ABSTRACT
The Trichophyton mentagrophytes complex comprises a group of dermatophyte fungi responsible for various dermatological infections. The increasing drug resistance of this species complex, especially terbinafine resistance of Trichophyton indotineae, is a major concern in dermatologist practice. This study provides a comprehensive analysis of T. mentagrophytes complex strains isolated from patients in Hue City, Vietnam, focusing on their phenotypic and genetic characteristics, antifungal susceptibility profiles, and molecular epidemiology. Keratinophilic fungi from dermatophytosis culture samples were identified morphologically and phenotypically, with species and genotypes confirmed by internal transcribed spacer sequencing and phylogenetic analysis. Antifungal susceptibility testing was carried out to evaluate their susceptibility to itraconazole, voriconazole, and terbinafine. The 24% (n = 27/114) of superficial mycoses were phenotypically attributed to T. mentagrophytes complex isolates. Trichophyton interdigitale, mainly genotype II*, was predominant (44.4%), followed by T. mentagrophytes genotype III* (22.2%), T. indotineae (14.8%), T. tonsurans (11.2%), and T. mentagrophytes (7.4%). While all isolates were susceptible to itraconazole and voriconazole, half of T. indotineae isolates exhibited resistance to terbinafine, linked to the Phe397Leu mutation in the SQLE protein. This study highlighted the presence of terbinafine-resistant T. indotineae isolates in Vietnam, emphasizing the need to investigate dermatophyte drug resistance and implement effective measures in clinical practice.
Species diversity within the Trichophyton mentagrophytes complex isolated from dermatophytosis in Hue City, Vietnam, was observed. Terbinafine-resistant T. indotineae isolates were detected for the first time in Vietnam, emphasizing the importance of implementing antifungal susceptibility testing to effectively manage and prevent the spread of resistant isolates.
Subject(s)
Antifungal Agents , Drug Resistance, Fungal , Genotype , Microbial Sensitivity Tests , Phylogeny , Terbinafine , Tinea , Humans , Vietnam , Antifungal Agents/pharmacology , Terbinafine/pharmacology , Tinea/microbiology , Arthrodermataceae/drug effects , Arthrodermataceae/genetics , Arthrodermataceae/classification , Arthrodermataceae/isolation & purification , Male , Sequence Analysis, DNA , Itraconazole/pharmacology , DNA, Ribosomal Spacer/genetics , Female , Middle Aged , DNA, Fungal/genetics , Molecular Epidemiology , Adult , TrichophytonABSTRACT
BACKGROUND: Nannizzia incurvata, a species belonging to the Nannizzia gypsea complex, is considered a neglected pathogen. OBJECTIVE: To detected N. incurvata isolates from dermatophytosis patients in Hue city - Viet Nam, and test the antifungal susceptibility of this species. Moreover, fungal capability to produce hydrolytic enzymes was evaluated. METHODS: Patients' samples were collected and cultured on Sabouraud-chloramphenicol-cycloheximide medium. Dermatophytes isolates were initially macroscopically and microscopically identified. ITS PCR-RFLP and ITS rDNA sequences were performed to determine and confirm species. An ITS Neighbor-Joining phylogenetic tree evaluated the genetic relationship among isolates. Fungal hydrolytic enzymes were examined, including lipase, phospholipase and protease. Antifungal susceptibility testing was carried out by the disk diffusion method. MICs of itraconazole, voriconazole, and terbinafine against these isolates were determined by the broth microdilution method. RESULTS: Twelve isolates of N. gypsea complex were preliminary morphologically identified. PCR-RFLP and ITS-rDNA sequencing identified and confirmed dermatophytes as N. incurvata strains, respectively. An evident polymorphism among isolates was highlighted in the phylogenetic tree. All isolates showed the activity of lipase, phospholipase, and protease production. Overall, all N. incurvata isolates were susceptible to itraconazole, voriconazole, clotrimazole, miconazole, and terbinafine. Few isolates were susceptible to griseofulvin, and none of them were susceptible to fluconazole. CONCLUSIONS: There was a presence of polyclonal N. incurvata isolates in dermatophytosis patients from Hue city, identified by PCR-RLFP and confirmed by ITS sequencing. We confirmed PCR-RLFP as a reliable technique to identify this species. Azole and terbinafine are the optimal choices for N. incurvata treatment except for fluconazole.