An evaluation, using computerized image analysis, of antimicrobial efficacy of an automatic hand washing machine with ultrasonic wave spraying.

We studied the antimicrobial efficacy of hand washing with a quick-dry hand washing machine [TE-KIREIKI] employing ultrasonic wave spraying and its incidental alcohol-based product [AROKULIN-E]. The subjects of this study were 10 males who had been instructed not to use any antimicrobial agent for the previous 2 weeks or any hand soap for the previous 5 hours. They pressed their palms on agar before and after washing their hands. After 48-hour incubation at 37 degrees C, the bacterial colonies grown on the agar were counted using the [ASPECT] image processing system. The colony count was expressed as the post-stamp versus pre-stamp percent (%) reduction. Two patterns of hand washing were examined in this study: [A] a 3-second hand wash using an alcohol-based product [AROKULIN-E] and [B] a 30-second hand wash using a nonmedicated detergent soap with running water in addition to hand washing by [A]. The percent (%) reduction after hand washing patterns [A] and [B] were 49.1% and 51.3%. These reduction rates indicated that these patterns did not eradicate bacteria from the hand surface. Therefore, we concluded that this quick-dry hand washing machine employing an ultrasonic wave spraying method combined with an alcohol-based product needs improvement.