Anti‐microbial hand washes for domestic use – their effectiveness in vitro and in normal use

Abstract

The killing or removal of microbes from the hands is a critical factor in food safety as many studies have shown the hands to be both an important source of microbes and powerful agents of cross‐contamination in hospital and domestic situations. In response to this concern, a number of novel hand‐washing products have appeared on the market. These products contain anti‐microbial agents and claim to be more effective at removing bacteria than soap bars and conventional liquid soaps. This study attempts to test these claims by comparing the effectiveness of a conventional soap bar, a conventional liquid soap and an anti‐microbial liquid soap containing triclosan. In vitro tests demonstrate that the anti‐microbial liquid soap is more effective than conventional liquid soaps in reducing the viability of six bacterial species and that this effect is both time and dose dependent. However, when the three soaps were compared for their ability to reduce microbial counts on the hands no differences were observed between the three products. For all three soaps, counts after washing sometimes went up and sometimes down when compared with pre‐wash counts. This was the case both when the soaps were used ‘normally’– that is, with great variation in the time taken, water and soap volumes used and method of washing and after a standardized, rigorous wash recommended in clinical situations. Furthermore, reduction in microbial counts from hands contaminated by handling raw meat was no greater for the anti‐microbial than for the conventional liquid soap.

Cross‐contamination from raw chicken during meal preparation

“…The work surface, the handles of tap, cupboard, kettle and microwave, the swing bin lid and the chopping board were sampled using standard cotton swabs which were placed in 10ml of buffered peptone water (BPW) and vortex mixed for ten seconds. The cook's hands were sampled by a glove juice method (Sharp et al ., 2001) in which the participant placed the hand in a sterile stomacher bag containing 20ml sterile BPW. The top of the bag was closed about the wrist and the hand was thoroughly rinsed in the BPW for 30 seconds.…”