Evaluation of the skin disinfecting activity and cumulative effect of chlorhexidine and triclosan handwash preparations on hands artificially contaminated with Serratia marcescens.

The initial and cumulative efficacy of two antiseptic handwash preparations in eliminating Serratia marcescens from hands was evaluated on volunteers. Two antiseptics with persistent skin antibacterial activity, 4% chlorhexidine gluconate in detergent and 1.5% triclosan in natural soap, were studied in a new protocol designed according to Food and Drug Administration guidelines. After a single handwash, both preparations exhibited a degerming action statistically superior to the mechanical elimination of the marker organism that was achieved by the nonmedicated controls. Following a further nine hand recontamination sequence with 10(9) colony-forming units (cfu)/mL S marcescens (mean predisinfection baseline, log10 6.6), the efficacy of chlorhexidine and triclosan was significantly augmented: the mean log10 reduction factors were 4.15 and 3.78, respectively. In the absence of internationally accepted testing standards for antiseptic handwash products, the significance of protocol variables is discussed. The advantages to preventative microbiology of antiseptics with persistent skin antibacterial activity are highlighted.