To date, limited published data exists regarding the efficacy of commonly used disinfectants in inactivating the Risk Group 3 dimorphic fungal pathogens, Coccidioides immitis and Coccidioides posadasii. Newer generation quaternary ammonium compounds, like Virex® II 256 and Virex® Tb, have not been previously evaluated. Herein, these disinfectants are evaluated against 10% bleach and 70% ethanol, for their ability to inactivate 5×107 arthroconidial spores of C. immitis RS or C. posadasii strain Silveira within 2, 5, 10 or 20 minutes contact time in aqueous solution. Evidence is provided that both Virex® II 256 and Virex® Tb are highly effective alternatives to 10% bleach or 70% ethanol for the disinfection of 5×107 arthroconidia of Coccidioides spp. within 2 minutes of contact time. 70% ethanol was seen as less effective in killing C.immitis RS arthroconidia and both 70% ethanol and 10% bleach were seen as less effective than the other disinfectants in killing C. posadasii strain Silveira, as longer contact times were required to completely inactivate the same number of arthroconidia.
Keywords: BSL-3; Coccidioides spp.; Virex® II 256; Virex® Tb; dimorphic fungal pathogens; disinfectant.