Abstract
Community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) strains are increasingly replacing hospital-acquired MRSA (HA-MRSA) strains in hospitalized patients leading to poor clinical outcomes. Hence, this study aimed to characterize clinical isolates of MRSA (HA-MRSA and CA-MRSA) and to understand their clonal origin. A total of 400 consecutive S. aureus clinical isolates were collected from the clinical bacteriology lab of a tertiary care hospital. All the isolates were screened for MRSA by cefoxitin disc diffusion test and mecA PCR, followed by SCCmec typing, antibiotic susceptibility testing, Panton Valentine Leukocidin (PVL) screening, and pulsed field gel electrophoresis (PFGE). Of the total 400 isolates, 134 categorized MRSA by cefoxitin, while 129 as mecA positive by PCR, of which 117 could be characterized into SCCmec types. SCCmecI and II were present in 1 isolate each, SCCmecIII in 36 (31%) representing HA-MRSA, While SCCmecIV in 51 (44%), and SCCmecV in 28 (24%) isolates representing CA-MRSA. Of all SCCmecIII isolates, 70% were multidrug resistant (MDR) while 59% of SCCmecIV and 29% of SCCmecV isolates were MDR. PVL (CA-MRSA virulence factor) positivity in mecIII, IV, V isolates was 9%, 31%, 46% respectively. PFGE typing showed MRSA clones of multiple origins. In conclusion, study showed the evolving epidemiology of HA-MRSA and CA-MRSA. CA-MRSA constituted the majority of clinical isolates amongst both community and hospital MRSA isolates. Various MDR clones of mecIV and mecV were circulating and replacing mecIII in hospital settings. SCCmecIV isolates were predominant and evolved as MDR, however, PVL was significantly associated with CA-MRSA. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12088-024-01195-9.