Persistent carriage of gram-negative bacteria on hands.

The hand floras of 103 hospital personnel and 50 controls were studied over a mean of 35 days. One or more of 22 species of gram-negative bacteria (GNB) were found to be carried persistently on the hands of 22 (21%) hospital personnel and 40 (80%) controls (age-adjusted relative risk (RR) 3.2; p less than 0.001). Males were significantly more often carriers than females (age-adjusted RR 1.8; p less than 0.01), and persons who washed hands less than eight times per day were significantly more likely to persistently carry the same species of GNB on the hands than those who washed more than eight times per day (group-adjusted RR 2.4: p less than 0.001). Predominant organisms from both groups were species of Acinetobacter (45%) and Klebsiella-Enterobacter (39%). Twenty-one percent of 541 nosocomial infections over a 7-month period in the study institution were caused by species found on personnel hands. The same distribution of species types between hospital personnel and controls indicated that handwashing regimens used by hospital personnel were reducing numbers of organisms without shifting the ecologic balance of bacterial populations on the hands. It was concluded that such organisms are much more prevalent on normal skin than generally thought.