Identification of thermophilic Campylobacter spp. by phenotypic and molecular methods

Abstract

The differences between phenotyping and genotyping (polymerase chain reaction- restriction fragment length polymorphism) of Campylobacter jejuni, Campylobacter coli, Campylobacter lari and Campylobacter upsaliensis were assessed. A total of 51, 63 and 88 strains from dogs, pigs and humans, respectively, were examined. The strains were first typed by biochemical methods, then by PCR-RFLP using AluI and Tsp509I. None of the strains were typed as Camp. lari by the PCR-RFLP. The biggest differences were found in the identification of Camp. jejuni and Camp. coli. The main discrepancies were caused with the hippurate hydrolysis test and sensitivity to cephalothin and nalidixic acid. Strains which were identified biochemically as Camp. coli and by digestion with AluI as Camp. jejuni (eight strains) were tested for the presence of the hippuricase gene. The PCR typing results showed the presence of the hippuricase gene as unique to Camp. jejuni. A reliable identification of Campylobacter spp. should be supplemented with a molecular method.