Colonization of the axilla by Propionibacterium avidum in relation to age.

The prevalence of Propionibacterium avidum in the axillae of 248 individuals aged 5 to 18 years was studied. Both caucasoids and negroids, males (132) and females (116), were included. The frequency of recovery of the organism increased with age and was associated with the onset of puberty. The organism was recovered from only 2 of 40 females (5%) aged 5 to 10 years and from 1 of 22 males (4.5%), whereas 45% of females and 58% of males aged 15 to 16 years were colonized. Females tended to become colonized at an earlier age than males did. It appeared that negroids carried the organism more frequently than caucasoids, but the difference in prevalence was not statistically significant in matching age groups. It is suggested that the increase of hydration of the axilla with age and increase in substrate availability play an important part in the colonization process.