Washing with contaminated bar soap is unlikely to transfer bacteria

Abstract

SUMMARYRecent reports of the isolation of microorganisms from used soap bars have raised the concern that bacteria may be transferred from contaminated soap bars during handwashing. Since only one study addressing this question has been published, we developed an additional procedure to test this concern. In our new method prewashed and softened commercial deodorant soap bars (08 % triclocarban) not active against Gram-negative bacteria were inoculated with Escherichia coli and Pseudomonas aeruginosa to give mean total survival levels of 4-4 x 105 c.f.u. per bar which was 70-fold higher than those reported on used soap bars. Sixteen panelists were instructed to wash with the inoculated bars using their normal handwashing procedure. After washing, none of the 16 panelists had detectable levels of either test bacterium on their hands. Thus, the results obtained using our new method were in complete agreement with those obtained with the previously published method even though the two methods differ in a number of procedural aspects. These findings, along with other published reports, show that little hazard exists in routine handwashing with previously used soap bars and support the frequent use of soap and water for handwashing to prevent the spread of disease.

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“…There was no significant correlation in the level of total coliforms between Darimu hotels and Yayo hotels. Therefore, results of total coliforms recorded in the present study showed that all examined samples from Darimu hotels and Yayo hotels exceeded the guideline values recommended in accordance with international standards [22] The total bacterial count from the hotel with the worst hand-washing water hygiene checks, accordingly no coverage container, irregular cleaning of water container or type of container that allow the accumulation of microbes,…”

“…perfringens they used as the appropriate indicator for quality of water [22]. Therefore, the presence of these bacteria further strength the contamination of hand-washing water by enteric pathogens Generally, study concluded that there was poor hygiene such as improper storage and handling of hand washing water.…”

Dual-resolution molecular dynamics simulation of antimicrobials in biomembranes

“…The study also showed that TCC did not act by damaging the membrane; in contrast, membrane leakage was shown to be partly responsible for the mode of action of the other four antimicrobials tested [24]. These results, together with TCC's observed lack of activity against Gram-negative bacteria [24,37], seem to suggest that TCC acts mainly through a specific (unknown) mechanism ( possibly similar to that proposed for TCS) rather than by generically disrupting lipid membranes. It is clear, however, that more research is needed to fully understand the antibacterial mode of action of TCC, particularly with regard to non-specific effects that might manifest themselves at high concentrations (as observed for TCS).…”

Hand Hygiene

“…160 Nevertheless, there is some evidence that the actual hazard of transmitting microorganisms through handwashing with previously used soap bars is negligible. 265,266 …”

“…When bar soap is used, small bars of soap in racks that facilitate drainage should be used to allow the bars to dry (II). 265,266,640,[1012][1013][1014][1015] …”