{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T20:26:29Z","timestamp":1775766389922,"version":"3.50.1"},"posted":{"date-parts":[[2025,9,29]]},"group-title":"Microbiology","reference-count":55,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2025,9,29]],"date-time":"2025-09-29T00:00:00Z","timestamp":1759104000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2025,9,25]]},"abstract":"<jats:label>1<\/jats:label>\n                <jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  <jats:italic>Malassezia pachydermatis<\/jats:italic>\n                  is a zoophilic yeast found on the skin and in the outer ear canal of many mammals. It normally maintains a commensal lifestyle but can cause dermatitis and otitis in predisposed hosts, particularly in atopic dogs.\n                  <jats:italic>M. pachydermatis<\/jats:italic>\n                  is genetically diverse, with strains clustering into at least three phylogroups based on molecular typing, a pattern we now confirm through whole-genome sequencing (WGS). Accurate species and strain-level identification is essential for understanding its epidemiology, pathogenic potential, and response to treatment. In this study, we established Fourier Transform Infrared (FTIR) spectroscopy as a rapid, cost-effective method for distinguishing\n                  <jats:italic>M. pachydermatis<\/jats:italic>\n                  from other\n                  <jats:italic>Malassezia<\/jats:italic>\n                  species, including\n                  <jats:italic>M. globosa, M. furfur, M. restricta<\/jats:italic>\n                  , and\n                  <jats:italic>M. sympodialis<\/jats:italic>\n                  . Within\n                  <jats:italic>M. pachydermatis<\/jats:italic>\n                  , FTIR spectroscopy resolved even closely related strains with high accuracy producing clusters congruent with WGS-based phylogeny. The incorporation of an Artificial Neural Network classifier further enhanced the discriminatory power, enabling robust and automated strain assignment. These findings demonstrate the potential of FTIR spectroscopy as a practical tool for large-scale epidemiological surveillance of\n                  <jats:italic>M. pachydermatis<\/jats:italic>\n                  and for clinical and veterinary applications where strain-level identification could inform treatment and management of\n                  <jats:italic>Malassezia<\/jats:italic>\n                  -associated diseases.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>Importance<\/jats:title>\n                  <jats:p>\n                    <jats:italic>Malassezia pachydermatis<\/jats:italic>\n                    is a yeast that commonly inhabits the skin and ear canals of mammals but can cause dermatitis and otitis in predisposed hosts, especially dogs with allergies. This species displays substantial genetic diversity, with strains falling into distinct phylogroups that may differ in their biology and clinical significance. Determining these differences has typically required advanced molecular or genomic methods, which can be costly and time-consuming. In this study, we demonstrate that Fourier transform infrared spectroscopy can rapidly and accurately distinguish\n                    <jats:italic>M. pachydermatis<\/jats:italic>\n                    from other\n                    <jats:italic>Malassezia<\/jats:italic>\n                    species and resolve genetic groups within the species in a way that reflects whole-genome relationships. This capability offers a practical tool for investigating the epidemiology and inter-\/intraspecies diversity of\n                    <jats:italic>M. pachydermatis<\/jats:italic>\n                    and for guiding targeted management of\n                    <jats:italic>Malassezia<\/jats:italic>\n                    -associated diseases in both veterinary and, potentially, human medicine.\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.1101\/2025.09.25.678493","type":"posted-content","created":{"date-parts":[[2025,9,29]],"date-time":"2025-09-29T14:35:21Z","timestamp":1759156521000},"source":"Crossref","is-referenced-by-count":2,"title":["Fourier transform infrared spectroscopy enables rapid species discrimination across\n                  <i>Malassezia<\/i>\n                  and strain-level typing in\n                  <i>M. pachydermatis<\/i>"],"prefix":"10.64898","author":[{"given":"Simon","family":"Kurmann","sequence":"first","affiliation":[]},{"given":"Marco A.","family":"Coelho","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5515-7625","authenticated-orcid":false,"given":"Marcia","family":"David Palma","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3195-8732","authenticated-orcid":false,"given":"Leyna","family":"D\u00edaz","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8404-0688","authenticated-orcid":false,"given":"Gemma","family":"Castell\u00e1","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2244-5778","authenticated-orcid":false,"given":"F. 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