Effect of organic mercurials and sulfhydryl compounds on the urease activity of Proteus: inhibition by urine and ascorbic acid.

Meralluride, mercaptomerin, ethacrynic acid, and penicillamine inhibited urease activity of Proteus mirabilis. The activity of the organic mercurials and ethacrynic acid was markedly inhibited by human and dog urine. Antiurease activity could not be detected in the urine of a human and a dog given meralluride by injection. Urine from patients receiving penicillamine also failed to inhibit urease activity. Ascorbic acid inhibited, whereas dehydroascorbic acid enhanced, the activity of the mercurials, but neither agent altered the inhibitory effect of urine. The lethal effect of meralluride against Proteus occurred at the same concentration at which urease activity was inhibited, but penicillamine inhibited the enzymatic activity without affecting viability of the organism. The data suggest that these sulfhydryl-reactive compounds will not be useful against Proteus infections of the urinary tract.