Chlorhexidine resistance in Proteus mirabilis

Abstract

A total of 104 clinical isolates of Pr. mirabilis from three hospitals were screened for their sensitivity to chlorhexidine. The minimum inhibitory concentrations of the antiseptic for these strains ranged from 10 to 800 μg/ml. Two strains sensitive to 20 μg of chlorhexidine/ml were adapted to resistance by growth in subinhibitory concentrations of the antiseptic, their minimum inhibitory concentration values increasing to 200 and 800 μg/ml. These derived strains exhibited slightly reduced sensitivity to cetrimide and benzalkonium chloride. The chlorhexidine resistant clinical isolates also exhibited this partially decreased sensitivity to the quaternary ammonium compounds. Both the chlorhexidine sensitive and resistant strains were uniformly sensitive to chloroxylenol (bettol), glutaraldehyde, and 2 phenoxyethanol.