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Superior bactericidal activity of N-bromine compounds compared to their N-chlorine analogues can be reversed under protein load

Authors

  • W. Gottardi,

    1. Division of Hygiene and Medical Microbiology, Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Innsbruck, Austria
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  • S. Klotz,

    1. Division of Hygiene and Medical Microbiology, Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Innsbruck, Austria
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  • M. Nagl

    Corresponding author
    1. Division of Hygiene and Medical Microbiology, Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Innsbruck, Austria
    • Correspondence

      Markus Nagl, Division of Hygiene and Medical Microbiology, Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Schöpfstr. 41, 1st floor, Innsbruck A-6020, Austria.

      E-mail: m.nagl@i-med.ac.at

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Abstract

Aims

To investigate and compare the bactericidal activity (BA) of active bromine and chlorine compounds in the absence and presence of protein load.

Methods and Results

Quantitative killing tests against Escherichia coli and Staphylococcus aureus were performed both in the absence and in the presence of peptone with pairs of isosteric active chlorine and bromine compounds: hypochlorous and hypobromous acid (HOCl and HOBr), dichloro- and dibromoisocyanuric acid, chlorantine and bromantine (1,3-dibromo- and 1,3 dichloro-5,5-dimethylhydantoine), chloramine T and bromamine T (N-chloro- and N-bromo-4-methylbenzenesulphonamide sodium), and N-chloro- and N-bromotaurine sodium. To classify the bactericidal activities on a quantitative basis, an empirical coefficient named specific bactericidal activity (SBA), founded on the parameters of killing curves, was defined:

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In the absence of peptone, tests with washed micro-organisms revealed a throughout higher BA of bromine compounds with only slight differences between single substances. This was in contrast to chlorine compounds, whose killing times differed by a factor of more than four decimal powers. As a consequence, also the isosteric pairs showed according differences. In the presence of peptone, however, bromine compounds showed an increased loss of BA, which partly caused a reversal of efficacy within isosteric pairs.

Conclusions

In medical practice, weakly oxidizing active chlorine compounds like chloramines have the highest potential as topical anti-infectives in the presence of proteinaceous material (mucous membranes, open wounds). Active bromine compounds, on the other hand, have their chance at insensitive body regions with low organic matter, for example skin surfaces.

Significance and Impact of the Study

The expected protein load is one of the most important parameters for selection of a suited active halogen compound.

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