The influence of plasma on the disinfecting activity of the new antimicrobial agent N-chlorotaurine-sodium in comparison with chloramine T

The phenomenon of increasing bactericidal activity of N-chlorotaurine in th e presence of chlorine-consuming material has been investigated both on a c hemical-analytical and microbiological basis using plasma as substrate and chloramine T for comparison. Chlorine consumption assessed by iodometric ti tration showed a biphasic time-course with a very fast loss of oxidation ca pacity within one minute (N-chlorotaurine: - 9.3 %, chloramine T: -16.8 %) followed by a slow loss which could still be detected after 24 h (total los s -61.7 % and -74.1 %, respectively). Killing curves revealed that an incre ase in bactericidal activity, in spite of improved consumption, did not occ ur with all strains, and could be detected only at a certain degree of cons umption. Escherichia coli and Pseudomonas aeruginosa showed the most pronou nced effect, Streptococcus pyogenes and Proteus mirabilis a medium-sized on e, while it was absent in Staphylococcus aureus. With chloramine T, an incr ease in bactericidal activity could not be proved. The chemical basis of th ese consumption effects can be reduced to four reaction types: oxidation of thiols; chlorine substitution of activated C-H compounds; transhalogenatio n; and hydrolytic degradation of N-chioro-alpha -amino acids and -peptides emerging by transhalogenation. The initial fast loss of oxidation capacity can be attributed mainly to oxidation of thiols, while the subsequent slowe r decrease is caused by the other types of reaction. The increase in bacter icidal activity, on the other hand, can be explained by transhalogenation, leading to the formation of more bactericidal N-chloro compounds by which t he loss of N-chlorotaurine is over-compensated.