Development of a combined carrier test for a disinfectant efficacy.

Abstract

There is mounting concern on the efficacy of many germicides on the market because officially recognized germicidal tests for various classes of microorganisms vary widely and lack reproducibility and proper quantitation. This project outlines a novel carrier method for simultaneously and quantitatively assessing the efficacy of liquid chemical germicides against a mixture of microorganisms of varying degrees of resistance. In the test, glass cups were contaminated with 10 $\mu$l of a standardized mixture of Staphylococcus aureus, Mycobacterium bovis BCG, Trichophyton mentagrophytes spores, Sabin poliovirus type 1 and Bacillus stearothermophilus spores in 5% fetal bovine serum. The inoculum was dried for 60 min at room temperature (22 $\pm$ 2$\sp\circ$C), covered with 60 $\mu$l of the disinfectant under test or a balanced salt solution for the desired contact time. The carrier was then placed in 2,940 $\mu$l of an eluent and eluates assayed separately for the five microorganisms. The findings demonstrate the feasibility of a novel approach to the testing of chemical germicides. The combined carrier test allows for concurrent evaluation of efficacy claims and demonstrates the resistance patterns of various classes of microorganisms. This method also permits a more reliable means of classifying germicides based on their spectrum of activity. (Abstract shortened by UMI.)