AbstractsBiology & Animal Science

Typewritten mss. Definite synergistic effects were noted by the use of a combination of sulfathiazole with penicillin and sulfathiazole with streptomycin. The growth of small numbers of cells (10 — 50) of sixteen species of Salmonella v/as inhibited by the synergistic activity of these antibacterial substances when a semisolid medium was used. Sulfathiazole alone, In sublethal amounts was able to inhibit the motility of all the flagellated species tested. The growth of the motile organisms in the semisolid medium in the presence of sulfathiazole appeared as "multiple granules" in comparison to the single-colony growth of the non-motile species. A new method for determining the most effective combination of any two antibacterial substances against any given sensitive organism is described. An attempt to demonstrate an in vivo synergistic activity in S. pullorum infected chicks was not successful under the conditions of the experiment.