Role of Plasmids in Antibiotic Resistance of Campylobacter Spp. Isolated from Children

Six clinical isolates of Campylobacter were examined for the occurrence of conjugative plasmids carrying antibiotic resistance markers. Kanamycin resistance was conjugally transferred from donors to recipients in all cases which indicated that it is plasmid mediated while the resistance to Erythromycin was considered to be chromosomally mediated because it was never transferred by conjugation. The Tetracycline resistance in one Campylobacter strain was encoded on a self-transmissible plasmid, while in other donor strains it was considered to be chromosomally mediated or carried on non-conjugative plasmid because it failed to transfer by conjugation. The Ampicillin and Kanamycin resistance markers of C. jejuni D101 were co-transferred by conjugation to C. coli A9 which indicated that both markers are on the same plasmid.
Occurrence of Ampicillin resistance gene on a plasmid in Campylobacter is reported here for the first time. The Erythromycin and Tetracycline resistance genes of C. hyointestinalis A14 and C. jejuni D101 proved to be chromosomally mediated because chromosomal DNA from both strains were successfully transformed to sensitive strains of Campylobacter which then became resistant to Erythromycin and Tetracycline.