Antifungal susceptibility patterns of dermatophytes clinical isolates from dermatophytosis patients before and after therapy

ABSTRACT

The determination of fungus in vitro antifungal susceptibility has been reported to be important for the ability to eradicate pathogenic dermatophytes. This work aims to assess the in vitro activity of fluconazole, ketoconazole and itraconazole against dermatophytes from dermatophytosis patients before and after oral antifungal therapy with itraconazole. The study was conducted on 80 patients with dermatomycosis attending the Deramtology Outpatient Clinic of Zagazig University Hospitals. The patients were clinically diagnosed and mycologically confirmed as having tinea capitis [42], tinea corporis [18], tinea pedis [12], tinea ungium [5] and tinea cruris [3]. All patients received a course of pulse itraconazole therapy. The clinical specimens were collected from all patients before and after 3 months of itraconazole oral therapy. Identification of dermatophytes to the species level was performed by colony morphology, microscopy and biochemical and physiological tests. All dermatophytes isolates were subjected to antifungal susceptibility testing by E-test method. In this work, the most frequently isolated species was T. rubrum, comprising 25 [31.25%] isolates, followed by T. mentagrophytes [21 isolates, 26.25%], T. violacium [17 isolates, 21.25%], M. canis [7 isolates, 8.75%], T. schoenlinii [6 isolates, 7.5%] and M. audouinii [4 isolates, 5%]. The most active agent against all dermatophytes species was itraconazole with an MIC range of 0.094 - 12 micro g/ml., MIC50 values of 0.125-0.5 micro g/ml and MIC90 values of 0.25-8 micro g/ml., followed by ketoconazole [MIC range of 0.0.64-24 micro g/ml., MIC50 values of 0.38-1 micro g/ml. and MIC90 values of 2-8 micro g/ml]. The least active agent was fluconazole [MIC50 of 64- >/= 256 micro g/ml. and MIC90 of 128- >/= 256 micro g/ml]. MIC values higher than MIC90 were observed for the azole drugs when testing isolates obtained post-treatment from four tinea unguium patients. In conclusion, our data showed that itraconazole was the most active azole against all dermatophytes isolates. Furthermore, the increase in MIC values for azole drugs found for some of our isolates after therapy might raise the possibility of increased antifungal resistance. Further studies on larger samples of dermatophytes are recommended to correlate the MIC values with the clinical outcome for each isolate-drug combination to allow clinician adapting different therapeutic options. In addition, these studies could be beneficial for investigation of development of in vitro resistance in dermatophytes species, and for management of cases clinically unresponsive to treatment