title: Population structure analyses of Staphylococcus aureus at Tygerberg Hospital, South Africa, reveals a diverse population, a high prevalence of Panton-Valentine leukocidin genes, and unique local methicillin-resistant S. aureus clones.
abstract: Studies reporting on the population structure of Staphylococcus aureus in South Africa have focused only on methicillin-resistant S. aureus (MRSA). This study describes the population structure of S. aureus, including methicillin-susceptible S. aureus (MSSA) isolated from patients at Tygerberg Academic Hospital, Western Cape province. Pulsed-field gel electrophoresis (PFGE), detection of Panton-Valentine leukocidin (PVL), spa typing, multilocus sequence typing (MLST), agr typing and SCCmec typing were used to characterize strains. Of 367 non-repetitive S. aureus isolates collected over a period of 1 year, 56 (15.3%) were MRSA. Skin and soft tissue infections were the most frequent source (54.8%), followed by bone and joint (15.3%) and respiratory tract infections (7.7%). For strain typing, PFGE was the most discriminative method, and resulted in 31 pulsotypes (n = 345, 94.0%), as compared with 16 spa clonal complexes (CCs) (n = 344, 93.4%). Four MLST CCs were identified after eBURST of sequence types (STs) of selected isolates. One hundred and sixty isolates (MSSA, n = 155, 42.2%) were PVL-positive, and agr types I-IV and SCCmec types I-V were identified. Our S. aureus population consisted of genotypically diverse strains, with PVL being a common characteristic of MSSA. MSSA and MRSA isolates clustered in different clones. However, the dominant MRSA clone (ST612) also contained an MSSA isolate, and had a unique genotype. Common global epidemic MRSA clones, such as ST239-MRSA-III and ST36-MRSA-II, were identified. A local clone, ST612-MRSA-IV, was found to be the dominant MRSA clone.
authors.affiliation: Division of Medical Microbiology, Tygerberg Hospital, Stellenbosch University, Cape Town, South Africa.
authors.forename: W F
authors.initials: WF
authors.lastname: Oosthuysen
authors.forename: H
authors.initials: H
authors.lastname: Orth
authors.forename: C J
authors.initials: CJ
authors.lastname: Lombard
authors.forename: B
authors.initials: B
authors.lastname: Sinha
authors.forename: E
authors.initials: E
authors.lastname: Wasserman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001427:Bacterial Toxins / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005098:Exotoxins / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006761:Hospitals; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007956:Leukocidins / Q000235:genetics*; D008297:Male; D016106:Methicillin Resistance; D058889:Molecular Typing; D013019:South Africa / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology* / Q000473:pathology; D013211:Staphylococcus aureus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics; D055815:Young Adult
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D037521:Virulence Factors
keywords: Methicillin resistance; PVL; S. aureus; SCC
  mec; South Africa