Methicillin Resistant S. aureus (MRSA) Bacteremia: A Case Series and the Clinical Implications of Vancomycin MIC Creep

Purpose: Methicillin resistant S. aureus (MRSA) bacteremia carries high morbidity and mortality. Very few studies from India have looked into the clinical features and outcome of MRSA bacteremia, at the same time some studies have noticed significant vancomycin MIC creep amongst MRSA isolates. Materials and Methods: It is a retrospective observational study conducted at a tertiary care centre over a period of five years, describing clinical characteristics and outcome of patients with MRSA bacteremia and attempted to analyse clinical implications of vancomycin MIC creep in MRSA bacteremia. Results: A total of 60 cases of MRSA bacteremia were studied. Prior antibiotic exposure (63.3%), recent hospitalisation (61.7%) and diabetes mellitus (40%) were the commonest potential risk factors. Fifteen percent of the study population had persistent bacteremia. There was no statistically significant difference in outcome between vancomycin and teicoplanin as empirical antibiotics. Our study demonstrated an increase in percentage of isolates with MIC ? 1 from 2011 to 2015. On an attempt to analyse clinical implication of this creep we found no statistically significant difference between high (MIC ? 1) and low (MICless than1) vancomycin MIC groups. Conclusion: We conclude that MRSA bacteremia is a serious infection with most patients requiring ICU admission, with almost one in seven patients having persistent bacteremia and an overall mortality rate of 16 percent. With a rise in vancomycin MIC further randomised studies are needed to see its clinical implication.