[Microbiological investigations with decentral dosing apparatuses for disinfectants. Part 1: investigations of cell number (author's transl)].

Cell numbers have been investigated for several months in disinfectant solutions which were measured out with tap water by decentral automatically dosing apparatuses. They differed not only quantitatively but also qualitatively with respect to the products used: With one product on the bases of aldehydes + organic tin compound 3 h after samples have been collected up to 100 bacteria/100 ml could be cultivated. Thus, cell numbers in disinfectant solutions were in the same range of cell numbers of tap water. Sometimes the cell numbers in both substrates seem to go parallel (Fig. 1). The bacterial compositions in both were similar (Table 3); gramnegative, yellow bacteria of the genera Pseudomonas and Flavobacterium dominated. After the disinfectant in one apparatus has been substituted by one which is composed of aldehydes + a quaternary ammonium compound cell numbers rapidly and permanently decreased to the limit of detectability. Only coryneform bacteria survived for a longer time which were characterized (Tab. 4) but not determined taxonomically. Their facultatively methylotrophic growth was conspicuously.