Odnos T. Interdigitalea prema T. Mentagrophytesu

Abstract

Simplified methods of systematizing dermatophytes have proved exceedingly helpful and of great value to medical mycology. The setting up of particular species solely on the basis of macroscopic looks of the colonies is a thing of the past in the light of factors conditioning the appearance of macroculture. Nor is there any ground for the other extreme, viz. the identification of particular species on the basis of botanical criteria only. A case in point presents the identification of T. interdigitale with T. mentagrophytes and T. granulosum respectively.

 The object of the present study is to decide the question whether the aforesaid fusion can be done, with due reference to recent publications in the literature. For purposes of differentiation the following criteria have been considered:

(1) aspects of the colonies on sacchariferous and conservatives mediums; (2) rate of growth on artificial mediums, especially on Hemmagar according to Goetz; (3) the phenomenon of filament fusion according to Davidson, Dowding and Buller; (4) the bearing of parasitical life of dermatophytes on human hair and results of transmission tests on the guinea­pig.

This theme has been chosen in view of the experience gained from our material that goes to shov that the macrocolonies picked from off the hands and feet with dermatophytic alterations present an entirely different aspect from those with trichophytic lesions of the cutis labra. The material for this study was obtained from 282 cases with diseased feet, both with and without regionary dermatophytes on the hand, 85 were isolated cases with diseased hands,

38 cases with inguinal dermato­ and epidermophyty as well as moniliasis, 8 cases with diseased nails and 2 cases of submammary moniliasis. From this material 134 separate cultures (48,1 % ) were made with the following fungi: T. interdigital ­ 79 cases ( 58,9%), E. Floccosum 21 cases {15,71%), T. Violaceum 8 cases (5,9%), T. Mentagrophytes 5 cases (3,7%), T. Granulosum 3 cases (2,2%), T. Rubrum 2 cases (1,4% ), T. Cerebriforme 1 case (0,7%), Scopulariopsis brevicaulis 1 case (0,2%), Candida and Torulopsis 14 cases (14,4%).

The leading dermatophyte in lesions of the extremities, particularly of the legs, is the T. Interdigitale. After the war the first separation of T. rubrum was effected on the territory of Bosnia and Hercegovina. Noteworthy are the separations of T. mentagrophytes and granulosum ins 8 cases of dermatophytic alterations of the legs, and these separations were tested partly by infecting guinea­pigs, partly by the aspect of the colonies on Peptonagar.

As a parallel to colonies of T. interdigitale served the material of 146 cultures of microidic trichophyton, which presented no special difficulties concerning identification. Separately, macroscopical look of the colony of T. mentagrophytes on pepton-agar never let one down unless the colonies had shown sings of pleomorphy, when the characteristic cratelike­nodular look of the colony on pepton­agar disappeard being replaced by a cottony­.snowy film­ plate, very similar to the colony of T. interdigitale on conservative medium.

T. interdigitale with its variants in the macroculture fluffy, gypseous and cerebriform is apt to be confounded with microid.al trichophytons. Thus the snowy­velvety variant may easily be mistaken for T. niveum, from which it differs in a yellow like centre on sacchariferous mediums. The gypseous variant mostly resembles the T. gypseum mentagrophytes. Another point of difference is a yellowish centre of the colony and a pronounced ring of yellowish spores around the centre on maltose­agar, while on glucose agar these spores are situated less closely, upon the periphery of the colony. Most pronounced is the aspect of the T. interdigitale on Pcpton agar, where it grows as a velvety, clearly bordered, yellow­ brownish plate with· a hollow or a tiny fluffy button in the centre. Finally, the aspect of the cerebriform variantis distinguished by yellowish spores on the curves of the surface giving it a special tone. The above features of macroscopic looks of the colonies are so important that they may well be used for the differentiation of the T. interdigital from the T. mentagrophytes.

The growth of the colonies on 10% Pepton water, as claimed by Goetz for the purpose of differentiation of the T. interdigitale from the T. mentagrophytes, could not be proved by tests on our material consisting of 1 colonies of T. interdigitalis, 8 colonies of T. mentagrophytes and 3 colonies of T. granulosum. All of them grow on the surface of Pepton water without a tendency to fall to the bottom. Nevertheless, the fact was established that it was not only the colonies of T. interdigital that stuck to the sides of the test tube but those of the T. mentagrophytes as well. Moreover, both species exhibited reddishyellowish tuberous formations on the back of their respective colony. The analysed species, incidentally, were both young. Consequently, the growth of the colonies on Pepton water cannot in itself be a reliable criterion of differentiation between the two dennatophytes.

The same applies to the phenomenon of inhibited growth of some dermatophytes in the presence of bac. colli, as described by Bidault, for there is not much difference in arrested growth between the T. interdigitale and the T. mentagrophytes.

Even with the naked eye we can observe a faster frowth of the T. interdigital on sacchariferous mediums than in the case of T. mentagrophytes. This is especially noticeable in the microculture on Gruetz’s agar TTT with added zine sulphate plus sodium hydroxide (Goetz’s growth inhibiting agar). In 43 microcultures, using Rivalier-Seydl’s method it was established that the growth of T. interdigitals’ mycelia during the first 5—6 days amounted to 200—300 microns as against that of T. mentagrophytes of only 30—50. As a result, the rate of growth on this Hemmagar can safely be used for differentiation between the two dermatophytes. As regards the conception of some mycologists to the effect that the T. inter­digitale is only a degenerative form of T. mentagrophytes adapted to growth on human beings, the evidence shows that the T. interdigitale really is, in its rate of growth, an animal species.

The phenomenon of filament fusion between two identical species of dermatophytes, as decribed by Davidson, Dowdinqr and Buller, may also be successfully used as a criterion of differentiation even though its practical use is rather limited, as it demands much time and patience. In contrast to identical species, no hyphafusion could be observed in 35 of our microcultures of the T. inter­ digitale and mentagrophytes.

By means of an analysis of vegetative and reproductive organs in microcultures of artificial and natural mediums it was seldom possible to separate the T. interdigitale from the T. mentagrophytes owing to the inadequacy of botanical criteria. Still, the reproductive organs štand out fairly prominent in the gypseous variety of the T. interdigitale, which goes to prove that the eventual discowery or absence of these organs in microcultures can be no criterion of differentiation form the two species.

The lack of lesions in the hair of man has always been considered as an absolute characteristic of T. interdigital, in con­trast to T. rubrum with a number of data on the occurrence of affections of the hair and the affinity of the parasite for it. A case of Miescher’s has recently been reported on referring to a separation, from banal folliculitides of the cutis labra. of the T. inter­digitale with peripilar situation of the spores in a histological preparation. Whatever the explanation may be. it does not in fact disprove the negative affinity of T. interdigitale for the follicular a.pparatus in man.

In appraising the results of experimental transplantation of T. interdigitale on guinea pigs. one must pay attention to the following points: (1) certainty that the treated case actually is T. interdigitale and (2) the results must be judged relatively, ccmparing them always with lesions, which is avoiding on genuin pigs of T. mentagrophytes. The peeling of guinea-pig skin a Ione without inflamatorv symptoms with negative finding of the fungus concerning the hair, cannot be taken as a positive result of inoculation. The finding of fungoid elements in the scales is not in itself a sign of parasitism for the experience has taught us that after the completion of treatment of our favuse patients, there still exist spores in the scaly elements of the head skin, without recidivs. Nbninflammatory occurences in T. interdigitale during experiments on animals have to be compared with current inflammatory lesions with infiltrates, scales, follicular changes, suppurations and alopecia, which are characteristic of T. mentagrophytes. VVithout a due allowance for these facts, one may easily come to the wrong conclusion, that experimental infections on animals can be no criterion for the classification of dermatophytic species. On the basis of a series of 12 transplantation of T. inter­digitale and mentagrophytes on rabbits the author concluds that the negative (aphlegmatic) results of the implantation on guinea-pigs have the same decisive importance for the T. interddgitale; the old school of medica! mycologists has always claimed this as the safest means of separaion from microidal trichophytons.

The T. interdigitale must be strictly differentiated from the T. mentagrophytes by the following criteria: (1) the macroscopic growth of the colonies on glucose, maltose and pepton agars; (2) the rate of grovvth on nurient mediums as well as on Goetz’s Hemmagar; (3)-the lack of filament fusion with microidal trihophytons, especially with the T. mentagrophytes; (4) the negative affinity to the hair in man and negative results of transmission in guinea-pigs.

The growth of the colonies on 10%' Pepton water according to Goetz, the inhibited growth in the presence of bac. coli, and the microcultural findings cannot be regarded as good criteria for the separation of T. interdigitale from. T. mentagrophytes.

The conclusion is therefore indicated that the T. interdigitale is a separate species, for there are as yet no grounds for identifying it with the T. mentagrophytes.