title: Plasmid and chromosomal basis of tolerance to cadmium and resistance to antibiotics in normal bovine duodenal bacterial flora.
abstract: Cadmium (Cd) tolerance and antibiotic resistance was studied in duodenal flora of 20 normal bovine samples. Twelve bacterial isolates (5 Staphylococcus spp, 4 Enterococcus faecalis, 2 Bacillus spp, and a Pseudomonas sp) were grown in Luria broth containing 0.05 to 0.8 mM of cadmium chloride (CdCl). All isolates displayed multiple antibiotic resistance, with 2 Enterococcus strains and Pseudomonas pickettii demonstrating resistance to 12/17 antibiotics tested. With the exception of Staphylococcus sp, all contained plasmid DNA. Curing to remove plasmid DNA determined if Cd tolerance and/or antibiotic resistance was plasmid or chromosomally mediated. None of the bacteria became sensitive to CdCl after curing, suggesting that tolerance was not plasmid-mediated. Six bacteria became sensitive to antibiotics after curing indicating that antibiotic2 resistance was plasmid mediated. Two of these bacteria became sensitive to multiple antibiotics; a Staphylococcus sp became sensitive to ampicillin, ceftiofur and cephalothin, and a Enterococcus strain became sensitive to neomycin, oxacillin, and tiamulin. All of the isolates were probed for the presence of known Cd-resistance genes (cadA, cadC, and cadD). DNA-DNA hybridization revealed cadA- and cadC-related sequences in chromosomal DNA of a Staphylococcus sp, an Enterococcus strain, and in plasmid DNA of another Staphylococcus sp. No cadD-related sequences were detected in any of the 12 isolates even under reduced stringency of hybridization.
authors.affiliation: Department of Diagnostic Medicine-Pathobiology, College of Veterinary Medicine, Manhattan, KS 66506, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Bruins
authors.forename: S
authors.initials: S
authors.lastname: Kapil
authors.forename: F W
authors.initials: FW
authors.lastname: Oehme
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D015139:Blotting, Southern; D002104:Cadmium / Q000494:pharmacology*; D002417:Cattle; D002875:Chromosomes / Q000187:drug effects* / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial / Q000235:genetics; D004386:Duodenum / Q000382:microbiology*; D005260:Female; D005798:Genes, Bacterial; D006094:Gram-Positive Bacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000187:drug effects* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C432939:CadR protein, Pseudomonas; D004269:DNA, Bacterial; D014157:Transcription Factors; D002104:Cadmium