Keratitis due to Aspergillus flavus successfully treated with thiabendazole

Susceptibility of Dermatophytes to Thiabendazole Using CLSI Broth Macrodilution

Objective. To evaluate in vitro antifungal activity of thiabendazole against strains of dermatophytes using a reference method for filamentous fungi. Materials and Methods. Dermatophytes' susceptibility to thiabendazole (TBZ) and fluconazole (FCZ) was evaluated using macrodilution method of protocol M38-A2 of the Clinical and Laboratory Standards Institute (CLSI). Results. MIC ranges of TBZ for all strains were narrower and/or smaller than those of FCZ. TBZ showed a significantly greater potency than FCZ (P = 0.05) against all isolates. Discussion. Although there have been approaches to evaluate the antifungal activity of TBZ in human mycoses, no tests had been made with a standardized protocol. Susceptibility data resulted from this study shows that although TBZ is not a particularly strong inhibitor of dermatophytes, it displays a stable and constant effect against all isolates tested. Conclusion. Results show that TBZ is more effective against strains of dermatophytes than FCZ. We acknowledge the antifungal effect of TBZ against dermatophyte isolates.

Identification of antifungal compounds active against Candida albicans using an improved high-throughput Caenorhabditis elegans assay

Candida albicans, the most common human pathogenic fungus, can establish a persistent lethal infection in the intestine of the microscopic nematode Caenorhabditis elegans. The C. elegans–C. albicans infection model was previously adapted to screen for antifungal compounds. Modifications to this screen have been made to facilitate a high-throughput assay including co-inoculation of nematodes with C. albicans and instrumentation allowing precise dispensing of worms into assay wells, eliminating two labor-intensive steps. This high-throughput method was utilized to screen a library of 3,228 compounds represented by 1,948 bioactive compounds and 1,280 small molecules derived via diversity-oriented synthesis. Nineteen compounds were identified that conferred an increase in C. elegans survival, including most known antifungal compounds within the chemical library. In addition to seven clinically used antifungal compounds, twelve compounds were identified which are not primarily used as antifungal agents, including three immunosuppressive drugs. This assay also allowed the assessment of the relative minimal inhibitory concentration, the effective concentration in vivo, and the toxicity of the compound in a single assay.

Mycotic keratitis--an underestimated mycosis

Mycotic keratitis, an important ophthalmologic problem, especially in outdoor workers in the tropics, is frequently caused by filamentous fungi such as species of Fusarium, Aspergillus and Curvularia, and by yeast-like fungi such as Candida. A rapid, presumptive diagnosis can be made by recognition of certain typical clinical features and by direct microscopic detection of fungi in corneal scrapings stained by various methods. The diagnosis is confirmed by culture. In difficult cases, microbiological studies on corneal biopsies or histopathological studies on tissue sections may need to be performed. The use of fluorescein-conjugated lectins and similar diagnostic tools is aimed at providing rapid, species-specific detection of fungi in corneal tissue. Antifungal therapy must be instituted as soon as the diagnosis is made. While keratitis due to Aspergillus, Candida and dematiaceous fungi can be successfully treated by many of the currently available polyenes and azoles, the treatment of Fusarium keratitis still frequently requires the use of pimaricin or econazole. Treatment by the oral and parenteral routes may prove useful in severe mycotic keratitis. Surgery may need to be performed on cases unresponsive to medical therapy or where serious complications are likely to occur. The pathogenesis of mycotic keratitis appears to involve agent factors, such as invasiveness and toxigenicity, and host factors, such as trauma and intrinsic defects in resistance. Areas for future research include the development of rapid, species-specific diagnostic aids, of broad-spectrum antifungal compounds active by various routes, and of therapeutic modalities which act on the fungus and on molecules involved in the pathogenesis of the condition.