Typing of Campylobacter isolates from humans and animals in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University

Abstract

Campylobacteriosis is currently the most commonly notified communicable disease in New Zealand. The sources of Campylobacter infections are not known, although the consumption of incompletly cooked poultry, untreated water, unpasteurised milk and contact with animals are associated with an increased risk of infection. The aim of this study was to establish a simple and reliable method for typing Campylobacter isolates in order to investigate the sources of Campylobacter infections in humans in New Zealand. Campylobacter isolates from humans and animals were identified to the species and subspecies level with a series of biochemical tests. The isolates were then examined by three genotypic typing methods: restriction fragment length polymorphism (RFLP) analysis of chromosomal DNA, randomly amplified polymorphic DNA (RAPD) typing using the polymerase chain reaction and RFLP analysis of the flagellin genes. The flagellin gene, flaB, was examined by PCR amplification followed by digestion with the restriction endonucleases PstI and HindIII. This method was the most reproducible of the three and provided a high level of discrimination, a total of 26 PstI/HindIII groups were found among 140 human Campylobacter isolates. Over 98% of C. jejuni and C. coli isolates could be typed using this method. The results of this study indicated that sheep, cows and calves may be important sources of Campylobacter infection in humans.