Trends in antibiotic sensitivity pattern and molecular detection of tet(O)-mediated tetracycline resistance in Campylobacter jejuni isolates from human and poultry sources

This study was conducted to determine the trends in Campylobacter antibiotic resistance occurring in our setting and to assess the differences in the isolates using patterns of plasmid profiles. One hundred Campylobacter jejuni strains of human and poultry origin isolated in 2002-2003 (phase A) and 2005-2006 (phase B) in the Kingdom of Bahrain were evaluated. Susceptibility to erythromycin, ciprofloxacin and tetracycline was determined, and plasmid extraction and polymerase chain reaction detection of the tet(O) gene was carried out. A single erythromycin-resistant isolate was identified, in sharp contrast to the high ciprofloxacin resistance which also showed an increment in phase B. Tetracycline resistance was higher in chicken (80.9%) compared to human (41.3%) isolates (P<0.01). Most isolates harbored two plasmids (23 kb and 35 kb) with significant correlation between tetracycline resistance and plasmid carriage in chicken isolates. The findings show continued effectiveness of erythromycin for campylobacteriosis but an increasing trend of high ciprofloxacin and tetracycline resistance. Tetracycline resistance is most likely due to the transfer of plasmids carrying the tet(O) gene between isolates.