Approach

The diagnosis of Campylobacter enteritis cannot be made solely by the clinical picture, although the presence of severe abdominal pain and diarrhoea suggests the diagnosis.

History and physical examination

A full history should be taken, including exposure to poultry, cattle, sheep, or other farm animals; eating raw or undercooked meat (especially chicken); recent foreign travel to high-risk areas, including Africa, South America, and Asia; and travel to developing countries.[14]​ History of drinking untreated water, and drinking unpasteurised milk should also be noted.​[26][27][28]​ In immunocompetent people, illness typically occurs within 2 to 4 days after exposure to the organism in contaminated food or drink, although ranges from 1 to 10 days after exposure are described.[6][14]​​​ Many Campylobacter jejuni infections are sub-clinical, especially in immunocompetent people.[31]

A history of HIV infection should be considered because the incidence of Campylobacter infection is increased in patients with HIV/AIDS, although the incidence is lower in HIV-positive patients on antiretroviral therapy.[5] People with HIV are also at risk of becoming long-term carriers ofCampylobacter. This is associated with recurrent enteritis and bacteraemia.[25]

The major clinical manifestations are diarrhoea and abdominal pain. Diarrhoea is often watery, with up to 8-10 bowel movements daily. It becomes bloody in approximately 20% to 25% of cases. Diarrhoea is considered inflammatory because of the prominent expression of fever and constitutional symptoms, and because the stools contain leukocytes and blood.[4] Abdominal pain associated with Campylobacter infection is usually more severe than in the other bacterial causes of enteritis/colitis. The pain often becomes continuous and radiates to the right iliac fossa (frequently described as right lower quadrant pain by patients).[32]​​

Less-frequent symptoms include vomiting and a prodrome consisting of headache, myalgias, chills, and fever. One third of patients will have a prodrome that lasts 24 hours before the onset of diarrhoea. Vomiting is most common in infants.[32]​​

While research has shown that there is an inverse relationship between advancing age and the typical Campylobacter presentation, there is a direct relationship between severity of illness and advancing age.[33]​​

Rare extra-intestinal manifestations include: perinatal infection, bacteraemia, meningitis, spontaneous peritonitis, cholecystitis, endocarditis, pancreatitis, cystitis, cellulitis, hepatitis, interstitial nephritis, placental infection, septic abortion, septic arthritis, septic thrombophlebitis, pneumonia, lung abscess, and empyema.[5]

Initial investigations

Stool samples should be collected for microscopy and culture as part of the initial investigation in all patients with suspected Campylobacter infection. A positive stool culture for Campylobacter is diagnostic.[14]​ Stool samples should be examined for red blood cells and neutrophils, which are present in the majority of patients with Campylobacter infection.[4][34][35]​​​

Current Canadian guidelines for investigating suspected infectious diarrhoea suggest that stool testing is not required in most cases of acute (≤7 days) or resolving diarrhoea.[36]​ The guideline recommends that the Infectious Diarrhea Panel, a new stool test that combines stool cultures, ova and parasites, and Clostridium difficile, should be requested if diarrhoea is severe of any duration or prolonged >7 days.[36]​ Isolation techniques and special media (Campy-BAP or Skirrow) are used to reduce the growth of other enteric organisms. Specific selective media and raised incubation temperatures are required to isolate Campylobacter species.[Figure caption and citation for the preceding image starts]: Campylobacter cultures grown on Skirrow's and Butzler's mediumSheila Mitchell, Image Library, US Centers for Disease Control and Prevention [Citation ends].com.bmj.content.model.Caption@7c5bf3f0​​​

Patients with late-onset complications from Campylobacter infection (e.g., bacteraemia, cardiac complications, extra-intestinal manifestations, reactive arthritis, and Guillain-Barre syndrome) may have negative stools, either due to loss of the bacteria or because of antimicrobial treatment. In these patients, a serological test can be used to detect antibodies to Campylobacter to indicate exposure.[4][37]

Blood culture can isolate Campylobacter species as bacteraemia can transiently occur in the early stages of infection.[38]​ Blood culture is not recommended as an initial test in people with features of Campylobacter infection, because the diagnosis can usually be made by stool culture alone. Symptoms of bacteraemia or other extra-intestinal manifestations do warrant additional investigation with blood cultures.

White blood cell count is often normal in cases of Campylobacter infection, but a left shift (increase in neutrophil predominance) may occur.[34]​ Campylobacter infection may be associated with lymphopenia.​[39]

Other tests

Intestinal biopsy is rarely used to make the diagnosis of Campylobacter infection but can help distinguish between infectious and inflammatory causes of diarrhoea if the diagnosis of infection is in question. Biopsy histological evaluation would detect oedema, inflammatory changes, cryptitis, or crypt abscess formation associated with Campylobacter infection.[2]​[4]​

Faecal microscopy is able to demonstrate the characteristic darting motility of the organisms, although in practice it is rarely performed. Examination by darkfield or phase-contrast microscopy can also be used to assist with presumptive diagnosis.[4]​​

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