In vitro susceptibility of hospital isolates of various bacterial genera to chlorhexidine

Abstract

Chlorhexidine (Hibitane@) is an effective agent against both Gram-positive and Gram-negative bacteria and is widely used in hospitals for skin disinfection. The concentrations recommended by the manufacturer range from 100-40,OOO mg 1-l in liquid preparations and up to 10,000 mg 1 -l in solid or semi-solid preparations. Originally, Davies et al. (1954) reported that lo-15 mg l-1 of chlorhexidine was required to inhibit the growth of Gram-negative species but recently there have been a number of reports in the literature of resistant strains of Proteus and Providencia spp. (Stickler and Thomas, 1980), Serratia marcescens (Marrie and Costerton, 1981) and Pseudomonas aeruginosa (Nakahara and Kozokue, 1982) with minimum inhibitory concentration (MIC) values in excess of 200 mg 1 -l. We have investigated, by a standard test, the MIC and minimum bactericidal concentration (MBC) of chlorhexidine against a wide range of bacterial genera, in particular those bacteria which are most frequently isolated from hospitalacquired infections (Meers et al., 1981).