Multiplex PCR based detection of mecA, mecC and PVL gene in analysis of prevalence, circulation, transmission of MSSA/MRSA strains in a tertiary care hospital

Abstract

Introduction: Staphylococcus aureus a Gram positive cocci causes major and minor infections in humans. It is the most important pathogen causing Hospital acquired and community-acquired (CA) infections. The commonest being the Methicillin resistant Staphylococcus aureus (MRSA) which is due to the insertion of SCC mec into methicillin-susceptible S. aureus (MSSA) lineages. Though, a number of toxins are involved in the pathogenesis of its infections, Panton Valentine leukocidin (PVL) is considered the common virulence factor for community acquired MRSA. Our study aimed to determine the prevalence of mec A and mecC gene and the presence of PVL toxin genes (lukS-PV and lukF-PV) in S. aureus isolates. Materials and Methods: The study was carried out in Department of Microbiology at Chettinad Hospital & Research Institute, a tertiary care center for 3 months. A total of 109 clinical isolates of S.aureus were subjected for the study (Wards and Outpatient departments). The identification and antimicrobial sensitivity testing were done by standard microbiological techniques. Multiplex PCR was used to detect mecA, mecC and PVL genes. Results: Out of 109 Staphylococcus aureus isolates, 24(22%) were MRSA and 85(78%) were Methicillin sensitive. Among MRSA strains, 13(54.1%) were positive for mecA, 8(33.3%) were positive for PVL, 3 (12.5%) were found positive for mecC. Among the 85(78%) MSSA isolates, 3(3.5%) were positive mecA gene and only 1(1.1%) isolate had mecC gene. The isolates from hospital environment were negative for both mecA and mecC but was positive for PVL genes. Conclusion: Our study showed high prevalence among community acquired MRSA isolates. Keywords: Community acquired staphylococcus aureus, MRSA, mecA, mec C, PVL gene, Multiplex PCR.