Isolation of dermatophytes from house dust on a medium containing gentamicin and flucytosine

Molecular Mechanisms of 5-Fluorocytosine Resistance in Yeasts and Filamentous Fungi

Effective management and treatment of fungal diseases is hampered by poor diagnosis, limited options for antifungal therapy, and the emergence of antifungal drug resistance. An understanding of molecular mechanisms contributing to resistance is essential to optimize the efficacy of currently available antifungals. In this perspective, one of the oldest antifungals, 5-fluorocytosine (5-FC), has been the focus of recent studies applying advanced genomic and transcriptomic techniques to decipher the order of events at the molecular level that lead to resistance. These studies have highlighted the complexity of resistance and provided new insights that are reviewed in the present paper.

Culturing Dermatophytes Rapidly from Each Toe Web by Fingertip

The diagnosis of tinea pedis is usually confirmed by microscopy and culture of skin scrapings. Isolating dermatophytes by fungal culture gives more reliable proof of infection and has the advantage of identifying the causative organisms. Nevertheless, culture examination is complementary to microscopy and is not routinely performed because it is time- and cost-consuming. Herein, we propose a new culturing method, the 'finger-sampling method', for collecting dermatophytes from patients' toe webs using the examiner's fingertip as a sample collection tool. Using this method, four toe webs of a foot can be examined at one time on one culture dish. Every toe web of 50 patients with untreated tinea pedis were examined, and dermatophytes were grown from 83 out of 107 (78%) KOH positive toe webs. The isolation ratio by the finger-sampling method was comparable to that by traditional slant culture of skin scrapings performed by skilled practitioners. Culture results were also positive in 19 out of 53 (36%) diseased but KOH negative toe webs and in 38 (16%) normal toe webs, suggesting the existence of unidentified infection. Additionally, we confirmed the efficacy of this method for detecting dermatophyte attachment on the healthy toe web skin of volunteers who had just been exposed to contaminated areas, i.e. Japanese public baths or a bath mat stepped on by a patient disseminating dermatophyte propagules.

An evaluation of the infection control potential of a UV clinical podiatry unit

BACKGROUND

Infection control is a key issue in podiatry as it is in all forms of clinical practice. Airborne contamination may be particularly important in podiatry due to the generation of particulates during treatment. Consequently, technologies that prevent contamination in podiatry settings may have a useful role. The aims of this investigation were twofold, firstly to determine the ability of a UV cabinet to protect instruments from airborne contamination and secondly to determine its ability to remove microbes from contaminated surfaces and instruments.

METHOD

A UV instrument cabinet was installed in a University podiatry suite. Impact samplers and standard microbiological techniques were used to determine the nature and extent of microbial airborne contamination. Sterile filters were used to determine the ability of the UV cabinet to protect exposed surfaces. Artificially contaminated instruments were used to determine the ability of the cabinet to remove microbial contamination.

RESULTS

Airborne bacterial contamination was dominated by Gram positive cocci including Staphylococcus aureus. Airborne fungal levels were much lower than those observed for bacteria. The UV cabinet significantly reduced (p < 0.05) the observed levels of airborne contamination. When challenged with contaminated instruments the cabinet was able to reduce microbial levels by between 60% to 100% with more complex instruments e.g. clippers, remaining contaminated.

CONCLUSIONS

Bacterial airborne contamination is a potential infection risk in podiatry settings due to the presence of S. aureus. The use of a UV instrument cabinet can reduce the risk of contamination by airborne microbes. The UV cabinet tested was unable to decontaminate instruments and as such could pose an infection risk if misused.

Dermatomycosis and Environment

Environments may act as reservoirs for pathogenic fungi, a determinant of the establishment of fungal infection, or an exacerbating factor of disease. In recent years, skin disease caused by geophilic fungi has been decreasing, while case reports of zoonoses from various animals are increasing. Outbreaks of anthropophilic T. tonsurans infection pose a problem to medical mycologists. Tinea pedis is the most common exogenous dermatomycosis in Japan. Although T. rubrum is presumed to be the dominant pathogen of this disease, T. mentagrophytes is detected more frequently from various environments, so far, the reason for this discrepancy has not been fully understood. The latest knowledge about the route of dermatophyte foot infection is as follows: (1) Dermatophyte propagules disseminated from patients may contaminate not only bath-mats but also wood floors, Japanese style mattings, concrete floors, slippers, cushions, etc., and from them adhere to healthy skin. (2) The agar stamping method can easily detect dermatophytes from the skin and the environment. (3) Propagules of T. mentagrophytes can survive for more than three months under certain conditions such as in rubber boots. (4) In order to eliminate dermatophytes gathered in socks and footwear, simple procedures (washing, bathing with hot water, or wiping with a towel) are all effective. (5) Prior application of an antifungal agent promptly eradicates dermatophyte propagules adhering to the skin from the environment. The author also mentioned the possibility of asymptomatic dermatophyte colonization, and the high prevalence of dysgeucia in oral carriers of Candida albicans.

Ecology of dermatophytes and other keratinophilic fungi in swimming pools and polluted and unpolluted streams

The biodiversity and richness of keratinophilic fungal communities including dermatophytes were assessed in three stream sites and three swimming pools in the Nablus district in Palestine, using hair baiting (HBT) and surface dilution plate (SDP) techniques, over 8- and 6-month periods, respectively. The effect of wastewater effluent and selected ecological factors on these fungi in relation to species diversity and population densities were also considered. Fifty keratinophilic fungal species were recovered from the aquatic habitats studied, of which 42 were recovered from stream sites and 22 from swimming pools. Of these fungi 6 were either dermatophytes (Microsporum gypseum, and Trichophyton mentagrophytes) or dermatophyte related species (Chrysosporium merdarium, Ch. tropicum, Ch. keratinophilum and T. terrestre). The most frequently isolated species in the three pools were Acremonium strictum and Cladosporium cladosporioides, using Sabouraud dextrose agar medium (SDA). The most abundant species were Acr. strictum, and Aspergillus flavus. However, only 4 species were isolated using the SDA medium amended with 5-flurocytosine (5-FC). The most frequent and abundant species in the three stream sites using SDA medium were Geotricum candidum, and Penicillium chrysogenum. The most frequent species in the three sites using the 5-FC medium, was Paecilomyces lilacinus. Using HBT, the most abundant and frequent species in the three stream sites were G. candidum, and Pa. lilacinus, on SDA medium, and Pa. lilacinus, and Gliocladium nigrovirens on the 5-FC medium. The 5-FC medium was more suitable for the isolation of dermatophytes and closely related species than the SDA medium; 6 were recovered on 5-FC, whereas only one on the SDA medium. Variation in the levels of keratinophilic fungal populations from the three stream sites sampled 5 times over an 8-month period, followed comparable fluctuation patterns. Wastewater affected fungal population densities with the highest levels in the un-polluted stream sites, and lowest in the heavily polluted sites. Swimming pools, polluted and un-polluted stream sites were found to be rich in pathogenic and potentially pathogenic fungi.

Keratomycosis due to Trichophyton mentagrophytes

We report the case of an Omani lady who presented with keratitis that grew Trichophyton mentagrophytes on culture media and responded to treatment with topical fluconazole.

Adhesion of dermatophytes to healthy feet and its simple treatment

At several public baths, we isolated dermatophytes from the soles of healthy volunteers by a new direct isolation method (foot-press culture method). We confirmed that a public bath is one of major sources of infection of dermatophytes. We showed that simple treatments such as (i) wiping the sole with a towel; (ii) washing with soap; (iii) 100 steps on another mat; and (iv) holding the foot up for an hour, significantly reduced the fungi on the soles of six healthy volunteers. These treatments may be effective for prevention of tinea pedis.

Demonstration of dermatophyte dissemination from the infected soles using the foot-press method

We have designed a new direct isolation method, the foot-press method, to survey dissemination of dermatophytes from the infected soles. A total of 56 untreated patients with tinea pedis were examined. The infected soles of 42 patients were pressed onto actidione-chloramphenicol-5-fluorocytosine (5FC)-gentamicin sulphate Sabouraud glucose medium prepared in a large culture dish; the culture media were then incubated at 25 degrees C. Dermatophytes were isolated in 30 out of the 42 patients, while no dermatophytes could be grown from 10 healthy controls. The number of isolated colonies from each patient ranged from 1 to 97 (mean +/- SD, 11 +/- 20). The isolation frequencies were higher in the patients of hyperkeratotic type and in those with tinea unguium, while causative organisms and the extent of the lesions did not affect the results of the footpress method significantly. In order to reveal the morphology of disseminated dermatophytes, 1 x 1 cm pieces of culture media were cut out from culture dishes after pressing infected soles and were examined microscopically. Dermatophyte-like spores or hyphae, most of which were detached from cornified cells, could be seen in 10 out of 14 patients. Subsequently performed slide cultures isolated dermatophytes from approximately 70% of the pieces on which dermatophyte-like fungi were observed.