Background: Numerous reports of resistance to terbinafine in Trichophyton spp. from all over the world are arousing justified attention and concern. Point mutations in the gene that encodes the squalene epoxidase (SQLE) enzyme are responsible for these therapeutic resistances. Objectives: Primary objective of the study was to describe first isolates of Trichophyton spp. resistant to terbinafine among the patients treated between September 2019 and June 2022 at the Dermatology Units of Ospedale Maggiore Policlinico and San Bortolo Hospital. Secondary objective was to study the resistance mechanism. Methods: Patients with confirmed Trichophyton spp. infection has been treated with systemic and topical terbinafine. Patients were then re-evaluated 12 weeks after the therapy. Patients with incomplete or absent response to terbinafine underwent a new skin scraping for direct mycological examination, new identification of dermatophyte species from culture and MALDI-TOF, molecular species identification, antifungal susceptibility testing and molecular analysis of SQLE gene. Results: We identified five patients without clinical response to treatment with terbinafine. The DNA sequencing of the ITS region identified one Trichophyton rubrum and four Trichophyton indotineae. The T. rubrum strain showed minimum inhibitory concentration (MIC) (90% growth inhibition) of 4 mg/L for terbinafine. The four T. indotineae strains showed a MICs range of 0.25-4 mg/L for terbinafine. The analysis of the SQLE gene in the T. rubrum strain showed a nucleotide substitution generating a missense mutation (L393F). The SQLE gene sequencing in the T. indotineae strains showed a nucleotide substitution generating a missense mutation (F397L) in two strains, a nucleotide substitution L393S in one strain and a nucleotide substitution F415C in another strain. Conclusions: We report the first cases of terbinafine-resistant Trichophyton isolates in the Italian population. Solid antifungal management programs will be needed to promote more responsible use of antimycotics and preserve their therapeutic efficacy to control antifungal resistance.

Report of terbinafine resistant Trichophyton spp. in Italy: Clinical presentations, molecular identification, antifungal susceptibility testing and mutations in the squalene epoxidase gene / P. Bortoluzzi, A. Prigitano, A. Sechi, V. Boneschi, F. Germiniasi, M.C. Esposto, L. Romano', G. Pavan, C. Matinato, S. Veraldi, A.V. Marzano, A. Grancini. - In: MYCOSES. - ISSN 0933-7407. - (2023). [Epub ahead of print] [10.1111/myc.13597]

Report of terbinafine resistant Trichophyton spp. in Italy: Clinical presentations, molecular identification, antifungal susceptibility testing and mutations in the squalene epoxidase gene

A. Prigitano
Secondo
;
M.C. Esposto;L. Romano';S. Veraldi;A.V. Marzano
Penultimo
;
2023

Abstract

Background: Numerous reports of resistance to terbinafine in Trichophyton spp. from all over the world are arousing justified attention and concern. Point mutations in the gene that encodes the squalene epoxidase (SQLE) enzyme are responsible for these therapeutic resistances. Objectives: Primary objective of the study was to describe first isolates of Trichophyton spp. resistant to terbinafine among the patients treated between September 2019 and June 2022 at the Dermatology Units of Ospedale Maggiore Policlinico and San Bortolo Hospital. Secondary objective was to study the resistance mechanism. Methods: Patients with confirmed Trichophyton spp. infection has been treated with systemic and topical terbinafine. Patients were then re-evaluated 12 weeks after the therapy. Patients with incomplete or absent response to terbinafine underwent a new skin scraping for direct mycological examination, new identification of dermatophyte species from culture and MALDI-TOF, molecular species identification, antifungal susceptibility testing and molecular analysis of SQLE gene. Results: We identified five patients without clinical response to treatment with terbinafine. The DNA sequencing of the ITS region identified one Trichophyton rubrum and four Trichophyton indotineae. The T. rubrum strain showed minimum inhibitory concentration (MIC) (90% growth inhibition) of 4 mg/L for terbinafine. The four T. indotineae strains showed a MICs range of 0.25-4 mg/L for terbinafine. The analysis of the SQLE gene in the T. rubrum strain showed a nucleotide substitution generating a missense mutation (L393F). The SQLE gene sequencing in the T. indotineae strains showed a nucleotide substitution generating a missense mutation (F397L) in two strains, a nucleotide substitution L393S in one strain and a nucleotide substitution F415C in another strain. Conclusions: We report the first cases of terbinafine-resistant Trichophyton isolates in the Italian population. Solid antifungal management programs will be needed to promote more responsible use of antimycotics and preserve their therapeutic efficacy to control antifungal resistance.
Trichophyton; dermatophytes; mycology; resistance; terbinafine
Settore MED/42 - Igiene Generale e Applicata
Settore MED/35 - Malattie Cutanee e Veneree
2023
4-mag-2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/968401
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