Microbiological and Molecular Characterization of methicillin-resistant Staphylococcus aureus in Clinical Cultures Collected from Two Tertiary Care Hospitals in Southern Sri Lanka

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant pathogen causing life-threatening infections. It can be classified as community-associated (CA) or healthcareassociated (HA), based on antibiotic susceptibility and molecular analysis. The objective of this study is to describe MRSA prevalence and predominant MRSA types identified in clinical cultures collected from patients admitted to Teaching Hospital-Karapitiya and General Hospital-Matara in Southern Sri Lanka. S. aureus isolates from consecutive clinical cultures and associated demographic data were collected from September 2019 for fourteen months from microbiology laboratories of the two hospitals. All S. aureus and MRSA isolates were confirmed using standard microbiological methods. Based on antibiotic susceptibility profile, isolates were classified as HA-MRSA (generally resistant to β-lactam antibiotics, erythromycin, clindamycin and fluoroquinolones) and CA-MRSA (generally resistant only to ß-lactam agents and erythromycin), as described by the Centers for Disease Control and Prevention, USA. These two types were further confirmed as HA-MRSA (generally habour SCCmecI, II and III) and CA-MRSA (generally harbour SCCmecIV and V) using Staphylococcal Cassette Chromosome mec (SCCmec) typing using standard methodology.