In Vitro Activity of Tigecycline in the Era of NDM-1

In the current era of New Delhi Metallo-betalactamase-1 (NDM-1) infections and a dry antibiotic pipeline, managing infections caused by Multi-Drug Resistant Gram-Negative Bacterial infections (MDR-GNBs) presents a great challenge to physicians in the developing world. Tigecycline, a broad spectrum glycylcycline is a one among the few treatment options against MDR-GNBs. However it has been studied mostly in the western world, where the prevalence of MDR-GNB infections is less than the developing world. In this study, we report the in vitro activities of tigecycline and selected antimicrobials against gram-negative bacterial isolates. We evaluated the in vitro activity of tigecycline against 80 gram-negative bacterial isolates and compared its susceptibility against Cefoperazone-Sulbactam (CS), imipenem and colistin in a tertiary care hospital in South India. Tigecycline showed 100% activity against E.coli, similar to colistin and better than impenem and cefoperazone-sulbactam. However only 80% of Klebsiella pneumoniae isolates remained susceptible to tigecycline and colistin had higher in vitro activity against Acinetobacter. Tigecycline is a good option for the management of MDR E.coli and an alternative option against Acinetobacter infections in India. However the decline in susceptibility of tigecycline against K.pneumoniae is a worrisome phenomenon.