title: Plasmid-mediated resistance and virulence mechanisms in the private health sector in KwaZulu-Natal, South Africa: An investigation of methicillin resistant Staphylococcus aureus (MRSA) clinical isolates collected during a three month period.
abstract: OBJECTIVE
  Due to the lack of information on the plasmid content of MRSA strains in South Africa (SA), this study investigated the resistance and virulence mechanisms of 27 clinical isolates from the private health care sector over a period of 3 months.
  
  
  METHODS
  Plasmids were extracted and the presence of MRSA confirmed by the presence of mecA. The isolates were subjected to antimicrobial susceptibility testing and molecular characterization of common resistance encoding genes and frequently encountered virulence factors by PCR using plasmid DNA as the template. The genetic relatedness between the isolates was determined by pulsed field gel electrophoresis (PFGE).
  
  
  RESULTS
  All isolates were plasmid positive, and displayed ampillicin, ciprofloxacin, gentamicin, rifampicin, tetracycline, erythromycin, and clindamycin resistance. They were all fully susceptible to daptomycin, linezolid, vancomycin, tigecycline and fusidic acid. Multidrug resistance (MDR) was found in 74.1% (20/27) of the MRSA isolates. The frequency of the resistance and virulence genes ranged from 100% to 0%. PFGE analysis revealed 10 pulsotypes, designated A-J, which showed correlation with resistance profile of the isolates in each group. Of note, 85.2% (23/27) of the isolates clustered into six major PFGE types giving an indication of similar circulating MRSA clones.
  
  
  CONCLUSIONS
  This study highlights the genetic diversity and resistance mechanisms in MRSA strains from the private health sector in SA hence the need for implementing effective infection control programs.
authors.affiliation: Antimicrobial Research Unit, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Amoako
authors.affiliation: Biomedical Resource Unit, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban, South Africa. Electronic address: besterl@ukzn.ac.za.
authors.forename: Linda A
authors.initials: LA
authors.lastname: Bester
authors.affiliation: Antimicrobial Research Unit, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Anou M
authors.initials: AM
authors.lastname: Somboro
authors.affiliation: Catalysis and Peptide Research Unit, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Sooraj
authors.initials: S
authors.lastname: Baijnath
authors.affiliation: Lancet Laboratories, Durban, KwaZulu-Natal & Honorary Research Fellow, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Chetna N
authors.initials: CN
authors.lastname: Govind
authors.affiliation: Antimicrobial Research Unit, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: Sabiha Y
authors.initials: SY
authors.lastname: Essack
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male; D016106:Methicillin Resistance / Q000235:genetics; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010957:Plasmids / Q000235:genetics*; D013019:South Africa / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000382:microbiology*; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents
keywords: MRSA; PCR; PFGE; plasmids