Occurrence of plasmids and tetracycline resistance among Campylobacter jejuni and Campylobacter coli isolated from whole market chickens and clinical samples.

Twenty whole market chickens, purchased from 10 different stores in the Taipei Metropolitan area, were examined for the presence of Campylobacter jejuni and Campylobacter coli. The microorganisms were recovered from 95% of the chickens. A survey of different sites on--breast, thigh and tail--showed that contamination was equally common on all these sites. One hundred and sixty-seven chicken isolates and the 41 clinical isolates of Campylobacter jejuni were examined for the occurrence of plasmid DNA in association with tetracycline resistance. A high plasmid occurrence rate of 91% and 44% was observed for C. jejuni from chickens and clinical isolates, respectively. Plasmids ranged in size from 16 to 208 Kb. A 61 Kb plasmid and a 50 Kb plasmid were common to the chicken isolates and clinical isolates, respectively. All chicken isolates and 78% of clinical isolates were tetracycline-resistant. The high rate of tetracycline resistance in chicken isolates probably related to use of tetracycline as a growth promoter for poultry. A tetO DNA Probe, highly specific for the detection of tetracycline resistance in C. jejuni and C. coli, was used to find the location of tetracycline resistance. Of 157 chicken isolates, 98% of isolates were positive with the tetO probe, 87% (137/157) on plasmids and 11% (17/157) on the chromosome; only three isolates did not hybridize with the tetO probe. Of 32 clinical isolates, 88% isolates hybridized with the tetO probe, 47% (15/32) on plasmids and 41% (13/32) on the chromosome; four isolates did not hybridize with the tetO probe.