Distribution of bacteria on hands and the effectiveness of brief and thorough decontamination procedures using...

Our perception of the role of hand washing in the clinical situation is based on experimental studies in which test-bacteria are usually inoculated onto the skin surface and removed using hand washing preparations containing antiseptics. In this study, we have investigated the distribution of bacteria on the hands of volunteers and the effectiveness of long (3 minute) and brief (10 second) washes in removing both naturally-occurring and artificially-inoculated bacteria (Micrococcus sp.), using only soap and water. There was a tenfold reduction in median counts of artificially inoculated bacteria following both long and brief washes. However, less than 50% of naturally-occurring bacteria were removed and, for hands previously disinfected by immersion in 70% ethanol, the washing procedure increased bacterial counts. In both unwashed hands, and hands washed following a strict protocol, the mean variation in counts of naturally-occurring bacteria at different sites (wrists, dorsal surface, palmar surface, fingertips and interdigital spaces) was only two-fold. The efficiency of recovery of naturally-occurring organisms was estimated by repeated swabbing, to be more than 60%. The data question the value of typical hand wash procedures recommended by many authorities for use in clinical situations and of the perfunctory hand washes frequently adopted by nursing staff in busy wards. Experimental evidence is required to justify procedures and to identify the precise circumstances in which they are of value.