This organism is a small, motile, and microaerophilic Gram-negative bacillus with a comma, S, or gull-wing shape. Growth is enhanced by incubation at elevated temperature and modified atmosphere (decreased oxygen and increased carbon dioxide). Campylobacter species do not produce acids from sugars, a trait that separates them from Vibrio species. Because of their selection using 42 C incubation, the number and variety of tests used for identification is limited.
Its reservoir is usually the reproductive organs, intestinal tracts, and oral cavities of animals and birds. Campylobacter jejuni is among the most common causes of severe gastroenteritis in humans, estimated to cause millions of cases of severe diarrhea each year in the United States. Source of the infection is typically via the oral route by ingestion of contaminated food, milk, or water providing an Infectious Dose (ID-50) of at least 10,000 organisms.