[Comparative study of four national disinfectant testing techniques (author's transl)].

Four methods for the evaluation of the bactericidal property of disinfectants have been compared. These methods are (1) the qualitative suspension test of the directives for the testing of disinfectants of the German Society for Hygiene and Microbiology, (2) the quantitative suspension test of the dutch committee on phytopharmacy, (3) the carrier or use-dilution method of the A.O.A.C. and (4) the KELSEY and SYKES' capacity test. Aim of this study has been the evaluation of (1) the repeatability and reproducibility of the test results of the four methods, and of (2) the agreement of the degree of efficiency as determined by the different techniques. At least three dilutions of the three disinfectant standards (a phenolic, an aldehyde solution and an iodophore) have been tested against Staphylococcus aureus and Pseudomonas aeruginoas. In this article the authors describe the methods used and the specific difficulties of these techniques. In the suspension technique of the DGHM, the use of only one subculture is stated as not sufficient for exact evaluation of the extinction. In the dutch suspension test, the use of pour plates leads to troubles. The preparative incubation time of the use-dilution method of the A.O.A.C. has been experienced as too long. The structure of the KELSEY and SYKES' test is complicated. Also the results by the two research-teams, are reported and summarized. It has been found that the transition from active to inactive dilution is most marked in the two suspension tests, whereas the distinction between the results of the use-dilution method of the A.O.A.C. is not so clear.