A STUDY OF VANCOMYCIN INTERMEDIATE RESISTANCE AND HETERORESISTANCE IN CLINICAL ISOLATES OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS AT A TERTIARY CARE HOSPITAL

Background: Methicillin resistant Staphylococcus aureus (MRSA) is known to cause various infections ranging from minor skin and soft tissue infections to devastating septicaemia and endocarditis. The only drug that is currently most effective against MRSA infections is a glycopeptide, vancomycin. Due to continued exposure and injudicious use of this novel drug, cases of reduced susceptibility to vancomycin are appearing which could be complete resistance (VRSA), intermediate resistance (VISA) or heterogeneous resistance (hVISA). Aims & Objectives: To study: The antimicrobial susceptibility pattern of MRSA to commonly used antibiotics and vancomycin, teicoplanin and linezolid. The proportion of VISA and hVISA among MRSA isolates. Material & Methods: The study was conducted in Microbiology department of GGSMCH, Faridkot in which 150 MRSA isolates were processed as per standard microbiological protocols. Vancomycin susceptibility was studied by 3 methods: vancomycin screen agar using 6 mg/mL of vancomycin, micro broth-dilution and Epsilometer test using Hi-media Vancomycin-Teicoplanin graded E-strip. Results: Of 11726 specimens received, Staphylococcus aureus (S. aureus) was isolated from 230 specimens. 85.22% (196) were methicillin resistant (MRSA). 150 consecutive MRSA isolates were considered for this study. Maximum resistance was observed against ampicillin (100%), followed by ciprofloxacin (88%), erythromycin (79.33%), cotrimoxazole (64.67%), clindamycin (52.1%)and amikacin (51.3%).  No MRSA isolate was resistant to teicoplanin, rifampicin and linezolid and also dint show any resistance to vancomycin (hVISA, VISA, VRSA). Conclusion: There is high prevalence of MRSA in our hospital and all isolates showed high level of resistance to multiple classes of antibiotics except linezolid, rifampicin, and glycopeptides, thereby limiting the therapeutic options. This indicates that there is an urgent need of implementation of effective infection control practices.