In-vitro Bactericidal and Virus-inactivating Effects of Various Hand-wash and Gargle Products

Hand washing and gargling are recommended for prevention of infectious diseases, especially in the case of epidemics. Currently, several disinfectant-containing hand-washing products and mouthwashes for general household use are available in the market. In this study, we compared the bactericidal or virusinactivating effects of these products. The pathogenic bacteria used for this study were MRSA and EHEC O 157, and the viruses were influenza A and feline calicivirus, used as a substitute for norovirus. The test solutions of various products were mixed with the pathogenic fluid at 9：1 or 5：5 and allowed to react for 15 seconds. The decrease in viable count and infectious virus titer after the reaction were measured with the dilution plate method and plaque method, respectively. Products containing povidone-iodine or acidic ethanol showed a high reduction value (exceeding 4 log10) against the bacteria and viruses tested. However, hypochlorous acid products and ordinary ethanol products for disinfection had little effect on feline calicivirus in this test method. A strong bactericidal or virusinactivating effect was confirmed when the test method was changed, with the mixing ratio at the time of reaction set to 9：1 and the coexisting cell culture medium components eliminated. These results suggested that the efficacies varied greatly depending on the test method. Products having reliable disinfection effects under the conditions in which they were used were considered useful for prevention of infectious diseases.