VISA AMONGST MRSA ISOLATES IN A TERTIARY CARE HOSPITAL IN MANIPUR
Journal of Evolution of Medical and Dental Sciences
BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital acquired and community-acquired infections. MRSA isolates are important for their resistance to many commonly used antibiotics. Vancomycin, a glycopeptide, was considered to be the best alternative for the treatment of MRSA. However, there are increasing number of reports indicating the emergence of vancomycin-resistant S. aureus (VRSA). The prevalence of MRSA in a similar setup in the state showed a
... state showed a prevalence of MRSA to be 84% in 2008. Therefore, the objective of this study was to find prevalence of the VISA amongst the MRSA isolates in our Hospital. MATERIALS AND METHODS A cross-sectional study was conducted in a tertiary care teaching hospital of Imphal, Manipur, India during the period from December 2015 to May 2016. A total of 126 Staphylococcus aureus isolates from different clinical specimens like wound swabs, pus and urine received from inpatients and outpatients of this referral tertiary care hospital were included in the study. Staphylococci were obtained either as pure culture or as an isolate of a polymicrobial infection. S. aureus was identified conventionally. MRSA were identified using cefoxitin disc (30 μg) by Kirby-Bauer disc diffusion technique according Clinical and Laboratory Standards Institute (CLSI) guidelines 2014. All MRSA isolates were subjected to susceptibility testing by the Kirby-Bauer's disc diffusion method using different antimicrobial agents. All the MRSA isolates irrespective of their susceptibility pattern to Vancomycin by disc diffusion were resorted to E-test (bioMerieux) to determine the minimum inhibitory concentration (MIC). MIC ≤2 µg/mL were identified as sensitive, 4 to 8 mg/L were identified as vancomycin-intermediate and isolates with a vancomycin MIC >16 mg/L were identified as vancomycin-resistant S. aureus according to CLSI, 2014. Quality control was performed using the S. aureus ATCC 25213 strain. Antibiotic susceptibility testing of VISA isolates was done by Kirby-Bauer's Disc diffusion method using the same drugs used for MRSA. RESULTS Prevalence of MRSA was (100/126) 79.36%. MRSA isolates were 100% resistant to Penicillin followed by Ampicillin (90%), Cotrimoxazole (76%). 100% sensitivity was seen with Linezolid followed by Ciprofloxacin (75%), Ofloxacin (79%), Nitrofurantoin (76%), Amikacin (62%), Gentamycin (70%) and Tetracycline (66%). Prevalence of VISA isolates was 3% (3/100) in this study. Amongst the VISA isolates, linezolid was the most sensitive for all the three isolates and nitrofurantoin was sensitive for both the urine isolates and clindamycin was also sensitive for the only pus isolate. CONCLUSION This study emphasises the need to study the prevalence and antimicrobial susceptibility pattern of MRSA isolates area-wise in order to guide policy on the appropriate use of antibiotics which would minimise the irrational use of vancomycin and so the emergence of resistance to vancomycin.