13693780310001602794

7/30/2019 13693780310001602794

1/4

Case Report

Onychomycosis caused by an isolate conforming to the

description of Trichophyton raubitschekii

MANUELA PAPINI, CONSUELO GRECO & FERRUCCIO PILERI

Perugia University, Terni Dermatological Clinic, Terni, Italy

Trichophyton raubitschekii is currently regarded as a synonymous name betokening

a variant form of Trichophyton rubrum . Nonetheless, isolates conforming to this

morphotaxonomic concept have morphological, physiological and clinical features

very different from those of typical T. rubrum . Isolates are mainly obtained from

subjects originating from certain tropical and subtropical countries, and are mainly

obtained from upper body skin infections, rarely from onychomycosis. In this

paper the authors report the first known Italian case of onychomycosis caused by

such an isolate. The patient, a male student from Cameroon, had a typicalfingernail tinea unguium, without any other sign of skin or nail infection. T.

raubitschekii was identified on morphological and physiological grounds by the

following features: velvety colony surface, brownish pigment, abundant macro-

conidia and microconidia, and positive urease activity. Such isolates may prove

very difficult to identify correctly, especially in areas like Italy where T. rubrum is

normally seen only as isolates presenting a strongly differing phenotype.

Keywords epidemiology, onychomycosis, taxonomy, Trichophyton raubitschekii

Introduction

Trichophyton raubitschekii was described as a species

morphologically and physiologically distinct from the

related T. rubrum by Kane et al. [1] in 1981. It was later

shown to have strong statistical differences from typical

T. rubrum in the spectrum of diseases it caused, in that

it was associated strongly with tinea corporis and tinea

cruris, only weakly with tinea pedis, and rarely with

tinea unguium [2]. T. rubrum , by contrast, was mainly

obtained from tinea pedis and tinea unguium. Up to

now only 47 cases caused by isolates conforming to the

description ofT. raubitschekii have been reported in the

literature [2/5] and although a definite worldwideprofile of the epidemiological and clinical aspects of

such isolates is still lacking, this dermatophyte seems to

have a strong connection with patients who have

resided in an Asian or African country. Onychomycosis

caused by T. raubitschekii-like isolates has been re-

ported in only three cases so far. In recent years,

molecular studies have suggested that T. raubitschekii is

genetically too close to T. rubrum to be maintained as a

separate species; for example, it is identical in nuclear

ribosomal internal transcribed spacer (ITS) sequence

with T. rubrum [6,7]. Nonetheless, as T. raubitschekii

presents a very distinct laboratory identification profile

and is connected with differing epidemiological data,

there is clearly still value in reporting new clinical

information about this phenotype. Indeed, the author

who formally synonymized T. raubitschekii with T.rubrum after molecular study, has already done so in

connection with a German case [5].

In the present paper, a case of thumbnail infection

caused by an isolate conforming with T. raubitschekii is

presented and the differential morphological and

cultural aspects of this dermatophyte phenotype are

briefly summarized.

Correspondence: Manuela Papini (MD): Viale degli Oleandri 62,

05100 Terni, Italy. Tel.: '/39 0744 404781; Fax: '/39 0744 205385;

E-mail: [email protected]

Received 27 June 2003; Accepted 10 July 2003

2004 ISHAM DOI: 10.1080/13693780310001602794

Medical Mycology June 2004, 42, 273/276

7/30/2019 13693780310001602794

2/4

Case report and mycology

A 22-year-old black male student from Cameroon

presented to the outpatient service of Terni Dermato-

logical Clinic, Terni, Italy, with a 2-year history of

thumbnail alteration. The patient had attended the

Perugia University School of Medicine for 4 years, but

paid regular visits to Cameroon, where he served as avolunteer social worker in a hospital.

The right thumbnail was destroyed in its distal

portion and the remaining nail plate had an irregularly

cracked margin. The denuded nail bed showed mild

erythema and fine scaling. A complete examination

failed to reveal additional infected finger- or toenails or

any other sign of disease affecting the skin or hair.

Microscopic examination of scales from the nail bed

and nail plate clarified with 40% KOH revealed fungal

hyphae. Culture test performed on Sabouraud dextrose

agar with and without chloramphenicol and cyclohex-

imide showed multiple velvety pinkish colonies.

Mycological evaluation of the isolate

After 10 days on Sabouraud dextrose agar at 258C the

isolate produced velvety to finely granular colonies with

a diameter of about 20 mm. The upper surface of the

colonies showed a central low, button-shaped, folded

elevation and a faint pinkish colour (Fig. 1); the reverse

was blood-red to brown (Fig. 2). Microscopically, the

isolate was characterized by abundant cigar- to pencil-

shaped macroconidia and club-like to pyriform micro-

conidia (Fig. 3); rounded inflated cells were occasion-

ally seen. Scanning electron microscope examination ofthe colonies clearly showed masses of cylindrical

macroconidia as well as pedicellate microconidia pro-

duced along the hyphae (Fig. 4). Bromcresol purple,

milk-solids yeast-extract agar showed restricted colo-nial growth without colour change of the indicator

within 14 days. The urease test on Christensen urea

broth was strongly positive after 5 days. Hair perfora-

tion was negative. These macroscopic and microscopic

aspects of the isolate and its cultural behaviour allowed

the identification ofT. raubitschekii. R. Summerbell (of

the Centraalbureau voor Schimmelcultures, Utrecht,

The Netherlands) confirmed the identification and the

culture was deposited as CBS 102856.

The patient was prescribed oral terbinafine 250 mg/

day and ciclopiroxolamine nail lacquer for 8 weeks. A

complete recovery was obtained in 3 months and no

relapse was observed at follow-up after 6 and 12

months.

Fig. 1 Isolate colonies after 10 days on Sabouraud glucose agar.

Fig. 2 Reverse side of the colonies showing red-brown pigmentation.

Fig. 3 Microscopic aspect, showing a typical mix of different

conidial forms, including macroconidia, globose inflated cells and

clavate microconidia ()/400 objective).

2004 ISHAM, Medical Mycology, 42, 273/276

274 Papini et al.

7/30/2019 13693780310001602794

3/4

Discussion

The epidemiology and the clinical manifestations of

dermatophyte infections in Europe have clearly chan-

ged over the last decade. After a relatively stable period

of approximately 30 years, in which scalp infections

caused by Microsporum canis and foot and nail

infections by T. rubrum were the most frequent

dermatophytoses, there are now numerous reports of

infections caused by unusual or exotic species [8/10]. A

large survey of tinea capitis conducted among 19

European countries [9] has shown a clear increase incases caused by anthropophilic fungi such as T.

violaceum, T. soudanense, T. tonsurans and M. audoui-

nii, in particular among urban populations and in

immigrants from Africa and the Caribbean. Now, an

apparently more rare dermatophyte type is being

introduced (i.e., isolates phenotypically corresponding

to T. raubitschekii). The first case reported in Europe

was recently reported from Germany [5]; the case

presented in the present paper is the first report of

nail mycosis caused by T. raubitschekii in Italy.

Of the 47 T. raubitschekii cases reported in the

literature, 32 involved immigrants from or residents of

subtropical and tropical areas such as China, Vietnam,

central Africa, and Brazil. The most common clinical

manifestation associated with this phenotype was tinea

corporis, seen in 25 of the recorded cases. Similar

clinical and epidemiological observations have emerged

from the recently summarized Vietnam war-era experi-

ences of Taplin [11], who found that ringworm in

Vietnamese adults was nearly always caused by T.

raubitschekii-like isolates producing a chronic, scaly,

dry rash generally confined to the waist. A case of

extensive tinea corporis in a Vietnamese immigrant is

described in detail by Kane et al. [2]. In the laboratory,

the most readily recognizable phenotypic characteris-

tics distinctive of the T. raubitschekii phenotype are its

velvety to granular surface, blood-red to brownish

pigmentation of colonies, abundant formation of

macroconidia, and positive urease test.

Until now T. raubitschekii has been considered a

rare dermatophyte variant, but some considerations

suggest that this phenotype may have been under-

recognized. First, the colonies may show a superficial

resemblance to more common species such as T.

rubrum and T. mentagrophytes or even to T. violaceum

[12]. Also, some microbiological laboratories identify

dermatophyte isolates on the basis of macro- and

microscopic aspects of the colonies without performing

specific test reactions such as the urease test. These

practices, coupled with poor knowledge of the T.raubitschekii phenotype, can easily lead to misidentifi-

cation. A better awareness of this phenotype can

probably increase its correct recognition, adding epide-

miological data of great importance to the under-

standing of the clinical relevance and geographic

distribution of this form. It should be noted that an

identification of such an isolate as T. rubrum is by no

means wrong, but rather is deficient in failing to convey

clinical and laboratory information that may be useful

or epidemiologically interesting. The name T. rau-

bitschekii cannot currently be used as a recognized

species name, but correct laboratory reports can be

issued making information about this phenotype ac-cessible and allowing report recipients to do compre-

hensive Medline searching (e.g., by using wording such

as T. rubrum , Afro-asiatic variant previously known as

Trichophyton raubitschekii).

Acknowledgements

We thank Richard Summerbell, CBS Fungal Biodiver-

sity Centre, Utrecht, the Netherlands, for his assistance

in confirming the identification of the T. raubitschekii

phenotype.

References

1 Kane J, Salkin IF, Weitzman I, Smitka C. Trichophyton rau-

bitschekii sp. nov. Mycotaxon 1981; 13: 259/266.

2 Kane J, Krajden S, Summerbell RC, Sibbald RG. Infections

caused by Trichophyton raubitschekii: clinical and epidemiological

features. Mycoses 1990; 33: 499/506.

3 Caiuby MJ, Monteiro PC, Nishikawa MM. Isolation of Tricho-

phyton raubitschekii in Rio de Janeiro (Brazil). J Med Vet Mycol

1996; 34: 361/363.

Fig. 4 Scanning electron microscopy showing fertile hyphae with

macro- and microconidia ()/3000 objective), in a report from Italy of

onychomycosis caused by an isolate conforming to the description of

Trichophyton raubitschekii.


T. raubitschekii onychomycosis 275

7/30/2019 13693780310001602794

4/4

4 Lacaz CZ, Zaitz C, Ruiz LR, et al. Dermatophytosis caused by

Trichophyton raubitschekii. Report of the first case in Sao Paulo,

Brazil. Rev Inst Med Trop Sao Paulo 1999; 41: 313/317.

5 Tietz HJ, Hopp M, Graser Y. First isolation of Trichophyton

raubitschekii (syn. T. rubrum ) in Europe. Mycoses 2002; 45: 10/

14.

6 Summerbell RC, Haugland RA, Li A, Gupta AK. rRNA gene

internal transcribed spacer 1 and 2 sequences of asexual,

anthropophilic dermatophytes related to Trichophyton rubrum. JClin Microbiol 1999; 37: 4005/4011.

7 Graser Y, Kuijpers AFA, Presber W, de Hoog GS. Molecular

taxonomy of the Trichophyton rubrum complex. J Clin Microbiol

2000; 38: 3329/3336.

8 Romano C, Massai L, Difonzo E. Dermatophytosis due to

Trichophyton violaceum in Tuscany from 1985 to 1997. Mycoses

2000; 43: 169/167.

9 Hay RJ, Robles W, Midgley G, Moore MK. European Confed-

eration of Medical Mycology Working Party of Tinea Capitis.

Tinea capitis in Europe: a new perspective on an old problem. J

Eur Acad Dermatol Venereol 2001; 15: 229/233.

10 Mohrenschlager M, Seidl HP, Ginter-Hanselmayer G, Abeck D.

Tinea capitis of childhood: incidence and pathogenetic role of

Trichophyton tonsurans in Central Europe. J Am Acad Dermatol

2001; 45: 320/321.

11 Taplin D. Dermatophytosis in Vietnam. Cutis 2001; 67(Suppl. 5):

19/20.

12 Summerbell RC, Kane J. The genera Trichophyton and Epider-

mophyton . In: Kane J, Summerbell RC, Sigler L, Krajden S, Land

G (eds). Laboratory Handbook of Dermatophytes. Belmont, CA:

Star Publishing Company, 1997: 131/191.


276 Papini et al.

Documents

13693780310001602794