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DEFINITION

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Bacteria of the genus Campylobacter and of the related genera Arcobacter and Helicobacter (Chap. 60) cause a variety of inflammatory conditions. Although acute diarrheal illnesses are most common, these organisms may cause infections in virtually all parts of the body, especially in compromised hosts, and these infections may have late nonsuppurative sequelae. The designation Campylobacter comes from the Greek for “curved rod” and refers to the organism’s vibrio-like morphology.

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ETIOLOGY

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Campylobacters are motile, non-spore-forming, curved, gram-negative rods. Originally known as Vibrio fetus, these bacilli were reclassified as a new genus in 1973 after their dissimilarity to other vibrios was recognized. More than 15 species have since been identified. These species are currently divided into three genera: Campylobacter, Arcobacter, and Helicobacter. Not all of the species are pathogens of humans. The human pathogens fall into two major groups: those that primarily cause diarrheal disease and those that cause extraintestinal infection. The principal diarrheal pathogen is Campylobacter jejuni, which accounts for 80–90% of all cases of recognized illness due to campylobacters and related genera. Other organisms that cause diarrheal disease include Campylobacter coli, Campylobacter upsaliensis, Campylobacter lari, Campylobacter hyointestinalis, Campylobacter fetus, Arcobacter butzleri, Arcobacter cryaerophilus, Helicobacter cinaedi, and Helicobacter fennelliae. The two Helicobacter species causing diarrheal disease, H. cinaedi and H. fennelliae, are intestinal rather than gastric organisms; in terms of the clinical features of the illnesses they cause, these species most closely resemble Campylobacter rather than Helicobacter pylori (Chap. 60) and thus are considered in this chapter. The pathogenic roles of Campylobacter concisus, Campylobacter ureolyticus, Campylobacter troglodytis, and Campylobacter pyloridis are uncertain. A new subspecies—C. fetus subspecies testudinum—has been described, chiefly in Asian patients; its close resemblance to strains isolated from reptiles suggests a food source.

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The major species causing extraintestinal illnesses is C. fetus. However, any of the diarrheal agents listed above may cause systemic or localized infection as well, especially in compromised hosts. Neither aerobes nor strict anaerobes, these microaerophilic organisms are adapted for survival in the gastrointestinal mucous layer. This chapter focuses on C. jejuni and C. fetus as the major pathogens in and prototypes for their groups. The key features of infection are listed by species (excluding C. jejuni, described in detail in the text below) in Table 64-1.

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Table Graphic Jump Location
TABLE 64-1CLINICAL FEATURES ASSOCIATED WITH INFECTION DUE TO “ATYPICAL” CAMPYLOBACTER AND RELATED SPECIES IMPLICATED AS CAUSES OF HUMAN ILLNESS

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