USE OF IMAGE-ANALYSIS TO MEASURE HANDWASHING EFFECTIVENESS

Background: This study tested a unique quantification technology (imag e analysis of fluorescent particles) for the measurement of handwashin g effectiveness, comparing an automated system with traditional manual handwashing. In this instance, handwashing ''effectiveness'' was defi ned as ability of the technique to remove surface soil, as opposed to removal of microorganisms. Methods: Sixty-five subjects washed their h ands by manual handwashing (day 1) and automated handwashing (day 2). Hands were coated with an oil-based fluorescent suspension, photograph ed under controlled conditions, washed for 10 seconds, and rephotograp hed. Photographs from before and after handwashing were subjected to i mage analysis. Results: Manual handwashing removed 73.1% of the partic les; the automated method removed 23.2%. Parameters for use of image a nalysis as a technique to examine removal of gross contamination from the hands are given in the text. Conclusions: Although this method wil l not replace traditional culture methods for examining microbial remo val, it is useful for measuring removal of particles (gross contaminat ion) from skin or other surfaces. Under the conditions tested, manual handwashing was found to be decidedly superior to use of an automated system for removal of oil-based soil on the hands.