Dermatophyte Culture Research Articles

A study of dermatophytoses in Hamadan, the governmentship of West Iran.

In order to determine the extent and causative agents of dermatophytoses in the Hamadan region of West Iran; a study was made during a 9-month period from October 1991 to June 1992. A total of 7495 individuals were studied of whom 681 (9%) were suspect of having cutaneous mycoses. Among them dermatophytoses were the commonest infections (259/681 = 38%). Of 259 individuals infected with dermatophytes, tinea capitis were observed in 163 (62.9%); t. corporis in 27 (10.4%); t. manuum and t. cruris in 19 (7.3%) each; t. barbae and faciei in 14 (5.4%); t. pedis in 13 (5%) and t. unguium in 4 (1.5%). A total of 144 patients yielded dermatophyte cultures. The frequency of the isolated species in decreasing order was as follows: Trichophyton verrucosum, 78 (54.1%); T. schoenleinii, 48 (33.3%); Microsporum canis, 8 (5.5%); Epidermophyton floccosum, 5 (3.5%); T. mentagrophytes and M. gypseum, 2 (1.4%) each; T. tonsurans, 1 (0.7%). In conclusion, the most prevalent dermatophytosis in this region was t. capitis with the infecting agent of T. schoenleinii.

Mucocutaneous fungal colonization in HIV-infected children.

The prevalence of symptomatic mucocutaneous candidiasis in HIV-infected children is well documented. Information, however, of the carriage rate of potential fungal pathogens is lacking. In this study we determined the fungal colonization rate of multiple mucocutaneous sites from 13 HIV-infected and 12 control children. The rate of yeast and mould colonization and the species of fungal isolates were essentially the same for both groups of patients. However, several HIV-infected children asymptomatic for thrush proved to be colonized by Candida albicans, and disseminated colonization with Trichosporon beigelii occurred in one HIV-infected child. All cultures for dermatophytes were negative. While the carriage rate with fungi other than C. albicans was not increased in the HIV-infected group, the isolates recovered are known pathogens in the immunocompromised host and the colonization of these organisms may be a potential source of infection.

The burning mouth syndrome: lack of a role for contact urticaria and contact dermatitis.

The burning mouth syndrome is poorly understood and mainly affects postmenopausal women. Dental allergens have seldom explained the burning. Eight patients (seven women, one man) (mean age 62.5 years) who wore dentures and had the burning mouth syndrome were investigated to determine whether contact urticaria, allergic contact dermatitis, or pressure urticaria played a role. Only patients who had minimal to no erythema of the mucosa were included. A complete blood cell count, fasting chemistry profile, and potassium hydroxide examination and cultures for Candida and dermatophytes were obtained. Contact urticaria and patch testing with control substances were performed with a panel of 25 potential denture allergens. Complete blood cell counts and fasting chemistry profiles were normal. One positive Candida culture was found, but no improvement in the symptoms was noted after treatment. All patients tested positive to histamine and to at least two of the nonimmunologic urticaria controls. No patient had a positive urticarial reaction to the potential dental allergens. Two patients with nonimmunologic urticaria to cinnamic aldehyde improved with avoidance. All patch tests were negative. In the six patients tested for pressure urticaria, the results were negative. We cannot indict contact dermatitis, contact urticaria, or pressure urticaria as a cause of the burning mouth syndrome in the denture-wearing patient who has a normal-appearing mucosa. The burning symptoms in this syndrome may be secondary to a simple frictional phenomenon of the denture on the mucosa.

Efficacy and tolerability of topical terbinafine in the treatment of tinea cruris

Thirty men with clinical and mycologie evidence of tinea cruris were enrolled in a controlled, randomized, double-blind trial comparing terbinafine 1 % cream and its cream vehicle as placebo. Patients applied the test medications to the affected area twice daily for 2 weeks. Therapeutic response was evaluable in 18 patients after each week of treatment and at a follow-up visit 2 weeks after therapy ended. At each visit, terbinafine was found to be more effective than the cream vehicle in the reduction of the signs and symptoms of infection and in the conversion of culture and microscopy findings to negative or normal. At the end of treatment, therapy was effective in 67% of the nine terbinafine-treated patients compared with only 11 % of the nine placebo-treated patients. At the follow-up examination, efficacy rates were 78% in the terbinafine treatment group and 33% in the placebo group—a difference of borderline statistical significance ( p = 0.077). Possible reasons for this result may include the higher incidence of chronic disease in the terbinafine group and the large number of patients who were classified as delayed exclusions because of negative initial culture for dermatophytes. No side effects or significant alterations in laboratory or hematologic tests were observed in either treatment group.

Sulconazole nitrate 1% cream in the treatment of chronic moccasin-type tinea pedis caused by Trichophyton rubrum

Sulconazole nitrate 1% cream applied twice daily was compared with its vehicle in the treatment of 229 patients with chronic moccasin-type tinea pedis confirmed by positive results of a potassium hydroxide preparation. At admission in this randomized, double-blind, parallel multicenter trial, 131 patients had positive dermatophyte cultures; Trichophyton rubrum was identified in 121 (92%). After 4 weeks of treatment, patients were examined and, if necessary, were treated for an additional 2 weeks. Sulconazole cream was significantly more effective than the vehicle in the treatment of chronic T. rubrum tinea pedis; 57% of patients were cured by sulconazole, compared with 13% cured with the vehicle. Relapse rates, assessed 2 weeks after the end of treatment, were significantly lower in patients treated with sulconazole than in those receiving vehicle (27% vs 71%). The 103 patients with moccasin-type tinea pedis whose cultures were not positive for T. rubrum achieved similar results.

Diseases of the Pinna

Many diseases can affect the pinna of the dog and cat. These diseases represent most categories of cutaneous disease, from infectious to neoplastic. Although some diseases affect primarily the pinna, most pinnal dermatoses occur in conjunction with other integumentary disorders. One should approach the diagnostic work-up of pinnal disease in an organized manner, obtaining first a thorough history and physical examination. A systematic approach is required in the diagnostic evaluation in order to arrive at a tentative or definitive diagnosis. Skin scrapings, cytologic examination, and culture for dermatophytes provide the minimum database. A variety of diagnostic tests, including hematology, serum biochemical profiles, urinalysis, serology, intradermal skin testing, hypoallergenic diet trials, histopathology, and direct immunofluorescence, may be necessary in some cases before a definitive diagnosis is reached. The ears are somewhat difficult to biopsy, although in many instances histopathologic examination is essential to the diagnosis. In this author's opinion, it is preferable to use a no. 15 scalpel blade rather than a punch biopsy when obtaining a pinnal biopsy. This allows the veterinarian to obtain an elliptical or wedge biopsy, which can frequently be sutured. In some instances, biopsies are required from the ear margin and a full ear thickness biopsy is obtained. Sutures may not hold in this situation, and cautery may be necessary for hemostasis. As in other situations in which the ear is bleeding (aural hematomas, vasculitis, fly bite dermatitis, and so on), bandaging and immobilization of the ear may be necessary to prevent further trauma. Although symptomatic therapy is sometimes helpful when treating pinnal diseases, a definitive diagnosis is preferred. This is especially important following the second or third presentation of an animal for ear disease. Although ear diseases are frequently viewed as a nuisance rather than a serious condition, anyone who has owned or worked closely with an animal suffering from chronic otitis externa should appreciate the animal's discomfort and the owner's frustration. All too frequently, the chronic otitis externa is the result of a hypersensitivity (either inhalant or food) that has been overlooked in the attempt to treat the subsequent infectious otitis. Thus, in animals with recurrent otitis externa, every attempt should be made to identify and treat the underlying etiology.

Bovine ringworm. An outbreak caused by Trichophyton mentagrophytes var. granulare in Greece.

Seven cattle barns were investigated during the years 1976 through 1977. Six of these barns located in central Euboea have been characterized as "suspect" barns because one or more persons working in these barns had been infected by dermatomycosis. The seventh barn serving as control was located on the opposite side of the Boeotic coast. A total of 60 "suspected as infected" animals were isolated from all these barns. Twenty-one of them (35%) gave positive cultures for dermatophytes in Sabouraud medium. Of the 113 "healthy" animals that were examined, 28 (24.8%) gave positive cultures. The only pathogenic strain of dermatophyte that was isolated was the Trichophyton mentagrophytes var. granulare.

Growth, Colonial Size and Sporulation of Lyophilized Cultures of the Genus Trichophyton on Agar Media

RybnikH A.: Growth, Colonial Size and Sporulation of Lyophilized Cultures of the Genus Trichophyton on Agar Media. Acta vet., Brno, 55, 1986: 73 -80. Lyophilized cultures of 4 species of the genus Trichophyton Malmsten 1845 were diluted with saline after one year of storage and inoculated onto agar media. Trichophyton equinum grew best on malt media, T. mentagrophyfes on Mycological Agar, T. terrestre on Trichophyton Agars 1, 4 and 5, and T. verrucosum on Sabou­ raud's agar. The rate of colonial size increase of all the four cultures was highest on Sabouraud's agar, malt media and Mycological Agar. The formation of micro­ conidia showed the highest values on malt media with all the cultures except T. terrestre which sporulated best on Sabouraud's agar. It is concluded that malt agar media and Sabouraud's agar are suitable culture media for recultivation of lyophilized dermatophyte cultures. Dermatophyte lyophilizate, recultivation, colonial size, formation of microconidia. Cultures of microscopic fungi deposited in culture collections as well as those used for pro­ duction purposes undergo gradual loss of viability on long-term storage. In recultivating frozen­ lyophilized or otherwise preserved fungal strains it is therefore necessary to choose optimum procedures and conditions that would allow one to obtain viable, well-growing and sporulating cultures. One of the major factors involved is the choice of a suitable culture medium. Its choice may also considerably affect the results of testing fungal cultures for their growth and sporulation capacity and may lead to changes in the characteristics of the strains on passage. These aspects are particularly important in dermatophytic fungi, causative agents of mycoses in numerous animal species and man. The present study is concerned with the choice of agar culture media for recultivation, growth and sporulation of four species of the genus Trichophyton maintained in the lyophilized state for one year. These were three zoophilic dermatophytes, namely T. equinum, T. mentagrophytes and T. verrucosum, and one geophilic species, T. terrestre, which lives as a saprophyte on keratin structures in soil and very rarely attacks man and animals.

Experimental Dermatophytic Infection of Guinea-pigs and Calves

Rybnikaf, A., Chumela, J., Vrzal, V.: Experimental Dermatophytic Injection of Guinea-pigs and Calves. Acta vet. Brno, 54, 1984: 73-78. Typical mycotic lesions occurred in all infected guinea-pigs after application of ca 103 viable units of Microsporum canis onto 1 em2 of shaved and scarified skin. However, similar lesions on shaved but non-scarified skin were only observed with inocula of the same culture containing 105 units/cm2 skin, i.e. 100 times higher doses. Minimum infective doses of Trichophyton equinum and T. verrucosum ne­ cessary to produce experimental clinical skin trichophytosis in guinea-pigs amounted ca 100 units/em2 of shaved scarified skin (1 animal showed signs of the disease after application of 10 units/cm2 of T. verrucosum). Susceptibility of calves to the infective agent T. verrucosum was lower than that of guinea-pigs. Trichophytosis occurred only after inoculation of 104 units/em2 T. verrucosum in shaved and sca­ rified skin, i.e. 100 times higher dose than that used with guinea-pigs. M. canis, T. equinum, T. verrucosum, inoculation doses. Experimental infection of animals has been an important component of efficacy testing of biolo­ gicals in veterinary medicine. The results of these tests may be influenced by a number of factors, e.g. the mode of experimental infection and the amount of inoculum. These factors also play an important role in challenge experiments with dermatophytic cultures. Experimental inoculation of pathogenic skin fungi is usually carried out by rubbing suspensions or pastes of the fungal culture into the shaved and often scarified skin of animals (Cox and Moore 1968; English et a!. 1979; Veronese et a!. 1981). Some workers inoculated the infective agent into non-scarified skin (Lepper 1972; Poulain et a!. 1980 and others). Various doses of infective material have been inoculated in such studies. However, no optimum inoculation doses for the individual dermatophyte cultures have been recommended. Therefore the present work was aimed at completion of these data.

Storage of Lyophilized Dermatophyte Cultures

Rybnikaf, A.: Storage of Lyophilized Dermatophyte Cultures. Acta vet. Brno, 54, 1985: 79-83. Viability of lyophilized fungus cultures was tested after one year storage at a tem­ perature of 2 to 6°C. In 10 of 13 lyophilized cultures a slight but non-significant decrease in viability occurred. Only for 3 lyophilized strains stored in a refrigerator less than 78 % of the fungus units were viable when compared with original values found immediately after lyophilization. This decrease was significant. Viability of all lyophilized cultures stored at room temperature decreased significantly or highly significantly with no differences between samples stored in the dark or light.

Permanent mounts of fungus cultures grown on media optimal for production of characteristic structures.

1. Dermatophyte cultures in plastic flasks were compared on four different media for total growth, sporulation, and pigment production. Czapek's agar favored more rapid and more abundant sporulation in most cultures than Sabouraud's dextrose agar, potato dextrose agar, or wort agar.

Experiments on the Biology of Fungous Infections of the Feet

Experiments on the Biology of Fungous Infections of the Feet

Crystal mimics in cultures of dermatophytes

Formation of crystal mimics, macroconidia-like and perithecium-like structures, is described in cultures of dermatophytes in hair-on-soil cultures and on Sabouraud glucose agar. The way how to recognize these mimics in white and in polarized light is discussed. The abundant crystal formation and the necessity to recognize it in the “mycotheca in chlorallactophenol” is underscored.

SOME REMARKS ON CULTURES OF DERMATOPHYTES ON HAIR-ON-SOIL MEDIUM.

(A) A layer of fungus vegetation on heavy agar substrate, (2–3 mm), deposited on wet soil is reached by the biochemical ingredients in the soil by diffusion through the agar layer. This fact was demonstrated and made visible by the use of a 1% eosin solution.

CRYSTAL FORMATION IN CULTURES OF FUNGI. II. APPEARANCE OF CRYSTALS IN WHITE LIGHT.

The present study offers the picture of crystal formation in cultures of dermatophytes photographed in white light. Isometric and anisometric crystal forms are profusely depicted. ‘Pranks’ and ‘mimics’ of crystal forms are pointed out. Photomicrographic data are given.

ANTIMICROBIAL ACTIVITY OF A MONOALKYL BENZENE SULPHONATE COMPLEX

The antimicrobial activities of a branched, monoalkyl benzene sulphonate complex (ABS), the active component of a commercial liquid household detergent, and of the detergent have been investigated. Cultures of dermatophytes, Candida albicans, saprophytic phycomycetes, ascomycetes, fungi imperfecti, Gram-positive and Gram-negative bacteria were tested. Only the Fusarium species and the Gram-negative bacteria were not inhibited by a concentration of 0.1 ml of the detergent/50 ml medium. Microgram quantities of ABS inhibited the Gram-positive bacteria and the fungi except Fusarium spp. ABS was lethal in microgram quantities, the effect being detectable within 30 minutes. Inhibition of exogenous respiration of glucose by C. albicans began upon contact and was complete within 50 minutes. A linear and biodegradable ABS was more active than the branched form against C. albicans.

Crystal formation in cultures of fungi: Dermatophytes and other Hyphomycetes.

The present study calls attention to crystal formations in cultures of Dermatophytes and other Hyphomycetes.

The Use of a Cycloheximide-Chloramphenicol Medium in Routine Culture for Fungi

Following the initial report of Whiffen, et al (1), cycloheximide f has been found to be of value in increasing the number of isolations of pathogenic fungi from clinical material and other sources. Georg (2) isolated many more cultures of dermatophytes from cases of suspected onychomycosis in human beings, and from cattle scales and hairs in suspected animal ringworm using a cycloheximide-containing medium than from a similar medium not containing cycloheximide. Fuentes, et al (3) and Sharvill and Talbot (4) found that the use of cycloheximide-containing media in human mycoses allowed for only a slightly higher number of isolations than did unfortified agar, but that the number of saprophytic fungi appearing on the tubes was reduced. Relatively few patients were examined in these studies. Shapiro, et al (5) found cycloheximide medium to be of value in culturing clinical material where contamination by saprophytic molds was suspected, but report that on Littman medium (6) in petri plates, growth of dermatophytes was initiated earlier.

The Action of Ultraviolet Radiation on Dermatophytes. II. Mutations Induced in Cultures of Dermatophytes by Exposure of Spores to Monochromatic Ultraviolet Radiation

The Action of Ultraviolet Radiation on Dermatophytes. II. Mutations Induced in Cultures of Dermatophytes by Exposure of Spores to Monochromatic Ultraviolet Radiation

RINGWORM FUNGUS GROWING AS A SAPROPHYTE UNDER NATURAL CONDITIONS

a paper entitled In Situ Cultures of Dermatophytes, Davidson and Gregory1stated that the cast-off hairs and epidermal scales of animals may be the medium for the spread of animal ringworm. They showed that when infected hairs are placed in a moist atmosphere the growth of the invading fungus continues with the production of a small saprophytic colony and the two usual types of accessory spores, aleuriospores and fuseaux, are borne in the manner normally observed in cultures made on artificial mediums. These authors considered that although it is possible that the saprophytic stage of ringworm fungi may one day be observed under natural conditions on substances other than keratinized animal tissue, it may well be that such tissue is the most important natural medium on which ringworm fungi exist as saprophytes and produce spores capable of infecting human and animal hosts. The probability that these fungi spend