Bile salts induce resistance to polymyxin in Enterohemorrhagic Escherichia coli O157:H7

ABSTRACT

Many enteric bacteria use bile as an environmental cue to signal resistance and virulence gene expression. Microarray analysis of enterohemorrhagic Escherichia coli O157:H7 (EHEC) treated with bile salts revealed up-regulation of genes for an efflux system (acrAB), a two-component signal transduction system (basRS/pmrAB) and lipid A modification (arnBCADTEF and ugd). Bile salt treatment of EHEC produced a basS- and arnT-dependent resistance to polymyxin.