(Trichomycosis Palmellina, Trichobacteriosis Axillaris)

Trichomycosis axillaris is a benign, relatively common superficial bacterial infection of the axillary hair shafts and to a lesser extent, pubic hair (trichomycosis pubis). It is caused by the overgrowth of several species of the gram-positive diphtheroid Corynebacterium (mostly Corynebacterium tenuis). Trichomycosis is a misleading term because the infection is not caused by a fungus as the name may imply. The source of the organism is the skin, where Corynebacteria are plentiful.

Corynebacterium prefers moist areas of the body thus mainly affects hair shafts in sweat gland-bearing areas, such as the armpits and the pubic area.

Superficial infection results in 1- to 2-mm adherent yellow, black or red granular nodules or concretions that surround and stick to each hair shaft, making it appear beaded or thicker. The concretions consist of tightly packed bacteria and are most common on the central portion of axillary hair.

The different color may be attributable to the species of Corynebacterium or to the changes in chemical environment of these organisms). The insoluble cement substance elaborated by the bacteria adheres to the hair shaft and, occasionally, invades and destroys cuticular and cortical keratin. The hair shaft may become brittle and thus, more easily broken, but this is rare.

Yellow concretions are the most common, whilst red and black are seen most often in tropical climates (the black the rarest). Sweat may be coloured according to the colour of the concretions and therefore clothing can be the same color. The underlying skin usually is normal. It occurs in both temperate and tropical climates: it is a trivial disease of worldwide occurrence. It is not limited by race or sex: nevertheless it appears to be more common in men than women but this is because many women shave their axillary hair. It can affect any age group from puberty through adulthood.

all that is noticed are sweaty, smelly armpits. Dermatologists are searched for the malodorous sweat and hyperhidrosis of the underarm area.

The treatment consists of  daily cleansing with soap and water and application of benzoyl peroxide (gel or wash formulations). Topical antibiotic preparations such as clindamycin or erythromycin are occasionally required to eliminate the infection. "Drying" powders may assist treatment. But the fastest method  to get rid of the problem is to clip  or to shave the affected hairs. Once treated, it may recur if preventive measures are not taken: the area has to be kept clean (with antibacterial soap) and dry. Regular use of antiperspirants (such as anhydrous aluminium chloride) provide an effective means of prevention by reducing sweating.

Shaving or trimming axillary hair usually is beneficial.