Infection is caused by gram-negative, spiral-shaped microaerophilic bacteria of the family Campylobacteraceae. Most infections are caused by Campylobacter jejuni; other species, including C. coli, also cause infection. C. jejuni and C. coli are carried normally in the intestinal tracts of many domestic and wild animals.
The major modes of transmission include eating contaminated foods (especially undercooked chicken and foods contaminated by raw chicken), drinking contaminated water or raw (unpasteurized) milk, and having contact with animals, particularly farm animals such as cows and chickens, as well as domestic cats and dogs. Campylobacter can also be transmitted from person to person by the fecal-oral route.
Campylobacter is a leading cause of bacterial diarrheal disease worldwide; in the United States, it is estimated to cause 1.3 million human illnesses every year. Campylobacter is the most common laboratory-confirmed enteric pathogen reported in travelers returning to the United States from every region of the world. The risk of infection is highest in travelers to Africa and South America, especially in areas with poor restaurant hygiene and inadequate sanitation. The infectious dose is thought to be small, typically <500 organisms.
Incubation period is typically 2–4 days. Campylobacteriosis is characterized by diarrhea (frequently bloody), abdominal pain, fever, and occasionally nausea and vomiting. More severe illness can occur, including dehydration, bloodstream infection, and symptoms mimicking acute appendicitis or ulcerative colitis. Guillain-Barré syndrome is a well-established postinfectious complication of campylobacteriosis.
Diagnosis is traditionally based on isolation of the organism from stools by using selective media incubated under reduced oxygen tension at 42°C (107.6°F) for 72 hours. Visualization of motile and curved, spiral, or S-shaped rods by stool phase-contrast or darkfield microscopy can provide rapid presumptive evidence for Campylobacter enteritis. Rapid culture-independent tests are becoming more widely available and commonly used. Although these tests are convenient to use, their sensitivity and specificity are variable; in settings of low prevalence, the positive predictive value is likely to be low. When feasible, laboratories should confirm positive results by culture.
The disease is generally self-limited, lasting a week or less. Antibiotic therapy decreases the duration of symptoms if administered early in the course of disease. Because campylobacteriosis generally cannot be distinguished from other causes of travelers’ diarrhea without a diagnostic test, the use of empiric antibiotics in travelers should follow the guidelines for travelers’ diarrhea.
Rates of antibiotic resistance, especially fluoroquinolone resistance, have risen sharply in the past 20 years, and high rates of resistance are now seen in many regions of the world. Travel abroad is a risk factor for infection with resistant Campylobacter. Clinicians should suspect resistant infection in returning travelers with campylobacteriosis in whom empiric fluoroquinolone treatment has failed. When fluoroquinolone resistance is proven or suspected, azithromycin is usually the next choice of treatment, although resistance to macrolides has also been reported.
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