Pathogenesis of enteric Campylobacter infection.

1. SUMMARY Campylobacter jejuni and related species are important human pathogens, causing acute human enterocolitis, and they are the most common cause of food-borne diarrhoea in many industrialized countries. Previous infection with certain strains of C. jejuni is also linked with the development of the neurological disorder Guillain±Barre  syndrome (GBS). Despite its importance as a human pathogen, relatively little is understood of the mechanisms of C. jejuni-associated disease. The recent release of the complete genome sequence of C. jejuni strain NCTC 11168, together with new strategies for random and directed mutagenesis, have allowed a better insight into some of the genetic determinants of C. jejuni virulence. In this review current knowledge on the pathogenesis of C. jejuni infection is summarized, and possible directions of future research indicated. Members of the genus Campylobacter colonize the gastro-intestinal tract of a broad range of animals. They are commensals in most animals, but notably are associated with disease in humans. The human pathogens C. jejuni and Campylobacter coli are causative agents of acute human enterocolitis, and are the most common cause of food-borne diarrhoea in many industrialized countries (Tauxe 1992; CPHLS 1999). There is also a link between infection with particular serotypes of C. jejuni and subsequent development of GBS (Nachamkin et al. 1998). Despite its importance as a human pathogen, our understanding of the mechanisms of Campylobacter-associated disease is still relatively poor. Focusing on C. jejuni and C. coli, the objective of this review is to summarize current progress on understanding the pathogenesis of Campylobacter infection. 3. CAMPYLOBACTER BIOLOGY Campylobacters are small, spirally curved, Gram-negative rods with a polar ¯agellum at one or both ends of the cell. The cells are highly motile. They are catalase and oxidase positive, and urease negative. Campylobacters are micro-aerophilic, requiring an oxygen concentration of 3±15% and a carbon dioxide concentration of 3±5%. The temperature range for growth of the thermophilic Campylobacter species C. jejuni and C. coli is 34±44°C, with an optimal temperature of 42°C, which probably re¯ects an adaptation to the intestines of warm-blooded birds. Campylobacter spp. are fastidious organisms that require complex growth media, and are unable to ferment carbohydrates. Campylobacter jejuni and C. coli have a genome of approximately 1600±1700 kilobases (kb), which is relatively small compared with that of enteropathogens such as Escherichia coli, which have a genome of approximately 4500 kb (Chang and Taylor 1990; Nuijten et al. 1990a). The G …