GUEST COMMENTARY Identification of Campylobacter Heat-Stable and Heat-Labile Antigens by Combining the Penner and Lior Serotyping Schemes

When a newly described infectious agent of human disease appears on the scene, there follows a major thrust to develop effective laboratory-based epidemiologic markers, including typing schemes to trace the source of the pathogen through to infection. Such was the case with Campylobacter jejuni and related species during the 1970s and 1980s. As a direct result of these activities, Campylobacter has been recognized as the most common bacterial enteric pathogen causing human diarrheal disease. Indeed, in developed countries, such as the United States, Canada, and the United Kingdom, the pathogen can be isolated from approximately 50 out of 100,000 persons, while in developing countries the pathogen can be isolated from 90 out of 100,000 persons. It should be noted that the actual incidence of disease has been estimated to be as much as 38 times higher than the organism isolation rate (15, 19). During the period of 1990 to 2000, surveillance data from across Canada was used to identify an average of 14,373 laboratory-confirmed cases of infection annually. This would equate to an incidence of approximately 550,000 cases of Campylobacter disease on an annual basis. The recognized public health challenge is to reduce this disease burden. Campylobacter infections are usually of food-borne origin, with poultry, bovine, and porcine products being most often implicated; however, outbreaks of human disease caused by waterborne pathogens occur frequently. Although infections are usually self-limiting and symptoms of enteritis clear without sequelae within 10 to 16 days, GuillainBarré syndrome (GBS), Miller-Fisher syndrome (MFS), or reactive arthritis may appear following Campylobacter infection. GBS and MFS are neuropathies, while reactive arthritis is a distinctive joint condition. These problems can result as a consequence of cross-reactivity between the antigens of specific serotypes of some Campylobacter species and human nerve or joint tissue components. It has been estimated that one case of GBS occurs for every 1,000 cases of campylobacteriosis (2), and approximately 20% of those individuals affected are left with some long term sequelae or disability. In addition, despite advances in respiratory care approximately 5% die (2). Serotyping has long been recognized as an important epidemiologic marker for a variety of enteric pathogens, including Salmonella, Shigella, and Escherichia coli. Indeed, serotyping schemes for other Enterobacteriaceae members have been modeled closely along the lines of that in use for Salmonella (11). During the early 1980s, two serotyping schemes were developed for Campylobacter in Canada. The Penner scheme, developed by John Penner of the University of Toronto, Toronto, Ontario, Canada, was based on a passive hemagglutination technique using soluble antigen extracts of isolates and specific antisera raised to the antigens of Campylobacter. This scheme is currently used to detect the heat-stable (HS), or O, antigens of C. jejuni and Campylobacter coli (22). The Lior scheme, developed by Hermy Lior at the National Laboratory for Enteric Pathogens (NLEP), formerly located in Ottawa, Ontario, Canada, was based on a slide agglutination procedure using live bacteria together with unabsorbed and absorbed antisera. This procedure was used for the detection of heatlabile (HL) antigens (14). Recently, a modification of the Penner serotyping scheme was developed at the Laboratory for Enteric Pathogens, Central Public Health Laboratory, London, United Kingdom. This serotyping assay was based on the same principle as that developed by Penner and also detected HS antigens of Campylobacter, though it did not use a passive hemagglutination technique; rather, antigens were detected by direct bacterial agglutination of heated suspensions by using specific antisera in microtiter plates (6).