Biocide efficacy determination

Crosslinked chloromethylated PS beads were reacted with hydantoin and imidazolidinone derivatives to produce functionalised beads which could be rendered biocidal by reaction with free chlorine or bromine. The biocidal efficacies of the N-chlorinated and, in one case, the N-brominated polymeric beads against Staphylococcus aureus or Escherichia coli 0157 H7 in aqueous suspension were determined. The N-halogenated polymeric beads were effective in aqueous disinfection application, requiring short contact times for inactivation of the two bacteria. The functionalised polymers could be tailored to the application, depending on whether rapid biocidal activity or long-term stability to loss of oxidative halogen was desired. 11 refs. (Pt.III, ibid, p.363-7)... 

The synthesis and biocidal efficacies of two PEG-N-halamine polymers were studied. The N-halamines were classified as dichlorohydantoins and chloroimidazolidin-4-ones, which were attached to a methoxy-PEG terminated amine. A1000 ppm solution of each N-halamine polymer was prepared in water and it was demonstrated that Staphylococcus aureus was inactivated when it was in contact with these polymeric solutions for ten minutes. The stability of these solutions was determined over prolonged periods of time, as well as the biocidal efficacies. These polymeric materials showed commercial potential as surface active biocides if the PEG moiety could be anchored to a srrrface. 22 refs. 

After defined exposure times, the test substrata can be removed from the system and treated with biocide, or they remain in the system and are analysed at the end of the experiment to determine biocide efficacy. Other, new variations of the CSTR can be suitable as test systems. These include the Calgary Biofilm Device, which utilises shaken microtitre plates (Ceri et al., 1999 Ceri et al., 2001), the flow-cell (Stoodley et al., 2001), the artificial biofilm system (Harkonen et al., (1999), the colony biofihn system (Anderl et al., 2000) and the drip flow reactor (Xu et al., 1998). 

Determination of biocide efficacy. As described previously, two basic aspects should be considered concerning the action of biocides ... 

H. von Rege and W. Sand, Evaluation of biocide efficacy by microalorimetric determination of microbial activity in biofilms. J. Microbiol. Methods 33 221-235 (1998). 

There are currently no recommendations or guidelines concerning the standardized cultivation of biofilms methods which give indications of practical efficacy are the most useful. Attempts have been made to unify procedures for determining the efficacy of biocides however, the findings of the available literature are difficult or impossible to compare. In principle, this can be described under several headings with respect to the duration of the investigations ... 

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