Antibiotic resistance, biofilm forming ability, and clonal profiling of clinical isolates of Staphylococcus aureus from southern and northeastern India

BACKGROUND: Staphylococcus aureus is a pathogen endemic in India and sometimes deadly for patients in intensive care units. OBJECTIVES: To determine the antibiotic-resistance pattern, biofilm forming ability, and clonal type of S. aureus from isolates collected in Tamil Nadu (south) and the Mizoram (northeast) regions of India. METHODS: We collected S. aureus isolates from diagnostic laboratories in Tamil Nadu and Mizoram. An antibiotic susceptibility test was performed according to Clinical Laboratory and Standards Institute methods. Antibiotic-resistant determinants such as mecA, mecC, blaZ, vanA, vanB, and vanC were confirmed by polymerase chain reaction (PCR). All isolates were further studied for biofilm forming ability. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was used for clonal analysis. RESULTS: A study of 206 clinical isolates showed 52.9% prevalence of methicillin-resistant S. aureus in Tamil Nadu and 49.4% in Mizoram. Minimum inhibitory concentration tests showed a high prevalence of 67% oxacillin resistance in isolates from Tamil Nadu and 49% in isolates from Mizoram. PCR showed 53% mecA in Tamil Nadu and 49% mecA in Mizoram. Vancomycin-intermediate resistance S. aureus (VISA) prevalence was lower in isolates from Tamil Nadu (4%) and Mizoram (5%). All methicillin-resistant S. aureus (MRSA) isolates formed biofilms. Clonal analysis revealed a genetic relatedness between the isolates. CONCLUSIONS: The prevalence of MRSA is high in the regions studied, with most of the clinical isolates being multidrug resistant. Adopting appropriate community-based preventive measures and establishing antimicrobial stewardship is highly recommended to minimize the dissemination in antibiotic resistance.