The only parasites that can be found normally on human skin are the demodex mites, which live in various regions of the pilosebaceous unit. Demodex brevis lives within the sebaceous gland ducts, whereas Demodex folliculorum lives in the hair follicle infundibulum. Demodex mites can cause demodex folliculitis. an infection of the hair follicles that manifests as superficial, follicle-based pustules.
The most important skin microbes, based on their ability to cause pathology, are the transient microbes. The best-known species is S. aureus. The ability of S. aureus to cause folliculitis, boils, abscesses, and bacterial sepsis is well documented and is a major cause of morbidity and mortality.