Evaluation of Virex® II 256 and Virex® Tb as Disinfectants of the Dimorphic Fungi Coccidioides immitis and Coccidioides posadasii

Natalie M. Mitchell, Dewey Magee, Thomas E. Grys, Douglas Lake

Research output: Contribution to journalArticle


Introduction: 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. Methods: 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. Results: 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. Discussion: Both 70% ethanol and 10% bleach were seen as less effective than the other disinfectants, requiring a longer contact time to completely inactivate the same number of arthroconidia. Conclusion: A contact time of > 2minutes is adequate for the disinfection of 5 × 107 Coccidioides spp. arthroconidia when using either the Virex® II 256 and Virex® Tb formulations.

Original languageEnglish (US)
JournalApplied Biosafety
StateAccepted/In press - Jan 1 2018



  • BSL-3
  • Coccidioidesspp
  • dimorphic fungal pathogens
  • disinfectant
  • Virex II 256
  • Virex Tb

ASJC Scopus subject areas

  • Biotechnology
  • Public Health, Environmental and Occupational Health
  • Management, Monitoring, Policy and Law
  • Health, Toxicology and Mutagenesis

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