In Vitro Activity of Antifungal Drugs Against Trichophyton rubrum and Trichophyton mentagrophytes spp. by E-Test Method and Non-supplemented Mueller–Hinton Agar Plates

  • Jari IntraEmail author
  • Cecilia Sarto
  • Selene Mazzola
  • Chiara Fania
  • Natalia Tiberti
  • Paolo Brambilla
Original Article


Trichophyton rubrum and Trichophyton mentagrophytes spp. are two of the most frequently isolated dermatophytes causing dermatophytosis worldwide. Since the incidence of resistance to antifungal agents is increasing, antifungal susceptibility tests are needed to successfully treat dermatophytoses. Most of the methods currently available are complicated, time-consuming and lack of reference procedures. The aim of this work was to establish a simple protocol to test the susceptibility of dermatophytes isolated from clinical samples against five antifungal drugs using E-test and disk diffusion methods. We used the E-test on non-supplemented Mueller–Hinton agar plates to determine the minimum inhibitory concentrations (MICs) of fluconazole, itraconazole, voriconazole and amphotericin B, and disk diffusion method to determine the interpretive MIC of terbinafine. Fifty dermatophytes—10 T. rubrum and 40 T. mentagrophytes spp.—were assessed after only 96 h of colony growth. Terbinafine was the most active antifungal agent with an inhibition diameter greater than 70 mm (sensitivity > 20 mm), followed by voriconazole, itraconazole and amphotericin B with MICs ranging from 0.032 to 0.38 µg/mL, from 0.006 to 0.125 µg/mL and from 0.5 to 1.5 µg/mL, respectively. All isolates were resistant to fluconazole. Collectively, the less laborious E-test and disk diffusion method were shown to be suitable and reliable to determine antifungal sensitivity of dermatophytes. This simple standard protocol could be employed in the routine of clinical laboratories.


Dermatophytosis Antifungal susceptibility Antifungal resistance Fluconazole Terbinafine 



We gratefully acknowledge Laura Colombo, Marco Santambrogio and Silvio Caimi from Desio Hospital for technical support. We also thank Dr. Elena Intra for reviewing the manuscript.

Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Department of Laboratory Medicine, Azienda Socio Sanitaria Territoriale di Monza ASST-Monza, Desio HospitalUniversity of Milano-BicoccaDesioItaly
  2. 2.Department of Infectious, Tropical Diseases and MicrobiologyIRCCS Sacro Cuore – Don Calabria HospitalNegrarItaly

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