[Comparative investigations on the efficacy of tap water, some detergents and ethanol on the transient flora of the hands (author's transl)].
The germ reducing efficacy of tap water, soap, pHisoHex, pHisoDerm and 70% ethanol was compared using the model of hands artificially contaminated with E. coli. Each of ten persons washed 1, 2 or 4 minutes. Reduction factors were calculated from pre- and post-values and were compared for each individual. After one minute the logarithms of the geometric means of the reduction factors amounted to 2,99, 3,23, 3,28, 3,61, 4,25 in the above used sequence (Table 2). After one minute the reductions came off more slowly and the slopes were linear and parallel as far as the mechanical germ reducing procedures are concerned (Fig. 2). In contrast, ethanol caused a steeper slope even after one minute wash. The strong reduction achieved by mechanical procedures (even with water for one minute 3 powers of ten were observed) demonstrates the high hygienic importance of hand washings for removal of the transient flora. Detergents like pHisoDerm produce further significantly higher reductions and seem to be more suitable than aggressive disinfectants for application in fields where bactericidal action is not imperative. The proposals for procedures aiming at disinfecting of the transient flora issued by the Austrian Society for Hygiene, Microbiology and Preventive Medicine require a reduction factor of at least 10(5) after two minutes hand wash. The results of this investigation show that this is practicable with ethanol and necessary, otherwise the bactericidal action would not be different from a mechanical removal of the transient flora.