Abstract
In a previous publication 1 one of us (Mellon) reported a poten-tiative effect of sulfanilamide on hemolytic streptococci when the organisms had been exposed to physiological salt solution during the process of dilution preliminary to seeding the test cultures. If this exposure was omitted and dilution in broth substituted, the remarkable bacteriostatic effect of sulfanilamide in low concentrations was not noted. In the presence of normal human serum the effect is enhanced. In other words, a sterilizing effect is obtained from the combined action of these minimal factors which exceeds many times a simple summation effect.
Kenny, Johnston, and von Haebler 2 have recently reported a very favorable series of clinical cases of E. coli infection of the urinary tract which were successfully treated with sulfanilamide. They showed that with oral medication of 1.5 gm. a day for 5-7 days sterilization of the urine was obtained during the period of treatment in all of 46 cases of infection with a typical E. coli. The concentration of free sulfanilamide obtained in the urine of treated cases ranged from less than 1:100,000 to 1:1,000. It was shown experimentally that the static or bactericidal action of the compound in vitro was roughly proportional to its concentration.
It appeared to us that a potentiation similar to that displayed by saline for hemolytic streptococci might be anticipated in this instance with the culture medium itself (the urine) playing the role of the potentiating agent. Bacteriostatic tests were accordingly made on a strain of E. coli freshly isolated from a case of cystitis which had had no sulfanilamide therapy. Normal pooled urine was adjusted to pH 7.2 and sterilized by Seitz filtration. The broth employed in the following experiments was a 2% proteose-peptone beef infusion of the same pH.
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