Background: The NCCLS M38-A standard for the susceptibility testing of conidium-forming filamentous fungi does not explicitly address special problems of dermatophytes such as conidium formation. Methods: This multicenter study investigated the minimum inhibitory concentration (MIC) reproducibility of seven antifungal agents tested against of 300 dermatophyte isolates (5 blinded pairs of five dermatophyte species per site) in six laboratories, using the method of dermatophyte testing developed at the Center for Medical Mycology, Cleveland, OH. The dermatophytes tested included Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Epidermophyton floccosum, and Microsporum canis. Seven antifungals with activity against dermatophytes were tested, including ciclopirox, fluconazole, griseofulvin, itraconazole, posaconazole, terbinafine, and voriconazole. Results: Interlaboratory MIC values for all isolates were in 92-100% agreement at the 50% inhibition endpoint, as compared to growth control, and 88-99% agreement at the 80% inhibition endpoint. Intralaboratory MICs between blinded pairs were in 97% agreement at the 50% inhibition endpoint, and 96% at the 80% inhibition endpoint. Conclusion: Data from this study supports consideration of this method as an amendment to the NCCLS M38-A standard for the testing of dermatophytes.
Full conference title:
43rd Interscience Conference on Antimicrobial Agents
- ICAAC 43rd