title: Characterization of a naturally occurring R plasmid in Salmonella isangi conferring unusually high resistance to ampicillin.
abstract: A strain of Salmonella isangi was isolated from HUMANA milk, used a baby food in Bulgarian hospitals. It harbours two stable plasmids, distinguishable by their molecular weight of 21 Mdal for the transfer factor (rRB 1) and 9,3 Mdal for R-factor rRB 2, confering resistance to ampicillin, cephalothin, streptomycin and sulfonamides. Both plasmids are maintained in different copy numbers per chromosome genome equivalent, 8 copies for rRB 1 and 158 copies for rRB 2, associated with an unusual high level of resistance to ampicillin (MIC 65 mg/ml).
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D000818:Animals; D002512:Cephalothin / Q000494:pharmacology; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000032:analysis; D004270:DNA, Circular / Q000032:analysis; D005516:Food Microbiology; D007225:Infant Food; D008892:Milk; D011815:R Factors; D012475:Salmonella / Q000032:analysis / Q000187:drug effects / Q000235:genetics*; D013307:Streptomycin / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D014169:Transformation, Bacterial
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular; D013449:Sulfonamides; D000667:Ampicillin; D002512:Cephalothin; D013307:Streptomycin