title: Effects of different levels of chlortetracycline in the diet of turkey poults artifically-infected with Salmonella typhimurium.
abstract: Two separate experiments were conducted to assess the shed rate and duration of shed of S . typhimurium organisms from turkey poults orally infected with chlortetracycline-sensitive S. typhimurium in relation to chloretetracycline (CTC) given in the feed at 0, growth promotant, subtherapeutic and therapeutic levels; the emergence of resistant S. typhimurium organisms in reference to the diet given; in vitro transfer of drug resistance from thses resistant S. typhimurium donor cultures to multiply-sensitive E. coli recipients; and phage type changes, is any, of these S. typhimurium isolates. The results showed that increasing CTC in the diet from 0 to the three levels of antibiotic supplementation, appeared to (a) reduce shed and duration of shed corresponding to each level used; (b) cause a minimal development of drug resistance and its transfer (usually at sub-therapeutic levels of CTC supplementation) for the duration of the experiment; and (c) induce phage type changes in some of the S. typhimurium isolates. These phage type changes question the validity of using phage typing as a tool in epidemiological investigations.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002432:Cecum / Q000382:microbiology; D002751:Chlortetracycline / Q000008:administration & dosage / Q000494:pharmacology*; D002988:Cloaca / Q000382:microbiology; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects; D005243:Feces / Q000382:microbiology; D008099:Liver / Q000382:microbiology; D011201:Poultry Diseases / Q000382:microbiology*; D011815:R Factors; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000302:isolation & purification*; D014422:Turkeys
chemical_list: D002751:Chlortetracycline