Avian Dermatophytosis Caused by Lophophyton gallinae in Thailand: Emergence in a Broiler Breeder Farm and Surrounding Community, Multilocus Molecular Characterization, and Antifungal Susceptibility.
Dachakul Nirawit N, Jenjirawatn Koramit K, Punperm Purun P, Thamprisarn Rapeewan R et al.
Avian dermatophytosis, caused by the zoophilic dermatophyte Lophophyton gallinae, is a neglected superficial mycosis. This study explored an outbreak across a commercial broiler breeder farm and neighboring backyard poultry flocks in Thailand. A total of 133 samples were collected for dermatophyte culture, comprising suspected chicken samples from broiler breeder farms (n = 89) and three backyard flocks around outbreak farms (n = 29), along with environmental samples from outbreak farms (n = 15). L. gallinae was isolated and morphologically identified from 40 birds, comprising 32/89 broiler breeders (36.0%) and 8/29 backyard poultry samples (27.6%). All environmental samples were negative for dermatophyte culture. To determine their phylogenetic relationships and genetic diversity, 10 representative positive isolates were subjected to single-locus sequence analysis of the internal transcribed spacer (ITS) region and concatenated multilocus sequence analyses of the combined ITS and partial β-tubulin (TUB2) loci. Phylogenetic inference revealed that the L. gallinae clade diverges into two groups associated with avian and nonavian hosts, with all Thai isolates clustering specially within the avian-associated group. Furthermore, in vitro antifungal susceptibility testing of 40 isolates revealed low minimum inhibitory concentration (MIC) values across all tested agents, with MIC ranges of < 0.016-0.125 µg/mL for enilconazole, <0.03-0.25 µg/mL for clotrimazole, 0.03-0.25 µg/mL for itraconazole, and < 0.125-1.00 µg/mL for griseofulvin. Overall, this study represents the first report of a severe L. gallinae outbreak within a commercial poultry farm in Thailand and provides molecular characterization of the L. gallinae clade within the Arthrodermataceae family.