RT Journal Article T1 Prevalence and genetic diversity of azole-resistant Malassezia pachydermatis isolates from canine otitis and dermatitis: a two year study A1 Álvarez Pérez, Sergio A1 Quevedo Caraballo, Sergio A1 García Sánchez, Marta Eulalia A1 Blanco Cancelo, José Luis AB Despite previous reports on the emergence of Malassezia pach y dermatis strains with decreased susceptibility to azoles, there is limited information on the actual pre v alence and genetic diversity of azole-resistant isolates of this yeast species. We assessed the prevalence of azole resistance in M. pach y dermatis isolates from cases of dog otitis or skin disease attended in a veterinary teaching hospital during a 2-year period and analyzed the ERG11 (encoding a lanosterol 14- α demethylase, the primary target of azoles) and whole genome sequence diversity of a group of isolates that displa y ed reduced azole susceptibility. Susceptibility testing of 89 M. pach y dermatis isolates from 54 clinical episodes (1-6 isolates/episode) re v ealed lo w minimum inhibitory concentrations (MICs) to most azoles and other antifungals, but 11 isolates from six different episodes (i.e., 12.4% of isolates and 11.1% of episodes) had decreased susceptibility to multiple azoles (fluconazole, itraconazole, ketoconazole, posaconazole, ravuconazole, and/or voriconazole). ER G11 sequencing of these 11 azole-resistant isolates identified eight DNA sequence profiles, most of which contained amino acid substitutions also found in some azole-susceptible isolates. Analysis of whole genome sequencing (WGS) results re v ealed that the az ole-resistant isolates from the same episode of otitis, or e v en dif ferent episodes af fecting the same animal, were more genetically related to each other than to isolates from other dogs. In conclusion, our results confirmed the remarkable ERG11 sequence variability in M. pachydermatis isolates of animal origin observed in previous studies and demonstrated the value of WGS for disentangling the epidemiology of this yeast species. PB Oxford University Press SN 1369-3786 YR 2024 FD 2024 LK https://hdl.handle.net/20.500.14352/122562 UL https://hdl.handle.net/20.500.14352/122562 LA eng NO Álvarez-Pérez, S., Quevedo-Caraballo, S., García, M. E., & Blanco, J. L. (2024). Prevalence and genetic diversity of azole-resistant Malassezia pachydermatis isolates from canine otitis and dermatitis: A 2-year study. Medical mycology, 62(5), myae053. https://doi.org/10.1093/mmy/myae053 NO Author contributions: Sergio Álvarez-Pérez (Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Supervision, Writing – original draft, Writing – review & editing), Sergio QuevedoCaraballo (Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review & editing), Marta E. García (Conceptualization, Investigation, Methodology, Resources, Writing – review & editing), and José L. Blanco (Conceptualization, Investigation, Methodology, Resources, Writing – original draft, Writing – review & editing) NO Ministerio de Ciencia, Innovación y Universidades ( España) NO European Commission DS Docta Complutense RD 25 dic 2025