Genomic variability among isolates of Campylobacter jejuni from broiler flocks in the Czech Republic

The bacterium Campylobacter jejuni naturally colonizes the gastrointestinal tract of many birds and animals, resulting in a harmless commensal relationship, but this microbe can also promote pathogenesis in humans, resulting in a productive gastroenteritis leading to a mild bloody diarrhoeal syndrome. Consumption or handling of poultry meats is prevalent source of. C. jejuni for infection in human. However, the majority of C. jejuni infections are considered to be sporadic, with the source of infection remaining unidentified. It is unclear whether certain types of C. jejuni strains are specific for particular hosts or whether they are associated with specific disease manifestations in humans. Genotyping performed by using two methods provided insights into the genomic relatedness of isolates from different broiler flocks from extensional farms with conventional rearing technology. 319 samples from 19 different flocks were clearly discrimined by PCR/RFLP flyA-typing (fla-RFLP) as well as by subtyping performed using pulsed-field gel electrophoresis (PFGE) and the enzyme used for cleavage was SmaI. One flock was colonized only by C. coli clone with identical PFGE profile. In other 18 flocks 17 fla-RFLP and 22 PFGE C. jejuni subtypes were found. In seven cases each individual flock was colonized by clones with identical profiles both after fla-RFLP typing and PFGE analysis. In three flocks C. jejuni strains with identical PCR/RFLP profile and only similar PFGE patterns were found. On the other hand, four flocks were colonized by strains with identical PFGE profiles, but different PCR types. Nevertheless all these fla-RFLP types in one flock can be explained by possible transition of one subtype after mutation of the recognition site for only one restriction enzyme. Based on identity or significant PFGE similarity and in most cases fla-type identity, we asssume that Campylobacter isolates from each of the 14 flocks are homogenous and belong to the same clone. Four flocks may be colonized by 2 3 different Campylobacter clones with quite different PFGE profiles and fla-RFLP types which could not be explained by point mutation in restriction site. The bacterial population in poultry appeared to be mostly homogenous – even though in three flocks isolates contained mixture of two C. jejuni clones with similar PFGE profile and identical fla-type and vice versa. To determine the significance of poultry as infectious source of C. jejuni, the PCR/RFLP and PFGE patterns of broiler chickens are compared with those of isolates from patients with diarrhea, at present. __________________________________________________________________________________