Global Epidemiology on Colistin Resistant Acinetobacter baumannii

While colistin remains a last resort agent to treat multi-drug resistant Acinetobacter baumannii, resistance to colistin has been reported throughout the world. The resistance has been attributed to mutations in lipid A biosynthesis genes and point mutation in PmrAB-two component response regulator and sensor kinase system. The emergence of plasmid mediated colistin resistance (mcr-1), in multidrug-resistant enterobacteriaceae raised concerns, though mcr-1 has not yet been reported in A. baumannii. Lately, colistin resistance has been attributed to efflux pumps belonging to RND family. While various reports of emergence of colistin resistance are associated with previous treatment with colistin, other reports concern patients without any prior therapy.