Trichophyton Yaoundei. A Dermatophyte Indigenous to Africa*

TRICHOPHYTON YAOUNDEI. A DERMATOPHYTE INDIGENOUS TO AFRICA* LUCILLE K. GEORG, Pn.D.,* PIERRE DOUPACNE, M.D.,t S. R. PATTYN, M.D4 AND HERMANO NEVES, M.1).I

During the past several years, the Mycology Unit of the Communicable Disease Center has had an opportunity to study a number of dermatophytes isolated from various parts of Africa. Among these, Trichophyton yaoundei, a new

and Haoussa tribes. Of these eases 80.8 per cent

were due to various triehophyton species and 19.2 per cent were due to mierosporum species.

Among the triehophytons, 241 (49.6%) were recognized as a new triehophyton species, later

species described by Coehet, Doby-Dubois, described as T. yaoundei. The other triehophyton Debloek and Vaiva in 1957 (1), merits special species isolated were T. sndonense Joyeux, consideration, as it is little known and its spe- 1912, 149 strains (30.7%), and T. ferruqineum'J cific identity has not been confirmed by other Ota, 1922, 64 strains (13.1%). workers In 9 instances, T. yaoundei was found in T. yaoundei, originally isolated from patients combined infections with other dermatophyte in the former French colony of Cameroon, was species. In unmixed infections the hairs were first described as T. camerounense by Coehet observed to be invaded in an endothrix pattern and Doby-Dubois in 1957 (2). Later in the same with large spores.

year, these authors along with Debloek and

Vaiva renamed the organism T. yaonndei since

they had found that the earlier combination had been used to describe a different organism. The specific name yaoundei was derived from the province of Yaoundé where the organism was first isolated. The authors stated that this species may have been observed previously by Catanei in 1939 (3) when he described a "prune-colored"

dermatopbyte among a group of isolates obtained from various African countries. In 1955 J. N. Doby and M. Doby-Dubois conducted a routine survey for tinea eapitis among 3,000 school children, both Caucasian and Negro, in the province of Yaoundé. Of

MATEEIALS AND METHODS

Among the African dermatophyte isolates studied at the Mycology Unit, 7 cultures have been identified as T. yaoundei. These cultures and their sources are listed in Table I. In one instance cultures were isolated at the Mycology Unit directly from hairs sent from Africa (Stan-

leyville, Belgian Congo). Of the remaining cultures, six were isolated in the Belgian Congo

from patients observed at the Laboratoires Medical Provincial of both Stanleyville and Elisabethville. **

When infected hairs were available, some were studied microscopically and others were cultured.

1.400 children with scalp lesions, 866 were diagnosed as having ringworm infections on the basis All strains were grown on Sabouraud dextrose of cultural studies. All the infections were found agar, easein agar, wort agar and rice grains.

Nutritional tests as used for the identification

among the children of the Bantu Bamiléké of dermatophytes (5) were carried out. The iso* From the Communicable Disease Center, lates were grown on hair in vitro (6) and on C. S. Public Health Service, Department of

¶ T. ferruqineum is considered to be a member Health, Education, and Welfare, Atlanta, Georgia. f Present address----Conseiller Technique, Serv- of the genus Microsporum by myself (Lucille ice de l'Rygiene. B. P. 180, Albertville, Katanga. K. Georg) and a number of other mnyeologists. Isolated by P. Dupagne, 1958. Present address—Institut de Medicine Trop** Isolated by 5. 11. Pattyn, 1959. ieale, Prince Leopold, Antwerp, Belgium. § Laboratorio de Mieologia da Cliniea Dermatt Casein Agar: Casamino acid (vitamin free) 2.5 gm. tologiea Universitaria. Hospital de Santa Maria, Glucose Lisbon -4, Portugal. Dr. Neves collaborated on 40.0 gm. these studies while in the United States under a 0.1 gm. Mg504 grant from the Instituto de Alta Cultura (PortuKR2PO4 1.8 gm. gese Government) and the American Educational 20.0 gal. Agar

Water (distilled) (Adjust pH to 6.8)

Commission.

Received for publication October 8, 1962. 19

1000.0 ml.

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PLATE I. a. Trichophyton yaoundei, Strain B253. Colony on Sabouraud dextrose agar at 8 weeks. b. T. yaoundei, Strain B253. Close-up of colony. c. T. yaoundei, Strain B124. Close-up of colony. d. T. yaoundei. Mycelium from glabrous colony X 256. e. T. yaoundci. Glabrous colonies with brown pig-

mentation. One colony showing development of area of white fluffy growth. f. T. yaoundei, Strain B309. Microconidia from growth on casein agar, X 512.

TRICHOPHYTON YAOUNDEI

J ;.'

21

PLATE II. a. Human hair infection by T. yaoundei. Shows endothrix pattern of invasion. X 128. b. Edge of hair infected by T. yaoundei, X 475.

RESULTS

some cases the central area became depressed or the surface of the colony had an irregular lumpy appearance with many knobs and depressions. Only 3 of the strains remained flat,

I. Study of Clinical Material

however, these developed shallow radial grooves

In one instance infected hairs were available for study. They were in the form of short, dark

or a finely wrinkled or vcrrucose surface. Colonies

moistened soil baited with hair (7). In addition, animal inoculation studies were carried out.

fragments usually bent or curved. In KOH mounts it was observed that they were invaded

obtained by inoculating infected hairs only attained a diameter of about 10 mm. after 4 to 6 weeks of incubation. Maximum colony size

in an endothrix pattern. The short hair frag- after 10 weeks incubation was 30 mm. diameter. ments were broken off bluntly at each end. Subcultures developed more rapidly than the They were filled with masses of large spores original isolates. In the early stages of development—up to 3

(2.1—7.3 t) with an average size of 4.7 M* (Plate to 4 weeks growth—the colonies were very simiI, a and b). After remaining in the alkaline solular to those of T. verrucosum, and could easily tion for an hour or longer, the hairs swelled and be mistaken for that organism. They resembled their walls ruptured. The spores which emerged

also the glabrous, non-pigmented form of T. were observed to be in chains. Cultures made from remaining hairs from violaceum (var. glabrum). Upon prolonged incubation however, the colonies of T. yaoundei this specimen yielded T. yaoundei. developed a characteristic tan to dark brown II. Morphological Studies of Fungus Isolates

a. Gross colony appearances

All isolates developed very slowly at room temperature on Sabouraud dextrose agar or on Cycloheximide Medium (8). Cycloheximide did not inhibit their growth. The colonies first appeared after 7 to 10 days of incubation as small, dull white, or slightly yellowish growths with a

moist or glabrous to wax-like surface. Their surface was at first either flat or raised in the form of small knobs. However, most colonies became definitely heaped and irregularly folded,

particularly at the center of the colony. In * Average spore size derived from measurement of 100 artbrospores.

pigmentation. In most of the isolates, pigmentation developed only after 4 weeks incubation at which time the colonies assumed a tan coloration. Some strains remained yellowish tan, but

others gradually darkened and eventually became deep chocolate brown. Some strains required 8 to 10 weeks incubation before the deep-

est brown was attained. The majority of the strains produced a tan pigment on the reverse side of the colony also. This pigment was soluble

and diffused throughout the medium. In the original description of the Cameroon strains by Cochet et al (1), all cultures became tan or dark chocolate brown, and the medium was always filled with brown pigment. Plate II illustrates the gross morphology of recently isolated strains.

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TABLE I List of isolates of 7'. yaoundei studied Stock No.

B250 B251 B252 B253 B289 X247 B308 B309 B310 B311

Senders'

r:ri0a

387

Culture Culture Culture Hair Hair Hair Culture Culture Culture Culture

537 887

84 124

30 617 633 646 708

Source

Tinea capitis, Cameroon Tinea capitis, Cameroon Tinea eapitis, Canieroon Tinea capitis, Stanleyville, Belgian Congo Tinea capitis, Stanleyville, Belgian Congo Tinea capitis, Stanleyville, Belgian Congo Tinea eapitis, Elisabethville,* Belgian Congo Tinea capitis, Elisabethville, Belgian Congo Tinea capitis, Elisabethville, Belgian Congo Tinea eapitis, Elisabethville, Belgian Congo

Sender ta?rt01t

C. Cochet C. Coehet C. Cochet P. Dupagne P. Dupagne P. Dupagne

S. H. Pattyn S. H. Pattyn S. H. Pattyn S. H. Pattyn

* The isolation of T. yaoundei from Elisabethville and its environs was reported by Pattyn and Sassen in 1660 (4).

Most of the strains studied at the CDC had a marked tendency to become polymorphic after several transfers. Not only did individual cobflies of an isolate vary in rate of growth, form, and pigmentation, but single colonies developed many different types of growth. Frequently the raised colony was surrounded by flat areas of tough, colorless, glabrous growth; or certain areas of the colony became covered with short white velvety aerial mycelium. Old cultures often

were covered completely with white, velvety, aerial inyeelium. Cultures which remained glabrous maintained some tan pigmentation. However both the pigmentation of the colonies as well as the diffusible brown pigment became partially or entirely lost after several subcul-

colonies. Growth was more rapid, and develop-

ment of the white, velvety aerial myeelium occurred earlier and covered most of the colony.

The characteristic chocolate brown, glabrous colonies were not obtained on these media. Growth on wort agar was similar to that on

Sabouraud dextrose agar. All strains grew at approximately the same rate whether incubated at 25°C or 37°C. The isolates grew very slowly on rice grains, producing only a small amount of white aerial myeelium after several months incubation. No growth was obtained on the soil-

hair plates. This medium, designed to induce sexual reproduction, consisted of autoelaved soil that had been moistened with water and baited with sterilized bits of horse hair (7).

tures.

Of the cultures obtained from Dr. Coehet, all

b. Microscopic appearance The colonies were tough and leathery in texfolded colonies. Two of the strains had glabrous ture. Teased preparations in laeto-phenol cotton areas with a light tan pigmentation and some blue revealed a branched myeelium of irregular areas covered with a white velvety aerial my- diameter which frequently broke up into short eelium. One of the strains \vas completely segments. 'The drier parts of the colonies were overgrown with white, velvety myeelium. None friable and composed of masses of ehlamydoof these strains became dark brown and no spores. The more or less submerged thin, glabrown pigment developed in the medium sur- brous growth at the edges of the colonies was rounding these colonies. * composed of very delicate, thin mycelium which Growth of our isolates on enriched media such was more regular in form. Attempts to make as casein agar, and brain heart infusion agar, mounts of the aerial growth were usually unsucappreciably changed the appearance of the cessful unless slide culture preparations were

grew slowly and formed slightly heaped and

* According to a communication from Dr. made. Slide culture preparations made with Cochet, these strains originally exhibited the Saboqraud dextrose agar revealed a thick irregcharacteristic chocolate brown pigment of this species. However, after several transplants, this ular non-sporulating mycelium. However, in casein agar slide cultures, a fine branched my pignsentation has completely disappeared.

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TRICHOPHYTON YAQUNDRI

celium of uniform diameter that bore numerous delicate microconidia developed. These were small, pyriform, hyaline, one-celled, smooth walled spores borne laterally on the aerial mycelium and attached directly by their slightly

This species was apparently first encountered

by Cochet and Doby-Dubois in the French Cameroon in 1957. It is doubtful that the "prune colored" dermatophyte isolated from the Cameroon by Catanei in 1939 represented T. yaovndei

truncate bases. Some terminal clusters of spores (as suggested by Cochet and Doby-Dubois) also developed. The conidia were approximately since he made no mention of a deep brown or 1.5 to 2.5 ji long by 0.75 x 1.0 /h wide. In general "chocolate colored" pigment. they were similar to the microconidia of other T. yaoundei is distinguished from the morphotrichophyton species. Hitherto, microconidia logically similar T. vcrrucosum by the following. had not been described for this species. Macro1. T. verrucosum grows much more slowly on conidia were not found in any preparation. Rice Sabouraud dextrose ngar. grains, wort agar and brain heart infusion agar 2. T. verrucosum grows better at 37°C than did not stimulate sporulation. Plate II (d and at room temperature. f) illustrates the microscopic morphology of T. 3. T. verrucosum has complete requirements

for one or more vitamins (thiamine, inositol,

yaoundei.

III. Physiological Studies

Nutritional studies were undertaken according

to the methods described by Georg and Camp (5). All strains were found to have the ability to develop equally well on vitamin-free media as on vitamin containing media. Growth was consistently better on cascin, vitamin-free agar than on ammonium nitrate, vitamin-free agar. In vitro hair tests as described by Ajello and Gcorg (6), were tried with all strains. The organisms grew well in the dilute yeast extract solution; however, no growth occurred on the hairs, and accordingly perforations were not observed after 4 weeks incubation.

pyridoxine), and will not grow on vitamin-free media (9). 4. T. verrucosum does not develop dark brown pigmentation. 5. T. verrucosum produces a large-spored ectothrix type of hair invasion. T. yaoundei is differentated from T. violaceum by the following. 1. T. violaceum usually develops some lavender or purple pigmentation. 2. T. violaceum., as well as its variety glabrum,

never develops colonies with dark brown pigmentation.

3. T. violaceum will develop very slowly on vitamin free casein agar, but is greatly stimu-

IV. Animal Inoculations

lated by the addition of thiamine to this medium

Attempts to produce experimental ringworm infections in guinea-pigs were unsuccessful.

Clinically T. yaoundei infections appear to be similar to those produced by other endothrix species such as T. violaccum, T. tonsorans, and

nlscussloN

Trichophyton yaoundei appears to be a distinct dermatophyte species. It is characterized

(10).

T. sudanense.

T. yaoundei apparently has a limited geographic distribution. At present it has been by the development on Sabouraud dextrose agar reported only from the Cameroon Republic, of irregularly heaped glabrous colonies which

and from the Republic of the Congo.

are at first cream to tan in color, but after several

weeks incubation, become a dark chocolate

STRAINS AVAILABLE

brown. During growth of the colony, the medium becomes diffused with a soluble brown pigment.

Three strains of T. yaoundci from this series

medium such as casein agar. It develops slowly

Culture Collection. The culture collection num-

incubation at 37°C. Microconidia characteristic

at the Mycology Unit, Com-

of the genus trichophyton are developed by

municable Disease Center, Atlanta, Georgia, from endothrix

The organism grows well on a vitamin-free have been deposited with the American Type on vitamin-free NH4NO3 agar. Its growth is hers are listed below. not stimulated by the addition of vitamins or ATCC 13946 Trichophyton yooundci. Isolated some strains on casein agar.

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hairs, Stanleyville, Belgian Congo

(Dee. 3, 1958) CDC B289. ATCC 13947 Trichophyton yaoundei. Isolated

by Dr. S. R. Pattyn from tinea capitis,

Elisabethville, Belgian

Congo (Aug. 15, 1959) CDC

REFERENCES 1. COCHET, 0., Dosy-Dusois, M., DEBLOCK, S., Don, J. M. AND VAIYA, C.: Contribution a la connaissanee des teignes infantiles du Cameroun. Ann. Parasit. Hum. Comp., 32: 580,

2.

%B309.

ATCC 13948 Trichophyton yaoundei. Same source as 13947 (Aug. 15, 1959) CDC yB311. SUMMARY

1. Seven strains of T. yaoundei from several areas in Africa were studied and described. 2. T. yao'undei appears to be a distinct derma-

tophyte species. It has been isolated from at least 250 eases of endothrix tinea eapitis in African natives. Cultures from infected hairs develop slowly on Sabouraud dextrose agar. The colony is irregularly heaped and folded and is largely glabrous with a wax-like surface. It is at first cream to tan, but after several weeks becomes a dark chocolate brown. The medium becomes filled with a diffusible brown pigment.

3. Mieroconidia were found for the first

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dans les colonies franeaises. Arch. Inst. Pasteur Algerie, 17: 47, 1939.

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7. Dwsoic, C. AND GENTLE5, J. C.: The perfect states of Keratinomyces ajetloi Vanbreuseghem, Trichophyton terrestre Dune & Frey and Microsporunv nanum Fuentes. Sabouraudia, 1: 49, 1961. S. Gxoo, L. K.: Use of a eyeloheximide medium for isolation of dermatophytes from clinical materials. Arch. Derm. (Chicago), 67: 355, 1953.

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time in this species by growing the isolates on easein agar.

4. Criteria useful in the identification of this species, and for its differentiation from morphologically similar species were defined.

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COCHET, 0. AND D0BY-DunoIs, M.: Contribution a la connaissance des teignes infantiles du Cameroun (Note préliminaire).

10.

Gnoaa, L. K.: The relation of nutrition to the growth and morphology of Trichophyton violaceum. 1. The vitamin and amino acid requirements of T. viotaceum. Mycologia, 43: 297, 1951.

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