Diagnosis of a Campylobacter Infection
How is Campylobacter infection diagnosed?
Diagnosis of Campylobacter infection is usually based on the isolation of Campylobacter jejuni from a stool culture. [1, 7]
A diagnosis can also be established by the direct examination of a stool sample using contrast microscopy or Gram’s strain. [5, 6] This direct examination provides for a rapid presumptive diagnosis that must still be confirmed by stool culture. 
Stool samples should be chilled, but not frozen, for transportation to the testing-lab.  Labs now routinely perform culture-procedures on stool specimens that are specifically designed to promote the growth and identification of Campylobacter jejuni and the other species of Campylobacter. [1, 11, 12] Only a small percentage of persons suffering from Campylobacter infections both present for medical care and have their infections culture-confirmed. [5, 12, 26] In the study of one Campylobacter outbreak, only 5.4% of the outbreak cases visited a physician.  It is estimated that 12,700 to 13,230 cases are hospitalized each year. [26, 28]
Many persons submit samples for culturing after they have started antibiotics, which may make it even more difficult for a lab to grow Campylobacter.  Blood cultures are often not performed and in most cases the blood stream is not infected. [1, 5]