<i>Ex vivo</i> biofilm-forming ability of dermatophytes using dog and cat hair: an ethically viable approach for an infection model

The aim of this study was to establish an <i>ex vivo</i> model for dermatophyte biofilm growth, using hair from dogs and cats. Strains of <i>Microsporum canis</i>, <i>M. gypseum</i>, <i>Trichophyton mentagrophytes</i> and <i>T. tonsurans</i> were assessed for <i>in vitro</i> and <i>ex vivo</i> biofilm production. All <i>T</i>. <i>mentagrophytes</i> and <i>T</i>. <i>tonsurans</i> isolates and 8/12 <i>M</i>. <i>canis</i> and 1/7 <i>M</i>. <i>gypseum</i> isolates formed biofilms <i>in vitro</i>, while all tested isolates presented biofilm growth on <i>ex vivo</i> models. <i>T. mentagrophytes</i> and <i>M. canis</i> formed more homogeneous and better-structured biofilms with greater biomass production on cat hair but <i>T. tonsurans</i> formed more biofilm on dog hair. Confocal and scanning electron microscopy demonstrated fungal hyphae colonizing and perforating the hair shaft, abundant fungal conidia, biofilm extracellular matrix and biofilm water channels. The present study demonstrated an <i>ex vivo</i> model for the performance of studies on biofilm formation by dermatophytes, using dog and cat hair.