Genomic Insights into a Complete Deletion of the mgrB Locus in Colistin-Resistant Klebsiella pneumoniae ST2268 Isolated from a Human Infection.

Abstract

OBJECTIVES\nThe emergence of colistin-resistant Klebsiella pneumoniae (CoRKp) is a serious public health issue because colistin is the last line of defense against infections caused by multidrug-resistant Gram-negative bacteria. Here, we generated a draft genome sequence for CoRKp strain P094-1, isolated from a sputum sample from an infected patient.\n\n\nMETHODS\nWhole genomic DNA of strain P094-1 was sequenced using the Pacific Biosciences platform. The generated reads were de novo assembled with Hierarchical Genome Assembly Process version 3.0. The colistin resistance-related genes were predicted from the genome sequence and validaed by experiments.\n\n\nRESULTS\nThe genome lacked a 20.3-kb region, including the complete deletion of mgrB. Molecular and genome sequencing-based analyses revealed that the observed colistin resistance of P094-1 could not be attributed to plasmid-borne mcr-1 to mcr-9 genes or to alteration of the pmr and pho operons (deletions, insertions, or substitutions), but was conferred by an insertion sequence 1 (IS1)-induced total deletion of mgrB.\n\n\nCONCLUSION\nThis is the first reported whole-genome sequence of an unusual CoRKp isolate containing an IS1-induced deletion of mgrB.