Bacterial contamination survey and a review of the control method for water for hand washing of operating rooms

Abstract

In September 2012, we started using tap water for hand washing in operating rooms instead of sterilized water. With this change, we conducted bacterial contamination surveys of tap water sampled from each of the seven faucets at two hand wash stations and reviewed the appropriate method for water quality control. Formerly, we tested for general bacteria and E scherichia coli, but this time, we tested for heterotrophic bacteria as well. Heterotrophic bacterial concentrations exceeded the desired value of 2,000 CFU/mL while no general bacteria or E. coli was detected. Among heterotrophic bacteria, Sphingomonas pausimobilis and Methylobacterium spp. were dominant. We then cleaned the water outlet of the faucets, made sure to run water before use, and measured chlorine level. Even after these steps, a significant number of heterotrophic bacteria were detected despite a sufficient chlorine level. This indicated the presence of chlorine-resistant bacteria. Heating sterilization but not chlorination seemed to be more effective. Since we started performing 65°C heat treatment, the heterotrophic bacterial concentration has been 2,000 CFU/mL or lower. The improvement of water for hand washing has been achieved by thoroughly reviewing the conventional method. This study shows that the cleanliness of water for hand washing will be maintained by continuous tests for heterotrophic bacteria.