MINIMUM INHIBITORY CONCENTRATION OF VANCOMYCIN AMONG METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS ISOLATES FROM A TERTIARY CARE CENTRE

Introduction: Infections due to methicillin resistant Staphylococcus aureus (MRSA) are increasing worldwide. Vancomycin is considered as the drug of choice to treat serious infections caused by MRSA strains. The emergence of S. aureus isolates with intermediate and complete resistance to vancomycin in the past two decades is a major public health concern. Aim and Objectives: To determine the MIC of vancomycin in MRSA isolates from various clinical specimens and to observe the occurrence of VRSA and VISA. Materials and Methods: This cross-sectional study was conducted between November 2020 to October 2021 in the department of Microbiology, RMCH, Bareilly. S. aureus isolates were identified using routine identification methods. MRSA isolates were subjected to E-test for detection of MIC of vancomycin through vancomycin Ezy MIC Strips (Hi Media Range .016-256μg/ml). Results: A total of 180 S. aureus strains were isolated during the study period. Out of these strains 100 (55.55%) MRSA and 80 (44.45%) MSSA were isolated. Out of 100 MRSA strains 8 strains showed vancomycin MIC of 0.75 μg/ml, 50 strains showed vancomycin MIC of 1 μg/ml, 36 strains showed vancomycin MIC of 1.5 μg/ml and 6 strains of MRSA showed vancomycin MIC of 2μg/ml. Conclusion: Among MRSA isolates, 6 strains with high vancomycin MIC (2μg/ml) were detected along with multidrug resistance to aminoglycosides, fluoroquinolones and macrolides. The study indicates a rising trend in MIC of vancomycin in MRSA isolates which has become a serious public health concern. Routine testing and reporting of vancomycin MIC is crucial so that effective treatment regimen can be initiated for patients and the development of resistance of S. aureus to this reserve drug can be prevented.