Differential susceptibility of Candida (Candidozyma) auris clades to surface disinfectants

Candida (Candidozyma) auris is a globally emerging multidrug-resistant fungal pathogen that causes nosocomial outbreaks in healthcare facilities.

To evaluate the susceptibility of different C. auris clade strains (I to V) and C. albicans ATCC 10231 strain to commonly used disinfecting agents and commercially available ready-to-use disinfecting wipes.

Standardized tests (EN 13624:2013 and EN 16615:2015).

Suspension tests under EN 13624:2013 guidelines revealed that the ethanol-based disinfectant at 40% concentration effectively achieved a 4 log₁₀ reduction for all tested Candida strains. Quaternary ammonium compound (QAC)-based disinfectants, however, displayed greater inter-species and inter-clade variations. When tested under the EN 16615:2015 four-field method, the ethanol-based commercial disinfectant wipe did not meet the required criteria (≥4 log₁₀ reduction, <50 cfu transfer) for C. albicans and C. auris under dirty conditions, with the exception of the clade II strain. The QAC-based product showed uniform efficacy across all C. auris strains under dirty conditions, while C. albicans test data did not meet the EN standard requirements. Propanol/QAC-based disinfectant wipes achieved effective inactivation of C. auris strains under clean conditions, but not the C. albicans ATCC strain. Hydrogen peroxide-based wipes failed to reach the necessary reduction factor across all tested Candida strains under dirty conditions.

These results emphasize the variability in the disinfecting efficacy of commercially available products with yeasticidal claim between C. auris clades and C. albicans in practice-like tests. Further research is needed to determine effective disinfection strategies against the various C. auris clades.