[Microbial flora and odor of the healthy human skin]

The microflora resident on human skin shows great interindividual and intraindividual differences. It is essentially composed of micrococci, staphylococci, aerobic and anaerobic coryneforms as well as pityrosporum species which, in accordance with the different environment in the different regions of the body, are in a steady state. With increasing age, human skin microflora undergoes qualitative changes: the streptococci, which are found in infants, disappear and coryneform bacteria occur, which are mainly responsible for odor production. Anaerobic propionibacteria are more numerous in juveniles and young adults, a fact that may be explained by increased sebum production. Only the coryneform bacteria are able to produce the typical axillary odor by decomposition of apocrine sweat. Cocci, however, obviously do not have this capacity. It remains to be established which substances participate in odor production. With sensitive chromatographic methods amino acids, steroids and free fatty acids were detected, which could be related to body odor. There are possibly only a few commonly occurring odorous substances. The necessity of analyzing these substances is stressed.