In vitro Studies on the Action of Sulfapyridine

Abstract

The use of sulfapyridine (2-sulfanilyl aminopyridine) in experimental pneumococcus pneumonia, 1 together with favorable clinical reports in the treatment of lobar pneumonia, led Fleming 2 to conduct in vitro studies on the action of the drug on the pneumococcus. He observed a marked bacteriostatic effect in deleukocyted blood, using his “slide-cell” technic. His criterion of bacteriostasis was the relative colony size of drug-treated cultures as compared with untreated controls. Whitby 1 reports a degeneration and final disappearance of the capsule in the peritoneum after 4 hours' growth in drug-treated mice. Fleming 3 has not been able to confirm this in his in vitro work.

The present studies were made to obtain data regarding the growth curve of the pneumococcus under the influence of the drug, which would give a quantitative measurement of bacteriostasis. In addition, morphological studies were made at regular intervals during the growth curve.

The organism used was a Type II pneumococcus which had been carried in mice for over a year by the method of Neufeld and Handel. 4 Eight-hour cultures, made by adding a drop of heart's blood from a freshly dead mouse to 20 cc of veal infusion broth, were used in all experiments. A culture of this age was chosen to prevent the appearance of a lag phase, which would result in exposure of resting cells to prolonged action of the drug. This is in accordance with previous work by Chesney, 5 showing that subcultures made during or immediately following the logarithmic growth phase exhibit little or no lag.

Two cubic centimeters of a 1:1000 solution of sulfapyridine were added to 18 cc of the menstruum to be tested.