Comparison of the sporocidal effects of two different disinfectants i a model experiment with pathogenic and nonpathogenic clostridial spore as well as with Bacillus cereus
Stockinger, H.; Böhm, R.; Strauch, D.
Zentralblatt für Hygiene und Umweltmedizin 188(1-2): 166-178
1989
ISSN/ISBN: 0934-8859 PMID: 2502997 Document Number: 340221
Official methods concerning the examination of sporocidal effects of disinfectants are presently lacking in the Federal Republic of Germany. Spore resistance of selected clostridial species towards formaldehyde and peracetic acid was examined by suspension tests and germ-carrier tests in comparison to spores of Bacillus cereus. Formaldehyde in concentrations between 5% and 20% as well as peracetic acid in concentrations between .004% and .125% were tested. Spore concentration of 10(6) spores/ml in the suspension-tests and 10(4) spores/ml in the germ-carrier tests with wooden germ-carriers were used. Against formaldehyde spores of Cl. septicum had the lowest resistance in the suspension tests followed by Cl. difficile, Cl. tertium, Cl. bifermentans and Cl. perfringens. Cl. sporogenes strain NCTC 532 had the most resistant spores. Concerning peracetic acid the situation was nearly the same. The resistance of all spores of pathogenic species under investigation towards chemical disinfectants was covered by those of Cl. sporogenes NCTC 532 treated with isopropanol. Isopropanol treated spores of B. cereus offer an alternative solution for practical disinfectant testing because spore production as well as growth of clostridia entail great expense. In order to cover the resistance of spores of Cl. perfringens A, the most resistant pathogenic clostridial species tested here, increased spore concentrations of B. cereus would be necessary.