Enzyme Patterns and Factors Associated with Mortality among Patients with Carbapenem Resistant Acinetobacter Baumannii (CRAB) Bacteremia: Real World Evidence from a Tertiary Center in India

Introduction: In the Indian setting, antimicrobial resistance in A. baumannii is a considerable problem, especially in intensive care units (ICUs). Due to the limited data, clinicians are left with very few choices except polymyxins for treating serious infections caused by A. baumannii. There is sparse data regarding the local mechanisms of resistance. Given the current therapeutic challenges, it is critical to know the local enzymatic patterns and antibiograms.Materials and methods: A retrospective analysis of 50 episodes of bacteremia caused by CRAB. We analyzed the enzyme patterns and the susceptibility rates to various antibiotics.Results: The resistance rates for amikacin, tigecycline, minocycline, and fluoroquinolones were 88, 82, 50, and 88% respectively. OXA-23 was the most commonly isolated enzyme (86% of the isolates produced OXA-23) followed by OXA-51 and NDM. The overall mortality was high (58%). On univariate analysis, pneumonia, and higher Pitt's bacteremia score were significantly associated with mortality (p = 0.04 and p = 0.001 respectively). Of the total patients who received combination therapy, a majority (58%) received polymyxin plus meropenem. Combination therapy using polymyxins as a backbone was not associated with reduced mortality (p = 0.1).Conclusion:A. baumannii is associated with significant morbidity and mortality, as shown in our study. The rates of resistance for aminoglycosides were very high, and minocycline showed better susceptibility rates in comparison with tigecycline. In our study, OXA-23 and NDM remained the most important enzymes. The routine use of the combination of polymyxin and meropenem may not offer a significant advantage over monotherapy.