Epidemiological typing of Campylobacter clinical and food isolates using pulsed-field gel electrophoresis.

Campylobacteriosis is the most frequently reported type of acute bacterial gastroenteritis in Canada. In 2000 alone, 11,846 campylobacteriosis cases were reported in Canada. The majority of these cases are sporadic, and their causes remain unknown. An attempt was made to gain a better understanding of the epidemiology of campylobacteriosis, both by identifying foods and environments that harbor Campylobacter spp., and by characterizing clinical, food and environmental isolates using pulsed-field gel electrophoresis (PFGE). Spot maps were also used to determine the geographical relationship of these campylobacteriosis cases. A variety of raw and ready-to-eat foods were tested for the presence of Campylobacter spp. From the 300 samples analyzed, Campylobacter spp. were detected in four samples, one raw beef liver sample and three raw chicken samples. An isolation rate of 9.7% was observed among the raw chicken samples tested, a significantly-reduced percentage, as compared to a 1981 Canadian survey. The prevalence of Campylobacter spp. in a poultry foodservice operation in Ottawa, was also determined from March to August 2001. No Campylobacter spp. were detected in the 125 samples tested. Campylobacter clinical and food isolates were characterized using PFGE with two restriction enzymes, SmaI and KpnI. KpnI produced more complex banding patterns than SmaI, and proved to be more discriminatory. Among the 154 isolates assigned to clusters by SmaI, only 42% gave concordant results with KpnI. In contrast, among the 53 isolates assigned to 23 clusters by KpnI, 87% gave concordant results with SmaI. Five of the 20 concordant clusters represented isolates obtained from the same person, suggesting that some of these individuals may have become re-infected. Spot map analysis revealed a significant clustering of campylobacteriosis cases in the former city of Ottawa, most of which, did not belong to the same postal code. In contrast, very few cases were observed in outlying regions; however, most of these cases belonged to the same postal code, suggesting the possible presence of local outbreaks