Factors influencing the rate of killing of Escherichia coli exposed to benzalkonium chloride.

The killing of bacterial cells by chemical agents may be considered as the resultant of a reaction between two systems, the cells and their suspending medium and the germicide and its solvent. The method for testing sanitizing agents proposed by Weber and Black (1948) allows evaluation, on the basis of the two systems, of factors such as ions present in the suspending or diluting medium, organic matter, time, temperature and the bacterial cell itself, that may influence the killing of the test organism. This method, therefore, was used in the experiments here reported.