MgrB variants in colistin-susceptible and colistin-resistant Klebsiella pneumoniae ST258

Resistance determinants of a colistin susceptible and five colistin resistant Klebsiella pneumoniae ST258 from a Hungarian outbreak were investigated. A novel MgrB variant in colistin susceptible strain was found. Elevated phoP and arn gene expressions and wild-type PmrB in all colistin resistant K. pneumoniae were detected. All strains lacked mcr-1.