Trichomycosis, also known as trichobacteriosis, is a superficial bacterial infection of hairs caused by Corynebacterium tenuis, mostly on the axillary hair and pubic hair, mainly in tropical and subtropical regions, also sporadic in temperate zones.
Corynebacterium tenuis is a Gram-positive diphtherold bacillus, grows in the hair cuticle intracellularly and intercellularly, can invade the skin cortex, and does not invade the hair root and skin. Different strains can produce different pigments under different chemical environments, thereby forming different colored nodules.
Signs and Symptoms
Patients with hyperhidrosis are susceptible to this disease. The disease occurs mostly in the armpit hair, the pubic hair can also be invaded, and the hair in other areas is not easily involved. Sparse, discrete, tiny nodules with solid texture are adhered firmly to the hair shaft. Sometimes the hair shaft is enveloped by vaginate sheaths. The nodules are generally yellow, sometimes red or black, obvious in summer when sweating, and subtle in winter. The affected hair is tarnished. If the pathogens invade the superficial hair, the hair shaft is damaged, and the hair is frangible. Nodular color can stain local sweat and clothes. The skin is generally unchanged, and subjective symptoms are usually absent.
Diagnosis is mainly based on clinical manifestations and examination of pathogens. The bacteria can be found in the nodules crushed and mixed by 10% potassium hydroxide in high power field microscopy. The hyphae are embedded in the viscous material and Gram stain is positive.
After removal of the affected armpit hairs and pubic hairs, topical sublimate-alcohol solution, 10% sulfur emulsion, or 1% formaldehyde solution can be used.