coli in wild animals in the Antarctic. The second study displays that spreading of antibiotic resistance mechanisms appears to be much more efficient than previously was known. Enterococcus faecium isolated from Alaskan birds showed high resistance to vancomycin and teicoplanin, but also to ampicillin and ciprofloxacin. These isolates also carried vanA genes and the virulent esp gene, which places the isolates in the clinical clone CC17 and indicates the isolates had a human origin. Bacteria from birds that reside in the Bering Strait region in the third study, demonstrates that only six of 145 E. coli from 532 birds had reduced antibiotic susceptibility. Despite this, selective screen on E. coli showed only four ESBL-producing isolates. The four E. coli isolates carried CTX-M genes. One isolate belonged to the E. coli O25b - ST131 genotype, which is a successful clone with a global spread. In the fourth study, 123 seawater samples and 400 fresh penguin feces were analyzed. From these, 71 E. coli strains were isolated and only one E. coli from penguins was resistant to one antibiotic (cloramfenicol), whereas in E. coli from seawater, resistance against ampicillin, tetracycline, streptomycin and trim-sulfa were detected. E. coli carrying ESBL type CTX -M genes were also detected and Multilocus Sequencing Typing (MLST) showed six different sequence types (ST) previously reported in humans: ST131, ST227, ST401, ST410, ST685 and ST937. In the short time interval between the second study (2005) and the third study (2010) in relation to the fifth study (2012) we found a dramatic increase in antibiotic-resistant genes in the Arctic region. Enterococci, E. coli, and Kl. pneumoniae carried antibiotic resistance genes to an extent and variety not previously reported. E. coli from Arctic birds showed resistant to 1, 2, 3, 4, and 5 different antibiotics. Resistant gene type vanA was confirmed in enterococci and ESBL genes type TEM, SHV and CTX-M in E. coli and Kl. pneumoniae was detected. Multilocus Sequencing typing (MLST), indicating that both E. coli and Kl. pneumoniae carrying ESBL markers that connects them to the humans. In summary, the combined studies strengthen that bacteria that cause infections in humans could spread to relatively pristine environments. We concluded that human and associated antibiotic-resistant bacteria has reached a global level, then we showed that ESBL- carrying bacteria circulating nowadays also in the last ESBL-free continent, Antarctica.
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Phillips, Zachary N. "Analysis of Phase-variable Genes in Human-adapted Bacterial Pathogens". Thesis, Griffith University, 2022. http://hdl.handle.net/10072/418254.
Testo completoAbstract (sommario):
This thesis contributes significantly to the understanding of phase-variable gene expression in Haemophilus influenzae and phasevarions in Streptococcus pneumoniae, and to the broader fields of bacterial genetics and epigenetics. This thesis has: (i) demonstrated that particular forms of lipooligosaccharide (LOS) are selected for during NTHi invasive infection; (ii) described the autotransporter Lav in NTHi, demonstrating that this protein is phase-variable, is an important virulence factor, and is a potential NTHi vaccine candidate; (iii) informed vaccine development by characterising the prevalence of Hgps across Haemophilus influenzae, while identifying expression in an invasive NTHi isolate collection; (iv) effectively doubled publicly available genomes for Haemophilus influenzae biogroup aegyptius isolates; and (v) carried out a detailed analysis of the pathobiology of the SpnIII system of S. pneumoniae.
As the body of work that constitutes each Chapter of this thesis is in manuscript format, abstracts can be found in these Chapters.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Institute for Glycomics
Griffith Health
Full Text
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Hussein, Khwam Reissan. "Source tracking of faecal indicator bacteria of human pathogens in bathing waters : an evaluation and development". Thesis, University of Plymouth, 2014. http://hdl.handle.net/10026.1/3011.
Testo completoAbstract (sommario):
Bacterial water pollution is a significant problem because it is associated with reduction in the ‘quality’ of water systems with a potential impact on human health. Faecal indicator bacteria (FIB) are usually used to monitor the quality of water, and to indicate the presence of pathogens in water bodies. However, enumeration alone does not enable identification of the precise origin of these pathogens. This study aimed to monitor the quality of bathing water and associated fresh water in and out of the ‘bathing season’ in the UK, and to evaluate the use of microbial source tracking (MST) such as the host-specific based polymerase chain reaction (PCR) and quantitative PCR (qPCR) to recognize human and other animal sources of faecal pollution. The culture-dependent EU method of estimating FIB in water and sediment samples was performed on beach in the South Sands, Kingsbridge estuary, Devon, UK- a previously ‘problematic’ site. FIB were present at significant levels in the sediments, especially mud, as well as fresh water from the stream and pond flowing onto South Sands beach. However, the quality of bathing water was deemed to be ‘good’ and met with the EU bathing water directive 2006. Using MST it was possible to successfully classify the nature of the source from which the bacteria came. PCR was applied to detect the Bacteroides species 16S rRNA genetic markers from human sewage and animal faeces. All water and sediment samples displayed positive results with a general Bacteroides marker indicating the presence of Bacteroides species. Host-specific PCR showed the human Bacteroides genetic marker only in the sediment of the stream. However, limitations in the ‘types’ of probes available and in the persistence of these markers were identified. Thus, novel dog-specific Bacteroides conventional PCR and qPCR primer sets were developed to amplify a section of the 16S rRNA gene unique to the Bacteroides genetic marker from domestic dog faeces, and these were successfully used to quantify those markers in water samples at a ‘dog permitted’ and ‘dog banned’ beach (Bigbury-on-Sea, Devon, UK). Generic, human and dog Bacteroides PCR primer sets were also used to evaluate the persistence of Bacteroides genetic markers in controlled microcosms of water and sediment at differing salinities (< 0.5 and 34 psu) and temperature (10 and 17 ºC). The rates of decline were found did not differ significantly over 14 and 16 days for the water and sediment microcosms, respectively. Beach sediments which were studied in this project may act as a reservoir for adhesive FIB, and this was confirmed using fluorescence in situ hybridisation (FISH). The similarity in the persistence of these Bacteroides 16S rRNA genetic markers in environmental water and sediment suggests that viable but non-culturable (VBNC) Bacteroides spp. do not persist in the natural environment for long. Therefore, 16S rRNA genetic markers can be of value as additional faecal indicators of bathing water pollution and in source tracking. Thus, in this study MST methods were successfully used and in future applications, dog-specific primer sets can be added to the suite of host-specific Bacteroides genetic markers available to identify the source(s) of problem bacteria found on failing beaches.
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Younis, Hussein Mariam. "Sources of human pathogens in urban waters". Thesis, Halmstad University, School of Business and Engineering (SET), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2354.
Testo completoAbstract (sommario):
The presence of human pathogens in water indicates the sanitary risk associated with different types of water utilization. This study surveyed the sources of human pathogens in urban waters. In order to evaluate the microbiological water quality of urban water, the enumeration of various indicator bacteria (total coliform, fecal coliform, E.coli and enterococci) is usually used.
The abundance of indicator bacteria in urban water indicates the level of fecal contamination and the presence of other human pathogens such as protozoan pathogens (Giardia lamblia & Cryptosporidium parvum).
Fecal pollution of urban waters can be from human and animal origin. Point sources of fecal contamination in an urbanized area are the effluents of urban wastewater treatment plants. While non-point sources are usually originated from diffuse sources such as (runoff from roads, parking lots, pets, leaks, failing septic systems and illegal sewer connections to storm drains). urban stormwater is considered as a major carrier for delivering human pathogens from diffuse sources to receiving waters. Increases in urban stormwater volumes have resulted from increasing urbanization and growth of impervious surfaces.
In order to reduce high amounts of human pathogens in urban waters, different methods are used nowadays to develop urban wastewater treatment plants technologies and urban stormwater management practices.
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Ou, Gangwei. "Human intestinal epithelial cells in innate immunity : interactions with normal microbiota and pathogenic bacteria". Doctoral thesis, Umeå : Umeå University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-18388.
Testo completoLibri sul tema "Human pathogenic bacterium"
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S, Drasar B., e Duerden B. I, a cura di. Anaerobes in human disease. London: Edward Arnold, 1991.
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L, Garland Jay, Lim Daniel V e United States. National Aeronautics and Space Administration., a cura di. Survival of potentially pathogenic human-associated bacteria in the rhizosphere of hydroponically grown wheat. [Washington, D.C: National Aeronautics and Space Administration, 1996.
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Liu, Dongyou. Molecular Detection of Human Bacterial Pathogens. Taylor & Francis Group, 2011.
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Liu, Dongyou. Molecular Detection of Human Bacterial Pathogens. Taylor & Francis Group, 2011.
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Liu, Dongyou. Molecular Detection of Human Bacterial Pathogens. Taylor & Francis Group, 2011.
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Food and Agriculture Organization of the United Nations. Selection and Application of Methods for the Detection and Enumeration of Human-Pathogenic Halophilic Vibrio Spp. in Seafood. Food & Agriculture Organization of the United Nations, 2017.
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Molecular detection of human bacterial pathogens. Boca Raton, FL: Taylor & Francis/CRC Press, 2011.
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Brief History of Bacteria: The Everlasting Game Between Humans and Bacteria. World Scientific Publishing Co Pte Ltd, 2018.
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Mitscherlich, E., e E. H. Marth. Microbial Survival in the Environment: Bacteria and Rickettsiae Important in Human and Animal Health. Springer London, Limited, 2012.
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Mitscherlich, E., e E. H. Marth. Microbial Survival in the Environment: Bacteria and Rickettsiae Important in Human and Animal Health. Springer, 2011.
Cerca il testo completoCapitoli di libri sul tema "Human pathogenic bacterium"
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Willis, D. Kyle, Thomas G. Kinscherf e Jessica J. Rich. "Conservation of the lema gene, a virulence regulator from the plant pathogen Pseudomonas syringae, within a human pathogenic bacterium". In Developments in Plant Pathology, 505–10. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0746-4_34.
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Gul Guven, Reyhan, e Kemal Guven. "Bacterial Toxins". In Food Safety, 69–85. Istanbul: Nobel Tip Kitabevleri, 2024. http://dx.doi.org/10.69860/nobel.9786053358787.5.
Testo completoAbstract (sommario):
In the globalizing world, food safety and food-borne pathogenic microorganisms are among the important public health problems. There are more than 250 known foodborne diseases and many different types of viruses, bacteria, parasites, toxins, metals and prions that cause these diseases. Toxic molecules generated by bacteria, whether within or outside the organisms, are commonly referred to as "toxins". Toxins serve as the primary virulence factors generated by a multitude of bacteria responsible for causing severe illnesses in both humans and animals. Toxins are the primary bacterial component leading to health problems. This chapter provides information about bacterial toxins.
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Hackney, Cameron R., e Morris E. Potter. "Human-Associated Bacterial Pathogens". In Environmental Indicators and Shellfish Safety, 154–71. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2035-1_4.
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Marathe, Nachiket P., e Michael S. Bank. "The Microplastic-Antibiotic Resistance Connection". In 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.
Testo completoAbstract (sommario):
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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Koc, Ibrahim. "Pathogenic Microorganisms and Human Brain Health". In Brain Biochemistry and Its Disease, 211–29. Istanbul: Nobel Tip Kitabevleri, 2024. http://dx.doi.org/10.69860/nobel.9786053359371.12.
Testo completoAbstract (sommario):
Microorganisms refer to invisible entities such as viruses, bacteria, fungi, and protozoa that have various structures and characteristics. These entities exist not only in the factors that humans come into contact with, such as soil, water, and air, but also on and inside humans. These living things have very different vital activities, and some of them can be pathogenic for humans. Human brain health can be negatively affected directly or indirectly by pathogenic microorganisms. In this book chapter, scientific studies on pathogenic microorganisms that have a negative impact on human brain health are included. Additionally, scientific studies on the microbiota-host context, which affects brain health, are also included in the context of brain health-pathogenic microorganism. It is anticipated that the current study, which was prepared in the form of a review, will contribute to those interested in the subject.
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Bliven, Kimberly A., e Anthony T. Maurelli. "Evolution of Bacterial Pathogens Within the Human Host". In Virulence Mechanisms of Bacterial Pathogens, 1–13. Washington, DC, USA: ASM Press, 2016. http://dx.doi.org/10.1128/9781555819286.ch1.
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Allison, Devon L., Hubertine M. E. Willems, J. A. M. S. Jayatilake, Vincent M. Bruno, Brian M. Peters e Mark E. Shirtliff. "Candida-Bacteria Interactions: Their Impact on Human Disease". In Virulence Mechanisms of Bacterial Pathogens, 103–36. Washington, DC, USA: ASM Press, 2016. http://dx.doi.org/10.1128/9781555819286.ch5.
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Bentley, Stephen, Mohammed Sebaihia, Nicholas Thomson, Matthew Holden, Lisa Crossman, Kenneth Bell, Ana Cerdeño-Tarraga e Julian Parkhill. "Bacterial Human Pathogen Genomes: an Overview". In Cellular Microbiology, 35–62. Washington, DC, USA: ASM Press, 2014. http://dx.doi.org/10.1128/9781555817633.ch2.
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Ramalingam, Karthikeyan, e Sucharithra Ganesh. "In Vitro and in Vivo Models for Pathogenic Neisseria gonorrhoeae Infections". In Research Anthology on Advancements in Women's Health and Reproductive Rights, 134–64. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-6299-7.ch009.
Testo completoAbstract (sommario):
The prevalence of gonorrhea has not discontinued in several countries and still remains as one of the top sexually transmitted diseases (STD) and it's caused by Neisseria gonorrhoeae. This bacterium gains entry into the human host via receptors, and by the usage of several virulence factors, it manages to spread through the cells and leads to severe complications. The study of these bacteria in various in vitro and in vivo models have paved the way for gaining insights on various aspects of bacterial infection, such as the study of pathogenesis of the organism in the host. It also drove the development of more appropriate drugs for the treatment of the gonorrhea illness caused by this ‘superbug'. This chapter focuses on providing a concise overview on the general aspects of N. gonorrhoeaeas an update and the in vitro and in vivo models used for understanding this bacterium over the years. Despite gonorrhea not being a rare STD, it is still a big challenge for researchers, healthcare professionals, and communicators with public awareness to communicate effectively with the general community.
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Ramalingam, Karthikeyan, e Sucharithra Ganesh. "In Vitro and in Vivo Models for Pathogenic Neisseria gonorrhoeae Infections". In Epidemiological Research Applications for Public Health Measurement and Intervention, 111–43. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-4414-3.ch008.
Testo completoAbstract (sommario):
The prevalence of gonorrhea has not discontinued in several countries and still remains as one of the top sexually transmitted diseases (STD) and it's caused by Neisseria gonorrhoeae. This bacterium gains entry into the human host via receptors, and by the usage of several virulence factors, it manages to spread through the cells and leads to severe complications. The study of these bacteria in various in vitro and in vivo models have paved the way for gaining insights on various aspects of bacterial infection, such as the study of pathogenesis of the organism in the host. It also drove the development of more appropriate drugs for the treatment of the gonorrhea illness caused by this ‘superbug'. This chapter focuses on providing a concise overview on the general aspects of N. gonorrhoeaeas an update and the in vitro and in vivo models used for understanding this bacterium over the years. Despite gonorrhea not being a rare STD, it is still a big challenge for researchers, healthcare professionals, and communicators with public awareness to communicate effectively with the general community.
Atti di convegni sul tema "Human pathogenic bacterium"
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Galieva, Gulnaz, Kamalya Karamova, Polina Galitskaya e Svetlana Selivanovskaya. "PATHOGENIC POLLUTION OF CROPS CAUSING BY CHIKEN MANURE BASED FERTILIZERS". In 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022v/6.2/s25.33.
Testo completoAbstract (sommario):
Chicken manure is one of the most wide spread waste worldwide. One of its hazardous properties is contamination with live pathogens or pathogens� spores. Being introduced into soil for fertilization, fresh, cured or treated manure can cause soil contamination with those pathogens. Further, transmission of the pathogens through soil and plant tissues to human or animal food is possible. The objective of the present work was to reveal the level of pathogenic contamination of wheat grains cultivated on soil that was previously treated with cured chicken manure. Two types of manures M1 and M2 sampled from the large poultry farms situated in Russia were used to fertilize soil and obtain wheat grains (samples G1 and G2, respectively). Grains obtained with mineral fertilizers were used as a control (G0). Among 10 pathogenic bacterial species investigated, 6 were detected in both M1 and M2 samples - Listeria monocytogenes, Mycobacterium paratuberculosis,, Enterococus spp,, Campylobacter jejuni,, Bacillus anthracis,, Streptococcus dysgalactiae, the gene copy numbers for those bacteria revealed using RT-PCR was found to range between 2.22*104 and 1.19*108 gene copies per g manure. 5 of those species, except of C. jejuni, were also detected in both types of grains, while the gene copies number were found to be lower, thus they ranged between 1.45*103 and 8.81*103 copies per g grain. No bacterial pathogens were detected in G0 sample. Viral particles of bursal disease virus and avian orthoreovirus were not found either in manures nor in grains. It can be concluded that the risk of pathogenic transmission from the manures to grains exists, and that higher attention should be paid on their treatment to avoid the secondary infection of livestock and human.
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Broeseker, T. A., M. D. P. Boyle e R. Lottenberg. "PATHOGENIC BACTERIA HAVE HIGH AFFINITY RECEPTORS SPECIFIC FOR PLASMIN". In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644391.
Testo completoAbstract (sommario):
Binding of the key fibrinolytic enzyme, plasmin, to certain pathogenic group A streptococci was studied. In these experiments the ability of a group A streptococcal strain, 64/14, to bind either 125I-human plasminogen or the same label following activation with urokinase was measured. It was found that this strain bound <10% of the labeled plasminogen but >70% of labeled plasmin. This property distinguishes the plasmin receptor from streptokinase. These bacteria did not express a common serine protease receptor/inhibitor since they failed to bind labeled trypsin or urokinase. Maximal binding of plasmin occurred between pH 6.0 and 8.0 and in the ionic strength range of 50-200 mM salt. The Kd of plasmin binding to bacteria was approximately 10-10 M at pH 7.4 in 150 mM salt. This was determined by a non-linear least squares analysis of equilibrium binding data. Binding was reversibly inhibited by either epsilon aminocaproic acid (I50 of 0.2 mM) or lysine (I50 of 3.0 mM) suggesting the involvement of the high affinity lysine binding site of plasmin in its binding to bacteria. Bacterial bound plasmin retains its enzymatic activity, being capable of cleaving chromogenic substrates and solubilizing a fibrin- clot. The bacterial bound enzyme activity was inhibited by the low molecular weight inhibitors aprotinin and phe-pro-arg chloromethyl ketone but not by alpha-2 plasmin inhibitor. The ability of bacteria to acquire membrane associated proteolytic activity which cannot be physiologically inhibited may contribute to their tissue invasive properties.
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Kumarasinghe, N. M. A., Charitha Thambiliyagodage, Madara Jayanetti e Heshan Liyanaarachchi. "Antibacterial Activity of Zn Decorated TiO2 Nanocomposites". In SLIIT International Conference on Advancements in Sciences and Humanities 2023. Faculty of Humanities and Sciences, SLIIT, 2023. http://dx.doi.org/10.54389/usor2577.
Testo completoAbstract (sommario):
Bacterial infections have a significant public health impact. Infections are caused by bacteria in animals, plants as well as humans. Pathogenic bacteria can produce toxins, which are chemical poisons that interfere with cell function such as digestion of normal human enzymes, evasion of infection-fighting white blood cells, and immune clearance. Antibiotic prophylaxis is used to prevent bacterial infection. Antibiotic resistance is one of the most serious concerns in world health. Antibacterial nanoparticles are one possible answer to antimicrobial resistance. These nanomaterials not only kill antibiotic-resistant bacteria through various modes of action but, they can also be employed in conjunction with existing clinically relevant antibiotics to help overcome antimicrobial resistance mechanisms. In this study, anodized titanium dioxide (TiO2 ) nanorods were treated hydrothermally with zinc oxide (ZnO) nanoparticles to give titanium (Ti) antibacterial properties. The antibacterial activity of synthesized samples was investigated by Agar Well Diffusion method at 40 mg/ml concentration, against gram negative Klebsiella pneumoniae. To determine the antibacterial activity, the diameter of the zone of inhibition was measured, and the resulting data were statistically analyzed. Zn/TiO2 nano particles were characterized by using X-ray diffraction (XRD) Analysis.
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Samoilova, Anna. "Effect of phages isolated from different sources against fire blight pathogen". In 5th International Scientific Conference on Microbial Biotechnology. Institute of Microbiology and Biotechnology, Republic of Moldova, 2022. http://dx.doi.org/10.52757/imb22.29.
Testo completoAbstract (sommario):
Fire blight of rosaceous plants is one of the economically most important diseases of fruit trees caused by the bacterium Erwinia amylovora. Plants are extremely vulnerable for fire blight infection at the bloom stage. Blossom blight can lead to the great crop losses and even the plant death. Since chemical treatments are forbidden in time of blossoming, bacteriophages, highly specific bacterial viruses could be used for the disease control. Being the natural components of ecosystems, phages infect only bacteria sensitive to them, are non-toxic to plants, animals and humans and are adapted to the bacteria environment. It has been shown that bacterium E. amylovora expresses its major pathogenicity factors during immature pear tissues infection. Therefore, in this study, the ability of four virulent E. amylovora bacteriophages, isolated from the aerial parts of the affected plants (phage isolate 1 from quince tissues; phage isolate 2 from hawthorn, Republic of Moldova) and from natural water reservoirs near fruits orchards or wild rosaceous trees (phage isolates 3 and 4, Swiss Confederation) to inhibit E. amylovora growth in the immature pear tissues was evaluated. Immature pear slices were inoculated with suspensions of E. amylovora CFBP1430 and EaM contained 104 CFU/ml. After four hours incubation in the humidified chamber at 280C infected immature pear slices were treated with 107 PFU/ml of phage isolates. Pear slices, treated with sterile distilled water were used as a control. Symptoms were recorded at 1, 2, 3, 5, 6, 7 and 8 days after inoculation. For each bacteria strain/phage isolate combination tested pear slices were assayed in triplicate and each experiment was repeated at least two times. Immature pear slices infected with bacteria EaM displayed the first symptoms of the fire blight, ooze formation and light necrosis, one day after inoculation. Pear slices, infected with E. amylovora CFBP1430 demonstrated ooze and necrosis two days after inoculation. In the bacteria/phage combinations the first symptoms of the fire blight appeared on the sixth day after inoculation in the variants of EaM/phage isolate 3 and CFBP1430/phage isolate 3. On the seventh and eighth days after inoculation symptoms of the fire blight infection have been recorded in the EaM/phage isolate 2 and CFBP1430/ phage isolate 2, respectively. Bacteria/phage combinations EaM/phage isolate 4 and CFBP1430/ phage isolate 4 showed disease symptoms on the seventh day after inoculation. Immature pear slices in the variants EaM/phage isolate 1 and CFBP1430/phage isolate 1 showed necrotic lesion eight days after inoculation. Thus, phage isolate 4, detected in water was able to suppress growth of phytopathogenic E. amylovora just a day less than highly virulent phage isolate 1 detected in the quince tissues. The conducted experiments have demonstrated that bacteriophages isolated from water revealed high efficacy against bacteria E. amylovora and all studied phage isolates successfully inhibited the fire blight causative agent growth in the plant host tissues for about seven days. Hence it has been shown that treatment with bacteriophages for the fire blight control in the fruit orchard should be carried out weekly if environmental conditions are favorable for the disease development.
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Terzić, Jelena, Marina Stanković e Olgica Stefanović. "ANTIBIOFILM ACTIVITY OF SELECTED PLANT SPECIES". In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.280t.
Testo completoAbstract (sommario):
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.
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Nonpanya, Nongyao, e Suwanna Niamsanit. "Efficiency of Streptomyces sp. RS2 Against Various Phyto-pathogenic Fungi and Human Pathogenic Bacteria". In Annual International Conference on Advances in Biotechnology (BIOTECH 2016). Global Science & Technology Forum (GSTF), 2016. http://dx.doi.org/10.5176/2251-2489_biotech16.12.
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Al-Asmar, Jawaher, Sara Rashwan e Layla Kamareddine. "The use of Drosophila Melanogaster as a Model Organism to study the effect of Bacterial Infection on Host Survival and Metabolism". In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0186.
Testo completoAbstract (sommario):
Enterobacteriaceae, a large family of facultative anaerobic bacteria, encloses a broad spectrum of bacterial species including Escherichia coli, Salmonella enterica, and Shigella sonnei, that produce enterotoxins and cause gastrointestinal tract diseases. While much is known about the regulation and function of enterotoxins within the intestine of the host; the lack of cheap, practical, and genetically tractable model organisms has restricted the investigation of others facets of this host-pathogen interaction. Our group, among others, has employed Drosophila melanogaster, as a model organism to shed more light on some aspects of host-pathogen interplays. In this project, we addressed the effect of Escherichia coli, Salmonella enterica, and Shigella sonnei infection on altering the metabolic homeostasis of the host. Drosophila melanogaster flies were orally infected with Escherichia coli, Salmonella enterica, or Shigella sonnei, a method that mimics the natural route used by enteric pathogens to gain access to the gastrointestinal tract in humans. The results of our study revealed that both Escherichia coli and Shigella sonnei pathogens were capable of colonizing the host gut, resulting in a reduction in the life span of the infected host. Escherichia coli and Shigella sonnei infected flies also exhibited altered metabolic profiles including lipid droplets deprivation from their fat body (normal lipid storage organ in flies), irregular accumulation of lipid droplets in their gut, and significant elevation of systemic glucose and triglyceride levels. These metabolic alterations could be mechanistically attributed to the differential down-regulation in the expression of metabolic peptide hormones (Allatostatin A, Diuretic hormone 31, and Tachykinin) detected in the gut of Escherichia coli and Shigella sonnei infected flies. Salmonella enterica; however, was unable to colonize the gut of the host; and therefore, Salmonella enterica infected flies exhibited a relatively normal metabolic status as that of non infected flies. Gaining a proper mechanistic understanding of infection-induced metabolic alterations helps in modulating the pathogenesis of gastrointestinal tract diseases in a host and opens up for promising therapeutic approaches for infection induced metabolic disorders
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Martín-González, A., M. T. García, C. Pelaz e J. C. Gutiérrez. "Microbial Pandora's box : Interactions of free living protozoa with human pathogenic bacteria". In Proceedings of the II International Conference on Environmental, Industrial and Applied Microbiology (BioMicroWorld2007). WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789812837554_0064.
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Issac, Linda Tracey, e P. Seedevi. "Antibacterial activity of ethanol extract from Tarenna asiatica against human pathogenic bacteria". In 2ND INTERNATIONAL INTERDISCIPLINARY SCIENTIFIC CONFERENCE ON GREEN ENERGY, ENVIRONMENTAL AND RENEWABLE ENERGY, ADVANCED MATERIALS, AND SUSTAINABLE DEVELOPMENT: ICGRMSD24, 020046. AIP Publishing, 2024. http://dx.doi.org/10.1063/5.0233369.
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Chaithanya, B. Sri, e P. Seedevi. "Antibacterial activity of methanolic extract from Derris scandens against human pathogenic bacteria". In 2ND INTERNATIONAL INTERDISCIPLINARY SCIENTIFIC CONFERENCE ON GREEN ENERGY, ENVIRONMENTAL AND RENEWABLE ENERGY, ADVANCED MATERIALS, AND SUSTAINABLE DEVELOPMENT: ICGRMSD24, 020104. AIP Publishing, 2024. http://dx.doi.org/10.1063/5.0233370.
Testo completoRapporti di organizzazioni sul tema "Human pathogenic bacterium"
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Coplin, David, Isaac Barash e Shulamit Manulis. Role of Proteins Secreted by the Hrp-Pathways of Erwinia stewartii and E. herbicola pv. gypsophilae in Eliciting Water-Soaking Symptoms and Initiating Galls. United States Department of Agriculture, giugno 2001. http://dx.doi.org/10.32747/2001.7580675.bard.
Testo completoAbstract (sommario):
Many bacterial pathogens of plants can inject pathogenicity proteins into host cells using a specialized type III secretion system encoded by hrpgenes. This system deliver effector proteins, into plant cells that function in both susceptible and resistant interactions. We have found that the virulence of Erwinia stewartii(Es; syn. Pantoea stewartii) and Erwinia herbicola pv. gypsophilae (Ehg, syn. Pantoea agglomerans), which cause Stewart's wilt of corn and galls on Gypsophila, respectively, depends on hrpgenes. The major objectives of this project were: To increase expression of hrpgenes in order to identify secreted proteins; to identify genes for proteins secreted by the type-III systems and determine if they are required for pathogenicity; and to determine if the secreted proteins can function within eukaryotic cells. We found that transcription of the hrp and effector genes in Es and Ehg is controlled by at least four genes that constitute a regulatory cascade. Environmental and/or physiological signaling appears to be mediated by the HrpX/HrpY two component system, with HrpX functioning as a sensor-kinase and HrpY as a response regulator. HrpYupregulateshrpS, which encodes a transcriptional enhancer. HrpS then activates hrpL, which encodes an alternate sigma factor that recognizes "hrp boxes". All of the regulatory genes are essential for pathogenicity, except HrpX, which appears only to be required for induction of the HR in tobacco by Es. In elucidating this regulatory pathway in both species, we made a number of significant new discoveries. HrpX is unusual for a sensor-kinase because it is cytoplasmic and contains PAS domains, which may sense the redox state of the bacterium. In Es, a novel methyl-accepting protein may function upstream of hrpY and repress hrp gene expression in planta. The esaIR quorum sensing system in Es represses hrp gene expression in Es in response to cell-density. We have discovered six new type III effector proteins in these species, one of which (DspE in Ehg and WtsE in Es) is common to both pathogens. In addition, Es wtsG, which is a homolog of an avrPpiB from P. syringae pv. pisi, and an Ehg ORF, which is a homolog of P. syringae pv. phaseolicola AvrPphD, were both demonstrated to encode virulence proteins. Two plasmidborne, Ehg Hop proteins, HsvG and PthG, are required for infection of gypsophilia, but interestingly, PthG also acts as an Avr elicitor in beets. Using a calmodulin-dependent adenylate cyclase (cyaA) reporter gene, we were successful in demonstrating that an HsvG-CyaA fusion protein can be transferred into human HeLa cells by the type-III system of enteropathogenic E. coli. This is a highly significant accomplishment because it is the first direct demonstration that an effector protein from a plant pathogenic bacterium is capable of being translocated into a eukaryotic cell by a type-III secretion system. Ehg is considered a limiting factor in Gypsophila production in Israel and Stewart’s Wilt is a serious disease in the Eastern and North Central USA, especially on sweet corn in epidemic years. We believe that our basic research on the characterization of type III virulence effectors should enable future identification of their receptors in plant cells. This may lead to novel approaches for genetically engineering resistant plants by modifying their receptors or inactivating effectors and thus blocking the induction of the susceptible response. Alternatively, hrp gene regulation might also provide a target for plant produced compounds that interfere with recognition of the host by the pathogen. Such strategies would be broadly applicable to a wide range of serious bacterial diseases on many crops throughout the USA and Israel.
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Cytryn, Eddie, Mark R. Liles e Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, gennaio 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
Testo completoAbstract (sommario):
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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Gillor, Osnat, Stefan Wuertz, Karen Shapiro, Nirit Bernstein, Woutrina Miller, Patricia Conrad e Moshe Herzberg. Science-Based Monitoring for Produce Safety: Comparing Indicators and Pathogens in Water, Soil, and Crops. United States Department of Agriculture, maggio 2013. http://dx.doi.org/10.32747/2013.7613884.bard.
Testo completoAbstract (sommario):
Using treated wastewater (TWW) for crop irrigation represents an important opportunity for ensuring adequate food production in light of growing freshwater scarcity worldwide. However, the environmentally sustainable approach of using TWW for irrigation can lead to contamination of produce with fecal pathogens that may remain in treated water. The overall goal of this research was to evaluate the correlation between the presence of fecal indicator bacteria (FIB) and that of a suite of human pathogens in TWW, the irrigated soil, and crops. Field experiments were conducted to compare secondary and tertiary TWW with dechlorinated tap water for irrigation of tomatoes, a typical commercial crop, in Israel, a semi-arid country. Human pathogens including bacteria (Salmonella), protozoa (Cryptosporidiumand Giardia), and viruses (Adenovirus [AV Types A, B, C & 40/41] and Enterovirus [EV71 subtypes]) were monitored in two field trials using a combination of microscopic, cultivation-based, and molecular (qPCR) techniques. Results from the field trials indicate that microbial contamination on the surface of tomatoes did not appear to be associated with the source of irrigated waters; FIB contamination was not statistically different on tomatoes irrigated with TWW as compared to tomatoes irrigated with potable water. In fact, Indicator bacteria testing did not predict the presence of pathogens in any of the matrices tested. High concentrations of FIB were detected in water and on tomato surfaces from all irrigation treatment schemes, while pathogen contamination on tomato surfaces (Cryptosporidiumand Salmonella) was only detected on crops irrigated with TWW. These results suggest that regular monitoring for pathogens should take place to accurately detect presence of harmful microorganisms that could threaten consumer safety. A notable result from our study is that the large numbers of FIB in the water did not appear to lead to FIB accumulation in the soil. With the exception of two samples, E. coli that was present at 10³ to 10⁴ cells/100 mL in the water, was not detected in the soil. Other bacterial targets associated with the enteric environment (e. g., Proteusspp.) as well as protozoal pathogens were detected in the TWW, but not in the soil. These findings suggest that significant microbial transfer to the soil from TWW did not occur in this study. The pattern of FIB contamination on the surfaces of tomatoes was the same for all treatment types, and showed a temporal effect with more contamination detected as the duration of the field trial increased. An important observation revealed that water quality dramatically deteriorated between the time of its release from the wastewater treatment plant and the time it was utilized for irrigation, highlighting the importance of performing water quality testing throughout the growing season at the cultivation site.
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James, Christian, Ronald Dixon, Luke Talbot, Stephen James, Nicola Williams e Bukola Onarinde. Assessing the impact of heat treatment on antimicrobial resistant (AMR) genes and their potential uptake by other ‘live’ bacteria. Food Standards Agency, agosto 2021. http://dx.doi.org/10.46756/sci.fsa.oxk434.
Testo completoAbstract (sommario):
Addressing the public health threat posed by AMR is a national strategic priority for the UK, which has led to both a 20-year vision of AMR and a 5-year (2019 to 2024) AMR National Action Plan (NAP). The latter sets out actions to slow the development and spread of AMR with a focus on antimicrobials. The NAP used an integrated ‘One-Health’ approach which spanned people, animals, agriculture and the environment, and calls for activities to “identify and assess the sources, pathways, and exposure risks” of AMR. The FSA continues to contribute to delivery of the NAP in a number of ways, including through furthering our understanding of the role of the food chain and AMR.Thorough cooking of food kills vegetative bacterial cells including pathogens and is therefore a crucial step in reducing the risk of most forms of food poisoning. Currently, there is uncertainty around whether cooking food is sufficient to denature AMR genes and mobile genetic elements from these ‘dead’ bacteria to prevent uptake by ‘live’ bacteria in the human gut and other food environments - therefore potentially contributing to the overall transmission of AMR to humans. This work was carried out to assess these evidence gaps.
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Splitter, Gary A., Menachem Banai e Jerome S. Harms. Brucella second messenger coordinates stages of infection. United States Department of Agriculture, gennaio 2011. http://dx.doi.org/10.32747/2011.7699864.bard.
Testo completoAbstract (sommario):
Aim 1: To determine levels of this second messenger in: a) B. melitensiscyclic-dimericguanosinemonophosphate-regulating mutants (BMEI1448, BMEI1453, and BMEI1520), and b) B. melitensis16M (wild type) and mutant infections of macrophages and immune competent mice. (US lab primary) Aim 2: To determine proteomic differences between Brucelladeletion mutants BMEI1453 (high cyclic-dimericguanosinemonophosphate, chronic persistent state) and BMEI1520 (low cyclicdimericguanosinemonophosphate, acute virulent state) compared to wild type B. melitensisto identify the role of this second messenger in establishing the two polar states of brucellosis. (US lab primary with synergistic assistance from the Israel lab Aim 3: Determine the level of Brucellacyclic-dimericguanosinemonophosphate and transcriptional expression from naturally infected placenta. (Israel lab primary with synergistic assistance from the US lab). B. Background Brucellaspecies are Gram-negative, facultative intracellular bacterial pathogens that cause brucellosis, the most prevalent zoonosis worldwide. Brucellosis is characterized by increased abortion, weak offspring, and decreased milk production in animals. Humans are infected with Brucellaby consuming contaminated milk products or via inhalation of aerosolized bacteria from occupational hazards. Chronic human infections can result in complications such as liver damage, orchitis, endocarditis, and arthritis. Brucellaspp. have the ability to infect both professional and non-professional phagocytes. Because of this, Brucellaencounter varied environments both throughout the body and within a cell and must adapt accordingly. To date, few virulence factors have been identified in B. melitensisand even less is known about how these virulence factors are regulated. Subsequently, little is known about how Brucellaadapt to its rapidly changing environments, and how it alternates between acute and chronic virulence. Our studies suggest that decreased concentrations of cyclic dimericguanosinemonophosphate (c-di-GMP) lead to an acute virulent state and increased concentrations of c-di-GMP lead to persistent, chronic state of B. melitensisin a mouse model of infection. We hypothesize that B. melitensisuses c-di-GMP to transition from the chronic state of an infected host to the acute, virulent stage of infection in the placenta where the bacteria prepare to infect a new host. Studies on environmental pathogens such as Vibrio choleraeand Pseudomonas aeruginosasupport a mechanism where changes in c-di-GMP levels cause the bacterium to alternate between virulent and chronic states. Little work exists on understanding the role of c-di-GMP in dangerous intracellular pathogens, like Brucellathat is a frequent pathogen in Israeli domestic animals and U.S. elk and bison. Brucellamust carefully regulate virulence factors during infection of a host to ensure proper expression at appropriate times in response to host cues. Recently, the novel secondary signaling molecule c-di-GMP has been identified as a major component of bacterial regulation and we have identified c-di-GMP as an important signaling factor in B. melitensishost adaptation. C. Major conclusions, solutions, achievements 1. The B. melitensis1453 deletion mutant has increased c-di-GMP, while the 1520 deletion mutant has decreased c-di-GMP. 2. Both mutants grow similarly in in vitro cultures; however, the 1453 mutant has a microcolony phenotype both in vitro and in vivo 3. The 1453 mutant has increased crystal violet staining suggesting biofilm formation. 4. Scanning electron microscopy revealed an abnormal coccus appearance with in increased cell area. 5. Proteomic analysis revealed the 1453 mutant possessed increased production of proteins involved in cell wall processes, cell division, and the Type IV secretion system, and a decrease in proteins involved in amino acid transport/metabolism, carbohydrate metabolism, fatty acid production, and iron acquisition suggesting less preparedness for intracellular survival. 6. RNAseq analysis of bone marrow derived macrophages infected with the mutants revealed the host immune response is greatly reduced with the 1453 mutant infection. These findings support that microlocalization of proteins involved in c-di-GMP homeostasis serve a second messenger to B. melitensisregulating functions of the bacteria during infection of the host.
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Brandl, Maria T., Shlomo Sela, Craig T. Parker e Victor Rodov. Salmonella enterica Interactions with Fresh Produce. United States Department of Agriculture, settembre 2010. http://dx.doi.org/10.32747/2010.7592642.bard.
Testo completoAbstract (sommario):
The emergence of food-borne illness outbreaks linked to the contamination of fruits and vegetables is a great concern in industrialized countries. The current lack of control measures and effective sanitization methods prompt the need for new strategies to reduce contamination of produce. Our ability to assess the risk associated with produce contamination and to devise innovative control strategies depends on the identification of critical determinants that affect the growth and the persistence of human pathogens on plants. Salmonella enterica, a common causal agent of illness linked to produce, has the ability to colonize and persist on plants. Thus, our main objective was to identify plant-inducible genes that have a role in the growth and/or persistence of S. enterica on postharvest lettuce. Our findings suggest that in-vitro biofilm formation tests may provide a suitable model to predict the initial attachment of Salmonella to cut-romaine lettuce leaves and confirm that Salmonella could persist on lettuce during shelf-life storage. Importantly, we found that Salmonella association with lettuce increases its acid-tolerance, a trait which might be correlated with an enhanced ability of the pathogen to pass through the acidic barrier of the stomach. We have demonstrated that Salmonella can internalize leaves of iceberg lettuce through open stomata. We found for the first time that internalization is an active bacterial process mediated by chemotaxis and motility toward nutrient produced in the leaf by photosynthesis. These findings may provide a partial explanation for the failure of sanitizers to efficiently eradicate foodborne pathogens in leafy greens and may point to a novel mechanism utilized by foodborne and perhaps plant pathogens to colonize leaves. Using resolvase in vivo expression technology (RIVET) we have managed to identify multiple Salmonella genes, some of which with no assigned function, which are involved in attachment to and persistence of Salmonella on lettuce leaves. The precise function of these genes in Salmonella-leaf interactions is yet to be elucidated. Taken together, our findings have advanced the understanding of how Salmonella persist in the plant environment, as well as the potential consequences upon ingestion by human. The emerging knowledge opens new research directions which should ultimately be useful in developing new strategies and approaches to reduce leaf contamination and enhance the safety of fresh produce.
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Cahaner, Avigdor, Susan J. Lamont, E. Dan Heller e Jossi Hillel. Molecular Genetic Dissection of Complex Immunocompetence Traits in Broilers. United States Department of Agriculture, agosto 2003. http://dx.doi.org/10.32747/2003.7586461.bard.
Testo completoAbstract (sommario):
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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Noga, Edward J., Angelo Colorni, Michael G. Levy e Ramy Avtalion. Importance of Endobiotics in Defense against Protozoan Ectoparasites of Fish. United States Department of Agriculture, settembre 2003. http://dx.doi.org/10.32747/2003.7586463.bard.
Testo completoAbstract (sommario):
Infectious disease is one of the most serious causes of economic loss in all sectors of aquaculture. There is a critical need to understand the molecular basis for protection against infectious disease so that safer, more reliable and more cost-effective strategies can be designed for their control. As part of this effort, the major goal of our BARD project was to determine the importance of endobiotics as a defense against protozoan ectoparasites in fish. Endobiotics, or antimicrobial polypeptides, are peptides and small proteins that are increasingly recognized as having a vital role in the innate defense of virtually all animals. One objective of our BARD project was to determine the antiparasitic potency of one specific group of endobiotics that were isolated from hybrid striped bass (Morone saxatilis x M chrysops). We found that these endobiotics, which we had previously named histone-like proteins (HLPs), exhibited potent activity against Amyloodinium and that the putative levels of HLPs in the skin were well within the levels that we found to be lethal to the parasite in vitro. We also found evidence for the presence of similar antibiotics in sea bream (Sparus aurata) and Mediterranean sea bass (Dicentrarchus labrax). We also examined the effect of chronic stress on the expression of HLP in fish and found that HLP levels were dramatically decreased after only one week of a crowding/high ammonia sublethal stress. We also began to explore the feasibility of upregulating endobiotics via immunostimulation. However, we did not pursue this objective as fully as we originally intended because we spent a much larger effort than originally anticipated on the last objective, the attempted isolation of novel endobiotics from hybrid striped bass. In this regard, we purified and identified four new peptide endobiotics. These endobiotics, which we have named piscidins (from "Pisces" meaning fish), have potent, broad-spectrum activity against a number of both fish and human pathogens. This includes not only parasites but also bacteria. We also demonstrated that these peptides are present in the mast cell. This was the first time that the mast cell, the most common tissue granulocyte in vertebrates, was shown to possess any type of endobiotic. This finding has important implications in explaining the possible function of mast cells in the immune response of vertebrates. In summary, the research we have accomplished in this BARD project has demonstrated that endobiotics in fish have potent activity against many serious pathogens in aquaculture and that there is considerable potential to use these compounds as stress indicators in aquaculture. There is also considerable potential to use some of these compounds in other areas of medicine, including treatment of serious infectious diseases of humans and animals.