Dissertations / Theses on the topic 'Antimicrobial infections'
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Baelo, Álvarez Aida. "New antimicrobial strategies against bacterial infections." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673587.
Full textIrom, Sara Julie. "High Dose Antimicrobial Protocols for Canine Urinary Tract Infections." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274464691.
Full textBraithwaite, M., Vuuren SF Van, and AM Viljoen. "Validation of smoke inhalation therapy to treat microbial infections." Elsevier, 2008. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000386.
Full textTrienekens, Theodora Antoinetta Maria. "Urinary tract infections and antimicrobial agents A study into factors influencing the efficacy of antimicrobial agents /." Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1993. http://arno.unimaas.nl/show.cgi?fid=5757.
Full textSmith, Sharon Phillips. "Community-acquired Urinary Tract Infections| Treatment, Outcomes, and Antimicrobial Resistance." Thesis, University of California, Berkeley, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3616604.
Full textCommunity-acquired urinary tract infections (CA-UTI) are common in young women. Reports of increasing resistance to the antimicrobial drugs commonly prescribed to treat CA-UTI, evidence of wide-spread dissemination of strains of multi-drug resistant i that can cause community outbreaks and expanding appreciation of the importance of the rational use of antibiotics are challenging the traditional management of this disease.
Two population-based studies were performed to investigate the epidemiological features of CA-UTI with an emphasis on the antimicrobial resistance of causative bacteria. An eight-year retrospective cohort study was conducted in a large health maintenance organization to identify changes in uropathogen etiology and antimicrobial resistance and in empirical antimicrobial treatment practices and outcomes. A cross-sectional study was performed in a university population to investigate the relationship between changes in the prevalence of genotype-based clonal groups of uropathogen E. coli and the prevalence of antimicrobial resistance.
From 1998 through 2005, less than 20% of the Escherichia coli causing uncomplicated CA-UTI (UCA-UTI) were resistant to the first line empirical treatment antimicrobial, trimethoprim/sulfamethoxazole (TMP/SMX). No trends were detected in the proportions of Escherichia coli that were resistant to TMP/SMX or to nitrofurantoin. In contrast, a small but steady increase in the proportion of Escherichia coli that were resistant to ciprofloxacin was observed. Over the same period of time, the use of ciprofloxacin as empirical treatment for UCA-UTI steadily increased while the use of TMP/SMX decreased. No sustained decreases in treatment failure or in microbiologically incompatible treatment were detected. Thus TMP/SMX remains a viable empirical treatment for women with UCA- UTI in these populations. Molecular typing of Escherichia coli causing CA-UTI revealed that the prevalence of antimicrobial resistance was influenced by a small number of Escherichia coli clonal groups. This suggests that the prevalence of antimicrobial resistant UTI in a community is not only the result of community prescribing practices and individual antimicrobial use but can be significantly impacted by the introduction and circulation of strains of uropathogens that are already drug resistant. Thus, strategies developed to maintain the usefulness of empirical treatment options for CA-UTI must include interventions that target sources of antimicrobial resistant uropathogens.
Fasugba, Oyebola. "Antimicrobial resistance in urinary tract infections caused by Escherichia coli." Thesis, Australian Catholic University, 2017. https://acuresearchbank.acu.edu.au/download/67ce6b272ae23ebc1ea1e8727d748f9cc7a61a59c3d5c0c98d2d1d0350c55a51/5885672/Fasugba_2017_Antimicrobial_resistance_in_urinary_tract_infections.pdf.
Full textBendall, J. B. "Bacterial resistance to antimicrobial agents in geriatric medical wards." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381441.
Full textPowis, Samantha. "Chlorine Dioxide for the Prevention of Biomaterial-Associated Infections." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1307%5F1%5Fm.pdf&type=application/pdf.
Full textTassev, Dimiter V. "Antimicrobial susceptibility testing of novel anticancer derivatives against infectious bacteria for the potential minimization of nosocomial infections." Connect to resource, 2006. http://hdl.handle.net/1811/6457.
Full textTitle from first page of PDF file. Document formatted into pages: contains 27 p.; also includes graphics. Includes bibliographical references (p. 24-27). Available online via Ohio State University's Knowledge Bank.
More, G. K. (Garland Kgosi). "Antimicrobial constituents of Artemisia afra Jacq. ex Willd. against periodontal pathogens." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/24659.
Full textDissertation (MSc)--University of Pretoria, 2012.
Plant Science
unrestricted
Lo, Joey Chor Yee. "Novel antimicrobial peptide coating to prevent catheter-associated urinary tract infections." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/56262.
Full textMedicine, Faculty of
Medicine, Department of
Experimental Medicine, Division of
Graduate
Halstead, Fenella. "Developing novel topical antimicrobial agents for the treatment of biofilm infections." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/101063/.
Full textBezruk, Т. О., and V. V. Bezruk. "Etiological structure and antimicrobial resistance in pathogens causing urinary tract infections." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47823.
Full textPhee, Lynette. "Unorthodox antimicrobial combination therapies for the treatment of multi-drug resistant Gram-negative infections." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/44695.
Full textIronmonger, Dean. "An investigation into the relationship between antimicrobial prescribing and antimicrobial resistance in urinary tract infections at a population level." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8531/.
Full textMottola, Carla. "Virulence characterization and antimicrobial resistance of major bacterial genera from diabetic foot infections." Doctoral thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/14119.
Full textDiabetes mellitus is a major chronic disease that continues to increase significantly. One of the most important and costly complications of diabetes is the development of foot ulcers, colonized by pathogenic and antimicrobial resistant bacteria, which may be responsible for impairing its successful treatment. Diabetic foot ulcer (DFU) bacterial communities can be organized in polymicrobial biofilms, which may be responsible for its chronicity. The ability of these communities to produce biofilm was evaluated and was higher when compared to biofilm formation by individual species. Staphylococcus aureus is one of the most prevalent species in diabetic foot infections (DFI). Staphylococci isolated from DFU in patients from the Lisbon area were identified, genotyped and screened for virulence and antimicrobial resistance traits. The isolates showed high genomic diversity, were resistant to important clinically antibiotics and expressed relevant virulence determinants. As biofilm formation is one of the most important virulence traits of S. aureus, the antimicrobial susceptibility patterns of biofilm-producing S. aureus strains were also analysed. The minimum biofilm inhibitory and eradication concentrations were determined for ten antimicrobial compounds. Staphylococci biofilms were resistant to antibiotic concentrations ten to thousand times higher than those effective for planktonic cells. Furthermore, the enterococci frequently isolated from DFI, were also identified and characterized, showing high antimicrobial resistance and important virulence traits. Since DFI are often caused by resistant bacteria, it is necessary to find alternatives to antibiotic therapy, such as phage therapy. The inhibitory potential of five bacteriophages, previously characterized, was evaluated against established biofilms formed by S. aureus, P. aeruginosa and A. baumannii. A significant cell reduction after phage exposure was observed, mainly after multiple treatments. DFI are very complex and studies on this topic are scarce. It is necessary to intensify research in order to develop more adequate therapeutic protocols for this type of infection.
RESUMO - Caracterização da virulência e resistência a antimicrobianos dos principais géneros bacterianos envolvidos em infeções de pé diabético - Diabetes mellitus é uma doença crónica com grande impacto em saúde pública e cuja incidência continua a aumentar significativamente em todo o mundo, atingindo atualmente mais de 400 milhões de pessoas. Uma das complicações mais importantes da diabetes e associada a gastos económicos significativos são as úlceras de pé diabético. Uma vez que a camada protetora de pele é danificada, os tecidos profundos ficam expostos à infeção bacteriana, a qual pode evoluir rapidamente. As infeções das úlceras de pé diabético são a causa mais comum de internamento hospitalar de pacientes diabéticos e uma importante causa de morbilidade, levando frequentemente à amputação dos membros inferiores. Estas infeções podem ser promovidas por bactérias potencialmente patogénicas e resistentes aos compostos antimicrobianos, prejudicando assim o sucesso do tratamento. As comunidades bacterianas presentes nas úlceras podem estar organizadas em biofilmes polimicrobianos, que contribuem para que as infeções se tornem crónicas e muito difíceis de resolver. Foi avaliada a capacidade de produção de biofilme por comunidades polimicrobianas de isolados bacterianos de pé diabético, utilizando um ensaio de microtitulação em placa com “Alamar Blue” (AB) e uma técnica de Hibridação In Situ Fluorescente Múltipla (MFISH). Esta avaliação foi realizada em três períodos de incubação distintos (24, 48 e 72 horas), depois da determinação da capacidade de formação de biofilme por 95 isolados de úlceras de pé diabético pertencentes a vários géneros bacterianos (Staphylococcus, Corynebacterium, Enterococcus, Pseudomonas e Acinetobacter). Todos os isolados apresentaram a capacidade de produzir biofilme às 24 horas, sendo que a quantidade de biofilme produzido aumentou com o tempo de incubação. Pseudomonas apresentou a capacidade mais elevada de produção de biofilme, seguida de Corynebacterium, Acinetobacter, Staphylococcus e por fim, Enterococcus. Foram encontradas diferenças estatisticamente significativas na capacidade de formação de biofilme entre os três períodos de incubação. As comunidades polimicrobianas produziram mais biofilme do que as espécies individualmente. As comunidades formadas por Pseudomonas + Enterococcus, Staphylococcus + Acinetobacter e Corynebacterium + Staphylococcus formaram mais biofilme do que as comunidades formadas por Enterococcus + Staphylococcus e por Enterococcus + Corynebacterium. O comportamento biológico das diferentes espécies bacterianas nos biofilmes polimicrobianos tem implicações clínicas muito importantes para o sucesso do tratamento deste tipo de infeções. A sinergia entre as bactérias presentes em biofilmes multiespécies foi descrita previamente, sendo que este trabalho representa o primeiro estudo sobre a evolução temporal da formação de biofilme por parte de comunidades polimicrobianas isoladas de úlceras de pé diabético, incluindo várias espécies. [...]
Centro de Investigação Interdisciplinar em Sanidade Animal” (CIISA) of Faculty of Veterinary Medicine, University of Lisbon, Portugal
N/A
Chu, Pui-shan, and 朱佩珊. "Antimicrobial resistant escherichia coli and sequence type 131 in urinary tract infections." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206499.
Full textpublished_or_final_version
Medical Sciences
Master
Master of Medical Sciences
Raja, Farah. "Development and characterisation of novel antimicrobial phosphate glasses for urinary tract infections." Thesis, Aston University, 2018. http://publications.aston.ac.uk/37661/.
Full textCzuban, Magdalena Anna [Verfasser]. "Antimicrobial biomaterials for treatment of bone and implant infections / Magdalena Anna Czuban." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1215572069/34.
Full textCarzoli, Joshua, and Cody Thompson. "A systematic review of pharmacotherapy for diabetic foot infections." The University of Arizona, 2010. http://hdl.handle.net/10150/623762.
Full textOBJECTIVES:The main purpose of this study was to review recent and good quality studies of the antimicrobial therapy of for moderate to severe (“limb threatening”) DFI. The analysis of these studies was to conclude with one or two “standard” approach to the routine management of this clinical entity. METHODS: This literature review study consisted of an evaluation of clinical trials that compare two or more active systemic antimicrobial regimens for the treatment of moderate to severe (i.e., “limb-threatening”) diabetic foot infections in human patients. Literature sources were identified primarily from OVID MEDLINE, but also included additional tertiary sources. The primary criteria for the clinical studies were: prospective, controlled, randomized and investigator blinded. Studies had to be published after the year 2003, and be available in full-text in English. RESULTS: Ultimately, only four studies were found that met the criteria for consideration. Trials differed in numerous features. All four studies were sponsored by the manufacturer of one of the comparator drugs. Three of the four were non-inferiority design. Evidence is lacking that any of the suggested regimens are superior. CONCLUSIONS: Instead of meeting our original goal of concluding that one or two regimens could be the “standard” management of DFI, we were limited to commentary on the quality and applicability of the current literature on this clinical entity. Numerous suggestions for improvement in the clinical information provided by DFI studies were offered. We eagerly anticipate the publication of the updated IDSA guideline document on DFI.
Gharse, Sachin. "Antibacterial strategies for improved eradication of Pseudomonas aeruginosa infections." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6110.
Full textPegg, Elaine. "Eimeria species as novel antimicrobial vaccine delivery vectors." Thesis, Royal Veterinary College (University of London), 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.701658.
Full textBeaumont, Paula Elizabeth. "Cathelicidin and its role in defence against bacterial infections of epithelial cells." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/15847.
Full textHuh, Youchin, and Tina Wang. "Appropriateness of Antimicrobial Therapy for Bloodstream Infection based on Reporting Conditions with a Rapid Species Identification Assay." The University of Arizona, 2012. http://hdl.handle.net/10150/623644.
Full textSpecific Aims: The primary aim of this study was to determine the time to appropriate therapy for all patients with candidemia and/or bacteriemia (due to either Enterococcus or Streptococcus species) during a one year period in relation to time of blood culture, time of Gram-stain result, time of PNA FISH species result, and time of final species determination result. The secondary and third aims were to compare the time to appropriate therapy based on clinician group that was notified of Gram-stain result and PNA FISH result and compare the time to appropriate therapy based on PNA FISH assay results reported during the day and night microbiology laboratory shifts. Methods: This Institutional Review Board approved project is a retrospective, chart review evaluation of the 24 hour/ 7 days a week use of PNA FISH assays with therapeutic interventions by infectious diseases pharmacists and physicians on patient outcome measures and time to appropriate therapy. All patients admitted to an academic medical center during a one year period (April 2010-March 2011) with either Enterococcus, Streptococcus, or Candida species isolated from blood were included. Main Results: A total of 168 subjects were identified with Candida species isolated from 31 subjects and Enterococcus/Streptococcus species isolated from blood in 137 subjects. Conclusions: While reporting conditions can affect interpretation and intervention rates, rapid species identification assays such as PNA FISH can be used by pharmacists to provide antimicrobial therapy recommendations based on the species identification and to decrease the time to appropriate antimicrobial therapy.
Sartelli, Massimo, Francesco M. Labricciosa, Pamela Barbadoro, Leonardo Pagani, Luca Ansaloni, Adrian J. Brink, Jean Carlet, et al. "The Global Alliance for Infections in Surgery: defining a model for antimicrobial stewardship—results from an international cross-sectional survey." BIOMED CENTRAL LTD, 2017. http://hdl.handle.net/10150/625526.
Full textCassin, Margaret Emily. "The Design of Antimicrobial Detachable Thin Films for the Study of Hepatic Infections." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/77426.
Full textMaster of Science
Omar, G. S. M. "Killing of organisms responsible for wound infections using a light-activated antimicrobial agent." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19414/.
Full textAdukwu, Emmanuel. "Investigating physiological and genetic characteristics of community acquired infections and potential antimicrobial interventions." Thesis, University of Northampton, 2013. http://nectar.northampton.ac.uk/8842/.
Full textVuori-Holopainen, Elina. "Etiology and antimicrobial treatment of pneumonia and other common childhood infections warranting hospitalization." Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/vuori-holopainen/.
Full textMatougui, Nada. "Development and characterization of antimicrobial peptides loaded lipid nanocapsules to treat bacterial infections." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0069.
Full textThe rapid increase in drug-resistant infections presents an acute problem in the healthcare sector, generating interest in novel antimicrobial strategies. The aim of this work is to explore the potential of lipid nanocapsules (LNCs) for Antimicrobial peptides (AMPs) delivery. Firstly, the experiments were focused on the development and optimization of AMP-loaded LNCs. Different strategies were investigated to deliver AA230,LL37 and DPK060 using LNCs (peptides adsorption atthe surface or encapsulated in the core of modified LNCs). The results demonstrated an association efficiency of 20 to 40%, when peptide is adsorbed, and over 80% encapsulation efficiency, when peptides are encapsulated. The second part concerned the study ofthe influence of peptides loading on their activity and stability against proteases. The results showed that peptides adsorption induced a potentiation of the antimicrobial activity of the native peptides, with a partial protection against proteolytic degradation. Conversely, peptides encapsulation allowed better peptide stability, correlated with higher encapsulation efficiencies and a preservation of the in vitro antimicrobial activity. In a third part, the mechanisms involved in LNC/AMP interactions and the complex interaction with model bacterial membrane have been evaluated. It has shown that structure and flexibility at solid-liquid interfaces govern peptide adsorption on the surface of the LNCs, which in turn is expected to change LNCs properties and interaction with bacterial membranes. Taken together, these results demonstrate the potential of LNCto deliver AMPs as an alternative anti-infective therapy
Ma, Menghan. "Local delivery of antimicrobial peptides using self-organized TiO₂ nanotubes for implant-related infections." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/30508.
Full textSakko, M. (Marjut). "Antimicrobial activity and suitability of 2-hydroxyisocaproic acid for the treatment of root canal infections." Doctoral thesis, Oulun yliopisto, 2016. http://urn.fi/urn:isbn:9789526211046.
Full textTiivistelmä Hampaan juurikanavan mikrobi-infektio aiheuttaa apikaalisen parodontiitin eli tulehdusreaktion juuren kärjen läheisyydessä oleviin kudoksiin. Silloin, kun infektio ei parane hoidon jälkeen, Enterococcus faecalis on yleisin löydös. Jos kalsiumhydroksidilääkitys ei ole tehokas, hoitoon suositellaan huolellista desinfektiohuuhtelua ja uusittavaa lyhytkestoista klooriheksidiinilääkitystä. Juurikanavainfektioiden hoitoon tarvitaan uusia antimikrobiaineita, joilla on pitkäaikainen vaikutus. Lactobacillus-bakteerit tuottavat proteiiniaineenvaihdunnassa 2-hydroksi-isokapronihappoa eli HICAa, jonka metaboloimiseen tarvittavia entsyymejä tunnetaan vain muutamilla muilla bakteereilla. Ihmissolut metaboloivat ja käyttävät sitä proteiinituotantoon. Se on hyvin siedetty aine ja se lieventää tulehdusreaktiota. Tutkimuksen hypoteesina oli, että HICA vaikuttaa mikrobien aineenvaihduntaan ja se voisi olla mahdollinen uusi antimikrobiaine. Tässä tutkimuksessa HICAn antimikrobitehoa tutkittiin bakteereita ja sienilajeja vastaan pienerälaimennusmenetelmällä tehdyissä herkkyystesteissä. Sen soveltuvuutta hampaiden juurikanavainfektioiden hoitoon arvioitiin dentiinin läsnäollessa sekä potilailta poistetuissa ja kokeellisesti infektoiduissa hampaissa. Tulokset osoittavat, että HICA tappaa laajakirjoisesti gram-positiivisia ja gram-negatiivisia bakteereita sekä hiivoja ja muita sienilajeja. Dentiinin vaikutus HICAn antimikrobitehoon on vähäinen. Sen vaikutus E. faecalista vastaan poistettujen hampaiden juurikanavissa on viikon jälkeen yhtä hyvä tai parempi kuin nykyisten lääkeaineiden vaikutus. Laajakirjoisen, pitkäkestoisen antimikrobitehon ja anti-inflammatorisuuden vuoksi HICA voisi olla uusi vaihtoehto juurikanavainfektioiden hoitoon. HICAn kliinisen tehokkuuden arviointiin tarvitaan kontrolloituja kliinisiä tutkimuksia
Kazemzadeh-Narbat, Mehdi. "Local delivery of antimicrobial peptides from titanium surface for the prevention of implant-associated infections." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44017.
Full textRavensdale, Joshua Thomas. "Investigations into the therapeutic potential of antimicrobial peptides: applications for treating topical Staphylococcus aureus infections." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/870.
Full textTrinkle, Mara. "The Inhibitory Effects of an Antimicrobial Gel on the Staphylococcus Species." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/honors/540.
Full textPhathekile, Bonke. "Synthesis of peptide-loaded chitosan nanoparticles for the treatment of sexually transmitted infections (STI’s)." University of Western Cape, 2019. http://hdl.handle.net/11394/7726.
Full textPeptides are among the main drugs which attract much attention because of their great potential in treating sexually transmitted diseases and other chronic diseases. There has been a major challenge of delivering these drugs in mucosal sites with low pH environment. The aim of this study is to synthesize acidic pH stable peptide loaded chitosan nanoparticles gels that could penetrate mucus layers covering the epithelial cells and kill HIV virus. Chitosan nanoparticles were synthesized by crosslinking method called Ionic gelation with Sodium tripolyphosphateTPP.
2023
Jooste, Marius Johannes. "The in vitro antimicrobial activity of amikacin and ceftazidime against multiple resistant gram-negative bacilli in nosocomial infections." Thesis, Cape Town : Cape Technikon, 1988. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1018&context=td_ctech.
Full textRamos, Martín V. "Optimization of antimicrobial therapy for Gram-positive bacterial infections in children using a translational pharmacological approach." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3008292/.
Full textLieberman, Mia Tova Rock. "Characterization of polymicrobial infections in macaques with chronic cranial implants and evaluation of alternative antimicrobial strategies." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120910.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 221-242).
Macaques are the most commonly used non-human primate in cognitive neuroscience research due to similarities between the macaque and human brain. Cephalic recording chambers (CRCs) are often surgically implanted to obtain neuronal recordings. CRCs represent a persistent source of microbial contamination, which can occasionally progress to clinical sequelae of meningitis and brain abscesses. In this thesis, we first examined aerobic and anaerobic bacterial species colonizing CRCs using both traditional culture-dependent methods and 16S microbiota culture-independent methods. We evaluated the most prevalent species, and compared CRC bacterial communities to skin, oral and fecal bacterial communities. Our results indicated that CRC bacterial communities are predominantly composed of anaerobic flora and are relatively unique between individual macaques. Additionally CRC bacterial communities are more similar to skin and oral bacterial communities than fecal bacterial communities, indicating that fecal contamination of CRCs is a less likely source of contamination. Aerobic culture and sensitivity data from samples collected in 2011 identified Staphylococcus aureus, Enterococcus faecalis and Proteus spp. as the most prevalent species isolated, and that E.faecalis isolates displayed marked resistance to multiple antimicrobial classes. Routine CRC sanitization procedures were revised in September 2014 to prohibit antimicrobial use within CRCs, and we evaluated how E.faecalis lineages persisted and evolved between 2011 and 2017. We identified a shift in sequence type (ST) from ST4 and ST55, predominating in 2011, to ST48 predominating in macaques implanted after 2013. ST48 lineages were less resistant to antimicrobials and stronger biofilm producers as compared to ST4 and ST55 lineages. We concluded that loss of selective pressure from antimicrobial use within CRCs permitted ST48 to emerge as the predominant lineage due to its strong biofilm-forming abilities. Finally, we evaluated alternative E.faecalis biofilm treatment strategies. We isolated lytic bacteriophages with activity against ST55 E.faecalis and evaluated the use of phages and antimicrobial peptides LL-37 and PR-39 against E. faecalis biofilm, alone, and in combination with antimicrobials. Our results identified that bacteriophages successfully decreased biofilm produced by ST55 and ST4 E. faecalis isolates and should be evaluated further for treatment of animal and human enterococcal-associated biofilm infections.
by Mia Tova Rock Lieberman.
Ph. D.
Santos, Tânia Raquel Martins dos. "Novel therapeutic strategies for the management of diabetic foot infections : the evaluation of selected antimicrobial peptides against clinically isolated bacterial pathogens." Doctoral thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2020. http://hdl.handle.net/10400.5/20150.
Full textDiabetic foot infections (DFIs) are a frequent complication of Diabetes mellitus. These ulcers are prone to be colonized by Staphylococcus aureus and Pseudomonas aeruginosa, including multidrug resistant and biofilm-producing strains, possibly leading to DFI chronicity and amputation. New therapeutic strategies for DFI management are urgent and the antimicrobial peptides (AMPs) nisin and pexiganan are potential candidates. This project aimed to evaluate the activity of these AMPs, incorporated in a guar gum biogel, against selected DFI clinical isolates. Firstly, nisin’s activity against a collection of S. aureus DFI clinical isolates was determined. Results showed that nisin was able to inhibit and eradicate S. aureus planktonic and biofilm cells at concentrations below its acceptable daily intake. When incorporated in the biogel, nisin kept its antimicrobial activity. This work also evaluated the potential of nisin to complement the activity of conventional antiseptics and antibiotics against established biofilms formed by these isolates. An in vitro antimicrobial schematic protocol was developed to mimetize DFI management guidelines. Fifteen antimicrobial combinations, including nisin-biogel, chlorhexidine, clindamycin, gentamicin and vancomycin, were tested. Results showed that the higher levels of biofilm inhibitory effects were presented by therapeutic combinations that included the nisin-biogel formulation. Nisin-biogel ideal storage conditions and cytotoxicity were also evaluated. Results demonstrate that if stored at temperatures between -20 and 22ºC, nisin-biogel is able to maintain its antimicrobial activity up to 24 months. Moreover, after 24 h of exposition, the nisin-biogel presented no significant levels of toxicity regarding the human keratinocytes under study. Lastly, to cover the complex microbiota present in DFIs, a combination of AMPs with different action spectra was developed, based on the simultaneous incorporation of nisin and pexiganan in the biogel. The activity of this dual-AMPs formulation was tested against two S. aureus and P. aeruginosa strains isolated from the same DFI. Acting together, these AMPs were able to diffuse from the biogel and inhibit and eradicate biofilms formed by these DFI isolates. The effectiveness of AMPs, particularly nisin and pexiganan, as novel antimicrobial strategies for the management of DFIs is still an unknown territory that merits investigation. In vitro biofilm models are the basis of preliminary research; however, they underrepresent the complex microbiota present in DFIs and their interaction with the immune system and skin cells constituents. Further research is necessary to understand the AMPs full potential regarding the clinical management of biofilm-related diseases, such as DFIs.
RESUMO - As infecções do pé diabético (IPDs) são uma complicação frequente da Diabetes mellitus. Estas úlceras tendem a ser colonizadas por Staphylococcus aureus e Pseudomonas aeruginosa, incluindo estirpes multirresistentes e produtoras de biofilme, possivelmente causando cronicidade da IPD e amputação. É urgente criar novas estratégias para o tratamento das IPD e os péptidos antimicrobianos (PAMs) nisina e pexiganan são potenciais candidatos. Este projecto avaliou a actividade destes PAM, incorporados num biogel de goma de guar, contra isolados de IPD. Primariamente, foi determinada a actividade da nisina contra uma colecção de S. aureus isolados de IPD. Os resultados mostraram que a nisina é capaz de inibir e erradicar S. aureus na forma planctónica e de biofilme a concentrações abaixo da dose diária recomendada. Quando incorporada no biogel, a nisina manteve a sua actividade. Foi ainda avaliado o potencial da nisina para complementar a actividade de antissépticos e antibióticos convencionais contra biofilmes formados por estes isolados. Foi criado um protocolo que simula in vitro o tratamento convencional das IPDs. Foram testadas 15 combinações de antimicrobianos, incluindo biogel de nisina, clorohexidina, clindamicina, gentamicina e vancomicina. Os resultados mostraram que o maior efeito inibidor de biofilmes pertencia a combinações que incluam o biogel de nisina. Foram também avaliadas as condições de armazenamento ideais para o biogel de nisina e a sua citotoxicidade. Quando armazenado a temperaturas entre -20 e 22ºC, o biogel de nisina manteve a sua actividade antimicrobiana durante pelo menos 24 meses. Adicionalmente, após exposição durante 24 horas, o biogel de nisina não apresentou níveis significativos de toxicidade relativamente aos queratinócitos humanos em estudo. Por último, para abranger a complexa microbiota presente nas IPDs, foi avaliada uma combinação de PAMs com diferentes espectros de acção, baseada na incorporação simultânea de nisina e pexiganan no biogel. A actividade desta formulação foi testada contra duas estirpes de S. aureus e P. aeruginosa isoladas da mesma IPD. Conjuntamente, estes PAMs foram capazes de se difundir do biogel e inibir e erradicar biofilmes formados por estes isolados. A eficácia dos PAMs como novas estratégias para o tratamento das IPD é ainda uma área desconhecida. Os modelos in vitro de biofilmes são a base da investigação; contudo, não representam a microbiota presente nas IPD nem a sua interacção com o sistema imunitário e outros constituintes celulares. É essencial continuar a investigar para compreender o potencial dos PAMs na terapêutica de doenças onde haja formação de biofilmes, como é o caso das IPDs.
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Guimond-Peron, Gabriel. "The ecology and evolution of antimicrobial resistance in asymptomatic Salmonella enterica /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99182.
Full textSingh, Shalini. "Amphiphilic Peptide Interactions with Complex Biological Membranes : Effect of peptide properties on antimicrobial and anti-inflammatory effects." Doctoral thesis, Uppsala universitet, Institutionen för farmaci, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-282781.
Full textRibera, Puig Alba. "Orthopaedic device-related infections: some thoughts on management and antimicrobial efficacy from a clinical and experimental perspective." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/587107.
Full textLes infeccions osteoarticulars relacionades amb implants ortopèdics són un problema de salut de primera magnitud: per la seva incidència creixent, la seva complexitat i l’alt cost sanitari. Suposen un gran repte per l’especialista en malalties infeccioses, principalment per les seves particularitats etio-patogènicas amb participació de bacteris en fase estacionària de creixement i la formació de biofilm. Els objectius d’aquesta tesi pretenen explorar alguns aspectes no resolts sobre el maneig i la eficàcia antimicrobiana en el marc de la infecció osteoarticular relacionada amb l’implant. Al través de 7 treballs s’han desenvolupat els següents punts: • Estudi de les característiques clíniques i microbiològiques dels casos d’afluixament asèptic protèsic sotmesos a revisió, amb l’objectiu d’entendre millor aquesta entitat (interpretació dels cultius positius aïllats). • Estudi comparatiu del maneig quirúrgic de la infecció protèsica crònica: recanvi en un o dos temps. • Estudi de la infecció protèsica estreptocòccica manejada amb desbridament, antibiòtics i retenció de l’implant (DAIR); amb l’objectiu d’avaluar el pronòstic d’aquesta entitat i els factors que poden millorar la seva taxa de curació. • Estudi sobre l’ús de betalactàmics en infusió continua en les infeccions osteoarticulars relacionades amb implants causades per BGN, amb els objectius: 1) estandarditzar un procediment basat en UHPLC-MS/MS para la determinació dels nivells plasmàtics de betalactàmics, 2) validar una equació senzilla per estimar la dosis de betalactàmics òptima en perfusió continua i els nivells plasmàtics. 3) avaluar la seguretat i eficàcia antimicrobiana de l’ús de betalactàmics en infusió continua. • Estudis sobre l’eficàcia d’afegir colistina al tractament amb betalactàmics en el maneig d’infeccions gram-negatives multiresistents: 1) estudi clínic , 2) model in vitro per la formació de biofilm. Les principals troballes: • Alguns casos amb sospita d’afluixament protèsic asèptic són realment infeccions o presenten microorganismes aïllats sobre la superfície de l’implant. • L`estratègia de revisió protèsica pel tractament de les infeccions de pròtesis articulars en un temps pot ser (en general) tan efectiva com la revisió en dos temps. • La infecció protèsica estreptocòccica manejada amb DAIR va mostrar un pitjor pronòstic del descrit prèviament a la literatura. Un bon maneig de les guies IDSA, el recanvi dels components mòbils i la potencial eficàcia del tractament combinat amb rifampicina podrien millorar aquest modest pronòstic. • L’estandardització d’un mètode UHLPC-MS/MS per la determinació de betalactàmics permet la monitorització de nivells en pacients tractats amb perfusió contínua. • Mitjançant la comparació amb els resultats UHLPC-MS/MS s’ha pogut validar una equació simple per una estimació individualitzada de la dosi òptima de betalactàmics en perfusió continua i de nivells en plasma . • L’ús clínic de betalactàmics en perfusió continua és segur y eficaç. • Afegir colistina als betalactàmics en el tractament de les infeccions osteoarticulars produïdes per BGN multiresistents mostra millors resultats que el tractament en monoteràpia amb betalactàmic. • En el model in vitro per la formació de biofilm, també hem objectivat el benefici de la teràpia combinada amb colistina.
Gómez, Junyent Joan. "Osteoarticular infections: insights on bacteremic clinical forms and antimicrobial alternatives against Pseudomonas aeruginosa from a translational perspective." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/670664.
Full textLos estudios clínicos y experimentales de esta tesis pretenden ampliar la información existente sobre las infecciones osteoarticulares bacteriémicas así como evaluar alternativas terapéuticas para estas infecciones por P. aeruginosa. La primera parte de la tesis aborda la problemática de las infecciones osteoarticulares bacteriémicas e incluye 4 estudios realizados en el Hospital Universitari de Bellvitge (1985-2014). La incidencia de infecciones osteoarticulares aumentó a lo largo de los años, con incremento de las infecciones nosocomiales y asociadas al ámbito sanitario, además de las infecciones asociadas a material ortopédico y la osteomielitis vertebral. Los casos por S. aureus meticilin-resistente (SARM), estreptococos, enterococos y bacilos gram-negativos aumentaron. La infección osteoarticular bacteriémica con afectación del esqueleto axial (artritis o espondilitis) se asoció independientemente a la presencia de endocarditis infecciosa. Los casos nosocomiales y asociados al ámbito sanitario se presentaron más frecuentemente en individuos mayores y con más comorbilidades y fueron causados por SARM y P. aeruginosa. La mortalidad fue del 12.2%, mayor en la artritis séptica periférica y en infecciones por SARM. La mortalidad fue menor en los pacientes con artritis séptica periférica tratados con desbridamiento quirúrgico. La segunda parte de la tesis pretende encontrar alternativas terapéuticas para la infección osteoarticular por P. aeruginosa. El primer estudio analiza infecciones osteoarticulares por P. aeruginosa tratados con beta-lactámicos en perfusión continua y monitorización plasmática de concentraciones. 52 pacientes incluidos, 19 con cepas resistentes a fluoroquinolonas (13;68.4% cepas MDR/XDR). La mayoría tenían concentraciones de 3-10xMIC, concentraciones superiores frecuntes en insuficiencia renal. No hubo diferencias en el fracaso entre aquellos con infecciones por cepas resistentes o sensible a fluoroquinolonas. Se realizaron dos estudios experimentales con un modelo in vitro dinámico de biofilm. El primero evalúa la actividad de ceftolozano-tazobactam, con/sin colistina, frente a P. aeruginosa multiresistente. Ceftolozano-tazobactam con colistina fue el tratamiento más eficaz ante la cepa resistente a meropenem, mientras que meropenem con colistina lo fue frente a cepas sensibles a carbapenems. El segundo analiza las características farmacocinéticas/farmacodinámicas de ceftazidima en infusión continua, con/sin colistina, frente P. aeruginosa sensible. Frente PAO1, se observó una actividad anti-biofilm ligeramente superior con concentraciones de ceftazidima de 20-40mg/L, además de mayor actividad anti-biofilm frente ambas cepas con combinaciones de colistina y ceftazidima a concentraciones de 40mg/L que con 4mg/L.
Martin, Siseko. "In Vitro antimicrobial synergy testing of Acinetobachter Baumannii." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5228.
Full textThesis (MMed (Pathology. Medical Microbiology))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: Acinetobacter baumannii has emerged as one of the most troublesome nosocomial pathogens globally. This organism causes infections that are often extremely difficult to treat because of the widespread resistance to the major antibiotic groups. Colonization or infection with multidrugresistant A. baumannii is associated with the following risk factors: prolonged hospital stay, admission to an intensive care unit (ICU), mechanical ventilation, and exposure to broad spectrum antibiotics, recent surgery, invasive procedures, and severe underlying disease. A. baumannii has been isolated as part of the skin flora, mostly in moist regions such as axillae, groin and toe webs. It has also been isolated from the oral cavity and respiratory tract of healthy adults. Debilitated hospitalized patients have a high rate of colonization, especially during nosocomial Acinetobacter outbreaks. This organism is an opportunistic pathogen as it contains few virulence factors. Clinical manifestations of A. baumannii include nosocomial pneumonia, nosocomial bloodstream infections, traumatic battlefield and other wound infections, urinary tract infections, and post-neurological surgery meningitis. Fulminant community-acquired pneumonia has recently been reported, indicating that this organism can be highly pathogenic. The number of multidrug-resistant A. baumannii strains has been increasing worldwide in the past few years. Therefore the selection of empirical antibiotic treatment is very challenging. Antibiotic combinations are used mostly as empirical therapy in critically ill patients. One rationale for the use of combination therapy is to achieve synergy between agents. The checkerboard and time-kill methods are two traditional methods that have been used for synergy testing. These methods are labor intensive, cumbersome, costly, and time consuming. The E-test overlay method is a modification of the E-test method to determine synergy between the different antibiotics. This method is easy to perform, flexible and time efficient. The aim of this study was to assess the in vitro activity of different combinations of colistin, rifampicin, imipenem, and tobramycin against selected clinical strains of A. baumannii using the checkerboard and the E-test synergy methods. The MICs obtained with the E-test and broth microdilution method were compared. The results of the disk diffusion for imipenem and tobramycin as tested in the routine microbiology laboratory were presented for comparison. Overall good reproducibility was obtained with all three methods of sensitivity testing. The agreement of MICs between the broth dilution and E-test methods was good with not more than two dilution differences in MIC values for all isolates, except one in which the rifampicin E-test MIC differed with three dilutions from the MIC obtained with the microdilution method. However, the categorical agreement between the methods for rifampicin was poor. Although MICs did not differ with more than two dilutions in most cases, many major errors occurred because the MICs clustered around the breakpoints. The combinations of colistin + rifampicin, colistin + imipenem, colistin + tobramycin, rifampicin + tobramycin, and imipenem + tobramycin all showed indifferent or additive results by the E-test method. No results indicating synergy were obtained for all the above-mentioned combinations. There was one result indicating antagonistic effect for the combination of colistin + tobramycin. The results of the checkerboard method showed results indicating synergy in four of the six isolates for which the combination of colistin and rifampicin was tested. The other two isolates showed indifferent/additive results. All the other combinations showed indifferent/additive results for all isolates except isolate 30 (col + tob) and isolate 25 (rif + tob) which showed synergism. No antagonistic results were observed by the checkerboard method. When the results obtained with the E-test and checkerboard methods were compared, it was noted that for most antibiotic combinations an indifferent/additive result was obtained. However, for the colistin + rifampicin combination, the checkerboard method showed synergism for 4 of 6 isolates, whereas the E-test method showed indifference and an additive result in one. For the rifampicin + tobramycin, and colistin + tobramycin combinations, synergism was also shown with the checkerboard method in one isolate for each combination. The E-test method however showed an indifferent and additive result respectively. . The E-test method was found to be a rapid, reproducible, easy-to-perform, and flexible method to determine synergistic antibiotic activity. This study was however limited by low numbers of isolates. This might explain why no synergistic results were obtained with the E-test method and few synergistic results with the checkerboard method. Genotypic analysis using pulse-field gel electrophoresis (PFGE) may be considered in future studies to determine relatedness of the isolates which will facilitate the selection of different strains for synergy testing. Furthermore, clinical studies are needed to establish whether in vitro synergy testing is useful in the clinical setting and whether the results of synergy testing will have any bearing on the clinical outcome of patients infected with multidrug resistant A. baumannii.
AFRIKAANSE OPSOMMING: Acinetobacter baumannii het wêreldwyd as een van die mees problematiese nosokomiale patogene verskyn. Hierdie organisme veroorsaak infeksies wat dikwels baie moeilik is om te behandel weens wydverspreide weerstandigheid teen major antibiotikagroepe. Kolonisasie of infeksie met multi-weerstandige A. baumannii word geassosieer met die volgende riskofaktore: verlengde hospitaalverblyf, toelating tot ‘n intensiewe sorgeenheid (ICU), meganiese ventilasie, blootstelling aan breëspektrum antibiotika, onlangse chirurgie, indringende prosedures en ernstige onderliggende siekte. A. baumannii kan deel vorm van die normale velflora, veral in die axillae, inguinale area en tussen die tone. Dit is ook al vanuit die mondholte en die respiratoriese traktus van gesonde volwassenes geïsoleer. Verswakte gehospitaliseerde pasiënte word veral gekoloniseer gedurende nosokomiale Acinetobacter uitbrake. Hierdie organisme is ‘n opportunistiese patogeen en bevat min virulensie faktore. Kliniese manifestasies van A. baumannii sluit nosokomiale pneumonie, nosokomiale bloedstroom infeksies, troumatiese slagveld- en ander wondinfeksies, urienweginfeksies en meningitis wat volg op neurologiese chirurgie in. Fulminerende gemeenskapsverworwe pneumonie is onlangs beskryf en dui aan dat hierdie organisme hoogs patogenies kan wees. Die aantal multi-weerstandige A. baumannii stamme het wêreldwyd toegeneem oor die laaste paar jare. Daarom is die seleksie van empiriese antibiotiese behandeling ‘n uitdaging. Antibiotika kombinasies word meestal as empiriese behandeling in ernstige siek pasiënte gebruik. Die beginsel hiervan is om sinergistiese werking tussen agente te verkry. Die “checkerboard” en “time-kill” metodes is twee tradisionele metodes van sinergisme toetsing. Hierdie metodes is werksintensief, duur en tydrowend. Die E-toets sinergisme metode is gebaseer op die E-toets metode. Hierdie metode is maklik, buigbaar en tydseffektief. Die doel van hierdie studie was om die in vitro aktiwiteit tussen verskillende antibiotika kombinasies van colistin, rifampisien, imipenem, en tobramisien teen geselekteerde kliniese A. baumannii isolate te toets met die “checkerboard” en E-toets sinergisme toetsing metodes. Die minimum inhibitoriese konsentrasies (MIKs) verkry met die E-toets en “broth microdilution” metode is ook vergelyk. Die resultate van die skyfie diffusie metode (die metode wat in die roetiene mikrobiologie laboratorium gebruik word) vir imipenem en tobramisien word ook verskaf vir vergelyking van die resultate van verskillende sensitiwiteitsmetodes. In oorsig is goeie herhaalbaarheid van resultate verkry met al drie metodes van sensitiwiteitstoetsing. Die ooreenstemming van MIKs tussen die “broth dilution” en E-toets metodes was goed en resultate het met nie meer as twee verdunnings in MIK waardes verskil nie. Daar is een uitsondering waar die rifampisien E-toets MIK waarde met drie verdunnings van die MIK waarde verkry met die “microdilution” metode verskil. Die ooreenstemming tussen die sensitiwiteitskategorie resultate tussen die twee metodes was egter swak vir rifampisien. Alhoewel die MIKs in die meeste gevalle met nie meer as twee verdunnings in waarde verskil het nie, was daar baie major foute aangetoon omdat die MIKs rondom die breekpunte geval het. Die kombinasies van colistin + rifampisien, colistin + imipenem, colistin + tobramisien, rifampisien + tobramisien, en imipenem + tobramisien het oorwegend slegs matige interaksie met die E-toets metode getoon. Geen sinergisme is verkry met enige van die antibiotika kombinasies met hierdie metode nie. Daar was egter een resultaat wat antagonisme getoon het vir die kombinasie van colistin + tobramycin. Die resultate van die “checkerboard” metode het sinergisme getoon in vier van die ses isolate wat vir die kombinasie van colistin en rifampisien getoets was. Die ander twee isolate het slegs matige interaksie getoon. Al die ander kombinasies het ook slegs matige interaksie getoon, behalwe in isolaat 30 (col + tob) en isolaat 25 (rif + tob) waar die spesifieke kombinasies sinergisme getoon het. Geen antagonisme is waargeneem met die “checkerboard” metode nie. Met vergelyking van die E-toets en “checkerboard” metodes, is dit opmerklik dat vir die meeste van die antibiotika kombinasies slegs matige interaksie verkry is. Vir die colistin + rifampisien kombinasie toon die “checkerboard” metode egter sinergisme vir 4 uit 6 isolate, terwyl die E-toets metode slegs matige interaksie toon. Vir rifampisien + tobramisien, en colistin + tobramisien kombinasies is sinergisme getoon met die “checkerboard” metode in een isolaat vir elke kombinasie. Die E-toets metode het slegs matige interaksie getoon. Die E-toets sinergisme metode was vinnig, herhaalbaar en maklik om uit te voer. Hierdie studie word egter beperk deur lae getalle van isolate. Dit mag verklaar waarom geen sinergistiese resultate met die E-toets metode verkry is nie en die min sinergistiese resultate met die “checkerboard” metode. Genotipiese analiese met “pulse-field gel electrophoresis” mag in aanmerking geneem word in toekomstige studies om die verwantskap tussen isolate te bepaal wat die seleksie van verskillende stamme vir sinergisme toetsing sal vergemaklik. Verder, kliniese studies is nodig om te bepaal of in vitro sinergisme toetsing van waarde is en of die resultate van sinergisme toetsing ‘n rol speel in die kliniese uitkoms van pasënte geïnfekteer met multiweerstandige A. baumannii.
The National Health Laboratory Serivice
Knoetze, Hendriette. "Characterization of a broad-spectrum antimicrobial peptide from Enterococcus mundtii active against bacteria associated with middle ear infections." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/17373.
Full textENGLISH ABSTRACT: Strain ST4SA, isolated from soya beans, was identified as Enterococcus mundtii. BacST4SA, a bacteriocin produced by strain ST4SA inhibited the growth of Acinetobacter baumannii, Bacillus cereus, Clostridium tyrobutyricum, Enterococcus faecalis, Enterococcus faecium, Lactobacillus sakei, Propionibacterium spp., Streptococcus caprinus, Pediococcus sp., Listeria monocytogenes, Staphylococcus aureus, Streptococcus pneumoniae, and unidentified middle ear isolates A, BW, DW, F, G, and H. BacST4SA was active against Pseudomonas aeruginosa G, BG, I, J, B and E, although variable degrees of resistance were observed for some strains. BacST4SA is positively charged, hydrophobic, contains the YGNGV sequence in the N-terminal, a double-glycine processing site and a disulphide bridge, all of which is typical of a class IIa bacteriocin. The operon, which contains a structural-, ATP-dependent transporter- and immunity gene, is located on a 50-kb plasmid. The 58-amino acid prepeptide is homologous to mundticin KS, mundticin AT06 and bacteriocin QU 2, and differs from enterocin CRL35 by only two amino acids. The 674-amino acid ATP-dependent transporter, consisting of a peptidase C39B domain, an ABC-transporter and an ABC-DLP family domain, displayed 98.9% homology to mundticin KS and 99.25% to enterocin CRL35. The 98-amino acid immunity gene of bacST4SA is completely homologous to enterocin CRL35 and 96.9% to mundticin KS. BacST4SA is 3.950 kDa in size, based on electron spray mass spectrometry. The peptide was isolated from the cell-free supernatant, precipitated with 80% saturated ammonium sulphate, dialysed and freeze-dried to 1 638 400 AU (arbitrary units) per ml. No change in antimicrobial activity was recorded when bacST4SA was incubated in buffer ranging from pH 2 to 12, heated to 100 °C for 90 min and 121 °C for 20 min, and when incubated in the presence of Tween 20, Tween 80, Triton X-100, SDS, urea, EDTA, middle ear fluid and blood. Optimal levels of bacST4SA production (51 200 AU/ml) was recorded after 14 h of growth in MRS broth at 30°C. Maximum production (102 400 AU/ml) was recorded in modified MRS media supplemented with tryptone, yeast extract, a combination of tryptone and yeast extract, K2HPO4 (10.0 or 20.0 g/l), or with the addition of DL-6,8-thoictic acid, L-ascorbic acid, and thiamine, respectively. BacST4SA is bactericidal towards E. faecium HKLHS and bacteriostatic towards S. pneumoniae 40 and middle ear isolates F, BW and H. The peptide adsorbed maximal (94%) to S. pneumoniae 40, P. aeruginosa 25 and E. faecium HKLHS. BacST4SA forms pores in the cytoplasmic membrane of sensitive cells, leading to dissipation of the cell membrane and leakage of cytoplasmic material. BacST4SA was compared with various other antimicrobial treatment agents, and revealed similar to a higher activity towards a number of these agents. BacST4SA revealed a similar level of activity against E. faecium HKLHS and middle ear pathogens P. aeruginosa J and S. pneumoniae 27 when compared with tetracycline (30μg). However, bacST4SA revealed much higher activity when compared to nasal sprays, aminoglycosides, cephalosporins, fluoroquinolones, lincosamides, macrolides, nitroimidazole, penicillin, quinolones, sulfonamides, chloramphenicol, furanzolidone, fusidic acid, rifampicin, trimethoprim, trimethoprim-sulfamethoxazole and vancomycin when tested in vitro.
AFRIKAANSE OPSOMMING: Stam ST4SA, geïsoleer uit sojabone, is as Enterococcus mundtii geidentifiseer. BacST4SA, ‘n bakteriosien geproduseer deur stam ST4SA het die groei van Acinetobacter baumannii, Bacillus cereus, Clostridium tyrobutyricum, Enterococcus faecalis, Enterococcus faecium, Lactobacillus sakei, Propionibacterium spp., Streptococcus caprinus, Pediococcus sp., Listeria monocytogenes, Staphylococcus aureus, Streptococcus pneumoniae en ongeïdentifiseerde middeloor isolate A, BW, DW, F, G, en H geinhibeer. BacST4SA is aktief teen Pseudomonas aeruginosa stamme G, BG, I, J, B en E, alhoewel effense weerstand soms waargeneem is. BacST4SA het ‘n netto positiewe lading, is hidrofobies, bevat die YGNGV-volgorde in die N-terminaal, ‘n dubbel-glisien prosesserings setel en ‘n disulfied brug, kenmerkend van klas IIa bakteriosiene. Die operon, wat bestaan uit ‘n strukturele geen, ‘n ATP-afhanklike transport sisteem geen en ‘n immuniteits-geen, is op ‘n 50 kb plasmied gelokaliseer. Die voorloper peptied (58 aminosure lank), is homoloog aan mundticin KS, mundticin AT06 en bakteriosien QU 2 en verskil van enterocin CRL35 met slegs twee aminosure. Die ATP-afhanklike transporter (674 aminosure lank) bestaan uit ‘n peptidase C39B domein, ‘n ABC-transporter en ‘n ABC-DLP tipe domein en is 98.9% homoloog aan mundticin KS and 99.25% aan enterocin CRL35. Die immuniteits-geen (98 aminosure lank) van bacST4SA is ten volle homoloog aan enterocin CRL35 en 96.9% homoloog aan mundticin KS. BacST4SA is 3.950 kDa groot, gebaseer op elektrosproei-massa spektrometrie. Die peptied is uit selvrye supernatant geïsoleer, met 80% versadigde ammonium sulfaat gepresipiteer, gedialiseer en gevriesdroog tot ’n finale konsentrasie van 1 638 400 AE (arbitrêre eenhede) per ml. Geen verandering in antimikrobiese aktiwiteit is waargeneem tydens inkubasie van bacST4SA in buffer van pH 2 tot 12, tydens verhitting (100 °C vir 90 min en 121 °C vir 20 min) en tydens inkubasie in die teenwoordigheid van Tween 20, Tween 80, Triton X-100, SDS, ureum, EDTA, middeloor vloeistof en bloed. Optimale vlakke van bacST4SA produksie (51 200 AE/ml) is na 14 h groei in MRS media by 30°C waargeneem. Maksimale vlakke van die peptied (102 400 AE/ml) is geproduseer in gemodifiseerde MRS medium, aangevul met triptoon, gisekstrak, ‘n kombinasie van triptoon en gisekstrak, K2HPO4 (10.0 of 20.0 g/l), of met byvoeging van DL-6,8-thioktiensuur, L-askorbiensuur, en tiamien onderskeidelik. BacST4SA is bakteriosidies teenoor E. faecium HKLHS en bakteristaties teenoor S. pneumoniae 40 en middeloor isolate F, BW en H. Die peptied adsorbeer optimaal (94%) aan S. pneumoniae 40, P. aeruginosa 25 en E. faecium HKLHS. BacST4SA vorm porieë in die selmembraan van sensitiewe selle en lei tot vernietiging van die selmembraan en lekkasie van die sitoplasma inhoud. In vergelykende studies het bacST4SA ‘n soortgelyke en selfs hoër antimikrobiese aktiwiteit teenoor ‘n aantal bekende antimikrobiese middels getoon. Die aktiwiteit van bacST4SA is soortgelyk aan dié van tetrasiklien (30μg) in toetse teen E. faecium HKLHS en middeloor patogene P. aeruginosa J en S. pneumoniae 27. BacST4SA het egter in ’n in vitro vergelyking met neussproeie, aminoglisiedes, cephalosporiene, fluoroquinolone, lincosamides, makroliede, nitroimidazole, penisilien, quinolone, sulfonamide, chloramphenicol, furanzolidone, fusiensuur, rifampisien, trimethoprim, trimethoprim-sulfamethoxazool en vankomisien ‘n baie hoër aktiwiteit teen patogene getoon.
Bergman, Peter. "Antimicrobial peptides and pathogenic Neisseria : experimental studies in mouse, man and rat /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-428-7/.
Full textGibson, Roger L. "Primary prevention of acute respiratory infection among United States Air Force recruits through the use of antimicrobial handwipes : a randomized clinical trial /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10905.
Full textSchlusselhuber, Margot. "Therapeutic potential of equine antimicrobial peptides against Rhodococcus equi and other major horse pathogens." Caen, 2012. http://www.theses.fr/2012CAEN3135.
Full textOver the last decade, the susceptibility of bacteria for conventional antibiotics decreased substantially and we are witnessing to the emergence of multidrug-resistant microbes in both human and equine medicine. Antimicrobial peptides (AMPs) are small molecules that participate in the innate immune response in almost all living organisms. They have been attracting greater interest as new class of antimicrobial drugs besides to antibiotics for number of reasons. Indeed, they are recognized to have a rapid and bactericidal mode of action, a broad spectrum of action and a low frequency in selecting resistance. In this work, the therapeutic potential of equine AMPs was assessed against various pathogens of the horse with a special focus on Rhodococcus equi, a major cause of death in foals. The most promising peptide, eCATH1, was shown to exert an antibacterial activity at low micromolar concentrations against R. Equi as well as Pseudomonas spp. , Escherchia coli, Salmonella enterica Typhimurium, Streptococcus zooepidemicus and Klebsiella pneumoniae independently of the antibiotic resistance of the strains. Moreover, the peptide proved to kill efficiently intramacrophage R. Equi in vitro as well as in mice model of infection without inducing toxicity and presented a positive interaction with rifampicin. Despite the high therapeutic potential of eCATH1 against rhodococcosis, it remains to set up a method of production in high amount and low costs in order to prove its efficacy in infected foals as well as to make its use viable for pharmaceutical industry
Jamieson, William David. "Nano-scale systems for the detection and treatment of bacterial infections in burn wounds : modes of action and efficacy." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.642025.
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