Chromosome-Mediated Colistin Resistance in Clinical Isolates of and : Mutation Analysis in the Light of Genetic Background.

Purpose: Colistin resistance mechanisms involving mutations in chromosomal genes associated with LPS modification are not completely understood. Mutations in genes coding for the MgrB regulator frequently account for colistin resistance in , whereas mutations in genes coding for PhoPQ and PmrAB are frequent in . Our aim was to perform a genetic analysis of chromosomal mutations in colistin-resistant (MIC ≥4 µg/mL) clinical isolates of (n = 8) and (n = 7) of different STs.