Predominance of SCCmec types IV and V among biofilm producing device-associated Staphylococcus aureus strains isolated from tertiary care hospitals in Mysuru, India

Abstract

Introduction: Device associated infections caused by Staphylococcus aureus in hospitalised patients is a serious healthcare problem. The present study was designed to determine the prevalence of biofilm-producing MRSA in device-associated infections.

Methods: Device-associated S. aureus strains (n=200) obtained from two tertiary care hospitals in Mysuru city, India were screened for biofilm production, antibiotic resistance, Panton-Valentine Leucocidin genes, SCCmec-types, spa-types, and intercellular adhesion (icaAD) dependent and independent genes. The efficacy of antibiotics (linezolid, vancomycin and rifampicin) on biofilms was studied using MTT assay, and the results were correlated with the occurrence of ica-dependent and independent factors.

Results: Multidrug resistance was observed in 155 strains (77.5%), and 124 strains (62%) were identified as biofilm producers. Methicillin resistance was identified in 145 strains (72.5%), and SCCmec typing of these isolates revealed high prevalence of type IV and type V. They also showed increased prevalence of pvl gene. icaAD was identified in 65 isolates, with 37 isolates showing both icaAD and ica-independent genes. spa types t852 and t657 were predominantly observed in MRSA isolates. Those isolates that had both ica-dependent and ica-independent genes showed more resistance to the screened antibiotics than the ica-dependent alone.

Conclusion: This study reports a high prevalence of SCCmec type IV and V in biofilm producing S. aureus strains isolated from device-associated infections. Increased prevalence of pvl in SCCmec types IV and V strains suggests the role of community associated S. aureus in device-associated infections. The simultaneous presence of ica-dependent and independent genes increased the antibiotic resistance in established biofilms. Thus, S. aureus on medical devices is a potential risk for patients.

Keywords: Biofilm; Biopelícula; MRSA; Multi-drug resistance; Multirresistencia antibiótica; SARM; SCCmec; Staphylococcus; ica dependiente; ica independiente; ica-dependent; ica-independent; spa-typing; tipos spa.