Doctor Answers (1) on Trichomycosis axillaris
yes its a bacterial infection if the hair shaft.
shave off your axillary hairs regularly.
apply benzoyl peroxide cream or wash with benzoyl peroxide soap.
if it still persists, you could go for clindamycin gel application on your underarm.
use antiperspirants. this will also help. this usually happens in people who sweat a lot.