Evaluation of nongermicidal handwashing protocols for removal of transient microbial flora

A method has been described which can compare the efficacy of different nongermicidal handwashing protocols for removal of transient microbial flora without the necessity of establishing or relying on a previously determined baseline for an individual subject. The wash effluent is collected, and colony counts for the effluent reflect the number removed by the wash protocol. A second standard wash in a handwashing machine is performed, and the test criterion is the percent removed in the test wash based on the sum of total CFU recovered from the two washes. The method was used to compare an 8-s cycle for a newly developed handwashing machine with a conventional 15-s Ivory soap wash. When machine pressure was adequate (42 lb/in2), there was no statistically significant difference in the percent removal of transient flora by the two methods (48.8% from the machine versus 45.1% from the Ivory soap wash). At 32 lb/in2, the Ivory soap wash recovered 60.3%, whereas the machine recovered 45.1%.