title: Determination of the activity of pyrimethamine, trimethoprim, sulfonamides, and combinations of pyrimethamine and sulfonamides against Sarcocystis neurona in cell cultures.
abstract: Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome in horses from the Americas and is usually caused by infection with the apicomplexan parasite, Sarcocystis neurona. The activities of pyrimethamine, trimethoprim, sulfachloropyridazine, sulfadiazine, sulfadimethoxine, sulfamethoxazole, sulfamethazine, and sulfathiazole were examined against developing S. neurona merozoites in bovine turbinate cell cultures. A microtiter plate host cell lesion based assay was used to determine the effects of agents on developing merozoites. A cell culture flask assay was used to determine if selective concentrations of the agents killed or only inhibited development of S. neurona. Pyrimethamine was coccidiocidal at 1.0 microg/ml and trimethoprim was coccidiocidal at 5.0 microg/ml. None of the sulfonamides had activity when used alone at 50.0 or 100.0 microg/ml. Combinations of sulfonamides (5.0 or 10.0 microg/ml) with 0.1 microg/ml pyrimethamine demonstrated improved activity.
authors.affiliation: Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg 24061-0342, USA. lindsayd@vt.edu
authors.forename: D S
authors.initials: DS
authors.lastname: Lindsay
authors.forename: J P
authors.initials: JP
authors.lastname: Dubey
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology* / Q000592:standards / Q000627:therapeutic use; D000963:Antimetabolites / Q000494:pharmacology* / Q000592:standards / Q000627:therapeutic use; D000981:Antiprotozoal Agents / Q000494:pharmacology* / Q000592:standards / Q000627:therapeutic use; D002417:Cattle; D002478:Cells, Cultured; D004338:Drug Combinations; D004679:Encephalomyelitis / Q000188:drug therapy / Q000469:parasitology / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D006734:Horse Diseases / Q000188:drug therapy / Q000469:parasitology; D006736:Horses; D011739:Pyrimethamine / Q000494:pharmacology* / Q000592:standards / Q000627:therapeutic use; D012522:Sarcocystis / Q000187:drug effects*; D012523:Sarcocystosis / Q000188:drug therapy / Q000469:parasitology / Q000662:veterinary; D013449:Sulfonamides / Q000494:pharmacology* / Q000592:standards / Q000627:therapeutic use; D014295:Trimethoprim / Q000494:pharmacology* / Q000592:standards / Q000627:therapeutic use; D014420:Turbinates / Q000166:cytology / Q000469:parasitology
chemical_list: D000890:Anti-Infective Agents; D000963:Antimetabolites; D000981:Antiprotozoal Agents; D004338:Drug Combinations; D013449:Sulfonamides; D014295:Trimethoprim; D011739:Pyrimethamine