Inactivation of Legionella pneumophila by hypochlorite and an organic chloramine

Abstract

The susceptibility of a strain of Legionella pneumophila to disinfection by an organic halamine, free chlorine, and a mixture of the organic halamine and free chlorine was assessed. The organic halamine was found to have superior stability in solution and to exhibit adequate disinfectant potential over a period of 1 month of repeated reinoculations of fresh bacteria. The combined halamine exhibited great potential for use in maintaining closed-cycle cooling water systems free of L. pneumophila.

Effects of Biocidal Treatments to Inhibit the Growth of Legionellae and Other Microorganisms in Cooling Towers

“…Cooling towers have often been implicated as a source for the production of aerosol containing viable legionellae (3). The efficiency of biocidal treatments by chemicals (2,4,(6)(7)(8) and ultraviolet irradiation (10) is known in preventing the growth of legionellae in laboratory studies. To estimate the effects of these treatments, we surveyed microorganisms in coolingtower water during tower operation in summer.…”

Effect of organic N-halamines on selected membrane functions in intact Staphylococcus aureus cells

“…Most of the work conducted has involved the assessment of biocidal activity of the compounds rather than investigations of the possible mode of action of these compounds. It has been shown that the halamine disinfectants discussed have a wide range of biocidal activities based on the compound, pH, water quality (high halogen demand versus demand free), temperature, and test organism (15,19,(23)(24)(25)(26)(27).…”

Is free halogen necessary for disinfection?

“…The structural feature responsible for the stability of these new N-halamines is the presence of the two methyl groups bonded to the rings adjacent to each nitrogen-halogen bond. The structural formulas for these compounds are shown in reference 10. The efficacies of disinfection for these compounds have been determined for a variety of microorganisms in water at variable pH, temperature, and water quality (9)(10)(11)13). In general the N-chloramine compounds 1 and A tend to require significantly longer contact times at a given total chlorine concentration than does free chlorine to provide sterile water.…”