The causative agents are bacteria of the genus Campylobacter, mainly C. jejuni, Campilobacteriaceae. The genus Campilobacter includes nine species. Campylobacter are motile gram-negative rods 1.5-2 μm long, 0.3-0.5 μm in diameter, and have a flagellum. They grow on agar media with the addition of erythrocytes and antibiotics (vancomycin, amphotericin B) to suppress accompanying flora, and form small colonies.
