Predominance and Emergence of Clones of Hospital-Acquired Methicillin-Resistant <i>Staphylococcus aureus</i> in Malaysia

<jats:title>ABSTRACT</jats:title> <jats:p> We define the epidemiology of predominant and sporadic methicillin-resistant <jats:italic>Staphylococcus aureus</jats:italic> (MRSA) strains in a central teaching and referral hospital in Kuala Lumpur, Malaysia. This is done on the basis of <jats:italic>spa</jats:italic> sequencing, multilocus sequence typing (MLST), staphylococcal cassette chromosome <jats:italic>mec</jats:italic> (SCC <jats:italic>mec</jats:italic> ) typing, and virulence gene profiling. During the period of study, the MRSA prevalence was 44.1%, and 389 MRSA strains were included. The prevalence of MRSA was found to be significantly higher in the patients of Indian ethnicity ( <jats:italic>P</jats:italic> < 0.001). The majority (92.5%) of the isolates belonged to ST-239, <jats:italic>spa</jats:italic> type t037, and possessed the type III or IIIA SCC <jats:italic>mec</jats:italic> . The arginine catabolic mobile element (ACME) <jats:italic>arcA</jats:italic> gene was detected in three (1.05%) ST-239 isolates. We report the first identification of ACME <jats:italic>arcA</jats:italic> gene-positive ST-239. Apart from this predominant clone, six (1.5%) isolates of ST-22, with two related <jats:italic>spa</jats:italic> types (t032 and t4184) and a singleton (t3213), carrying type IVh SCC <jats:italic>mec</jats:italic> , were detected for the first time in Asia. A limited number of community-acquired (CA) MRSA strains were also detected. These included ST-188/t189 (2.1%), ST-1/t127 (2.3%), and ST-7/t091 (1%). Panton-Valentin leukocidin (PVL) was detected in all ST-1 and ST-188 strains and in 0.7% of the ST-239 isolates. The majority of the isolates carried <jats:italic>agr</jats:italic> I, except that ST-1 strains were <jats:italic>agr</jats:italic> III positive. Virulence genes <jats:italic>seg</jats:italic> and <jats:italic>sei</jats:italic> were seen only among ST-22 isolates. In conclusion, current results revealed the predominance of ST-239-SCC <jats:italic>mec</jats:italic> III/IIIA and the penetration of ST-22 with different virulence gene profiles. The emergence in Malaysia of novel clones of known epidemic and pathogenic potential should be taken seriously. </jats:p>