Trends in antibiotic susceptibility profile and assessment of tet(O)-mediated tetracycline resistance in Campylobacter jejuni isolates from human and poultry sources

Abstract number: P2037

Senok A., Mazi W., Al-Mahmeed A., Arzese A., Bindayna K., Botta G.

Objective: This study was conducted to determine the trends in Campylobacter antibiotic resistance occurring in our setting. Isolates of human and poultry origin were assessed to determine the plasmid profiles and occurrence of the tet(O) gene in Campylobacter jejuni strains ciruculating in our population..

Methods: One hundred C. 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. The disc diffusion and agar dilution methods were used to assess antimicrobial susceptibility and the minimum inhibitory concentrations of erythromycin, ciprofloxacin and tetracycline. Plasmid extraction was performed using QIAprep® Miniprep kit. PCR detection of the tet(O) gene in purified plasma DNA carried out.

Results: Erythromycin resistance rates were low in both chicken and human C. jejuni isolates. Ciprofloxacin resistance rates were high with an increasing trend observed in isolates obtained from both sources during Phase B. Tetracycline resistance was higher in chicken (80.9%) compared to human (41.3%) isolates [p < 0.01]. However, tetracycline resistance rates in human isolates increased to 60.5% during Phase B. The minimum inhibitory concentration for the tetracycline resistant C. jejuni isolates ranged from 16 to >512ug/ml. There were 13 isolates with MIC >512ug/ml with 12 of these being of poultry origin. With the exception of a tetracycline sensitive human isolate, all the remaining 99 isolates harboured plasmids ranging in size from 15–35kb. The most commonly detected plasmids were the 23kb and 35-kb size with significant correlation between tetracycline-resistance and plasmid carriage being observed in isolates of poultry origin. All tetracycline-resistance C. jejuni strains were positive for the tet(O) gene, while none of the susceptible strains gave a positive PCR product.

Conclusion: 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 transfer of plasmid carrying tet(O) gene between isolates. Possible trafficking of resistance genes between isolates of poultry and human sources has the potential for generating increased resistance in humans even without previous antibiotic exposure.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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