[Comparative study between the surface-active substances präwozell NBX (Nekal BX) and Ditalan WO hc for homogenization and decontamination of specimens for the cultivation of mycobacteria (author's transl)].

In cooperation of eight laboratories the new surface-active substance Ditalan WO hc was compared with Präwozell NBX (Nekal BX) used for homogenization and decontamination of the specimens for culture investigations of mycobacteria in routine. Under routine conditions Ditalan showed a slight, but statistically not significant advantage. Out of 1672 specimens pretreated with both detergents 482 cultures were positive in all, 429 (89,0%) after homogenization with Ditalan and 413 (85,7%) after pretreatment with Präwozell. The rate of contamination of the cultures was low in both cases (about 0,5%). Ditalan had a better mucolytic effect than Präwozell. In quantitative investigations the number of positive cultures was equal with both methods, but the number of colonies was somewhat higher and the time of growth was a little shorter after using Ditalan. In the third part the influence of both detergent-reagent-solutions on mycobacteria of different species was compared to that of physiological sodium chloride solution. The rate of growth was decreased by both the detergents in nearly the same degree. But the damaging effect is caused less by the detergent itself than by the sodium hydroxide contained in the solution used for pretreatment of the specimens.