Campylobacter species - Overview

Electron micrograph of Campylobacter. (De Wood 2008, Wikimedia commons)

Overview

Campylobacter live on the mucosa of the intestinal and genital tract and can be commensals or pathogens. The enteric species cause disease in humans and other species cause infertility and abortion in cattle and sheep. Campylobacteriosis is caused by Campylobacter organisms. C.jejuni and C. lari is excreted in the faeces of birds and pigs and can contaminate water and food supplies. C.fetus is restricted to the bovine prepucial mucosa.

Characteristics

The bacteria are curved, Gram negative rods with polar flagellum to aid motility. The daughter cells remain joined, giving a gull-wing or spiral appearance. They are microaerophilic and sensitive to drying. Campylobater species can be divided into; Thermophilic species, including C.jejuni and C. coli and Non-thermophilic species e.g. C.fetus. They can grow on enriched selective media e.g. Skirrow agar in 1-10% carbon dioxide and 5-10% oxygen tension. Many grow on MacConkey, however C.jejuni requires increased temperatures for growth.

C.fetus subspecies venerealis and subspecies C.fetus have small, round, smooth, translucent colonies. C.jejuni has small, flat, grey colonies with watery appearance.

Smears are stained with dilute carbol fuschin for 4 minutes.

Pathogenesis and pathogenicity

C. fetus subspecies fetus and subspecies venerealis possess a microcapsule (S layer) which resists phagocytosis and serum-mediated destruction and enhances survival in the genital tract. Antigens of the S layer undergo antigenic shifts in C. fetus subspecies venerealis, allowing persistence in the host. C.jejuni attaches and invades host enterocytes and produces enterotoxin-like substances. The Flagellae of C.jejuni are required for colonisation.