Serratia marcescens contamination of antiseptic soap containing triclosan: implications for nosocomial infection

Abstract

During a recent investigation in our surgical intensive care unit, we found that several bottles of the antiseptic handwashing soap, OR Scrub, were contaminated with Serratia marcescens. OR Scrub contains 1% triclosan, lanolin, and detergents. The antimicrobial efficacy of OR Scrub was examined in vitro using serial two-fold dilutions of soap inoculated with various concentrations of different nosocomial pathogens. The minimal bactericidal concentration (MBC) of OR Scrub against Pseudomonas aeruginosa and several strains of S. marcescens was less than or equal to 1:2. By comparison, a non-antiseptic soap from the same manufacturer (Wash) and 4% chlorhexidine (Hibiclens) had MBCs for all strains tested of at least 1:64. Time-kill curves confirmed the findings of the initial experiments. This is the first report of extrinsic contamination of antiseptic soap containing triclosan. No infections could be attributed to the contaminated soap, but sporadic outbreaks of Serratia have occurred in the intensive care unit with no identifiable source. Although there have been few studies on the impact of antiseptic soap in reducing nosocomial infection, we question whether a soap with the limitations of OR Scrub should be used in intensive care units or operating rooms.