Distribution of Bacteria in the Epidermal Layers and Hair Follicles of the Human Skin

Abstract

Previous studies over recent years have revealed the presence of a resident bacterial population in the human skin throughout the entire body. However, the localization and composition of the bacteria within the epidermis and the skin appendages have not been fully investigated. Using differential tape stripping, cyanoacrylate skin surface biopsies and mapping of hair follicles, bacteria on the forearms of study participants were isolated, mapped, cultured and identified with respect to their origin within the epidermis and the hair follicles. Our studies showed that 85% of the bacteria were found within the first 6 corneocyte layers and roughly 25% of the cutaneous bacterial population were localized within the hair follicles. The microbial flora of the skin between individuals is subject to considerable fluctuations. Micrococcaceae represent the biggest fraction of hair-follicle-associated bacteria. The techniques developed for this study allowed us to selectively investigate the bacterial population within the hair follicles. Our results point out the role of skin appendages as potential microbial reservoirs and the need to develop new antiseptic formulations that sufficiently penetrate into the hair follicles.

Memory regulatory T cells reside in human skin

“…HFs are constantly cycling, with waves of new protein expression at each stage of the cycle that change over time (24). In addition, HFs are colonized by a multitude of microbes (25). Thus, it is likely that many HF-associated antigens are not expressed in the thymus, making peripheral tolerance mechanisms essential to prevent autoimmune attack.…”

Toll-Like Receptor Signaling in Burn Wound Healing and Scarring

“…11 Therefore, once the epidermis is disrupted by burn, these bacterial PAMPs likely activate TLR signaling, possibly most strongly in the microenvironment surrounding hair follicles where bacteria are concentrated. 12 With time as the epidermal barrier remains disrupted, ambient external pathogens have opportunity to infiltrate the wound.…”

“…At the wound perimeter and at appendage stubs, 31 such as hair follicles where bacteria are concentrated, 12 LTA-TLR2 signaling might be predominantly anti-inflammatory-hypothetically, to protect sites of regenerative growth.…”

Anti-MRSA malleable liposomes carrying chloramphenicol for ameliorating hair follicle targeting

“…Cutaneous bacteria were found within the entire epidermis and appendages. 4,32 The epidermis and follicles can be an efficient reservoir for drug delivery. Topically applied malleable liposomes provided a possibility of sustained and targeted drug permeation in the sites of action, achieving efficient treatment and minimizing side effects.…”