Organisms of the genus Campylobacter are Gram-negative, microaerophiles that cause 5-11% of all diarrhea cases in the United States. Cell motility is achieved through polar flagella which emanate from a curved rod-shaped cell. The unique shape of the cell and flagella are extremely useful in Gram-stain identification. Campylobacter are microaerophiles, which means that they can survive in a low oxygen environment. What is unusual about the organism, though, is that it also prefers a relatively high concentration of carbon dioxide in the environment. You can imagine the difficulty of producing an environment suitable for culturing this organism.
The most commonly isolated species of Campylobacter is C. jejuni, an organism that causes gastro-intestinal infection. Humans acquire the organisms by eating undercooked chicken or drinking contaminated milk and water. Infection usually leads to fever, cramps, and bloody diarrhea. The bloody diarrhea indicates that Campylobacter is an invasive pathogen that infiltrates the lining of the small intestine. Along the way, the organism excretes toxins that destroy the gut mucosa. Erythromycin is the preferred antibiotic for treatment.
As previously mentioned, these organisms require special environmental conditions for optimal growth. Camp blood agar is a selective medium which can be used for isolating C. jejuni. A series of biochemical tests can then distinguish C. jejuni from other species of Campylobacter.
