In vitro activity of trimethoprim in association with sulfimidazole against aerobic gram-negative and gram-positive microorganisms and Clostridia.

The in vitro activity of a chemotherapeutic agent, sulfimidazole (SIZ), obtained by combining two molecules belonging to groups of extremely different antibacterial drugs, p-aminobenzene sulfonamide and a derivative with a 5-nitroimidazole ring, was studied. In association with trimethoprim, SIZ induces an intense synergistic antibacterial effect on gram-negative and gram-positive aerobic microorganisms and Clostridia. The results show that, in SIZ, the activity of each starting molecule remains unchanged providing that its structure-action relationship is kept intact.