oa Southern African Journal of Epidemiology and Infection - Staphylococcus aureus from public hospitals in KwaZulu-Natal, South Africa - infection detection and strain-typing : original research
The objectives of the study were: 1) to determine the range of infections caused by Staphylococcus aureus, 2) to establish one / more rapid, reliable, reproducible and cost-effective methods for the detection of methicillin-resistant S. aureus (MRSA) in resource-constrained healthcare settings, and 3) to compare South African strains with those found globally using multi-locus strain typing (MLST). A total of 241 S. aureus isolates collected from 16 hospitals in KwaZulu-Natal were subjected to antibiotic susceptibility testing using the CLSI disc sensitivity testing method. A random selection of 24 putative MRSA and a matched control group of methicillin-sensitive S. aureus isolates were subjected to agar-based methods, the Etest and screen latex agglutination methods for MRSA detection using polymerase chain reaction as the gold standard. Strain typing was undertaken by MLST. S. aureus was implicated in a range of infections. Sensitivity, specificity, positive predictive values, negative predictive values and costs of the various detection tests showed that the use of oxacillin disc agar diffusion and oxacillin screening salt agar was appropriate for routine laboratory testing for the identification of MRSA. MLST identified the ST8- SCCmec type IV (67%), ST239-SCCmec type III (13%), ST8- SCCmec type II (8%), ST5- SCCmec type IV (8%) and ST45- SCCmec type IV (1%) clones confirming the mobility of SCCmec type IV (79%). Infections by S. aureus are a public health concern in South Africa as they are worldwide. Antibiotic prescribing trends may account for the de novo evolution of strains identified globally. Routine surveillance for MRSA is thus advocated.
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