Efficacy of four commercial biocidal products (noted A to D), using manufacturers’ recommendations, and a contact time of 30minutes, were evaluated in the purpose of standard SR EN1657: 2006 adapted.
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 48h for C. albicans and 72hours 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 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 log10, 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 log10). The biocide retested at a greater concentration (of 5%), showed a biocidal effect against A. fumigatus after 30minutes, the CFU value being reduced, by more than 5.29 log10, evidencing the resistance emergence of A. fumigatus under the repeated pressure of biocides.
It is re-confirming that merely the “chemical” defense measures to defuse the fungi's strategies become unproductive.Le texte complet de cet article est disponible en PDF.
Keywords : Aspergillus, Candida, Biocides, Efficacy, SR EN1657: 2006 adapted