Abstract

INTRODUCTION

Trichomycosis is asymptomatic, superficial infection, which is generally caused by a coryneform-actinomycetes bacteria which, from the very first reports, has been called Corynebacterium tenuis.[1,2] While on rare occasions the pubic, scrotal and intergluteal hairs may also be affected, this infection predominantly affects the hairs of the axilla, and thus the condition is referred to as “trichomycosis axillaris.” It is characterized by the appearance of concretions (hair-nodules), which grow around the hair shaft.[3,4,5,6]

Trichomycosis is a rare condition and few cases are reported in the literature, its name is wrong because it is not a fungal infection but is a superficial bacterial infection, so it should be called trichobacteriosis. Due to the fact that the condition is asymptomatic and causes practically no discomfort,[4,6] patients generally do not seek medical attention. However, when a careful, deliberate search is performed in the clinical setting, it tends to appear more frequently.[3,6]

Our principal objective is to present a series of cases, their clinical and microbiological aspects and emphasize that this clinical entity in axillar and genital hairs maybe is underestimated.

MATERIALS AND METHODS

This is a retrospective study of 15 years (from 1997 to 2011). All patients included had diagnosis of clinical trichomycosis and were confirmed microbiologically. A clinical history, an examination under Wood's light and microbiological tests was performed on each patient. In all cases, there took hair of the affected region, by means of court with scissors and the sample was divided in two parts for its study, for examination and culture. The samples were examined microscopically with KOH 20% and cotton blue preparations, and cultured in brain-heart infusion agar, and chocolate-blood agar. Positive cultures were Gram-stained to identify coryneform-bacteria forms, and isolated cultures were subsequently identified by biochemical testing using the MicroScan-system^®.

RESULTS

The main demographic characteristics and microbiological findings of the study are shown in Table 1. It is important to point out that 32 out of the 56 patients (57.1%) sought medical attention because they felt a change in the texture of the affected hair, and the rest of the patients were diagnosed during careful, deliberate search by visual inspection and examination under Wood's light [Figures ​[Figures11–3]. Eighteen of the fifty-six patients (32.2%) related their condition to athletic activities and to the use of clothing made of lycra. Of the 56 cultures that were obtained, only 18 were identified by the MicroScan WalkAway^® 9651 system, which identified Corynebacterium Centers for Disease Control (CDC) group G/LD; according to Bergey's Manual,[7] this is indicative of Corynebacterium flavescens [Figures ​[Figures4a4a & b and ​and55].

Table 1

Demographic characteristics and findings of the study

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Figure 1

Chronic trichomycosis axillaris (var. flava)

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Figure 3

Yellow-fluorescence of trichomycosis pubic’ hairs (Wood light)

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Figure 4

Direct examination of trichomycosis hair (a) KOH 10%, ×10; (b) KOH 10%, ×40

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Figure 5

Culture of Corynebacterium sp., in chocolate-blood agar plate

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Figure 2

Initial trichomycosis pubis (var. flava)

There were two patients who, in addition to axillary trichomycosis, also presented with two related conditions affecting the inguinal zone (erythrasma) and the soles of the feet (pitted keratolysis) Table 2.

Table 2

Microbiological characteristics of the study

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DISCUSSION

Trichomycosis, a more correct term would be trichobacteriosis or bacterial trichonodosis is a superficial infection, primarily of the axillary hair, which can exhibit three different clinical presentations: The most common clinical variant is trichomycosis flava (yellow), while rubra (red) and nigra (black) variants occur much less frequently.[3,6,8] From the earliest reported cases of trichomycosis, the causative agent was classified as C. tenuis. In light of the new taxonomic position of the genus Corynebacterium, however, that particular species is no longer considered, and thus, the majority of the reports are left as Corynebacterium sp. However, some studies[9] have shown that the causative agent belongs to the so-called group 2 (LD2) (also referred to as the CDC-G/LD group), that it corresponds to the C. flavescens species, and that it is related to the flava variant.[7,10] In the present study, we were able to identify this particular species in 18 of the cases. No specific causative agent could be identified in the remaining 38 cases, which were simply classified as Corynebacterium sp., according to their microscopic characteristics because presented Gram-positive rod-shaped forms.

There are indications that the rubra and nigra variants of trichomycosis are actually caused by other microorganisms, specifically Micrococcus castelani and Micrococus nigricans, although this has yet to be proven definitively.[5,6] The causative agent of trichomycosis has not yet been isolated in nature, only from infected human hairs. The disease is quite cosmopolitan, however, it is reported more frequently in humid and tropical climates; it is an affliction of adolescents and young adults.[3,9] There are no differences in the rates of infection with respect to race or gender, although, in our culture it is seen with greater frequency in male patients since it is customary for women to shave their axillary hair. There have been reports of man-to-man transmission of trichomycosis, particularly in groups that live in very close quarters, such as soldiers and athletes.[1,9,11,12,13]

Trichomycosis infection begins when the causative agent comes in contact with the hair shaft, and the bacteria adhere to the surface, or the cuticle, of the hair, using a cement-like substance, the chemical composition of which is not yet known, that is insoluble in water as well as in the other principal solvents (i.e., acetone, ethanol). Electron microscopy studies have clearly shown that the microorganism does not penetrate to the medulla's cortex of the hair; instead, it only adheres strongly to the surface of the hair and develops slowly until it forms concretions around the hair shaft.[14,15] Levit[11] has suggested that the adhesive substance is synthesized by both the apocrine glands of the human host and by the microorganism, which would explain why the disease develops in the areas of the body where it does (i.e., axillary, pubic and inter-gluteal hairs).[13,16,17]

As it pertains to our study, it is noteworthy that the majority of cases involve adult males, due to the fact that, in our culture, women generally tend to shave their axillary hair. There were cases involving both extremes of age, but by the mean age of all the patients, it can be deduced that trichomycosis appears more often in young adults.[2,9,17]

The specific results concerning the clinical location of the lesions are shown in Table 1. Out of all the cases studied, 97.4% presented with an infection of the axillary hairs, a figure, which is consistent with the majority of reports found in the literature.[2,11,13] There were two particularly noteworthy cases in which trichomycosis affected three different areas of the body at the same time (axillary, pubic and inter-gluteal regions). According to some authors, a more thorough examination of trichomycosis patients is particularly important, since they feel that the figures reported of the frequency of genital involvement underestimate the actual number of cases.[5,16] Another remarkable case in this study was the one in which the eyebrows were also affected. This is truly an exceptional finding and we were not able to find a similar case reported in the literature, most likely resulted dissemination from the axillary region by means of auto-inoculation.[17] De-Almeida et al. have recently reported a case of trichomycosis capitis, in an 8-year-old boy, this report also indicates that there may be cases distant areas and apocrine glands that can be clinically similar to cases of white piedra.[18]

In general, trichomycosis is characterized by the formation of concretions around the hair shaft; these are invisible at first and there is only a slight thickening, which can be “felt” on palpation. Initially, the bacterial masses remain isolated or independent, and it is at this stage when it could be mistaken for pediculosis (nit-lice). As the infection becomes chronic, the concretions extend along the entire length of the hair until they form a sheath, causing the hair to thicken, turn a yellowish, red or black color, and become creamy, opaque and soft.[7,9,16,17]

It should also be mentioned that only 32/56 of patients (57.1%) sought medical attention as a result of having felt a change in the texture of the hair, odor and in most cases accompanied by increased sweating (hyperhidrosis), while the rest of the patients were diagnosed during a careful, deliberate search.[1,9] Practically, all of the patients (98%) presented with the flava variant, and only one patient, who sought medical attention after developing “reddish sweat,” presented with the rubra variant, and was and was proven by the isolation of cultures, which was due to a mixture of microorganisms: Corynebacterium sp. (white-yellow growth) and Serratia mascescens (red growth), and probably the red form due to the latter bacteria produce carotenoid pigments. There is a series of case reports in the literature involving patients with mixed infections caused by different corynebacteria, the so-called corynebacterial triad consisting of trichomycosis, erythrasma and pitted keratolysis; in our study, there were two patients who also presented with erythrasma and pitted keratolysis,[19,20,21] another example is the report of Rho and Kim,[22] whom found a high incidence of trichomycosis in Korean soldiers, co-existing with erythrasma (20.4% of cases) and with pitted keratolysis (13% of cases).

As far as the microbiology is concerned, it is important to note that all of the cases in this study were confirmed by means of direct examination, in which the infection of the hair, in the form of concretions or bacterial masses consisting of coccoid and diphtheroid shapes measuring between 0.5 and 1 μm, could be seen adhered to the hair, which rules out the majority of mycoses that affect the hair (tinea and piedra).[23] Wood's light is extremely useful for diagnostic purposes, and above all, for delineating the extent of the infection, since the bacterial concretions emit fluorescence under low-intensity Ultraviolet (UV) light, making it much easier to find the affected hairs.[9,11,15,16]

In terms of causative agents, Corynebacterium sp. was identified and isolated in all cases (single agent in 98.2% and mixture in 1.8%). Microscopic examination revealed the presence of various Gram-positive, coccoid and diphtheroid shapes or rod-shapes, measuring, on average, from 1.2 μm to 1.8 μm in length, and 0.4-0.6 μm in width, and resembling “little drum sticks.” It is important to note that 18 strains were identified as C. flavescens, which is consistent with the results obtained by García-Martos et al.[9] This organism is not generally considered virulent, although, it has been reported to cause endocarditis in some intravenous drug users.[24] An interesting finding in our study involved the case of the rubra variant, where two different pathogens were isolated, Corynebacterium sp. and Serratia marcescens, the latter being an extremely opportunistic type of bacteria, with low virulence, and which produces a carotenoid pigment.[25,26]

In general therapy of trichomycosis, many authors consider that the most effective treatment consist in shaving of the affected area for a period of 2-3 weeks, but the use of a concomitant treatment, such as sulfur soaps, is also recommended. Those 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. Topical treatments containing any of the following: 3% sulfur, 2% formalin, 1% mercury (II) chloride (or mercuric chloride) or 2% sodium hypochlorite, as well as topical antibiotics with fusidic acid, erythromycin and clindamycin, may also be used.[9,12,22] Antimycotic agents like naftifine and some azole derivatives are effective as well.[23,27]

Footnotes

REFERENCES