Bacterial abundance on hands and its implications for clinical trials of surgical scrubs.

The numbers of bacteria on the hands of 157 subjects volunteering for a clinical trial of a surgical scrub preparation were evaluated statistically. Differences among the volunteers with respect to day-to-day variability in bacterial counts were the most important source of variation in these counts. Generally, more bacteria were found on the left hand than on the right. The experimental plan, proposed by the U.S. Food and Drug Administration, contained criteria for acceptability of subjects which were found to exclude at least as many suitable volunteers as they admitted. The plan was also found to require more testing on more volunteers than was necessary to establish the efficacy of the surgical scrub.