Contamination of bar soaps under "in-use" conditions.

Bar and liquid soaps from 26 public lavatories were investigated for microbial colonies. Of 84 samples obtained from bar soaps, 100% yielded positive cultures; liquid soaps were essentially negative (3/39). Where quantitative data were gathered, bar soaps were found to contain as few as 100-200 CFU/ml but ranged to a high of greater than 6000 CFU/ml. Although laboratory-challenged bar soaps showed a quick loss of microorganisms (less than 6 hours), "in-use" bars continued to contain high levels of organisms, even after more than 48 hours. Qualitatively, bar soaps were found to harbour 2 to 9 different genera of organisms per bar. The microbial population obtained from bar soap represented over 16 different genera. The discovery of so many and such different microorganisms on bar soaps indicates that this form of soap may be a potential reservoir for the spread of cross-infection in public institutions.