Practice Essentials
Trichomycosis, also called trichobacteriosis, is a bacterial infection of the hair shaft, caused by Corynebacterium species, in sweat gland–bearing areas [1] ; it has been described most commonly in the axillary region and is a common but underdiagnosed skin condition. [2] While initially believed to be uncommon in the inguinal region, a series of papers has described trichomycosis pubis, a particular variant occurring in the inguinal area, and has suggested that the incidence of this disease is underestimated in the general population. The condition is often a marker of poor hygiene.
Also see trichomycosis axillaris.
Etiology
Risk factors appear to be geographic, with the highest incidence in tropical areas. In addition, poor hygiene often is present.
Prognosis
Aside from the risk of recurrence, prognosis is excellent and treatment is effective. Morbidity is low, with most patients unaware of the colonization. When presenting, the most common reported symptom is a foul odor, and this may continue to cause problems, since trichomycosis often recurs.
Patient education
Instruct patients to keep skin dry and to practice proper hygiene.
History
While many patients are asymptomatic, patients may present with reports of pubic rash, foul odor, or growths on the pubic hair. Colored sweat also has also been reported, resulting in a consideration of chromhidrosis.
Diagnostics
See Workup.
Treatment
See Medical Care and Medication.
Pathophysiology
This discussion of trichomycosis, a disease specific to the hair and sweat gland–bearing regions of the body, concentrates on the involvement of the pubic region (trichomycosis pubis). First described in the axillary region by Paxton in 1869, the causative role of multiple bacterial Corynebacterium species was established by Freeman et al in 1969. [3, 4, 5, 6, 7] Use of the term trichomycosis, which incorrectly implies the causative role of fungi, has been maintained, although the condition is also increasingly recognized as trichobacteriosis, which is a more correct term. [8] The color differences noted at presentation of the condition, their association with particular corynebacteria, or the possible role of associated cocci have not been clarified.
The causative organism associated with most cases is Corynebacterium tenuis, which favors warm and moist microenvironments. Poor hygiene may also play a role. Other noted species include Corynebacterium propinquum, [9] Corynebacterium flavescens, [10] and Serratia marcescens. [2] While as many as 33% of adults have colonization by these bacteria in the inguinal or axillary regions, factors such as hyperhidrosis initiate more extensive growth and clinical manifestations. Hence, disturbances in apo-eccrine sweat production and bacterial proliferation are crucial for development. [5, 8] The exact origin of the cement substance that creates the grossly visible nodules is debated. Electron microscopy studies favor origin from the causative agents, while others have favored elaboration from apocrine sweat. [11, 12] The actual nidus may be through the modification of apocrine sweat by elaborated cement substance to create the insoluble material that holds bacteria to the hair shaft. The white or yellowish, and less commonly, red or black, material on the hair contains an extremely high number of bacteria. [2]
Epidemiology
United States
Detailed examination of racial, age, or geographic incidence has not been performed, and examinations in the United States are limited to case reports. A more detailed examination (but still limited) has been performed outside the United States.
International
Studies in Panama and the United Arab Emirates revealed rates as high as 39% in patients attending a dermatology clinic. [13, 14] These results correlated with the notably higher incidence and prevalence in areas of high humidity, warmth, and poor hygiene. The only other study to mention incidence noted the presence of trichomycosis pubis upon examining institutionalized patients for trichomycosis axillaris in Edinburgh, Scotland, and noted that of the 609 men examined, 16 (2.6%) had pubic disease, of which three of the cases (0.5%) were not associated with axillary involvement. Ages of the males affected were 18 and 21 (3 patients) years and can be culled only from case reports. There is no universal consensus as to racial or sex preferences, [10] although some reports note higher infection rates in men. [15] Infection with C tenuis is also associated with poor hygiene, obesity, and hyperhidrosis. [16] Human-to-human transmission has been noted and is particularly common in overcrowded groups such as soldiers, athletes, and among homosexuals. [10]
A 2013 retrospective study of 56 trichomycosis cases over 15 years revealed the axillae as the affected sites in the vast majority (51 cases, 92%) of cases. The pubic region was only involved in 4 (7.2%) cases. [17]
