Hygienic hand disinfection: a comparative study with chlorhexidine detergents and soap

The efficacy of two chlorhexidine hand-wash detergents and liquid soap was compared in a laboratory trial using artificial contamination of fingers with Micrococcus and Serratia. Agents were assessed for both a rapid and sustained effect after a single contact, and for a cumulative persistent effect after multiple contact over four days. Disinfectant activities were compared by statistical analysis of log reduction factors and log count time gradients (decimal reduction times). The latter analysis attempted to accommodate significant subject variation in response to both agent and organism. All handwashing methods significantly reduced contamination levels. Both chlorhexidine formulations were significantly better than soap in their activity against Micrococcus, but were not more effective than soap in removing contamination with Serratia. Both chlorhexidine preparations showed significant skin persistence and were generally acceptable to subjects after prolonged use. Some effect of the formulation of the hand-wash on chlorhexidine activity was demonstrated.