The microbiology of the human axilla and its relationship to axillary odor.

The axillary microflora of 229 subjects was characterized quantitatively and the results correlated with whether the odor was pungent body odor or instead a faint "acid odor". The axillary flora was found to be a stable mixture of Micrococcaceae, aerobic diphtheroids and Propionibacteria. Significantly higher numbers of bacteria were recovered from the axilla of those with pungent axillary odor than in those with acid odor. Aerobic diphtheroids in high numbers were recovered in all subjects having typical body odor. These included lipophilic as well as large-colony diphtheroids. When droplets of apocrine sweat placed on the forearm were inoculated with various bacteria which reside in the axilla, only diphtheroids generated typical body odor. Cocci produced a sweaty odor attributable to isovaleric acid.