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Brian G Spratt - One of the best experts on this subject based on the ideXlab platform.
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the evolutionary history of methicillin resistant staphylococcus aureus mrsa
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Mark C Enright, Ashley D Robinson, Gaynor Randle, Edward J Feil, Hajo Grundmann, Brian G SprattAbstract:Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired infections that are becoming increasingly difficult to combat because of emerging resistance to all current antibiotic classes. The evolutionary origins of MRSA are poorly understood, no rational nomenclature exists, and there is no consensus on the number of major MRSA clones or the relatedness of clones described from different countries. We resolve all of these issues and provide a more thorough and precise analysis of the evolution of MRSA clones than has previously been possible. Using multilocus sequence typing and an algorithm, burst, we analyzed an international collection of 912 MRSA and methicillin-susceptible S. aureus (MSSA) isolates. We identified 11 major MRSA clones within five groups of related genotypes. The putative ancestral genotype of each group and the most parsimonious patterns of descent of isolates from each ancestor were inferred by using burst, which, together with analysis of the methicillin resistance genes, established the likely evolutionary origins of each major MRSA clone, the genotype of the original MRSA clone and its MSSA progenitor, and the extent of acquisition and horizontal movement of the methicillin resistance genes. Major MRSA clones have arisen repeatedly from successful epidemic MSSA strains, and isolates with decreased susceptibility to vancomycin, the antibiotic of last resort, are arising from some of these major MRSA clones, highlighting a depressing progression of increasing drug resistance within a small number of ecologically successful S. aureus genotypes.
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multilocus sequence typing for characterization of methicillin resistant and methicillin susceptible clones of staphylococcus aureus
Journal of Clinical Microbiology, 2000Co-Authors: Mark C Enright, Catrin E Davies, Sharon Peacock, Brian G SprattAbstract:A multilocus sequence typing (MLST) scheme has been developed for Staphylococcus aureus. The sequences of internal fragments of seven housekeeping genes were obtained for 155 S. aureus isolates from patients with community-acquired and hospital-acquired invasive disease in the Oxford, United Kingdom, area. Fifty-three different allelic profiles were identified, and 17 of these were represented by at least two isolates. The MLST scheme was highly discriminatory and was validated by showing that pairs of isolates with the same allelic profile produced very similar SmaI restriction fragment patterns by pulsed-field gel electrophoresis. All 22 isolates with the most prevalent allelic profile were methicillin-resistant S. aureus (MRSA) isolates and had allelic profiles identical to that of a reference strain of the epidemic MRSA clone 16 (EMRSA-16). Four MRSA isolates that were identical in allelic profile to the other major epidemic MRSA clone prevalent in British hospitals (clone EMRSA-15) were also identified. The majority of isolates (81%) were methicillin-susceptible S. aureus (MSSA) isolates, and seven MSSA clones included five or more isolates. Three of the MSSA clones included at least five isolates from patients with community-acquired invasive disease and may represent virulent clones with an increased ability to cause disease in otherwise healthy individuals. The most prevalent MSSA clone (17 isolates) was very closely related to EMRSA-16, and the success of the latter clone at causing disease in hospitals may be due to its emergence from a virulent MSSA clone that was already a major cause of invasive disease in both the community and hospital settings. MLST provides an unambiguous method for assigning MRSA and MSSA isolates to known clones or assigning them as novel clones via the Internet.
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multilocus sequence typing for characterization of methicillin resistant and methicillin susceptible clones of staphylococcus aureus
Journal of Clinical Microbiology, 2000Co-Authors: Mark C Enright, Catrin E Davies, Sharon Peacock, Nicholas P J Day, Brian G SprattAbstract:A multilocus sequence typing (MLST) scheme has been developed for Staphylococcus aureus. The sequences of internal fragments of seven housekeeping genes were obtained for 155 S. aureus isolates from patients with community-acquired and hospital-acquired invasive disease in the Oxford, United Kingdom, area. Fifty-three different allelic profiles were identified, and 17 of these were represented by at least two isolates. The MLST scheme was highly discriminatory and was validated by showing that pairs of isolates with the same allelic profile produced very similar SmaI restriction fragment patterns by pulsed-field gel electrophoresis. All 22 isolates with the most prevalent allelic profile were methicillin-resistant S. aureus (MRSA) isolates and had allelic profiles identical to that of a reference strain of the epidemic MRSA clone 16 (EMRSA-16). Four MRSA isolates that were identical in allelic profile to the other major epidemic MRSA clone prevalent in British hospitals (clone EMRSA-15) were also identified. The majority of isolates (81%) were methicillin-susceptible S. aureus (MSSA) isolates, and seven MSSA clones included five or more isolates. Three of the MSSA clones included at least five isolates from patients with community-acquired invasive disease and may represent virulent clones with an increased ability to cause disease in otherwise healthy individuals. The most prevalent MSSA clone (17 isolates) was very closely related to EMRSA-16, and the success of the latter clone at causing disease in hospitals may be due to its emergence from a virulent MSSA clone that was already a major cause of invasive disease in both the community and hospital settings. MLST provides an unambiguous method for assigning MRSA and MSSA isolates to known clones or assigning them as novel clones via the Internet.
James O Robinson - One of the best experts on this subject based on the ideXlab platform.
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a comparison of long term outcomes after meticillin resistant and meticillin sensitive staphylococcus aureus bacteraemia an observational cohort study
Lancet Infectious Diseases, 2014Co-Authors: Lai Kin Yaw, James O RobinsonAbstract:Summary Background Findings from previous studies have suggested that outcomes after meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia are worse than after meticillin-sensitive S aureus (MSSA) bacteraemia. We assessed whether patients who had MRSA bacteraemia had a higher risk of death and recurrent infections than those who had MSSA bacteraemia. Methods For this observational cohort study, we assessed data from the microbiology laboratory database at the Royal Perth Hospital (WA, Australia). Data were for all patients who had an episode of MRSA bacteraemia between July 1, 1997, and June 30, 2007, and, by use of a computer-generated randomisation sequence, a randomly selected subgroup of patients who had an episode of MSSA bacteraemia (patients with one or more set of blood cultures positive for S aureus ). The primary outcomes were survival time and subsequent infection-related hospital readmissions, analysed by Cox proportional hazards regression with adjustment for important prognostic factors. Findings Of the 583 patients who had an episode of MRSA or MSSA bacteraemia, we used data for the 582 who had complete data linkage: 185 patients who had MRSA bacteraemia and 397 patients who had MSSA bacteraemia. The crude survival time of patients after MRSA bacteraemia was shorter than it was for patients with MSSA bacteraemia (14 months [IQR 1–86] vs 54 months [3–105]; hazard ratio 1·46, 95% CI 1·18–1·79; p=0·01). The adverse association between MRSA and all-cause mortality (0·98, 0·77–1·30; p=0·87) or infection-related mortality (1·22, 0·89–1·69; p=0·22) were not statistically significant after adjustment for important prognostic factors including age, comorbidities, severity of acute illness, metastatic infections, and long-term care facility resident status. After adjustment for these confounding factors, we saw no difference in infection-related hospital readmissions between patients who had MRSA bacteraemia and those who had MSSA bacteraemia (odds ratio 1·06, 95% CI 0·67–1·68; p=0·81). Interpretation Long-term outcomes after MRSA bacteraemia were worse than those after MSSA bacteraemia through its confounding associations with other prognostic factors. Our findings might have implications for management strategies to control MRSA colonisation. Funding The Medical Research Foundation of Royal Perth Hospital.
Mark C Enright - One of the best experts on this subject based on the ideXlab platform.
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the evolutionary history of methicillin resistant staphylococcus aureus mrsa
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Mark C Enright, Ashley D Robinson, Gaynor Randle, Edward J Feil, Hajo Grundmann, Brian G SprattAbstract:Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired infections that are becoming increasingly difficult to combat because of emerging resistance to all current antibiotic classes. The evolutionary origins of MRSA are poorly understood, no rational nomenclature exists, and there is no consensus on the number of major MRSA clones or the relatedness of clones described from different countries. We resolve all of these issues and provide a more thorough and precise analysis of the evolution of MRSA clones than has previously been possible. Using multilocus sequence typing and an algorithm, burst, we analyzed an international collection of 912 MRSA and methicillin-susceptible S. aureus (MSSA) isolates. We identified 11 major MRSA clones within five groups of related genotypes. The putative ancestral genotype of each group and the most parsimonious patterns of descent of isolates from each ancestor were inferred by using burst, which, together with analysis of the methicillin resistance genes, established the likely evolutionary origins of each major MRSA clone, the genotype of the original MRSA clone and its MSSA progenitor, and the extent of acquisition and horizontal movement of the methicillin resistance genes. Major MRSA clones have arisen repeatedly from successful epidemic MSSA strains, and isolates with decreased susceptibility to vancomycin, the antibiotic of last resort, are arising from some of these major MRSA clones, highlighting a depressing progression of increasing drug resistance within a small number of ecologically successful S. aureus genotypes.
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multilocus sequence typing for characterization of methicillin resistant and methicillin susceptible clones of staphylococcus aureus
Journal of Clinical Microbiology, 2000Co-Authors: Mark C Enright, Catrin E Davies, Sharon Peacock, Brian G SprattAbstract:A multilocus sequence typing (MLST) scheme has been developed for Staphylococcus aureus. The sequences of internal fragments of seven housekeeping genes were obtained for 155 S. aureus isolates from patients with community-acquired and hospital-acquired invasive disease in the Oxford, United Kingdom, area. Fifty-three different allelic profiles were identified, and 17 of these were represented by at least two isolates. The MLST scheme was highly discriminatory and was validated by showing that pairs of isolates with the same allelic profile produced very similar SmaI restriction fragment patterns by pulsed-field gel electrophoresis. All 22 isolates with the most prevalent allelic profile were methicillin-resistant S. aureus (MRSA) isolates and had allelic profiles identical to that of a reference strain of the epidemic MRSA clone 16 (EMRSA-16). Four MRSA isolates that were identical in allelic profile to the other major epidemic MRSA clone prevalent in British hospitals (clone EMRSA-15) were also identified. The majority of isolates (81%) were methicillin-susceptible S. aureus (MSSA) isolates, and seven MSSA clones included five or more isolates. Three of the MSSA clones included at least five isolates from patients with community-acquired invasive disease and may represent virulent clones with an increased ability to cause disease in otherwise healthy individuals. The most prevalent MSSA clone (17 isolates) was very closely related to EMRSA-16, and the success of the latter clone at causing disease in hospitals may be due to its emergence from a virulent MSSA clone that was already a major cause of invasive disease in both the community and hospital settings. MLST provides an unambiguous method for assigning MRSA and MSSA isolates to known clones or assigning them as novel clones via the Internet.
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multilocus sequence typing for characterization of methicillin resistant and methicillin susceptible clones of staphylococcus aureus
Journal of Clinical Microbiology, 2000Co-Authors: Mark C Enright, Catrin E Davies, Sharon Peacock, Nicholas P J Day, Brian G SprattAbstract:A multilocus sequence typing (MLST) scheme has been developed for Staphylococcus aureus. The sequences of internal fragments of seven housekeeping genes were obtained for 155 S. aureus isolates from patients with community-acquired and hospital-acquired invasive disease in the Oxford, United Kingdom, area. Fifty-three different allelic profiles were identified, and 17 of these were represented by at least two isolates. The MLST scheme was highly discriminatory and was validated by showing that pairs of isolates with the same allelic profile produced very similar SmaI restriction fragment patterns by pulsed-field gel electrophoresis. All 22 isolates with the most prevalent allelic profile were methicillin-resistant S. aureus (MRSA) isolates and had allelic profiles identical to that of a reference strain of the epidemic MRSA clone 16 (EMRSA-16). Four MRSA isolates that were identical in allelic profile to the other major epidemic MRSA clone prevalent in British hospitals (clone EMRSA-15) were also identified. The majority of isolates (81%) were methicillin-susceptible S. aureus (MSSA) isolates, and seven MSSA clones included five or more isolates. Three of the MSSA clones included at least five isolates from patients with community-acquired invasive disease and may represent virulent clones with an increased ability to cause disease in otherwise healthy individuals. The most prevalent MSSA clone (17 isolates) was very closely related to EMRSA-16, and the success of the latter clone at causing disease in hospitals may be due to its emergence from a virulent MSSA clone that was already a major cause of invasive disease in both the community and hospital settings. MLST provides an unambiguous method for assigning MRSA and MSSA isolates to known clones or assigning them as novel clones via the Internet.
Hans-peter Heinz - One of the best experts on this subject based on the ideXlab platform.
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Enterotoxin and toxic shock syndrome toxin-1 production of methicillin resistant and methicillin sensitive Staphylococcus aureus strains
European Journal of Epidemiology, 1997Co-Authors: Franz- Josef Schmitz, Colin R. Mackenzie, Roland Geisel, Silvia Wagner, Helga Idel, Jan Verhoef, Ulrich Hadding, Hans-peter HeinzAbstract:In this study the production of enterotoxin A-D and toxic shock syndrome toxin-1 (TSST-1) of 181 methicillin resistant (MRSA) and 100 methicillin sensitive (MSSA) Staphylococcus aureus first isolates from different patients was investigated. All the MRSA- and MSSA isolates in the study were collected in a period between 1993 and 1995 from specimens sent from 11 different acute care hospitals in the greater Düsseldorf area. As far as possible the isolates were matched according to ward and hospital. The isolates were collected in the same time period and matched for specimen from which isolated. Furthermore, only first isolates were analysed in both groups. No significant difference in the production of toxin of any type between MRSA and MSSA could be detected (51 and 40% respectively). When the individual toxins were analysed, again no significant difference between MRSA and MSSA was demonstrable (enterotoxin production by MRSA 40% and MSSA 36%, and TSST-1 16% and 8% respectively). Despite this, a slight tendency for MRSA to produce enterotoxin A and B and for MSSA to produce enterotoxin C was observed. In addition, generation of TSST-1 by both groups was independent of enterotoxin A-D production. Interestingly, no increase in the proportion of TSST-1- or enterotoxin-producing MRSA and MSSA isolates was observed in strains isolated from blood cultures from patients with a clinical diagnosis of sepsis. Genotypical pulsed-field-gel-electrophoresis (PFGE) and phenotypical (bacteriophage typing, lysotyping) characterization of the 181 MRSA isolates resulted in 28 different PFGE patterns (of which 19 were toxin producers) and 22 lysotyping groups (18 of which produced toxin). In summary, the investigated clinical S. aureus isolates showed no difference in their ability to produce toxin and this was independent of their sensitivity to methicillin.
Kenneth Okon - One of the best experts on this subject based on the ideXlab platform.
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cooccurrence of predominant panton valentine leukocidin positive sequence type st 152 and multidrug resistant st 241 staphylococcus aureus clones in nigerian hospitals
Journal of Clinical Microbiology, 2009Co-Authors: Kenneth Okon, P Basset, Auwalu Uba, Johnson Lin, Bukola Oyawoye, Adebayo Shittu, Dominique S BlancAbstract:Ninety-six clinical isolates of Staphylococcus aureus from Nigeria were characterized phenotypically and genetically. Twelve multidrug-resistant methicillin (meticillin)-resistant S. aureus (MRSA) isolates carrying a new staphylococcal cassette chromosome mec element and a high proportion of Panton-Valentine leukocidin (PVL)-positive methicillin-susceptible S. aureus (MSSA) isolates were observed. The cooccurrence of multidrug-resistant MRSA and PVL-positive MSSA isolates entails the risk of emergence of a multidrug-resistant PVL-positive MRSA clone.
