Comparison of Molecular Typing Methods Useful for Detecting Clusters of Campylobacter jejuni and C. coli Isolates through Routine Surveillance

Campylobacter spp. may be responsible for unreported outbreaks of food-borne disease. The detection of these outbreaks is made more difficult by the fact that appropriate methods for detecting clusters of Campylobacter have not been well defined.We have compared the characteristics of five molecular typing methods on Campylobacter jejuni and C. coli isolates obtained from human and nonhuman sources during sentinel site surveillance during a 3-year period. Comparative genomic fingerprinting (CGF) appears to be one of the optimal methods for the detection of clusters of cases, and it could be supplemented by the se-quencing of the flaA gene short variable region (flaA SVR sequence typing), with or without subsequent multilocus sequence typing (MLST). Different methods may be optimal for uncovering different aspects of source attribution. Finally, the use of sev-eral different molecular typing or analysis methods for comparing individuals within a population reveals muchmore about that population than a single method. Similarly, comparing several different typing methods reveals a great deal about differ-ences in how the methods group individuals within the population. Despite being the most frequently detected bacterial agentcausing gastroenteritis worldwide (4, 9, 55), Campylobacter spp. are infrequently associated with outbreaks of disease (1, 19, 41). Point-source outbreaks have been associated with exposur