title: Role of Cj1211 in natural transformation and transfer of antibiotic resistance determinants in Campylobacter jejuni.
abstract: Campylobacter jejuni, an important food-borne human pathogen, is increasingly resistant to antimicrobials. Natural transformation is considered to be a main mechanism for mediating the transfer of genetic materials encoding antibiotic resistance determinants in C. jejuni, but direct evidence for this notion is still lacking. In this study, we determined the role of Cj1211 in natural transformation and in the development of antibiotic resistance in C. jejuni. Insertional mutagenesis of Cj1211, a Helicobacter pylori ComH3 homolog, abolished natural transformation in C. jejuni. In vitro coculture of C. jejuni strains carrying either kanamycin or tetracycline resistance markers demonstrated the development of progenies that were resistant to both antibiotics, indicating that the horizontal transfer of antibiotic resistance determinants actively occurs in mixed Campylobacter populations. A mutation of Cj1211 or the addition of DNase I in culture media completely inhibited the formation of progenies that were resistant to both antibiotics, indicating that the horizontal transfer of the resistance determinants is mediated by natural transformation. Interestingly, the mutation of Cj1211 also reduced the frequency of emergence of spontaneous mutants that were resistant to fluoroquinolone (FQ) and streptomycin but did not affect the outcome of FQ resistance development under FQ treatment, suggesting that natural transformation does not play a major role in the emergence of FQ-resistant Campylobacter strains during treatment with FQ antimicrobials. These results define Cj1211 as a competence factor in Campylobacter, prove the role of natural transformation in the horizontal transfer of antibiotic resistance determinants in Campylobacter, and provide new insights into the mechanism underlying the development of FQ-resistant Campylobacter strains.
authors.affiliation: Department of Veterinary Microbiology and Preventive Medicine, 1116 Veterinary Medicine Complex, Iowa State University, Ames, IA 50011, USA.
authors.forename: Byeonghwa
authors.initials: B
authors.lastname: Jeon
authors.forename: Wayne
authors.initials: W
authors.lastname: Muraoka
authors.forename: Orhan
authors.initials: O
authors.lastname: Sahin
authors.forename: Qijing
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D016123:Campylobacter jejuni / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics*; D024841:Fluoroquinolones / Q000494:pharmacology; D022761:Gene Transfer, Horizontal / Q000235:genetics; D005816:Genetic Complementation Test; D007612:Kanamycin / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D017386:Sequence Homology, Amino Acid; D013752:Tetracycline / Q000494:pharmacology; D014169:Transformation, Bacterial / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C534733:Cj1211 protein, Campylobacter jejuni; D024841:Fluoroquinolones; D007612:Kanamycin; D013752:Tetracycline