title: pJT2: unusual H1 plasmid in a highly virulent lactose-positive and chloramphenicol-resistant Salmonella typhimurium strain from calves.
abstract: A lactose-positive and chloramphenicol-resistant strain of Salmonella typhimurium of high virulence was isolated from an outbreak of enteric and septicemic salmonellosis in veal calves. the lactose-positive marker was located on an H1 plasmid, pJT2, together with resistance to chloramphenicol, streptomycin, sulfonamides, and tetracycline, pJT2 was unusually large and had a molecular weight of about 150 X 10(6). A similar plasmid was also present in a third of the Escherichia coli strains isolated from the intestines of septicemic calves during the outbreak. Spontaneously derived Lac- derivatives of pJT2 had an approximate molecular weight of 140 X 10(6).
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology; D002701:Chloramphenicol / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000235:genetics; D007785:Lactose / Q000378:metabolism; D010957:Plasmids; D012480:Salmonella Infections / Q000382:microbiology; D012481:Salmonella Infections, Animal; D012486:Salmonella typhimurium / Q000235:genetics* / Q000472:pathogenicity
chemical_list: D002701:Chloramphenicol; D007785:Lactose