Cloning of a Cation Efflux Pump Gene Associated with Chlorhexidine Resistance in Klebsiella pneumoniae

Expression libraries of a chlorhexidine-resistant Klebsiella pneumoniae strain were constructed and transformed into Escherichia coli XLOLR. Twenty chlorhexidine-resistant transformants were obtained after selection. All clones contained a novel 903-nucleotide locus. Its sequences were compatible with a cation efflux pump, and the locus was thus designated as cepA. Retransformation using cepA-containing plasmids conferred chlorhexidine resistance to both XLOLR and a chlorhexidine-sensitive K. pneumoniae strain. Therefore, CepA is associated with chlorhexidine resistance and may act as a cation efflux pump.