PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF VANCOMYCIN RESISTANT ENTEROCOCCUS ISOLATES FROM CLINICAL SAMPLES AT A RURAL TERTIARY CARE HOSPITAL

Abstract

Introduction: Vancomycin-resistant enterococcal (VRE) infections have become a significant concern in healthcare settings due to their emergence as a cause of nosocomial infections. These strains possess various resistance genes, leading to high-level inducible or low-level intrinsic resistance to vancomycin. Infections caused by VRE strains are associated with elevated mortality rates. This study aimed to characterize phenotypically and genotypically VRE strains isolated from diverse clinical samples.

Methods: One hundred enterococcal strains were isolated from various clinical samples between January 2015 and June 2016. Identification and speciation were performed using the Vitek ® 2 Compact system. Minimum inhibitory concentrations (MIC) of vancomycin and teicoplanin were determined using the E-test and agar dilution method. Genotypic characterization was conducted through multiplex polymerase chain reaction (PCR).

Results: Among the 100 Enterococcus isolates, six exhibited resistance to vancomycin by MIC testing. None of the isolates showed the VanA phenotype, while one demonstrated the VanB phenotype, speciated as E. faecalis. Three isolates displayed the VanC phenotype, identified as motile species E. gallinarum and E. casseliflavus. The three VanC phenotype isolates were positive for the vanC1 gene, indicating low-degree intrinsic vancomycin resistance. The VanB phenotype isolate positive for the vanB gene showed high-level inducible vancomycin resistance.

Conclusion: Although the VanA phenotype is commonly observed, this study did not find any VanA phenotype or genotype. These findings emphasize the need for strict protocols involving VRE screening and MIC testing.