Abstract

In order to have an understanding of the distribution of MRSA clones in Pakistan, where unregulated antibiotic use is widespread and the distribution of MRSA is thought to be high, an epidemiological study was designed. In this study, epidemiological relationships between 123 methicillin resistant Staphylococcus aureus strains, isolated between 2006 and 2008 from three tertiary care hospitals of Rawalpindi and Islamabad, were examined using six loci in a multilocus variable number tandem repeat analysis (MLVA). A total of 63 haplotypes were obtained by MLVA. Analysis of restriction modification (RM) genes detected an RM3 type, associated with CC8 in 98% of strains and an RM1 type, associated with CC30, in only two strains. On further typing of selected strains by Spa typing and MLST, it was found that the RM3/CC8 isolates were ST113-t064, ST113-t451 or ST239, with one of four spa types, while the RM1/CC30 isolates were ST30-t021. We concluded that there is a high prevalence of CC8 MRSA strains in Rawalpindi/Islamabad, Pakistan and frequent exchange of strains between closely-linked hospitals.

Key words: Epidemiology, MRSA, MLVA, MLST, Pakistan, spa