Methods for determining the distribution of bacteria in the skin

Five methods used to study bacteria in the skin are reviewed: swabbing, scrubbing, or scraping; biopsy; impression plate; adhesive stripping; and air‐sampling for bacteria‐shedders. Scraping and swabbing methods give only a rough idea of the numbers and kinds of bacteria on a given area of skin. More recent adaptations of these techniques have introduced the use of soaps or surfactants to disperse the bacteria, followed by quantitative plate counts on serial dilutions. Biopsy methods are little used because they give only qualitative results and are traumatic to the experimental subject. Impression plates give low counts in most cases and enumerate only those bacteria which are lying on the surface layer of the stratum corneum . Adhesive stripping methods are the only ones which give a precise determination of the distribution of colonies of bacteria with regard to both area and depth in the stratum corneum . Counts run much higher than impression plates.