An investigation was undertaken to visualize the location of bacteria in normal human skin.
Samples of normal skin were used from forehead, posterior neck, upper back, scalp, anterior forearm, abdomen, pubic area, leg, and toewebs. Skin following occlusion, small uninflamed comedones, and specimens of intertrigo were also employed. For electron microscopy, part of each specimen was fixed according to the technique of Ryter-Kellenberger, Caulfield, or Hess. The remainder of each specimen was processed for light microscopy.
Some bacteria were located on the skin surface and beneath superficial cells of the stratum corneum. Microcolonies were occasionally seen in the latter location. Openings of hair follicles contained numerous microorganisms which were often associated with sebum. Bacterial population increased in normal skin after occlusion. Comedones displayed more bacteria than any sample studied.
Montes LF, Wilborn WH. Anatomical Location of Normal Skin Flora. Arch Dermatol. 1970;101(2):145–159. doi:10.1001/archderm.1970.04000020015004