Any of a group of 50 or more compounds characterized by the presence of both sulfur and nitrogen, with high specificity for certain bacteria. Because of their toxicity and often serious side effects, their use in treating disease is limited, since the less toxic antibiotics are generally available. Many are used in veterinary medicine. Among the best known are sulfanilamide, sulfadiazine, sulfapyridine, sulfamerazine, sulfasoxazole, and gantricin.