English Abstract In this report experience is descrived with a
quantitative carrier test or QCT for the evaluation of surface
disinfectants, that has been developed in our laboratory. the results
confirm that with normal use ditlutions the threshold microbicidal effect
(M.E.) value of 5 decimals reduction (D.R.), that is requested for the
European Suspension Test (EST), is often not reacht`ed in the QCT. for the
latter a minimum required reduction of 3 D.R., as proposed earlier (van
Klingeren, 1983) is apparently more reasonable. As in the EST Treptococcus
faecium was found to be more resistant tot disinfectants than S.aureaus.
Agains yeast (Candida albicans and Saccharomyces cerevisiae) the proposed
minimum required reduction of 3 D.R. within 15 minutes is usually attained.
In experiments using relatively low concentrations of a quaternary ammonium
compound and a phenolic product the microbicidal effect was not or hardly
found to increase at prolonged exposure times. From the studies with
ethanol and propanols it can be concluded that small amounts of 40%
n-propanol, 50% 2-propanol and 60% ethanol (v/v) on surfaces rapidly kill
Gram-positive and Gram-negative bacteria (> 5 D.R. in 2 minutes). Finally
the tuberculocidal effect of Lyorthol, active chlorine and formaldehyde in
the QCT was tested against Mycobacterium terrae as a representative
testorganism showing similar resistance to disinfectants as M.tuberculosis.
We conclude that the experiments described and discussed in this report
confirm that the present Quantitative Carrier Test allow the reproducable
evaluation of the microbicidal activity of disinfectants under circumstances
simulating practical conditions.
