Multisensitive Panton-Valentine Leukocidin-Positive Methicillin-Resistant Staphylococcus aureus in Kuala Lumpur, Malaysia

Abstract

Background: Recent years have seen the emergence of methicillin-resistant Staphylococcus aureus (MRSA) strains often characterised by community acquisition, unusual susceptibility to antimicrobials, and the Panton-Valentine leukocidin (PVL) virulence factor. The epidemiology of these strains varies between geographical locations. This study aimed to determine the occurrence and clinical features of such strains in the University of Malaya Medical Centre, Kuala Lumpur. Methods: Laboratory records were examined for MRSA isolates from 2002–2007. Using CLSI disc diffusion standards, multisensitive MRSA was defined as susceptibility to erythromycin, clindamycin, fusidic acid, rifampicin, gentamicin, ciprofloxacin, cotrimoxazole, and tetracycline. PCR detection of mecA and PVL genes lukS-PV-lukF-PV, SCCmec typing, and MLST were carried out. The PVL product was confirmed by sequencing. Only cases with isolates available for PCR confirmation were included in clinical records review. Centers for Diseases Control and Prevention criteria were used to distinguish between community-associated (CA-MRSA) and healthcare-associated MRSA. Results: Multisensitive MRSA from 13 distinct patient-episodes were identified; 1 in 2003, 2 in 2006, and 10 in 2007 (0.27%, 0.62%, and 3.1% of new MRSA cases, respectively). 9 isolates from 2007 were available for mecA confirmation. Of these, only 2 were PVL-positive CA-MRSA; the remaining 7 were healthcare-associated, of which 3 were PVL-positive. All isolates were of SCCmec type IV. There were 3 isolates of each sequence type (ST) ST30 and ST6, 1 ST22 strain, and 2 untypeable isolates. Clinical presentations included skin or soft-tissue infections (6), probable colonisation (2 babies), bacteraemia (1), and no deaths. All 4 isolates unavailable for confirmation were healthcare-associated. Conclusion: We describe the first confirmed clinical infections with multisensitive, SCCmec type IV, PVL-positive MRSA in Malaysia, which were mainly skin or soft-tissue infections. In view of the predominance of healthcare-associated acquisition, and the apparent increase in cases in 2007 (albeit small numbers), further work including multilocus sequence typing is necessary to fully understand the local epidemiology of MRSA.