Genotyping of Campylobacter coli and C. jejuni from retail chicken meat and humans with campylobacteriosis in Slovenia and Bosnia and Herzegovina

Thermotolerant Campylobacter jejuni and C. coli are one of the major causes of bacterial foodborne enteric infection. Consuming and/or handling poultry meat is the most consistent risk factor, linked to the high prevalence of campylobacters in retail poultry meat. The aim of the present study was to ascertain the genetic diversity and/or possible specificity of thermotolerant Campylobacter isolates according to species (C. coli, C. jejuni), isolation source (retail chicken meat and human clinical samples) and geographic origin (Goriška in Slovenia and Zenica-Doboj Canton in Bosnia and Herzegovina (BIH)). With the pulsed-field gel electrophoresis (PFGE) after SmaI macrorestriction we distinguished 80 PFGE types among 118 strains and CfoI restriction fragment length polymorphism of the amplified flagellin gene (fla-RFLP) gave 12 fla-RFLP types. Beside the higher discriminatory power and strain typeability, PFGE discriminated the C. jejuni and C. coli groups of isolates. A high proportion of C. coli strains was isolated, especially from poultry samples. Identical or very similar PFGE types among the isolates from animal, food and human samples indicate the transmission of C. jejuni and C. coli from the chickens on the farm to the retail chicken meat, as well as possible cross-contamination of retail meat and transmission to humans. However, the identity of the isolates from non-related samples but with identical PFGE and fla-RFLP types should be confirmed with additional typing. Reliable tracing of the source of Campylobacter strains by molecular typing of the chicken meat isolates is therefore very difficult. The reasons include contamination of meat samples with multiple strains, possible cross-contamination and extreme heterogeneity of the isolates (mainly for C. jejuni) on one side and a limited power of the genotyping methods used to distinguish non-related strains on the other side (mainly for C. coli).