The Antagonism of the Antibacterial Action of Mercury Compounds

Abstract

Qualitative experiments previously reported showed dimercaprol to be the most, and thioglycollate the least, efficient antagonist of mercuric chloride. Quantitative experiments reversed this order, but the greater susceptibility of dimercaprol to oxidation is responsible for its apparent lack of efficiency. The recovery of mercuric chloride-treated E. coli on media containing an antagonist is affected by the incubation conditions especially when thioglycollate is used as the antagonist. Plots of the percentage of recovered cells against the contact time give different shaped curves for glutathione compared with those for cysteine and thioglycollic acid. Glutathione only inactivates mercuric chloride in the system or adsorbed onto the bacterial cells whereas cysteine and thioglycollic acid, in addition, penetrate the cell and antagonise mercuric chloride within. The incomplete recoveries obtained indicate that the action of mercuric chloride is bactericidal, not bacteriostatic. The rate of kill of E. coli by mercuric chloride was logarithmic under the experimental conditions used.