title: Natural transformation-mediated transfer of erythromycin resistance in Campylobacter coli strains from turkeys and swine.
abstract: Erythromycin resistance in Campylobacter coli from meat animals is frequently encountered and could represent a substantial barrier to antibiotic treatment of human infections. Erythromycin resistance in this organism has been associated with a point mutation (A2075G) in the 23S rRNA gene. However, the mechanisms responsible for possible dissemination of erythromycin resistance in C. coli remain poorly understood. In this study, we investigated transformation-mediated acquisition of erythromycin resistance by genotypically diverse C. coli strains from turkeys and swine, with total genomic DNA from erythromycin-resistant C. coli of either turkey or swine origin used as a donor. Overall, transformation to erythromycin resistance was significantly more frequent in C. coli strains from turkeys than in swine-derived strains (P < 0.01). The frequency of transformation to erythromycin resistance was 10(-5) to 10(-6) for turkey-derived strains but 10(-7) or less for C. coli from swine. Transformants harbored the point mutation A2075G in the 23S rRNA gene, as did the erythromycin-resistant strains used as DNA donors. Erythromycin resistance was stable in transformants following serial transfers in the absence of the antibiotic, and most transformants had high MICs (>256 microg/ml), as did the C. coli donor strains. In contrast to the results obtained with transformation, spontaneous mutants had relatively low erythromycin MICs (32 to 64 microg/ml) and lacked the A2075G mutation in the 23S rRNA gene. These findings suggest that natural transformation has the potential to contribute to the dissemination of high-level resistance to erythromycin among C. coli strains colonizing meat animals.
authors.affiliation: Department of Food Science, North Carolina State University, Raleigh, NC 27695-7624, USA.
authors.forename: Joo-Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Donna K
authors.initials: DK
authors.lastname: Carver
authors.forename: Sophia
authors.initials: S
authors.lastname: Kathariou
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D017000:Campylobacter coli / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004917:Erythromycin / Q000494:pharmacology*; D005516:Food Microbiology; D005798:Genes, Bacterial; D006801:Humans; D008460:Meat / Q000382:microbiology*; D008969:Molecular Sequence Data; D009154:Mutation; D017354:Point Mutation; D012329:RNA, Bacterial / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D034421:Sus scrofa / Q000382:microbiology*; D014170:Transformation, Genetic; D014422:Turkeys / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D004917:Erythromycin