Effect of ethylenediaminetetraacetic acid and related chelating agents on whole cells of gram-negative bacteria.

The effects of ethylenediaminetetraacetic acid and of four other chelating agents on seven strains of gram-negative bacteria are described. Changes in viability, cell lysis, and release of intracellular materials from suspensions in various buffers, pH 7.8 or 9.2, were observed. Cyclohexane-1,2-diaminotetraacetic acid was the most toxic compound, whereas iminodiacetic acid and nitrilotriacetic acid had little bactericidal activity. The activity of the five drugs appeared to be related to their chelating ability. Of the bacterial strains used, Pseudomonas aeruginosa NCTC 1999 and NCTC 6750 were the most susceptible, and Klebsiella aerogenes K1 was the most resistant. In contrast, the two strains of P. aeruginosa were the most resistant to the nonchelating antibacterial agents cetrimide, chlorhexidine, and benzalkonium chloride.