Tinea capitis in south Wales--observations in change of causative fungi.

We report an observed change in the causative organisms in 45 consecutive cases of tinea capitis seen in the Cardiff area over the last 9 years. Direct microscopy using potassium hydroxide was positive in all but one case, but this was subsequently positive on culture. This retrospective analysis shows that more cases are being seen in our department, and that a higher proportion of cases are due to Trichophyton violaceum whereas previously we would have expected the majority of cases to be due to Microsporum canis. We believe that the change in causative organism that we have identified has important practical and diagnostic implications. Endothrix fungi such as T. violaceum do not fluoresce under Wood's lamp unlike ectothrix fungi such as M. canis, and therefore failure to perform adequate mycological examination of specimens could result in missed diagnoses. We are not aware of this change having been reported from other UK centres. The finding indicates a need for further prospective epidemiological studies to confirm this apparent trend.

Determination of sensitivity to antifungal drugs: evaluation of an API kit.

Evaluation of a commercial kit method for testing sensitivity of yeasts to antifungal drugs was performed employing agar gel dilution as the reference method. For the cidal drugs amphotericin B and flucytosine, results were closely comparable. For the three azole drugs tested, miconazole, econazole and ketoconazole, the discrepant results obtained probably relate to a number of factors affecting the end-point when testing these agents. Although easy to perform, the kit method is relatively expensive and the newer antifungal agents (e.g. fluconazole and itraconazole) are not included. Though showing promise, the kit method has limitations in its present format.

Preliminary report on the isolation of a dysgonic variety of Microsporum canis together with the normal variety from a cattery.

The isolation of a dysgonic variety of Microsporum canis from a large number of cats and kittens in a cattery is described. The normal variety of this fungus was isolated at the same time from the same animals. Dysgonic varieties are thought to be mutants of normal strains, but this isolation of both forms together suggests that the relationship may be more complex.

Hazards from hedgehogs: two case reports with a survey of the epidemiology of hedgehog ringworm.

Two related cases of ringworm caused by contact with an infected hedgehog are reported. The causal fungus, Trichophyton erinacei, was isolated from human and animal cases. The epidemiology of hedgehog ringworm is discussed.

Dermatophyte onychomycosis in children.

Four-hundred and ninety-four schoolchildren and 200 children attending a paediatric medical out-patient clinic were screened for clinical evidence of dermatophyte onychomycosis. Only one case was found and mycological investigation showed this to be due to Trichophyton rubrum. The overall prevalence of dermatophyte onychomycosis in the prospective survey of schoolchildren was 0.2%, confirming that this type of infection is very uncommon in children. Seven further cases of nail infection occurring in children under the age of 12 years are reported. These represent all cases collected by our laboratory over a 3-year period. In six cases where culture of nail was positive, the causative organism was T. rubrum. In four cases at least one parent was also found to have dermatophyte onychomycosis; again, T. rubrum was the causative organism in all cases. Dermatophyte onychomycosis in children appears to be of low infectivity, (in contrast to viral wart infection), and a parental source should be suspected and sought.

Cutaneous cryptococcosis: treatment with oral fluconazole.

A case of cutaneous cryptococcosis is described in an immunocompromised patient. The initial lesion developed on the dorsum of the hand following trauma and was initially thought to be neoplastic. Satellite subcutaneous lesions developed in a 'sporotrichoid' pattern along the forearm. Treatment with oral fluconazole resulted in the complete resolution of the lesions. This is the first published report of the use of fluconazole in the treatment of cutaneous cryptococcosis.

Cutaneous fungal infection following renal transplantation: a case control study.

The prevalence of cutaneous fungal infection was studied in 72 patients who had undergone renal transplantation and compared with a group of age and sex matched controls. Samples were obtained from toe nails, toe webs, and the upper back; clinically suspicious lesions from other areas were also examined. A total of 576 sites were sampled (288 in each group). Pathogenic fungi were identified from 44 sites (15%) in the renal transplant (RT) group compared with 26 sites (9%) in the control group, (P less than 0.05). However, site-specific differences were less marked; no difference was found between the RT group and controls when the results from the toe nails and toe webs were analysed separately. Trichophyton mentagrophytes was the most common species isolated from both groups. Colonization of the back with Pityrosporum yeasts was significantly more common in the RT group, but few patients in either group had tinea versicolor. 'Mixed infections', with more than one species of fungus isolated in an individual, were only found in the RT group. We also examined the relationship between the presence of fungal infection and the presence or absence of cutaneous malignancy in the renal transplant group. No increase in the prevalence of fungal colonization was found in those patients who had developed cutaneous malignancy compared with those who had not.

The normal fungal flora of dogs. A preliminary report.

A survey of the fungal flora of dogs was carried out over a calendar year. The objective was to establish a normal pattern, in order to assess the significance of the finding of dematiaceous species, in particular Alternaria. Alternaria has been implicated as a cause of dermatitis in humans and possibly in dogs as well. It was found that Cladosporium was a normal component of the flora, Alternaria was found less often. Non-sporulating hyphomycetes were usually the dominant component.

Utilization of standard laboratory methods in the laboratory diagnosis of problem dermatophytes.

The identification of certain dermatophytes may be simplified by using biochemical tests such as urease, nutritional requirements (with commercially available media), and the in-vitro hair penetration test. No study that combines these tests in a diagnostic scheme for identification of the common dermatophytes has been published. one to 20 isolates each of 29 species of dermatophytes (one Epidermophyton floccosum, 10 Microsporum species, and 18 Trichophyton species) were used. They were grown on Christensen's urea agar and the seven nutritional media for the differentiation of the Trichophyton species; the in-vitro hair penetration test was performed in duplicate. Patterns were developed that have been tested and proven to be useful for more than 22 months. In addition, the Microsporum species were all grown on polished rice, and color and sporulation were recorded. All dermatophytes in this study were grown on either Mycosel agar or 2% malt extract agar, and on modified potato dextrose agar and modified Sabouraud agar. Macroscopic and microscopic examinations were made to determine qualitatively the amounts of growth and sporulation on each medium.

Serological differences among the dermatophytes.

Antigens were prepared from young mycelial growth of 20 species of dermatophytes, and tested by double diffusion against homologous and heterologous antisera raised in rabbits. 48 distinct antigens were recognised by the procedures used. Although there were a considerable number of common reactions, there were significant differences between species and groups. Species of Microsporum, with the exception of M. gypseum and M. persicolor, form a coherent group distinct from Epidermophyton and Trichophyton. All Trichophyton species investigated with the exception of T. ajelloi, were serologically closely related. M. gypseum, T. ajelloi and M. persicolor showed affinities with both Microsporum and Trichophyton, and possibly form an intermediate group. The system used does not permit differentiation of species by serological means, but gives a new dimension to the inter-relationships of these fungi.

Geographical distribution of the dermatophytes: a review.

In these days of rapid transit from continent to continent, and the increasing mobility of people, agents of disease are no longer geographically restricted. Disease contracted half way across the world may become manifest in a country in which the pathogen is not normally found. Thus knowledge of the geographical distribution of pathogens becomes increasingly important when a diagnosis is being made. This is as true of ringworm fungi as of any other group of microorganisms. In the last 12 years, in the Mycological Reference Laboratory, an increasing number of exotic dermatophytes have been seen, related in part at least to the great increase in the number of non-British residents. Not all species of dermatophytes are cosmopolitan in their distribution throughout the world. While some have been recorded from every continent, others have geographically limited areas of greater or lesser extent. Surveys taken at intervals in a country may show a rise and fall in occurrence of several species as habits change, populations move and medical facilities became increasingly well-distributed. There have been few geographical surveys of ringworm fungi that have covered the world. Ajello (1960, 1974) has reviewed the individual species with regard to geographical location, while Vanbreuseghem & de Vroey (1970) attempted to estimate the relative importance of the various species in terms of numbers of isolations reported. This paper therefore reviews the world dermatophyte flora in terms of the dominant agents in the various countries, and some of the changes that have been recorded.

The use of nutritional tests for the differentiation of dermatophytes.

One hundred and forty-seven isolates distributed among 22 species of dermatophytes were tested for ability to assimilate 23 carbon sources and 4 nitrogen sources, and to hydrolyse casein, tyrosine, gelatine, starch and urea. Differences were found among species in the rate of growth on 11 of the carbon sources, 2 of the nitrogen sources and the time taken to hydrolyse urea. Based on these findings, a practical scheme allowing differentiation of the 22 species investigated is presented. Since the differences in assimilation pattern did not correlate with morphological divisions, this scheme may prove useful in situations where conventional morphological techniques fail to provide an adequate identification of an unknown isolate.

Counterimmunoelectrophoresis as a routine mycoserological procedure.

Counterimmunoelectrophoresis (CIE) has been compared in a diangostic laboratory with agar gel double diffusion (DD) as a routine procedure for detection of antibodies to pathogenic and allergenic fungi and actinomycetes. It was shown to be of particular value in detecting antibodies to Aspergillus fumigatus. Thus 72 of 106 sera in which precipitins were detected were positive by CIE alone. Some sera were positive only by CIE to antigens prepared from Histoplasma capsulatum, Allescheria boydii, Candida albicans and C. parapsilosis.