Computerized image analysis of full-hand touch plates: a method for quantification of surface bacteria on hands and the effect of antimicrobial agents.

A method is described for quantification of the bacterial flora on the hand surface. Computer-assisted image analysis of bacterial growth of large full-hand touch plates provides a quantifiable measure of the bacterial flora on the hand surface. Image analysis pixel intensity values showed a significant correlation (P less than 0.0001) with colony forming unit values determined by the glove juice method. Image analysis of impressions from hands treated with various antimicrobial agents in detergent bases showed that 4% chlorhexidine gluconate produces a 96% reduction after a 30 s washing and 98% reduction after a 3 min washing while 7.5% povidone-iodine and 1% triclosan produce a 77% and 70% reduction after 3 min respectively, and 70% isopropanol produces a 98% reduction after a 30 s wash.