Molecular characterization of methicillin-resistant Staphylococcus aureus: Dissemination of multidrug-resistant community-associated MRSA and emergence of LA-MRSA, in a healthcare setting.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a significant cause of healthcare-associated infections (HAIs). In this study, we aimed to characterize the MRSA isolates obtained from HAIs.

METHODS: A total of 200 clinical and 13 nasal MRSA isolates were collected and tested. The samples were analyzed for SCCmec typing by using multiplex PCR. Microtiter for biofilm formation were performed and molecular typing for the samples were performed for spa and agr typing.

RESULTS: The isolates showed 100 % sensitivity to vancomycin and linezolid, while 92.5 % were multidrug-resistant. Strong biofilm-forming ability was observed in 47 % of the isolates. SCC mec typing identified 52.5 % of the isolates as classical hospital-associated MRSA or HA-MRSA (SCC mec type III), 23.5 % as community-associated MRSA or CA-MRSA (type IV and V), and 16.5 % as non-typeable, with 7.5 % having multiple SCCmec types.

CONCLUSION: Comparison of HA and CA-MRSA traits revealed that both groups had multidrug resistance, but HA-MRSA was distinguished by its strong capacity for biofilm formation, whereas CA-MRSA was marked by a high count of toxin gene. Our study, to the best of our awareness, documents the presence of LA-MRSA (SCCmec V- t127-agr III) causing HAIs in Indian patients for the first time.