The Genus Campylobacter
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The Genus Campylobacter TRUDY M. WASSENAAR AND DIANE G. NEWELL
Introduction The genus Campylobacter comprises a diverse group of Gram-negative bacteria, which colonize the mucosal surfaces of the intestinal tracts, oral cavities, or urogenital tracts of a wide range of bird and animal hosts. Both commensals and pathogens are represented within this group of organisms.
Phylogeny The genus Campylobacter is placed in the Epsilonproteobacteria (Trust et al., 1994) and now classified in the bacterial family Campylobacteraceae (Vandamme and De Ley, 1991a), which includes the genera Campylobacter, Arcobacter and Sulfurospirillum (formally known as freeliving campylobacters) and certain misclassified Bacteroides species. The closest genetically related genera are Helicobacter and Wolinella, which together form the family, Helicobacteraceae (Vandamme, 2000). Currently, the genus Campylobacter comprises 15 species (one of which is still disputed) and 6 subspecies: Campylobacter coli, C. concisus, C. curvus, C. fetus subsp. fetus, C. fetus subsp. venerealis, C. gracilis, C. helveticus, C. hyoilei (controversial), C. hyointestinalis subsp. hyointestinalis, C. hyointestinalis subsp. lawsonii, C. jejuni subsp. jejuni, C. jejuni subsp. doylei, C. lari, C. mucosalis, C. rectus, C. showae, C. sputorum and C. upsaliensis (Fig. 1). Recently a new species was described as Campylobacter lanienae sp. nov. The type strain for the genus is Campylobacter fetus subsp. fetus. The most commonly isolated pathogenic species are (in order of frequency) C. jejuni, C. coli and C. fetus.
Taxonomy Historical Overview Originally, campylobacters were described as members of the genus Vibrio. The first citation in
the literature (McFadyean and Stockman, 1913) described the isolation of “Vibrio fetus” from an aborted lamb. This organism became C. fetus subsp. fetus, which is the type species for the genus. Later other veterinary pathogens were isolated. The first campylobacter, then called Vibrio jejuni, was isolated by Jones and Little (1931) from the jejunum of calves with enteritis, followed by V. coli isolated from pigs by Doyle (1944). The first report of an isolate from human gastrointestinal disease was by Levy (1946). However, one can argue that Escherich, in 1889, was the first to describe small vibrios in the large intestinal mucus of infants who had died of “cholera infantum,” presumably caused by C. jejuni or C. coli. Important bacteriological progress was made by King (1957), who cultured microaerophilic vibrios at 42∞C. She correctly hypothesized that the organism was involved in diarrheal illness (King, 1962). The genus Campylobacter was introduced in 1963 (Sebald and Veron, 1963) to differentiate, from the traditional members of the genus Vibrio, those organisms with a low G+C DNA content, a strict microaerophilic nature, and a nonsaccharolytic biochemistry. In 1973, Veron and Chatelain (1973) published the first accepted taxonomy of the genus Campylobacter. The human gastric pathogen Campylobacter
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