Retrospective Analysis of The Distribution of Vancomycin MIC Values Among Clinical Isolates of Methicillin-Resistant Staphylococcus Aureus In A Tertiary Care Hospital, Surat.
Retrospective Analysis Of The Distribution Of Vancomycin MIC Values
Keywords:
E test, MRSA, vancomycin, MICAbstract
Background: Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as the most common hospital-acquired pathogen and is associated with increased morbidity and mortality compared with other strains. Patients with MRSA infections caused by isolates with a high but ‘susceptible’ minimum inhibitory concentration (MIC) to vancomycin may suffer poor outcomes. The aim of this study is to determine the distribution of vancomycin MIC values for MRSA isolates in a tertiary care hospital, Surat. Method: Methicillin-Resistant Staphylococcus aureus isolates from different clinical samples of patients admitted in New Civil Hospital, Surat from January 2016 to July 2016 were included in this study. Epsilometer test (E test) method was used to determine vancomycin MIC values for MRSA isolates as per Clinical Laboratory Standards Institute (CLSI) guidelines 2016. Result: A total of 63 Methicillin-Resistant Staphylococcus aureus isolates were studied. The vancomycin MICs were 0.50, 0.75, 1, 1.5 and 2 μg/ml for 1 (2%), 2 (3%), 19 (30%), 38 (60%), 3 (5%) isolates, respectively. No MRSA isolate presented a MIC of 4-8 μg/ml (VISA-Vancomycin Intermediate S. aureus) or MIC of ≥16 μg/ml (VRSA-Vancomycin Resistant S. aureus) in present study. Conclusion: Vancomycin is the primary treatment for MRSA infection. However, different studies shows that increasing proportions of MRSA isolates with high MICs in the susceptible range (MIC ≤ 2 μg/ml) (vancomycin MIC creep) lead to treatment failure. There is a need to re-establish newer breakpoints of vancomycin MIC for determining sensitivity of MRSA isolates. [Manthan S NJIRM 2017; 8(2):5-8]
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