Use of Synthetic Medium in Study of Antibacterial Effect of Sulfathiazole. ∗

Abstract

In the present study we have employed the synthetic medium previously reported as being valuable for the study of the antibacterial effect of the thiazole compounds against Salmonella enteritidis and, as originally employed in demonstrating the inhibiting effect of p-aminobenzoic acid upon these drugs. 1 This liquid medium contains the same nutritive materials as are present in Simmon's citrate agar and is quite suitable for the cultivation of this organism even though very small inocula are employed.

This synthetic medium possesses definite advantages over ordinary broth containing meat extractives and peptone, since it is invariably uniform in composition, devoid of growth factors, essential metabolites, and of such substances as are known to interfere with the activity of the sulfonamide drugs. That this synthetic medium is superior to ordinary broth is further revealed by our experimental observations wherein 0.3 mg % of sulfathiazole prevents growth (as judged by visible turbidity) of S. enteritidis in the former whereas 20 mg % does not prevent growth in the latter medium.

Recognizing this superiority, it was deemed of interest to ascertain the relative effects of sulfathiazole upon S. enteritidis in each of these media as would be elicited by a comparison of viable population curves. In Fig. 1 are recorded the growth curves of the organism in meat extract-peptone broth, without drug, and with 5 and 10 mg % sulfathiazole. One of the effects of sulfathiazole is seen as a delay in the inception of the logarithmic phase of multiplication. During this phase, the drug (5 mg %) serves to increase the generation time by about five-fold as is reflected in the slope of the curve. The stationary phase is reached much earlier in control cultures. However, the ultimate number of cells developing in the drug-containing media is about one-fourth the number found in the control.