Independent risk factors for campylobacteriosis (eating raw, rare, or undercooked poultry; consuming raw milk or raw milk products; and eating chicken or turkey in a commercial establishment) account for <50% of cases in Québec. Substantial regional and seasonal variations in campylobacteriosis were not correlated with campylobacter in chickens and suggested environmental sources of infection, such as drinking water.

Pulsed-®eld gel electrophoresis (PFGE) was used to analyse 147 isolates collected in two regions of Que Âbec province (Estrie and Montre Âal) between March 1998 and Feb. 1999, to determine the utility of molecular strain typing for a population-based collection of Campylobacter jejuni and to compare directly the discriminatory power of Sma I and Kpn I restriction digests. With a combination of epidemiological criteria including space and time plus molecular strain typing, 49% of isolates from Estrie and 39% of isolates from Montre Âal were identi®ed as belonging to a putative cluster. For 41% of the cases, sources were either missing or explicitly unknown; the remaining sources were subject to recall bias. Thus, the evaluation of sporadic cases of campylobacter enteritis by descriptive clinical investigation alone is neither sensitive nor reliable for identifying sources of infection. In the PFGE analysis, Kpn I digests provided appreciably greater discriminatory power than Sma I digests. When combining the PFGE analyses with basic epidemiological criteria, 30% of the putative Sma I clusters were inconsistent with the epidemiological criteria compared with 17% of the Kpn I clusters. Among the 98 isolates assigned to clusters by Sma I, only 65% gave concordant results with Kpn I. In contrast, among the 81 isolates assigned to clusters by Kpn I, 92% gave concordant results with Sma I. Finally, clusters that were epidemiologically related to ingestion of raw milk and speci®c water sources correlated better with the typing results based on Kpn I than Sma I. Thus, Kpn I is the enzyme of choice for molecular epidemiology studies of C. jejuni. The combination of continuous epidemiological surveillance and molecular strain typing may be useful for identifying new sources and mechanisms of transmission for community-acquired C. jejuni infection and ultimately for developing new approaches to prevention.

No abstract

The goal of the present study was to assess the contribution of real-time molecular typing, used alone or with clinical surveillance, to the prompt identification of clusters of Campylobacter enteritis. Potential poultry sources were sought by comparing the pulsed-field gel electrophoresis genotypes of human and fresh whole retail chicken isolates collected during the same study period. Among 183 human isolates, 82 (45%) had unique genotypes, 72 (39%) represented 26 clusters of 2 to 7 isolates each, and 29 (16%) represented three clusters of 8 to 11 isolates each. Molecular typing was useful for the confirmation of outbreaks suspected on the basis of epidemiological surveillance, but for most small clusters, no epidemiological link could be established. Thus, the added value of real-time molecular typing is questionable, since the numerous small clusters identified were of unclear public health significance. Among 177 chickens, 41 (23%) yielded campylobacter isolates; of these, 19 (46%) had genotypes similar to those of 41 (22%) human isolates. However, a temporal association was demonstrated in only a minority of cases, and most genotypes were present only in a single species, suggesting that sources other than chickens are important in human campylobacteriosis. Further investigation with samples from water and other possible environmental sources is needed to define the most efficient strategy for the application of molecular typing and identification of the source(s) of sporadic cases of campylobacteriosis.