Molecular characterisation of Campylobacter jejuni isolated from healthy bovine, ovine and free-range poultry faeces in the Basque Country (northern Spain)

Abstract number: P1694

Oporto B., Esteban J., Aduriz G., Juste R., Hurtado A.

Objectives: Domestic farm animals are reservoirs of pathogenic campylobacters like Campylobacter jejuni, the most frequently isolated bacterial pathogen in cases of human gastroenteritis in developed countries. A prevalence study carried out in the Basque Country identified 28.3% (34/120) of ovine and 18.0% (37/206) of bovine farms positive for C. jejuni, and even higher values (38.2%, 13/34) in free-range poultry farms. The high incidence of human Campylobacter infections in the Basque Country (121 cases per 100,000 inhabitants in 2005) and the relatively high prevalence in primary production units of this foodborne pathogen prompted us to further characterize the animal isolates to investigate the relationships among strains from different sources.

Methods: A selection of isolates from the different host species (sheep, cattle and poultry) were analysed using three molecular typing techniques: pulsed-field gel electrophoresis (PFGE) of pure cultures digested with SmaI, restriction fragment length polymorphism analysis of the PCR amplified flaA gene (flaA PCR-RFLP) and multilocus sequence typing (MLST) of seven housekeeping genes (aspA, glnA, glyA, gltA, pgm, uncA and tkt).

Results: PFGE and MLST showed higher discriminatory power than flaA PCR-RFLP since flaA PCR-RFLP profiles present in different production systems were further discriminated by both PFGE and MLST. Nevertheless, different genetic types were observed between farms and within the same farm suggesting the co-existence of several strains probably originating from different sources.

Conclusion: The use of at least two molecular typing methods is needed for optimal discrimination. Typing of C. jejuni strains was a useful tool for the identification of sources of infection within the farm. In addition, MLST data provided information on the overall population structure of the organisms that can be used in future population genetic approaches.