Antibiotic resistance plasmids and bactericidal effect of chlorhexidine on Enterobacteriaceae

The effect of plasmid RP4 on the bactericidal effect of chlorhexidine on five Enterobacteriaceae has been tested. Escherichia coli, Serratia marcescens and Proteus mirabilis strains harbouring RP4 were more susceptible than R^- strains to this antiseptic. The role of 17 other plasmids harboured in the same bacterial host ( E. coli ) on the bactericidal effect of chlorhexidine has also been examined. Six plasmids (R751, R702, R144, RP4, pME206, S-a), of which four belonged to incompatibility group P, produced an increased bactericidal effect of chlorhexidine.