Comparative Analysis of New Zealand Campylobacter Isolates Using MLST, PFGE and flaA PCR RFLP Genotyping

Campylobacter jejuni and Campylobacter coli are the most commonly identified sources of campylobacteriosis in New Zealand, yet little is known about the distribution of genotypes within the respective population structures. Using multi-locus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and flaA genotyping, the current study identified the distribution of genotypes within New Zealand C. jejuni and C. coli isolates from an outbreak situation, as well as isolates present in the ESR Campylobacter collection. Although the most commonly identified MLST genotypes were similar to international genotypes, a number of internationally rare, or unique to New Zealand genotypes were observed. One rare dominant genotype, ST-474, arising from a point source outbreak, was found to cause a large proportion of human campylobacteriosis cases in New Zealand. A unique cluster of New Zealand genotypes were isolated only from river water, identifying a potentially water adapted C. jejuni strain. Frequent homologous recombination and horizontal gene transfer events were identified within the seven housekeeping genes characterised in the New Zealand sample and the MLST C. jejuni/C. coli database. The identified genetic instability within the current study questions the legitimacy of bacterial species boundaries, especially when examining closely related species such as C. jejuni and C. coli.