Author(s): Farrell Tobolowsky, Mark Laughlin, Rachael Aubert, Daniel Payne

Infectious Agent

Campylobacteriosis is caused by gram-negative, curved microaerophilic bacteria of the family Campylobacteriacae. Most infections are caused by Campylobacter jejuni; ≥18 other species, including C. coli, also cause human infections. C. jejuni and C. coli are carried normally in the intestinal tracts of many domestic and wild animals.

Transmission

The major modes of transmission include eating contaminated foods, especially undercooked chicken and foods contaminated by raw chicken, and consuming contaminated water or dairy products, most commonly unpasteurized milk. Transmission also occurs less commonly from contact with pets, particularly kittens and puppies, and farm animals (e.g., cows, poultry). Rarely, Campylobacter can be transmitted from person to person by the fecal–oral route. The infectious dose is small; <500 organisms can cause disease.

Epidemiology

Campylobacter is a leading cause of bacterial diarrheal disease worldwide and caused ≈96 million cases in 2010. In the United States, Campylobacter causes ≈1.5 million human illnesses every year. About 15% of illnesses are associated with international travel, and Campylobacter comprises a large proportion of travel-related enteric infections. All travelers are at risk for infection, but children <5 years of age, adults ≥65 years of age, males, and people with immunodeficiencies are at increased risk. Risk is greatest in US travelers to Africa, Asia, and South America, especially to areas where food handling practices and sanitation might not be adequate. The incidence of Campylobacter infection is greater in rural areas. Infection occurs year-round in low- and middle-income countries and exhibits late summer and fall seasonality in developed countries.

Clinical Presentation

The incubation period is typically 2–4 days but can range from 1–10 days. Illness is characterized by diarrhea (frequently bloody), abdominal pain, fever, and occasionally nausea and vomiting. More severe illness can occur, characterized by dehydration, bloodstream infection, or symptoms mimicking acute appendicitis or ulcerative colitis. Postinfectious complications include irritable bowel syndrome (in 9%–13% of patients), reactive arthritis (2%–5%), and Guillain-Barré syndrome (GBS; 0.1%). C. jejuni is the most frequently observed bacterial infection preceding GBS, and ≈5%–41% of all GBS cases could be attributed to campylobacteriosis; symptoms usually begin 1–3 weeks after the onset of enteritis.

Diagnosis

Campylobacteriosis diagnosis is traditionally based on isolation of the organism from stool specimens or rectal swabs by using selective media incubated under reduced oxygen tension at 42°C (107.6°F) for 72 hours. Direct detection in stool specimens using multi-analyte PCR panels has become common.

Collect stool specimens as early as possible after symptoms begin and before initiating antimicrobial drug treatment. Because the organism is fastidious, a delay in transporting the specimen to the laboratory will affect viability. If transport and processing are not possible within 2 hours of stool sample collection, place specimens in a transport medium, (e.g., Cary-Blair) according to standard guidelines. Laboratories might reject stool specimens without preservative that have been in transit for >2 hours. Campylobacter cannot be recovered from frozen specimens.

Culture and isolation of Campylobacter from the specimen are needed to subtype and test for antimicrobial susceptibility. Identification to the species level can be difficult using traditional biochemical methods; molecular methods, including PCR, 16S rRNA sequencing, or whole-genome sequencing often are required. Matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectroscopy provides a rapid, sensitive method for identifying Campylobacter species.

Culture-independent methods for direct detection of Campylobacter from stool specimens include both immunologic (antigen-based) and nucleic-acid amplification-based tests (NAATs). Several NAAT gastrointestinal panels are approved by the US Food and Drug Administration (FDA) to detect Campylobacter and a variety of other gastrointestinal pathogens. However, many of these panels detect only Campylobacter species, and reflex culture is required for further identification, subtyping, and antimicrobial susceptibility testing (AST). The Clinical and Laboratory Standards Institute (CLSI) provides methods and interpretive criteria for AST.

Broth microdilution or disk diffusion can be performed under microaerophilic conditions, and clinical interpretive criteria (also known as susceptibility breakpoints) are available for both methods for ciprofloxacin, erythromycin, and tetracycline. Broth microdilution breakpoints are also available for doxycycline. Azithromycin susceptibility or resistance can be predicted by erythromycin testing.

Sensitivity and specificity of stool antigen tests are variable; in settings of low prevalence, the positive predictive value is likely to be low. Therefore, laboratories should confirm positive results of stool antigen tests by culture. Campylobacteriosis is a nationally notifiable disease in the United States.

Treatment

Campylobacteriosis is generally self-limited in healthy people, lasting ≤1 week and requiring only fluids and supportive care. Antimicrobial drug therapy decreases the duration of symptoms and bacterial shedding if administered early during illness. Because campylobacteriosis generally cannot be distinguished from other causes of travelers’ diarrhea without a diagnostic test, use of empiric antibiotics in travelers should follow the guidelines for travelers’ diarrhea (see Sec. 2, Ch. 6, 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, especially in South America and Southeast Asia. Travel abroad is a risk factor for infection with antimicrobial-resistant Campylobacter. Suspect resistant infections in returning travelers with campylobacteriosis in whom empiric fluoroquinolone treatment has failed. Macrolides like azithromycin are the current drugs of choice when antimicrobial drug treatment is indicated. Intravenous antibiotics might rarely be required for severe infections or for highly resistant strains.

Prevention

No vaccine is available. Travelers can best prevent infection by adhering to standard food and water safety precautions (see Sec. 2, Ch. 8, Food & Water Precautions) and by washing hands thoroughly with soap and water after contact with animals or environments that might be contaminated with animal feces. Antibiotic prophylaxis is not recommended.

CDC website: Campylobacter