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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

The Use of Trimethoprim-Sulfamethoxazole for Serious MRSA Infections

Shams, Wael E., McCormick, Malkanthie, Rapp, Robert P., Evans, Martin E. 01 October 2005 (has links)
Vancomycin has been considered first-line treatment for bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) despite treatment failures in up to 20% of patients with MRSA bacteremia secondary to endocarditis. However, trimethoprim-sulfamethoxazole (TMP-SMX) is as effective as vancomycin for the management of MRSA bacteremia. secondary to endocarditis in injection drug users. We report the successful management of a left ventricular assist device-related MRSA infection with persistent MRSA bacteremia that failed to respond to vancomycin, linezolid, and quinupristin/dalfopristin but did respond to TMP-SMX.
42

Isolation and Host Range of Staphylococcus aureus Bacteriophages and Use for Decontamination of Fomites

Jensen, Kyle C 01 June 2015 (has links) (PDF)
Staphylococcus aureus is a common bacterium found on the skin and mucosal membranes of about 20% of the population. S. aureus growth on the skin is harmless, but if it bypasses the skin it can causes life-threatening diseases such as pneumonia, meningitis, bacteremia, and sepsis. Antibiotic-resistant strains of S. aureus, called Methicillin Resistant S. aureus (MRSA), are resistant to most antibiotics except vancomycin. However, vancomycin resistant strains of MRSA are becoming more common. In this study, 12 phages were isolated capable of infecting human S. aureus and/or MRSA strains. Five phages were discovered through mitomycin C induction of prophages and seven phages were found through enrichment of environmental samples. Primary S. aureus strains were also isolated from environmental sources to be used as tools for phage discovery and isolation as well as to examine the target cell host range of the phage isolates. S. aureus isolates were tested for susceptibility to oxacillin in order to determine methicillin-resistance. Experiments were performed to assess the host range and killing potential of newly discovered phage. The M1M4 phage had the broadest host range and lysed 12% of the S. aureus strains that were tested. The host ranges were reinforced by spectrophotometric assay data which showed a reduction in bacterial optical density of 1.3 OD600. The phages were used to decontaminate MRSA from fomites (glass and cloth) and successfully reduced colony forming units by 1-2 logs, including tests of a phage cocktail against a cocktail of MRSA isolates. Our findings suggest that phage treatment can be used as an effective tool to decontaminate human MRSA from both hard surfaces and fabrics.
43

Identification of antibiotic-resistant staphylococci and epidemiological typing of methicillin-resistant Staphylococcus aureus by Fourier transform infrared spectroscopy

Amiali, Mohamed Nassim January 2003 (has links)
No description available.
44

Patienters upplevelser av vård och bemötande i samband med MRSA-smitta : en litteraturöversikt / Patients' experiences of care and treatment in connection with MRSA-infection : a literature review

Serko, Sawin, Johansson, Sofia January 2018 (has links)
Meticillinresistent staphylococcus aureus (MRSA) är en bakterie som är resistent mot ett flertal antibiotika. Det är en bakterie som har ökat både i Sverige och i resten av världen. Tidigare var smittspridningen av MRSA vanligt förekommande på sjukhusen men har på senare tid även blivit allt mer förekommande utanför sjukvården. Att smittas av MRSA kan innebära svåra infektionssjukdomar som pneumoni, urinvägsinfektion och sepsis. För att minimera smittspridningen av MRSA flyttas patienter till isoleringssalar, vilket kan resulterat i lidande för patienten. Syfte är att belysa MRSA smittade patienters upplevelse av möten med hälso- och sjukvårdspersonal. Denna litteraturöversikt är baserad på tio vetenskapligt granskade artiklar, nio av artiklarna är kvalitativa och en är kvantitativ. De vetenskapliga artiklarna har noggrant granskats och därifrån har en sammanställning med teman till resultatet bildats. Databaserna CINAHL Complete, PubMed och Academic Search Complete har använts. Utifrån de tio artiklarna sammanställdes fyra teman som belyser patienters upplevelser. Dessa redovisas under i följande rubriker: Hälso- och sjukvård samt närståendes bemötande av patienter med MRSA, Psykologiskt trauma, Negativa och positiva upplevelser av isolering samt Kunskap om MRSA. Katie Erikssons teori med fokus på lidande diskuteras tillsammans med resultatet, utifrån patientens perspektiv. En av sjuksköterskornas centrala roll inom omvårdnadsarbetet är förebyggandet av smittspridning av MRSA, främst genom basala handhygienrutiner. Resultatet påvisade faktorer som kan påverka patienters syn på vården gällande MRSA. Där många patienter upplever att hälso- och sjukvårdspersonalen saknar kunskap angående smittspridning, infektioner och isoleringsrestriktioner. / Meticillin-resistant staphylococcus aureus (MRSA) is a bacteria that is resistant to a variety of antibiotics. This bacteria has increased both in Sweden and worldwide. Previously, the spread of MRSA was common in hospitals, but has recently become more common outside the healthcare sector. To be infected with MRSA often involves severe infectious such as pneumonia, urinary tract infection and sepsis. To minimize the spread of MRSA, patients are moved to isolation, which can result in suffering. To shed light on the experiences of MRSA-infected patients’ interactions with healthcare professionals. This literature review is based on ten scientifically reviewed articles, nine are qualitative and one is quantitative. The scientific articles have been carefully reviewed and from there have a summary with the themes to the result, been formed. Databases CINAHL Complete, PubMed and Academic Search Complete have been used. Based on the ten articles, four themes summarized the patient's experiences. These are listed under the following headings: Healthcare, and relatives response to patients with MRSA, Psychological trauma, Negative and positive experiences of insulation, and Knowledge of patients and healthcare professionals. Katie Eriksson's theory on suffering is discussed with the result, based on patient's perspective. One of the nurses' central role in nursing work is preventing contagious spread of MRSA, primarily through basic hand hygiene routines. Our results indicate that there are factors that may affect patients' views on the care of MRSA. Where many patients experience that healthcare professionals lack knowledge about spread of infection, infections and isolation restrictions.
45

Faktorer i sjuksköterskans omvårdnadsarbete som påverkar smittspridning av Methicillin-resistent Staphylococcus aureus (MRSA) : En litteraturöversikt / Factors in the nurse's nursing work that affect the spread of Methicillin-resistant Staphylococcus aureus (MRSA) : A literature review

Friberg, Emma January 2022 (has links)
Bakgrund: Methicillin-resistent Staphylococcus aureus (MRSA) är en variant av gula stafylokocker som är resistenta mot meticillin vilket resulterar i att MRSA är svår behandlat. MRSA är infektioner som finns på bland annat huden och i slemhinnor, bakterien kan orsaka svåra livshotande infektioner. Vilket resulterar i ett stort lidande för patienten och höga samhällskostnader. Syfte: Syftet var att beskriva faktorer i sjuksköterskans omvårdnadsarbete som kan påverka smittspridningen av Methicillin-resistent Staphylococcus aureus (MRSA). Metod: Denna litteraturöversikt utgår från åtta kvalitativa och kvantitativa vetenskapliga artiklar som systematiskt söktes fram i databaserna PubMed och Cinahl Complete. Artiklarnas resultat tematiserades enligt Fribergs analysmodell. Resultat: Resultatet visade att sjuksköterskor behöver få mer kunskap genom upprepade utbildningar av MRSA och smittspridning samt ha en god handhygien för att påverka smittspridning. De hygienrutiner och riktlinjer som finns angående MRSA och smittspridning behöver utvecklas och förtydligas.  Sammanfattning: Sjuksköterskor behöver ta ansvar för sin yrkesmässiga utveckling genom att initiera utbildning för att kunna bidra till en säker vård. Sjuksköterskor behöver ta ansvar för att ständigt utvecklas och söka nya kunskaper. Kunskap och utbildning bidrar till evidensbaserad vård vilket kan förhindra smittspridning av MRSA. / Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a variant of staphylococcus aureus that is resistant to methicillin, which results in MRSA being difficult to treat. MRSA infections can be found on the skin and in mucous membranes of afflicted patients. Which results in great suffering for the patient and high societal costs. Aim: The aim of this study was to describe how nurse’s nursing care can affect spread of infection of Methicillin-resistant Staphylococcus aureus (MRSA). Method: This literature review is based on eight qualitative and quantitative scientific articles that were systematically searched in the databases PubMed and Cinahl Complete. The results of the articles were themed according to Friberg's analysis model. Results: The results showed that nurses need to gain more knowledge through repeated training on MRSA and the spread of infection and have good hand hygiene to affect spread of infection. The hygiene routines and guidelines that exist regarding MRSA and the spread of infection need to be developed and clarified. Summary: Nurses need to take responsibility for their professional development by initiating training in order to contribute to safe care. Nurses need to take responsibility for constantly developing and seeking new knowledge. Knowledge and education contribute to evidence-based care, which can prevent the spread of MRSA.
46

Παράγοντες κινδύνου για νοσοκομειακές λοιμώξεις από ανθεκτικό στην μεθικιλλίνη χρυσίζοντα σταφυλόκοκκο σε σύγκριση με λοιμώξεις από ευαίσθητο στη μελικιλλίνη χρυσίζοντα σταφυλόκοκκο : ο ρόλος των αντιβιοτικών, από ποιοτική και ποσοτική άποψη, ως ιδιαίτερου παράγοντα κινδύνου για εκλεκτική λοίμωξη από ανθεκτικό στην μεθικιλλίνη χρυσίζοντα σταφυλόκοκκο

Μπαραμπούτης, Ιωάννης 10 August 2011 (has links)
Η χρήση αντιμικροβιακών παραγόντων συνολικά καθώς και ειδικές κατηγορίες αντιμικροβιακών έχουν ενοχοποιηθεί ως παράγοντες κινδύνου για νοσοκομειακές λοιμώξεις (ΝΛ) από ανθεκτικό στη μεθικιλλίνη χρυσίζοντα σταφυλόκοκκο (methicillin-sensitive Staphylococcus aureus, MRSA). Οι στόχοι της μελέτης ήταν: 1. η διερεύνηση προβλεπτικών παραγόντων για νοσοκομειακή λοίμωξη από MRSA, 2. η σε βάθος αξιολόγηση του ρόλου της πρόσφατης χρήσης αντιμικροβιακών από ποιοτική και ποσοτική άποψη. Υλικό και μέθοδοι. Η χρονική περίοδος της μελέτης ήταν από Οκτώβριο1997 έως και τον Σεπτέμβριο του 2001. Οι ασθενείς με ΝΛ από MRSA σε κρατικό νοσοκομείο φροντίδας βετεράνων πολέμου των ΗΠΑ συγκρίθηκαν με αντίστοιχη ομάδα με ΝΛ από ευαίσθητο στη μεθικιλλίνη Staphylococcus aureus (MSSA). Οι λοιμώξεις στις 2 ομάδες καταγράφηκαν και τεκμηριώθηκαν μα βάση αυστηρά κριτήρια. Καταγράφηκαν δεδομένα σχετικά με παράγοντες κινδύνου (συμπεριλαμβανομένης της ποιοτικής και ποσοτικής χρήσης αντιμικροβιακών) για λοίμωξη από MRSA και ελήφθησαν υπόψη γεγονότα μέχρι 30 ημέρες πριν την ημερομηνία της θετικής καλλιέργειας. Αποτελέσματα. Εκατόν είκοσι επτά ασθενείς (127) με ΝΛ από MRSA και 70 ασθενείς με ΝΛ από MSSA αναλύθηκαν περαιτέρω. Σε μονοπαραγοντική ανάλυση, οι 2 ομάδες διέφεραν σημαντικά στην ηλικία, ιστορικό αιμοκάθαρσης και χρονίων ελκών, είδος κλινικής όπου ελήφθη το δείγμα, διάρκεια προηγούμενης νοσηλείας και παραμονής σε γενική ή καρδιολογική ΜΕΘ, πρόσφατη χειρουργική επέμβαση, άλλες επεμβατικές πράξεις, διασωλήνωση και παρουσία καθετήρα κύστεως για πάνω από 24 ώρες. Επίσης διέφεραν σημαντικά στη χρήση ή όχι τουλάχιστον 1,2 ή 3 αντιμικροβιακών, στο μέσο αριθμό αντιμικροβιακών που είχαν χρησιμοποιηθεί, μέσο αριθμό αντιμικροβιακών-ημερών για κάθε ασθενή, καθώς και ποιοτική και ποσοτική χρήση συγκεκριμένων κατηγοριών αντιμικροβιακών. Σε 2 μοντέλα πολυπαραγοντικής ανάλυσης, εξετάζοντας είτε την ποιοτική (μοντέλο Ι) είτε την ποσοτική (μοντέλο ΙΙ) χρήση αντιμικροβιακών, η διάρκεια παραμονής στο νοσοκομείο τον τελευταίο μήνα αναδείχθηκε ο ισχυρότερος προβλεπτικός παράγοντας λοίμωξης από MRSA (p 0.000), ενώ ιστορικό διασωλήνωσης έδειξε σημαντικότητα στο μοντέλο Ι και οριακή σημαντικότητα στο ΙΙ. Η χρήση αμινογλυκοσιδών και η παρουσία χρονίων ελκών έδειξαν τάση για σημαντικότητα στο μοντέλο Ι. Δεν παρατηρήθηκαν σημαντικές διαφορές στην έκβαση. Συμπεράσματα. Καταλήγουμε στο συμπέρασμα ότι η διάρκεια παραμονής στο νοσοκομείο τις τελευταίες 30 ημέρες αποτέλεσε τον ισχυρότερο προγνωστικό παράγοντα μεταγενέστερης ΝΛ από MRSA στον πληθυσμό των ασθενών μας. Παρά τη σαφώς μεγαλύτερη χρήση αντιμικροβιακών στην ομάδα MRSA, η χρήση αντιμικροβιακών δεν αποτέλεσε ανεξάρτητο προγνωστικό παράγοντα κινδύνου. Όσον αφορά την υπομελέτη, σκοπός ήταν η χρήση αντιμικροβιακών παραγόντων συνολικά καθώς και ειδικές κατηγορίες αντιμικροβιακών έχουν ενοχοποιηθεί ως παράγοντες κινδύνου για νοσοκομειακή βακτηριαιμία (ΝΒ) από ανθεκτικό στη μεθικιλλίνη χρυσίζοντα σταφυλόκοκκο (methicillin-resistant Staphylococcus aureus, MRSA). Από τα δεδομένα της κύριας μελέτης, που ήδη έχει περιγραφεί περιληπτικά παραπάνω, απομονώθηκαν και αναλύθηκαν σε ξεχωριστή υπομελέτη αυτά που αφορούσαν σε ασθενείς που ανέπτυξαν νοσοκομειακή βακτηριαιμία. Οι στόχοι της υπομελέτης ήταν: 1. η διερεύνηση προβλεπτικών παραγόντων για νοσοκομειακή βακτηριαιμία από MRSA, 2. η σε βάθος αξιολόγηση του ρόλου της πρόσφατης χρήσης αντιμικροβιακών από ποιοτική και ποσοτική άποψη. Υλικό και μέθοδοι. Η χρονική περίοδος της μελέτης ήταν από Οκτώβριο1997 έως και τον Σεπτέμβριο του 2001. Οι ασθενείς με ΝΒ από MRSA σε κρατικό νοσοκομείο φροντίδας βετεράνων πολέμου των ΗΠΑ συγκρίθηκαν με αντίστοιχη ομάδα με ΝΒ από ευαίσθητο στη μεθικιλλίνη Staphylococcus aureus (MSSA). Καταγράφηκαν δεδομένα σχετικά με παράγοντες κινδύνου (συμπεριλαμβανομένης της ποιοτικής και ποσοτικής χρήσης αντιμικροβιακών) για λοίμωξη από MRSA και ελήφθησαν υπόψη γεγονότα μέχρι 30 ημέρες πριν την ημερομηνία της θετικής καλλιέργειας Αποτελέσματα. Είκοσι οκτώ ασθενείς (28) με ΝΒ από MRSA και 32 ασθενείς με ΝΒ από MSSA αναλύθηκαν περαιτέρω. Σε μονοπαραγοντική ανάλυση, οι 2 ομάδες διέφεραν σημαντικά στην ηλικία, ιστορικό αιμοκάθαρσης και χρονίων ελκών, διάρκεια προηγούμενης νοσηλείας, ιστορικό και διάρκεια παραμονής σε γενική ή καρδιολογική ΜΕΘ, πρόσφατη χειρουργική επέμβαση, διασωλήνωση και παρουσία καθετήρα κύστεως για πάνω από 24 ώρες. Επίσης διέφεραν σημαντικά στη χρήση ή όχι τουλάχιστον 1,2 ή 3 αντιμικροβιακών, το μέσο αριθμό αντιμικροβιακών που είχαν χρησιμοποιηθεί, μέσο αριθμό αντιμικροβιακών-ημερών για κάθε ασθενή, καθώς και ποιοτική και ποσοτική χρήση συγκεκριμένων κατηγοριών αντιμικροβιακών. Στο μοντέλο πολυπαραγοντικής ανάλυσης Ι (ποιοτική χρήση αντιμικροβιακών), παρατηρήθηκε τάση (trend) για τη διάρκεια της προηγούμενης παραμονή στο νοσοκομείο ως προβλεπτικού παράγοντα (p 0,088), ενώ, από το μοντέλο ΙΙ (ποσοτική χρήση αντιμικροβιακών), ο μέσος αριθμός αντιμικροβιακών-ημερών ανά ασθενή αναδείχθηκε ως ο μόνος ανεξάρτητος προγνωστικός δείκτης ΝΒ από MRSA (p 0,03). Δεν παρατηρήθηκαν σημαντικές διαφορές στην έκβαση. Συμπεράσματα. Καταλήγουμε στο συμπέρασμα ότι η ποσοτική χρήση αντιμικροβιακών, υπό τη μορφή του μέσου αριθμού αντιμικροβιακών-ημερών ανά ασθενή κατά τη διάρκεια του περασμένου μήνα, ήταν ο ισχυρότερος προγνωστικός δείκτης της μεταγενέστερης ΝΒ από MRSA στον πληθυσμό των ασθενών μας, περισσότερο από άλλους παραδοσιακούς παράγοντες κινδύνου. / Both total antimicrobial use and specific antimicrobials have been implicated as risk factors for healthcare-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) infection. Aims. The aims of the study were: 1.to explore predictors of a new HA-MRSA infection in comparison with a new healthcare-associated methicillin-sensitive Staphylococcus aureus (HA-MSSA), 2. to thoroughly assess the role of recent antibiotic use qualitatively and quantitatively. Methods. The time-period for our study was from October 1997 through September 2001. Applying strict criteria, we identified two groups of inpatients, one with a new HA-MRSA infection and one with a new HA-MSSA infection. We recorded demographic, clinical and antibiotic use – related data up to 30 days before the positive culture date. Results.We identified 127 and 70 patients for each group respectively. Two logistic regression models were carried out to assess the role of antimicrobial use (qualitatively and qualitatively). In model I, duration of hospital stay, presence of chronic wounds, aminoglycoside and fluoroquinolone use retained statistical significance. In model II, duration of hospital stay and history of intubation during the last month stood out as the only significant predictors of a subsequent HA-MRSA infection. No siginificant differences in outcome were noted. Conclusions. The length of exposure to the hospital environment may be the best predictor of a new HA-MRSA infection. Use of aminoglycosides and fluoroquinolones may also stand independently along with presence of chronic ulcers and exposure to surgical procedures. No independent association between quantitative antibiotic use and subsequent HA-MRSA infection was documented. As for the substudy, the antimicrobial use has been implicated as risk factor for healthcare-associated methicilin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI). The aims of the study were: 1. to explore predictors of a new MRSA BSI, 2. to thoroughly assess recent antibiotic use qualitatively and quantitatively. Methods. Patients in contact with the healthcare system and MRSA BSI were compared with a methicillin-sensitive BSI group, considering events and risk factors up to 30 days before the positive culture date. Results. Twenty eight patients with MRSA BSI and 32 patients with MSSA BSI were further analyzed. In univariate analysis, significant differences were noted in specific demographic, comorbidity and hospital event-related parameters and also in mean number of antibiotics used, mean number of antibiotic-days per patient, and qualitative and quantitative use of specific classes of antibiotics. From logistic regression model I (qualitative antibiotic use), a trend was noted for duration of prior hospital stay, while, from model II (quantitative antibiotic use), mean antibiotic-days per patient emerged as the single independent predictor of HA-BSI by MRSA (p 0.03). No significant differences in outcome were noted. Conclusion. We conclude that the mean number of antibiotic-days per patient during the last month was the strongest predictor of a subsequent MRSA BSI in our patient population, more than other traditional risk factors.
47

Clinical and microbiological characteristics of purulent and non-purulent cellulitis in hospitalized Taiwanese adults in the era of community-associated methicillin-resistant Staphylococcus aureus

Lee, Chun-Yuan, Tsai, Hung-Chin, Kunin, Calvin M., Lee, Susan SJ, Chen, Yao-Shen January 2015 (has links)
BACKGROUND: The risk factors, microbial etiology, differentiation, and clinical features of purulent and non-purulent cellulitis are not well defined in Taiwan. METHODS: We conducted a retrospective cohort study of hospitalized adults with cellulitis in Taiwan in 2013. The demographic characteristics, underlying diseases, clinical manifestations, laboratory and microbiological findings, treatments, and outcomes were compared for patients with purulent and non-purulent cellulitis. RESULTS: Of the 465 patients, 369 had non-purulent cellulitis and 96 had purulent cellulitis. The non-purulent group was significantly older (p = 0.001) and was more likely to have lower limb involvement (p < 0.001), tinea pedis (p = 0.003), stasis dermatitis (p = 0.025), a higher Charlson comorbidity score (p = 0.03), and recurrence at 6 months post-infection (p = 0.001) than the purulent group. The purulent group was more likely to have a wound (p < 0.001) and a longer hospital stay (p = 0.001) and duration of antimicrobial therapy (p = 0.003) than the non-purulent group. The etiological agent was identified in 35.5 % of the non-purulent cases, with β-hemolytic streptococci the most frequent cause (70.2 %). The etiological agent was identified in 83.3 % of the purulent cases, with Staphylococcus aureus the predominant pathogen (60 %): 50 % of these were methicillin-resistant S. aureus (MRSA). In multivariable analysis, purulent group (odds ratio (OR), 5.188; 95 % confidence interval (CI), 1.995-13.493; p = 0.001) was a positive predictor of MRSA. The prescribed antimicrobial agents were significantly different between the purulent and non-purulent groups, with penicillin the most frequently used antimicrobial agent in the non-purulent group (35.2 %), and oxacillin the most frequent in the purulent group (39.6 %). The appropriate antimicrobial agent was more frequently prescribed in the non-purulent group than in the purulent group (83.2 % vs. 53.8 %, p < 0.001). CONCLUSIONS: The epidemiology, clinical features, and microbiology of purulent and non-purulent cellulitis were significantly different in hospitalized Taiwanese adults. Purulence was a positive predictor of MRSA as the causal agent of cellulitis. These findings provide added support for the adoption of the IDSA guidelines for empirical antimicrobial therapy of cellulitis in Taiwan.
48

Carbon based nutrition of Staphylococcus aureus and the role of sugar phosphate transporters in intracellular bacterial replication

Bell, John Alexander January 2014 (has links)
The Gram positive bacterium Staphylococcus aureus is a major cause of human disease in industrialized countries. This multifaceted pathogen is adapted to thrive in a variety of host niches, including the intracellular compartment. S. aureus rapidly develops antibiotic resistance, and infections due to resistant clones pose a global threat, calling for novel therapeutic approaches. The ability to exploit host nutrients and efficiently metabolize these resources for growth is paramount for bacterial pathogenesis. Understanding the nutritional and metabolic determinants that underpin bacterial virulence may lead to the identification of novel antimicrobial targets. This thesis investigates carbon nutrition and metabolism of community-acquired methicillin resistant S. aureus (CA-MRSA) USA300, a widely spread, hyper virulent multi-resistant strain. The dependence of S. aureus on carbohydrates for growth was considered first. In vitro studies in supplemented chemically defined media showed that sugar phosphates, such as hexose phosphates and glycerol phosphates, promote staphylococcal growth more efficiently than glucose. Deletion mutations were introduced to the two putative sugar phosphate transporter genes present in the S. aureus genome, uhpT (hexose phosphate permease) and glpT (glycerol phosphate permease). Phenotypic analysis of USA300 mutants and heterologous expression of the transporters in a previously described Listeria monocytogenes Δhpt mutant, totally unable to use sugar phosphates, confirmed that S. aureus UhpT and GlpT have different substrate specificities. Whilst both can transport glycerol monophosphate (excluding glycerol-2-phosphate) and the organophosphate antibiotic fosfomycin, hexose monophosphates are only imported via UhpT. Since sugar phosphates are only present in significant amounts inside living tissues, particularly the intracellular compartment, the role of S. aureus UhpT and GlpT in pathogenesis was investigated by constructing a double deletion mutant. The ΔuhpTΔglpT USA300 mutant was used to infect several relevant mammalian cell lines. In the conditions tested, it was found that UhpT and GlpT played no role in the intracellular replication of S. aureus. By contrast, Listeria exploits sugar phosphates from the host cell cytosol via the homologous hexose phosphate transporter, Hpt, to maximise replication and enhance virulence. The distinct requirement of sugar phosphates for intracellular proliferation may reflect intrinsic differences in carbon nutrient dependence between the two organisms. It was confirmed that S. aureus can efficiently use other readily available carbon sources for growth, such as amino acids. In contrast, Listeria is strictly dependent upon sugar-derived carbon for growth, due to an incomplete tricarboxylic acid cycle. Whilst the double ∆uhpT∆glpT mutation had no effect in S. aureus, expression of staphylococcal uhpT or glpT restored wild-type intracellular growth in the L. monocytogenes ∆hpt mutant. Taken together, the results illustrate that sugar phosphate permeases have a contextual role in bacterial virulence, where the background in which the genes are expressed determine their contribution as a virulence factor. The intracellular dynamics of S. aureus was also explored using immunofluorescence microscopy. It was observed that, during epithelial cell infection, USA300 remains enclosed in a membrane-bound vacuole. This localisation may form a barrier to cytosolic sugar phosphates and potentially explain the absence of effect of the sugar phosphate permease deletions in intracellular proliferation. Preliminary characterisation of the S. aureus containing vacuole (SACV) was performed and it was found to be positive for the Rab7 late-endosomal GTPase and for trans-Golgi markers. This suggests that SACVs converge at the Golgi apparatus. Interestingly, a USA300 mutant lacking the global regulatory system agr was unable to proliferate intracellularly and did not acquire Rab7 or Golgi markers. Since the Δagr mutation did not cause any impairment in carbon source dependent growth, these preliminary data suggest that modification of the SACV by Agr-regulated effectors may play a key role in modulating cellular processes that control staphylococcal intracellular survival and/or replication. Evidence presented in this thesis provides a platform for further exploration of S. aureus host cell nutrient dependence and the mechanisms that drive replication.
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Smittad av den moderna pesten : Att vara smittbärare av meticillinresistenta staphylococcus aureus (MRSA)

Kristensson, Nina, Lindberg, Ulrika January 2016 (has links)
Historiskt sett har personer med smittsamma infektioner uteslutits från samhället. Personerna har setts med avsky och rädsla från omgivningen med risk för att överföra smittan. Multiresistenta bakterier (MRB) är ett ökande problem världen över och orsakar stort lidande för patienter. Syftet med litteraturstudien var att undersöka patienters upplevelse av att vara smittbärare av meticillinresistenta staphylococcus aureus (MRSA). Litteraturstudiens resultat baseras på nio vetenskapliga artiklar, där resultatet utföll i två kategorier. I kategorin känslan av att vara smittsam framkom underkategorierna att vara smutsig, skuld och skam samt rädsla och oro. I kategorin känslan av att vara annorlunda framkom underkategorierna känna sig kränkt, ilska och frustration samt känna sig stigmatiserad. För att patienter med MRSA-smitta ska få en god vård krävs det att vårdpersonalen har evidensbaserad kunskap. Därför skulle det vara av stort intresse att forskning i framtiden fokuserar på patienters upplevelse av att vara smittbärare. Ytterligare forskning behövs inom området på grund av ett ökat globalt problem med MRB. / Historically, people with contagious infections has been excluded from society. The characters have been seen with disgust and fear from the environment with the risk of transmitting the infection. Multi-drug resistant bacteria (MRB) is a growing problem worldwide and causes great suffering for patients. The purpose of this study was to investigate patients' experience of being carriers of methicillin-resistant staphylococcus aureus (MRSA). Literature study results are based on nine scientific articles, which precipitated the result of two categories. In the category of feeling of being contagious emerged subcategories to be dirty, guilt and shame and fear and anxiety. In the category of the feeling of being different subcategories emerged feel hurt, anger and frustration, and feel stigmatized. For patients with MRSA infection should get good care requires that health professionals have evidence-based knowledge. Therefore, it would be of great interest to future research focusing on patient experience of being contaminated. Further research is needed in this area because of the increasing global problem of MRB.
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Development of antimicrobial resistance in Acinetobacter spp and methicillin-resistant Staphylococcus aureus

Davies, Sarah Elisabeth January 2009 (has links)
Background: Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA) represent the most worrying Gram-negative and Gram-positive nosocomial pathogens of the present age. They are of increasing concern in the clinical environment due to their multi-drug resistance and the dwindling therapeutic options available. A. baumannii is the most frequently isolated clinical species of the genus, and is able to rapidly acquire resistance. Hypermutators, most frequently deficient in mismatch repair (MMR) via defects in the mutS gene, have been associated with antimicrobial resistance in several bacterial populations. To date, however, the potential role of MMR-deficient mutators in the development of resistance in clinical Acinetobacter spp. has not been investigated. Biocides, most notably chlorhexidine (CHX), are increasingly used in the hospital environment to prevent bacterial spread. This has led to concerns about the development of reduced biocide susceptibility and associated antibiotic resistance in hospital bacterial populations, where there is frequent exposure to both of these factors. The effect of CHX upon defined clinical MRSA isolates is examined here. Methods: The mutS gene of clinical Acinetobacter spp. isolates with varying sensitivities was sequenced and compared to establish whether any variations were present. Mutation studies were performed on isolates by challenging them with ciprofloxacin to determine whether different mutS types correlated with any variation in their ability to develop significant fluoroquinolone resistance. The response of clinical MRSA isolates to a range of CHX concentrations was examined with susceptibility testing methods, and effects were compared with standard strains. Determination of post-exposure minimum inhibitory concentrations (MICs) of a range of antibiotics enabled evaluation of whether exposure to CHX had an effect on susceptibility to antibiotics. Results: Variation was observed in the mutS gene of clinical Acinetobacter spp. isolates, with greater homology observed as resistance increased. A highly conserved and previously unreported amino acid sequence was discovered in resistant isolates. Nonresistant isolates with this ‘R-type’ mutS sequence appeared to have a greater ability to develop significant ciprofloxacin resistance. Clinical MRSA isolates had varying susceptibility to CHX, and there were differences in the susceptibility of standard strains compared to clinical isolates. CHX residues exerted a prolonged minimal inhibitory effect, and several increases in antibiotic MICs following CHX exposure were observed. Conclusions: The correlation of the mutS sequence with mutation ability suggests that defects in the mutS gene may have a role to play in the ability of certain Acinetobacter spp. to rapidly acquire resistance. This could have implications for the treatment of Acinetobacter spp. infections, and may enable quick determination of which clinical isolates have the potential to develop clinically significant resistance. Incomplete eradication due to the prolonged minimal effect of CHX residues may act as a selective pressure in the hospital environment, allowing survival of reduced susceptibility MRSA isolates. Increases in antibiotic MICs following CHX exposure is of grave concern for the future of biocide usage.

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