''Trichobacteriosis axillaris'' is a superficial bacterial colonization of the hair shafts in sweat gland–bearing areas, such as the

armpit The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superior ...

s and the groin. It is a trivial disease of worldwide occurrence that is believed to be caused by the genus ''

Corynebacteria ''Corynebacterium'' () is a genus of Gram-positive bacteria and most are aerobic. They are bacilli (rod-shaped), and in some phases of life they are, more specifically, club-shaped, which inspired the genus name (''coryneform'' means "club-shape ...

''. The condition has been called extensively ''trichomycosis axillaris'' in the literature, but because it is a bacterial infection and not a fungal infection, it should be called ''trichobacteriosis''.

Presentation

It is characterized by the presence of concretions along the hair shafts, clinically observed as yellow, and rarely as red or black nodules. These concretions derive from bacterial colonization along the hair shaft containing dried apocrine sweat with a cementing substance generated by the bacteria.

Cause

It is caused by several species of ''Corynebacterium''.

Obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

hyperhidrosis Hyperhidrosis is a condition characterized by abnormally increased sweating, in excess of that required for regulation of body temperature. Although primarily a benign physical burden, hyperhidrosis can deteriorate quality of life from a psycholog ...

, poor local hygiene, and warm, moist environments are common predisposing factors.

Diagnosis

The infection is diagnosed by close examination of the hair shafts where brown to yellow material called concretions are seen. There is usually an associated rancid odour. A microscopic examination can confirm the diagnosis, but this is rarely needed. Some patients with excessive sweating present the so-called corynebacterial triad, that is, the simultaneous presence of trichobacteriosis axillaris, erythrasma, and

pitted keratolysis Pitted keratolysis (also known as Keratolysis plantare sulcatum, Keratoma plantare sulcatum, and Ringed keratolysis) is a bacterial skin infection of the foot. The infection is characterized by craterlike pits on the sole of the feet and toes, pa ...

Treatment

No specific therapeutic studies on trichobacteriosis are available. Many authors consider that the most effective treatment consist in shaving of the affected area for a period of 2–3 weeks. The use of a concomitant treatment, such as sulfur soaps or benzoyl peroxideSwart MN, Weinberg AN. Bacterial diseases with cutaneous involvement. In: Fitzpatrick’s Dermatology in General Medicine, 6th edn. New York: McGraw-Hill, 2003: 1843–1878. is also recommended. Rubbing whilst washing may help to disrupt the biofilm, hence increasing the accessibility of

antiseptic An antiseptic (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") is an antimicrobial substance or compound that is applied to living tissue/skin to reduce the possibility of infection, sepsis, or putre ...

s to the bacteria. Patients who shave the affected area only once will generally experience a recurrence of the infection, since, the bacteria begin to develop the concretions once again as the hair grows back. Corynebacterium infections are related to excessive sweating; for this reason, deodorants containing an

aluminum chloride Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contam ...

solution may be used for treatment and prevention. Maintaining good local hygiene is recommended.

References

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