Microbicidal activity of monochloramine and chloramine T compared
Abstract number: O102
Arnitz R., Nagl M., Gottardi W.
Objectives: Chloramine T (CAT) and monochloramine (NH2Cl) are active chlorine compounds and well-known antiseptics with broad-spectrum microbicidal activity. CAT has stronger oxidative activity than NH2Cl, while the latter one is a smaller molecule and more lipophilic. The question arose if lower oxidative activity can be compensated by higher lipophilicity regarding microbicidal effectiveness.
Methods: Bacterial strains (Escherichia coli ATCC 11229, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853) and clinical isolates of Aspergillus fumigatus, Aspergillus flavus and Candida albicans were used for quantitative killing assays. All microorganisms were tested separately in equimolar solutions of CAT and NH2Cl, respectively. Pathogens treated in buffer without antiseptics served as controls.
Result: NH2Cl showed a markedly stronger bactericidal and fungicidal activity than CAT.
At a concentration of 0.011 mM, NH2Cl killed all test bacteria within 30 min, while 0.011 mM CAT did not cause a reduction in colony forming units after that time. At a concentration of 0.036 mM and 0.107 mM, NH2Cl led to a 34 log10 reduction of E. coli approx. 200 times faster than CAT. The killing of S. aureus and P. aeruginosa by NH2Cl was 46 times faster. NH2Cl (0.355 mM) caused a 3 log10 reduction of C. albicans after 1 min compared to a 2 log10 reduction by the same concentration of CAT after 60 min. Conidia of Aspergillus were even killed approximately 200 times faster by NH2Cl than by CAT.
Conclusion: The enormous difference between both agents can be attributed to the lipophilicity and lower bulk of NH2Cl which by far overcompensate its lower oxidative activity.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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