Campylobacter

The genus Campylobacter are Gram-negative, spiral, microaerophilic bacteria. Motile, with either uni- or bi-polar flagella, the organisms have a somewhat curved, rod-like appearance, and are oxidase-positive. Campylobacter jejuni is now recognised as one of the main causes of bacterial foodborne disease in many developed countries. At least a dozen species of Campylobacter have been implicated in human disease, with C. jejuni and C. coli the most common. C. fetus is a cause of spontaneous abortions in cattle and sheep, as well as an opportunisitic pathogen in humans.

Genome
The genomes of several Campylobacter species have been sequenced, providing insights into their mechanisms of pathogenesis.

Campylobacter species contain two flagellin genes in tandem for motility, flaA and flaB. These genes undergo intergenic recombination, further contributing to their virulence. Non-motile mutants do not colonize.

Pathogenesis
Campylobacteriosis is an infection by campylobacter. The common routes of transmission are fecal-oral, person-to-person sexual contact, ingestion of contaminated food or water. It produces an inflammatory, sometimes bloody, diarrhea, periodontitis or dysentery syndrome, mostly including cramps, fever and pain. The infection is usually self-limiting and in most cases, symptomatic treatment by reposition of liquid and electrolyte replacement is enough in human infections. The use of antibiotics, on the other hand, is controversial.

Cause
This is most commonly caused by C. jejuni, a spiral and comma shaped bacterium normally found in cattle, swine, and birds, where it is non-pathogenic. But the illness can also be caused by C. coli (also found in cattle, swine, and birds) C. upsaliensis (found in cats and dogs) and C. lari (present in seabirds in particular).

One cause of the effects of campylobacteriosis is tissue injury in the gut. The sites of tissue injury include the jejunum, the ileum, and the colon. C jejuni appears to achieve this by invading and destroying epithelial cells.

Some strains of C jejuni produce a cholera-like enterotoxin, which is important in the watery diarrhea observed in infections. The organism produces diffuse, bloody, edematous, and exudative enteritis. In a small number of cases, the infection may be associated with hemolytic uremic syndrome and thrombotic thrombocytopenic purpura through a poorly understood mechanism.