Phenotypic Detection and Molecular Characterization of VISA/VRSA among MRSA Isolates from A Tertiary Care Centre: An Observational Study

In recent years, the cases of vancomycin-resistant Staphylococcus aureus (VRSA) have increased worldwide. The overuse of vancomycin has significantly contributed to the emergence of VRSA, a serious public health concern. This study aimed to observe the trends of VRSA in the Indian population. This study was conducted with 440 S. aureus clinical isolates at a tertiary care centre. The study processes samples through several stages: isolating and identifying S. aureus, screening for MRSA and VRSA, performing antibiotic susceptibility testing, differentiating between VISA and VRSA, extracting DNA, and detecting vanA and vanB genes via the PCR method. Among the isolated S. aureus (440), 150 (34.1%) were MSSA, and 290 (65.9%) were MRSA. From the 290 MRSA isolates, 272 (93.8%) were VSSA strains, while 18 (6.2%) were VRSA. No strains of VISA were isolated. In the genotypic analysis of VRSA strains, the proportion of the vanA gene was 33.33%, while the vanB gene was found in 11.11%. These findings emphasize the emergence of VRSA strains in community-acquired infections. The isolation of these resistance genes in our research is alarming, as it suggests the potential transmission of vancomycin resistance genes within Staphylococcus aureus populations. Understanding the patterns of vanA and vanB gene spread in VRSA strains is crucial for developing targeted interventions and a nationwide surveillance program.