title: Chlortetracycline and sulfonamide resistance of fecal bacteria in swine receiving medicated feed.
abstract: The fecal bacterial flora of swine receiving a ration supplemented with chlortetracycline, sulfamethazine, and penicillin was tested for resistance to chlortetracycline and sulfamethazine using anaerobic techniques and medium M-10. Approximately 15.5 and 1.4% of the flora grew in the presence of 25 and 100 microgram of tetracycline/mL, respectively. Higher numbers of bacteria grew in the presence of similar concentrations of sulfamethazine. Thirty-five chlortetracycline-resistant isolates were tentatively identified by genera. Nine different genera were identified, four of these were Gram-positive and five were Gram-negative. The most common genera isolated were Streptococcus and Eubacterium. This demonstrates that in the fecal flora of swine fed rations supplemented with chlortetra-cycline, a wide variety of bacterial genera can be resistant to this antibiotic.
mesh_terms: D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001419:Bacteria / Q000187:drug effects*; D002751:Chlortetracycline / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D005243:Feces / Q000382:microbiology*; D005503:Food Additives; D008297:Male; D013045:Species Specificity; D013418:Sulfamethazine / Q000494:pharmacology*; D013552:Swine / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D005503:Food Additives; D013418:Sulfamethazine; D002751:Chlortetracycline