title: Trimethoprim-resistant bacteria: cross-resistance patterns.
abstract: One hundred and eighty one strains (clinically isolated) of trimethoprim-resistant bacteria were tested for sensitivity to proguanil, pyrimethamine, methotrexate and methasquin. All these agents had less intrinsic antibacterial activity than trimethoprim, and there was marked cross-resistance between trimethoprim on the one hand and pyrimethamine and methasquin on the other. Methotrexate was of very low activity against Gram-negative bacilli, but was highly inhibitory for streptococci. Proguanil had approximately the same activity for all the organisms tested, and appears not to act as an anti-folate agent.
mesh_terms: D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000382:microbiology*; D003429:Cross Reactions; D004352:Drug Resistance, Microbial; D006801:Humans; D008727:Methotrexate / Q000494:pharmacology; D002727:Proguanil / Q000494:pharmacology; D011739:Pyrimethamine / Q000494:pharmacology; D011815:R Factors; D013045:Species Specificity; D014295:Trimethoprim / Q000494:pharmacology*; D014556:Urine / Q000382:microbiology
chemical_list: D001224:Aspartic Acid; D014295:Trimethoprim; D002727:Proguanil; D008727:Methotrexate; D011739:Pyrimethamine