Concurrent presence of Staphylococcal Cassette Chromosome mec types of Meticillin-Resistant Staphylococcus aureus in hospital environments and post-operative patients at a hospital in Kathmandu, Nepal.

Abstract

Introduction: Meticillin resistant S. aureus (MRSA) is a major contributor to surgical site infections in post-operative patients. Hospital environments harbor MRSA, contributing to higher risk of nosocomial infections. Meticillin resistance is conferred by acquisition of mecA gene, typically carried on mobile genetic element called Staphylococcal Cassette Chromosome mec (SCCmec).

Objective: This study aimed to determine the prevalence of MRSA, detect mecA, characterize SCCmec types and compare their concurrent presence in clinical and environmental isolates.

Methods: A cross sectional study was conducted at Bhaktapur Hospital, Nepal among clinical specimens collected from postoperative patients. Air and environmental samples were collected by plate exposure and swabbing methods. Samples were processed for culture and antibiotic susceptibility testing by Kirby-Bauer Disc diffusion method, and identification of MRSA using cefoxitin disc. SCCmec typing was done by conventional PCR.

Results: The culture positivity among samples from post-operative patients was 13.9% (326/2350) with S.aureus (39.7%,29/73) being predominating Gram positive bacteria. MRSA accounted for 68 % (20/29) of clinical isolates and 66% (22/33) of environmental isolates, with mecA detected in 85% (17/20) and 72.8% (16/22) respectively. SCCmec Type II predominated followed by Type V and I, while other types were absent. Comparison of SCCmec elements between post-operative patients and hospital environmental samples revealed concurrent presence in both setting, with Type II being the most prevalent.

Conclusions: SCCmec Type I, II, V and mecA elements were concurrently present in both post-operative patients and hospital environments. Effective preventive measures are warranted to break the MRSA transmission between these settings.