Guidelines for the Management of Onychomycosis 2014
Guidelines for the Management of Onychomycosis 2014
Oral antifungal therapy with agents such as terbinafine and itraconazole is the treatment of choice for onychomycosis and dermatophytosis that does not respond to topical therapies. The activity spectrum of these drugs is variable, leading to treatment failure in 25–40% of treated patients, possibly due to poor patient compliance, lack of drug penetration into the nail, medication bioavailability, or drug interactions and resistance.
The European Committee on Antimicrobial Susceptibility Testing has described a reference broth microdilution method for testing Candida susceptibility, and the Clinical and Laboratory Standards Institute has developed the M38-A technique for testing filamentous moulds; however, dermatophytes have not been included in this method. Little research has focused on the drug resistance of dermatophytes and nondermatophytic species. Importantly, the in vitro activity of antifungal medications has not been shown to be a predictor of clinical outcomes. In an illustrative study, terbinafine and voriconazole were the most potent agents against dermatophytes. Itraconazole and voriconazole were the most active agents against yeast species.
Importantly, these studies cannot be used for clinical guidelines, and the MIC values obtained must be tested in a well-designed clinical study. Such future work is necessary to assist clinicians in choosing the best therapeutic option.
Mycological Resistance
Oral antifungal therapy with agents such as terbinafine and itraconazole is the treatment of choice for onychomycosis and dermatophytosis that does not respond to topical therapies. The activity spectrum of these drugs is variable, leading to treatment failure in 25–40% of treated patients, possibly due to poor patient compliance, lack of drug penetration into the nail, medication bioavailability, or drug interactions and resistance.
The European Committee on Antimicrobial Susceptibility Testing has described a reference broth microdilution method for testing Candida susceptibility, and the Clinical and Laboratory Standards Institute has developed the M38-A technique for testing filamentous moulds; however, dermatophytes have not been included in this method. Little research has focused on the drug resistance of dermatophytes and nondermatophytic species. Importantly, the in vitro activity of antifungal medications has not been shown to be a predictor of clinical outcomes. In an illustrative study, terbinafine and voriconazole were the most potent agents against dermatophytes. Itraconazole and voriconazole were the most active agents against yeast species.
Importantly, these studies cannot be used for clinical guidelines, and the MIC values obtained must be tested in a well-designed clinical study. Such future work is necessary to assist clinicians in choosing the best therapeutic option.
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