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Quantitative microbial risk assessment of antibacterial hand hygiene products on risk of shigellosis

There are conflicting reports on whether antibacterial hand hygiene products are more effective than non-antibacterial products in reducing bacteria on hands and preventing disease. This research used new laboratory data, together with simulation techniques, to compare the ability of non-antibacterial and antibacterial products to reduce shigellosis risk. One hundred sixty-three subjects were used to compare five different hand treatments: two non-antibacterial products and three antibacterial products, i.e., 0.46% triclosan, 4% chlorhexidine gluconate, or 62% ethyl alcohol. Hands were inoculated with 5.5 to 6 log CFU Shigella; the simulated food handlers then washed their hands with one of the five products before handling melon balls. Each simulation scenario represented an event in which 100 people would be exposed to Shigella from melon balls that had been handled by food workers with Shigella on their hands. Analysis of experimental data showed that the two non-antibacterial treatments produced about a 2-log reduction on hands. The three antibacterial treatments showed log reductions greater than 3 but less than 4 on hands. All three antibacterial treatments resulted in statistically significantly lower concentration on the melon balls relative to the non-antibacterial treatments. A simulation that assumed 1 million Shigella bacteria on the hands and the use of a non-antibacterial treatment predicted that 50 to 60 cases of shigellosis would result (of 100 exposed). Each of the antibacterial treatments was predicted to result in an appreciable number of simulations for which the number of illness cases would be 0, with the most common number of illness cases being 5 (of 100 exposed). These effects maintained statistical significance from 106 Shigella per hand down to as low as 100 Shigella per hand, with some evidence to support lower levels. This quantitative microbial risk assessment shows that antibacterial hand treatments can significantly reduce Shigella risk.

Author: Schaffner DW, Bowman JP, English DJ, Fischler GE, Fuls JL, Krowka JF, Kruszewski FH

Citation: J Food Prot. 2014 Apr;77(4):574-82. doi: 10.4315/0362-028X.JFP-13-366

Posted: 19/12/2014

Published: 19/04/2014

Publication Type: Journal article

Publisher: Journal of Food Protection