Quantitation of skin bacteria: lethality of the wash solution used to remove bacteria.

A widely used technique for the quantitative removal of bacteria from the skin uses a detergent, Triton X-100 (p, t-octylphenoxynonaethoxyethanol), to remove and suspend the bacteria. We determined the half-life for the survival of five common skin bacteria suspended in the solution. The shortest-lived was Streptococcus pyogenes with a half-life of 0.9 hours. All of the others (Propionibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, and Klebsiella pneumoniae) had half-lives of 1.5 hours or longer. K. pneumoniae, the only Gram-negative species tested, had a half-life of more than 30 hours. Thus, a one hour delay in plating and incubation of samples suspended in this detergent solution inhibits quantitation of most species tested.