DISCUSSION
We have already reported the effectiveness of bidets with in vitro experiments. Namely, a model of the buttocks was smeared with artificial diarrheal feces containing Serratia marcescens, and wiped by the participants wearing disposable gloves with 4 sheets of toilet paper after the use and non-use of bidets. Subsequently, the presence of S. marcescens on the surface of the gloves was quantified. After using the bidets, the mean count ± standard deviation of S. marcescens was 0.067 ± 0.249 cfu/ glove, and it was 4,275 ± 6,069 cfu/ glove when bidets was not used. The results obtained were that the cfu of S. marcescens was significantly lower when the bidets were used (p < 0.00001) prior to wiping the artificial diarrheal feces. Although the effect of bidets in this fieldwork was not as significant as that of the previous in vitroexperiment, the effectiveness of bidets was confirmed as in the previousin vitro experiment. It is estimated that microbial contamination from feces of hand after defecation has a major impact on the spread of intestinal infections such as norovirus gastroenteritis, Clostridioides difficilerelated infections, and enterohemorrhagic Escherichia coliinfections.5-10 For example, outbreaks resulting from food handlers who are infected or subclinical infected with the norovirus and does not sufficiently wash or disinfect their hands after using the toilet, then handling food.11-14Accordingly, hand hygiene after defecation is of course important,15 but it is also important to prevent fecal contamination of the hand after defecation as much as possible. In this experiment, the use of bidets was found to be effective in reducing microbial contamination of fingers after defecation. Although bidets were originally developed for medical use, they are presumed to be also effective in the prevention of spreading intestinal infections.
In conclusion, the use of electric toilet seats with water spray (bidets) was an effective method in reducing faces adhering to hands at the time of defecation.