The Genera Campylobacter and Helicobacter

Abstract

The genus Campylobacter encompasses a diverse group of organisms that are either cornmensals for pathogens for both humans and animals. Thirteen species are currently included in the genus (Table 1). The new genus Helicobacter contains two species previously classified as Campylobacter (Table 1). All of these organisms are Gram-negative, nonsporeforming, oxidase positive, indole negative, asaccharolytic organisms that neither ferment nor oxidize carbohydrates (Smibert 1978, 1984; Penner, 1988). Energy is produced through respiration and the metabolism of amino acids. The GC content for members of the genus falls between 29–39 mol% (Fox et al., 1989; Owen, 1983; Owen and Leaper, 1981; Harvey and Greenwood, 1983b; Ursing et al., 1983). All these organisms are slender, helically curved Gram-negative rods that are 0.2–0.5 μm wide and 0.5–8.0 μm long (Fig. 1). Pairs of cells have an S-shaped or gull-wing morphology while longer chains of cells form spirals. The shorter campylobacter forms move in a rapid, darting manner while spiral forms rotate along the long axis like corkscrews. The wavelength, amplitude, and length of the spirals vary among species. With the exceptions of Helicobacter pylori and H. mustelae,the organisms are motile by means of a long single, polar flagellum found at one or both ends of the cell (Smibert 1984). H. pylori has multiple flagella located at only one end of the cell while H. mustelae has both polar and lateral flagella (Fox et al., 1989).