ABSTRACT
Few antibiotics are left that are effective against methicillin-resistant Staphylococcus
aureus (MRSA) and even strains resistant to these agents have been isolated. Previous
studies have identified five distinct MRSA clonotypes, which are present globally. No
comprehensive national study has previously been undertaken to investigate the MRSA
types in South Africa, and this study was aimed at elucidating the genotypic population
structure of South African MRSA isolates. SmaI digested genomic DNA, separated by
pulsed-field gel electrophoresis, was used to characterise 349 S. aureus isolates, obtained
from various state and private diagnostic laboratories. PFGE results were complemented
with those of spa typing and staphylococcal cassette chromosome mec (SCCmec) typing
results. Two-hundred-and-five different PFGE patterns were identified, which were
grouped into twenty-four clusters. Three were major lineages, containing more than 20%
of the isolates with a similarity cut-off of 70%. Only thirty-seven spa types were identified
(fourteen novel spa types), which clustered into six spa-Clonal Complexes after BURP
analysis. SCCmec types I-IV were identified, including variants of each type. Data
suggest that the Archaic clone (RSA05), oldest of the epidemic clones, represents one of
the major clones in South Africa. Strains that were part of this complex (n=98 (28.2%);
t064; SCCmec type I-pls) clustered together with strain E2125/ATCC BAA-38 (t051;
SCCmec type I). Another major complex, RSA16 (n=90 (25.7%); t012; SCCmec type
II/IIB) possessed a single-locus variant (SLV) spa type and the same or a SLV SCCmec
types as EMRSA-16 (t018; SCCmec type II). The third major complex, RSA03 (n=74
(21.2%); t037; SCCmec type III/IIIE), had similar spa and SCCmec types to control strainANS46 (t037; SCCmec type III). One MRSA and twelve MSSA isolates were also
identified as carrying genes for the toxin Panton-Valentine leukocidin, which was
confirmed by DNA nucleotide sequencing.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/4919 |
| Date | 03 June 2008 |
| Creators | Oosthuysen, Wilhelm Frederick |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 6655915 bytes, application/pdf, application/pdf |
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