title: Prevalent genotypes of meticillin-resistant Staphylococcus aureus: report from Pakistan.
abstract: Meticillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen in Pakistan and is emerging in the community. This is one of the first reports of the prevalent genotypes of MRSA in both hospital and community settings in Pakistan. Isolates collected in 2006-2007 were characterized by PFGE, staphylococcal cassette chromosome mec (SCCmec) typing and multilocus sequence typing (MLST). PFGE identified nine pulsotypes, the majority of isolates belonging to pulsotypes A (n=70) and B (n=38), which were predominant among hospital-onset MRSA (HO-MRSA) and community-onset MRSA (CO-MRSA) isolates, respectively. Among the HO-MRSA isolates, variants of SCCmec type III were prevalent, whilst SCCmec type IV or variants were predominant in the CO-MRSA isolates. MLST identified two principal sequence types, ST8 and ST239. An association was observed between ST8, PFGE pulsotype B and SCCmec type IV in the CO-MRSA (ST8-MRSA-IV). Similarly, ST239, PFGE pulsotype A and SCCmec type III were associated with HO-MRSA (ST239-MRSA-III). Therefore, the prevalent genotypes circulating in Pakistan at the time of study were ST8-MRSA-IV and ST239-MRSA-III in the community and hospital settings, respectively. A set of HO-MRSA isolates collected in 1997 were characterized by PFGE and SCCmec typing for comparison. The isolates belonged to two PFGE pulsotypes (A, n=28; B, n=11) and contained just two SCCmec types. These results suggest that an increase in genetic diversity occurred over the period 1997-2007 as a result of either microevolution or the importation of strains from surrounding areas.
authors.affiliation: Aga Khan University Hospital, Karachi, Pakistan.
authors.forename: A
authors.initials: A
authors.lastname: Zafar
authors.affiliation: Department of Microbiology, Imperial College Healthcare NHS Trust, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Stone
authors.affiliation: Aga Khan University Hospital, Karachi, Pakistan.
authors.forename: S
authors.initials: S
authors.lastname: Ibrahim
authors.affiliation: Aga Khan University Hospital, Karachi, Pakistan.
authors.forename: Z
authors.initials: Z
authors.lastname: Parveen
authors.affiliation: Aga Khan University Hospital, Karachi, Pakistan.
authors.forename: Z
authors.initials: Z
authors.lastname: Hasan
authors.affiliation: Aga Khan University Hospital, Karachi, Pakistan.
authors.forename: E
authors.initials: E
authors.lastname: Khan
authors.affiliation: Aga Khan University Hospital, Karachi, Pakistan.
authors.forename: R
authors.initials: R
authors.lastname: Hasan
authors.affiliation: Laboratory of Enteric Pathogens, Health Protection Agency, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Wain
authors.affiliation: Department of Microbiology, Imperial College Healthcare NHS Trust, London, UK.
authors.forename: K
authors.initials: K
authors.lastname: Bamford
mesh_terms: D015373:Bacterial Typing Techniques; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005838:Genotype; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D017720:Molecular Epidemiology; D010154:Pakistan / Q000453:epidemiology; D015995:Prevalence; D017422:Sequence Analysis, DNA / Q000379:methods; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial