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. (9th December 2013) - Oosthuysen, W. F.
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.