Efficiency of four currently used decontamination conditionings in Romania against Aspergillus and Candida strains

Summary Introduction Efficacy of four commercial biocidal products (noted A to D), using manufacturers’ recommendations, and a contact time of 30 minutes, were evaluated in the purpose of standard SR EN1657: 2006 adapted. Methods Were used four strains, two as reference: Aspergillus brasiliensis ( niger ) (ATCC 16404) and Candida albicans (ATCC 10231), and two isolates: Aspergillus flavus and respectively Aspergillus fumigatus . The inoculum plates containing Malt Extract Agar (MEA) were incubated 48 h for C .  albicans and 72 hours for Aspergillus spp. The standard SR EN1657: 2006 adapted was conducted in two phases: the test cultures preparation and the method validation. Method validation included: the control of experimental conditions and of neutralizant solution, and the method verification. Results Results revealed that three from the four tested products (A, B and D) had exerted biocidal effect on the studied strains at the recommended concentrations, the registered CFU values being reduced by more than 4 log 10 , conversely in the case of the product (C), applied against A .  fumigatus at the recommended concentration of 2%, the biocidal effect was not detected, fact confirmed also by the CFU's value (3.59 log 10 ). The biocide retested at a greater concentration (of 5%), showed a biocidal effect against A .  fumigatus after 30 minutes, the CFU value being reduced, by more than 5.29 log 10 , evidencing the resistance emergence of A .  fumigatus under the repeated pressure of biocides. Conclusion It is re-confirming that merely the “chemical” defense measures to defuse the fungi's strategies become unproductive.