In vitro antifungal susceptibility of Trichophyton interdigitale isolated from tinea patients

Saham Ansari, Mohammad T. Hedayati, Mojtaba Taghizadeh, Haleh Rafati, Henrich van der Lee, A.J.M.M. Rijs, Paul E. Verweij, Seyedmojtaba (Amir) Seyedmousavi


Background: Trichophyton interdigitale is an anthropophilicthe dermatophyte that mainly cause superficial fungal infections in humans. Although it has considerable medical importance, its antifungal susceptibility profile remains poorly examined.

Material/methods: In this study, we tested the in vitro antifungal susceptibility of a set of clinical T. iterdigitale isolates obtained from 66 tinea patients worldwide, using the CLSI (Clinical and Laboratory Standards Institute) broth microdilution method. All isolates were phylogenetically identified at the species level by using sequences of the ribosomal DNA internal transcribed spacer (rDNA ITS).

Results: The geometric mean minimum inhibitry concentrations (MICs) for itraconazole (ITC), voriconazole (VRC), posaconazole (POS), miconazole(MCO), ketoconazole (KTZ), terbinafine (TRB) and griseofulvin (GEZ) and minimum effective concentrations (MEC) for caspofungin (CAS) across all isolates were as follows, in increasing order: TRB 0.06 mg/L, POS 0.11 mg/L, ITC 0.18 mg/L, VRC 0.22 mg/L, CAS 0.46 mg/L, KTZ 0.98 mg/L, GRZ 0.96 mg/L and MCO 1.10 mg/L. The MIC ranges across all islates were as follows: TRB 0.016–0.32 mg/L, POS 0.016–0.5 mg/L, ITC 0.032–0.5 mg/L, VRC 0.032-0.5 mg/L, CAS 0.063-1 mg/L, KTZ 0.032-4 mg/L, GRZ 0.125-4 mg/L and MCO 0.125-4 mg/L. No statistically significant differences in the susceptibility profiles of T. interdigitale were detected within the geographical regions tested.

Conclusions: Terbinafine, posaconazole and itraconazole were shown to be the most potent antifungal agents against T. interdigitale isolates obtained from tinea capitis patients worldwide. These results suggests that antifungl susceptibility testing could help clinicians to select appropriate antifungal therapies that have a high probability of successfully treating dermatophytsis due to T. interdigitale.



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26th European Congress of Clinical Microbiology and Infectious Diseases