Polymyxin Resistance Caused bymgrBInactivation Is Not Associated with Significant Biological Cost in Klebsiella pneumoniae

Abstract

ABSTRACTThe inactivation of themgrBgene, which encodes a negative-feedback regulator of the PhoPQ signaling system, was recently shown to be a common mutational mechanism responsible for acquired polymyxin resistance among carbapenemase-producingKlebsiella pneumoniaestrains from clinical sources. In this work, we show thatmgrBmutants can easily be selectedin vitrofrom differentK. pneumoniaelineages, andmgrBinactivation is not associated with a significant biological cost.