Evaluating the Efficacy of Disinfectant Methods against Emydomyces testavorans, a Fungus Associated with Shell Disease in Freshwater Aquatic Turtles

Emydomyces testavorans is an onygenalean fungus associated with shell and skin lesions in chelonians and is increasingly linked to morbidity and mortality. Effective disinfection methods are a critical component of biosecurity protocols to prevent and manage emydomycosis; however, disinfectant efficacy against E. testavorans is unknown. This study determined the in vitro efficacy of 13 disinfectants across a range of concentrations and exposure times used in veterinary, wildlife, and environmental settings against E. testavorans. Pure E. testavorans culture material was exposed to each disinfectant at manufacturer-recommended concentration and exposure times in triplicate. Disinfectant was removed via centrifugation and cultures were inoculated onto inhibitory media plates, maintained at room temperature (20–22 C), and examined weekly for fungal growth. After 6 wk of incubation, ethanol, Virkon S (active ingredient potassium peroxymonosulfate 21.41%), benzalkonium chloride, and desiccation proved ineffective at completely inhibiting fungal growth. All other agents, including bleach, chlorhexidine, and accelerated hydrogen peroxides, effectively inhibited fungal growth. These data suggest that several effective disinfection options are available for use against E. testavorans. These findings can be used in managed care and field settings to reduce transmission of E. testavorans between turtles through contaminated surfaces and equipment.