Campylobacter jejuni is a Gram-negative bacterium and one of the most important causes of bacterial gastroenteritis worldwide. It is particularly associated with poultry, but it can also spread through contaminated water, unpasteurized milk, other foods, animals, and contaminated surfaces. Infection usually affects the intestinal tract and causes diarrhea, abdominal pain, and fever. Most people recover without specific treatment, but some infections can be severe or lead to complications after the initial illness. Understanding how C. jejuni is transmitted and how the infection is diagnosed and treated can help reduce the risk of illness.
What is the history and naming of Campylobacter jejuni?
Campylobacter jejuni has a long history in microbiology, although its importance as a human pathogen became clear only after better laboratory methods were developed.
Spiral-shaped organisms resembling Campylobacter were described as early as the 1880s. Theodor Escherich produced drawings of organisms now understood to have been campylobacters, although the bacteria could not initially be studied using the culture techniques available at the time.
During the twentieth century, related organisms were increasingly identified in animals and humans. Improvements in bacterial culture and identification eventually established C. jejuni as an important cause of human intestinal infection. By the late 1970s, its role in human enteritis was well recognized.
The name Campylobacter comes from Greek words referring to a curved or bent rod, reflecting the organism's characteristic shape. The species name jejuni refers to the jejunum, part of the small intestine.
Today, C. jejuni belongs to the family Campylobacteraceae and is one of the principal human-pathogenic species within the genus Campylobacter. Campylobacter coli is another important human pathogen in the same genus.
What disease does Campylobacter jejuni cause and what are the symptoms?
Campylobacter jejuni causes campylobacteriosis, an intestinal infection that most often produces acute diarrhea, abdominal pain, and fever.
· Diarrhea, which may be watery or bloody
· Abdominal cramps or pain
· Fever
· Nausea
· Vomiting in some people
· Fatigue and general weakness
Symptoms usually develop after an incubation period following exposure to the bacterium. The infection can produce inflammation and injury in the intestinal tract, which contributes to diarrhea and abdominal pain. Bacterial factors involved in movement, attachment to intestinal cells, invasion, and interaction with the immune system all contribute to disease.
Most cases are self-limiting, meaning they improve without specific antimicrobial treatment. However, illness can occasionally become severe, particularly in people who are more vulnerable to complications.
In uncommon cases, Campylobacter infection can be followed by conditions affecting other parts of the body. Recognized post-infectious complications include reactive arthritis and Guillain–Barré syndrome.
Guillain–Barré syndrome is particularly important because Campylobacter infection is a recognized trigger for this uncommon neurological disorder. The condition occurs when the immune system attacks components of the peripheral nervous system and can cause weakness or, in severe cases, paralysis.
How is Campylobacter jejuni transmitted?
Campylobacter jejuni is transmitted mainly through the fecal–oral route, with contaminated food and water being important sources of human infection.
Poultry is a particularly important reservoir. Chickens can carry C. jejuni in their intestinal tract without appearing ill. During slaughter and processing, intestinal contents can contaminate poultry meat. If contaminated meat is not adequately cooked, bacteria can survive and cause infection.
1. Undercooked poultry: Insufficient cooking can leave viable bacteria in meat.
2. Cross-contamination: Bacteria from raw poultry can spread to hands, utensils, cutting boards, kitchen surfaces, or foods that will not be cooked.
3. Unpasteurized milk: Raw milk can become contaminated with Campylobacter.
4. Contaminated water: Untreated or contaminated water can carry the bacterium.
5. Animal contact: Domestic animals, livestock, and other animals can carry Campylobacter.
6. Environmental exposure: Wild birds and agricultural environments can contribute to contamination.
Person-to-person transmission can occur but is generally less important than foodborne and animal-associated routes.
The bacterium is challenging to control because it occurs in a wide range of animal hosts and can move through several stages of the food chain. Prevention therefore requires measures at farms, during food processing, in retail settings, and in the home.
How is Campylobacter jejuni diagnosed?
Campylobacter jejuni infection is diagnosed using laboratory testing, usually from a stool sample.
Stool culture has traditionally been an important diagnostic method. The bacterium is relatively fastidious, meaning that it needs specific environmental and nutritional conditions to grow. Laboratories therefore use selective culture media and controlled atmospheric conditions to recover the organism.
Modern laboratories can also use molecular tests that detect bacterial genetic material. These tests can provide rapid detection and are increasingly used for diagnosing gastrointestinal infections.
Culture remains useful even when molecular testing is available because obtaining a bacterial isolate can allow further characterization and antimicrobial susceptibility testing.
The choice of test depends on the clinical situation and the laboratory facilities available.
How is Campylobacter jejuni infection treated?
Most uncomplicated Campylobacter jejuni infections are treated with supportive care, particularly adequate fluid and electrolyte replacement.
Because many infections resolve on their own, antibiotics are not automatically required. They may be considered when illness is severe, prolonged, invasive, or occurs in a person at increased risk of complications.
When antibiotic treatment is appropriate, macrolides such as azithromycin are important treatment options. However, antimicrobial resistance is a significant concern in Campylobacter. Resistance to fluoroquinolone antibiotics has increased substantially, and resistance to other antimicrobial classes is also monitored.
Treatment decisions can therefore depend on:
· Severity of the illness
· Duration of symptoms
· Whether the infection has spread beyond the intestine
· Individual risk factors
· Local antimicrobial-resistance patterns
· Laboratory susceptibility results when available
People with diarrhea should pay particular attention to fluid replacement because significant diarrhea can lead to dehydration.
Antibiotics should not be self-started for suspected Campylobacter infection. A healthcare professional can determine whether testing or antimicrobial treatment is appropriate.
How can Campylobacter jejuni infection be prevented?
Preventing Campylobacter jejuni infection depends largely on reducing exposure to contaminated food, water, animals, and surfaces.
In the kitchen
· Cook poultry and other meats thoroughly.
· Keep raw poultry separate from ready-to-eat foods.
· Wash hands after handling raw meat.
· Clean cutting boards, knives, counters, and other food-contact surfaces.
· Avoid unpasteurized milk and dairy products.
· Use safe drinking water.
· Refrigerate perishable foods appropriately.
Cross-contamination is especially important. Raw poultry can transfer bacteria to foods that will not subsequently be cooked. Keeping raw and cooked foods separate reduces this risk.
Around animals
Wash hands after touching pets, livestock, poultry, animal feces, cages, bedding, or other materials that may be contaminated.
Across the food chain
Prevention does not begin in the kitchen. Measures at farms and food-processing facilities can also reduce contamination. These include improved farm biosecurity, environmental controls, hygienic slaughter and processing, and interventions designed to reduce Campylobacter colonization in poultry.
Because the bacterium has multiple animal and environmental reservoirs, no single intervention eliminates the risk. Combining measures across the food chain provides a stronger prevention strategy.
What are the key characteristics of the Campylobacter jejuni microbe?
Campylobacter jejuni has several distinctive microbiological features that influence how it grows, survives, and causes infection.
C. jejuni is Gram-negative, meaning its cell envelope has the structural characteristics associated with Gram-negative bacteria, including an outer membrane.
Its characteristic curved or spiral shape is readily visible under suitable microscopy. The organism is also motile, with flagella that help it move through its environment and contribute to colonization of the intestinal tract.
It is microaerophilic, meaning it requires oxygen but grows best at oxygen concentrations below those found in ordinary atmospheric air. This requirement is important when laboratories culture the organism.
C. jejuni also has a preference for relatively high temperatures, with approximately 42°C commonly used for selective growth. This characteristic is associated with its adaptation to avian hosts, whose body temperatures are generally higher than those of humans.
Unlike some bacterial pathogens, C. jejuni does not form bacterial endospores.
Taxonomy
Domain: Bacteria
Phylum: Campylobacterota (formerly Proteobacteria)
Class: Campylobacteria
Order: Campylobacterales
Family: Campylobacteraceae
Genus: Campylobacter
Species: Campylobacter jejuni
What are the most important facts about Campylobacter jejuni?
· It is a major foodborne pathogen: C. jejuni is an important cause of bacterial gastroenteritis worldwide.
· It commonly comes from animals: Poultry and other animals can carry the bacterium without obvious illness.
· Food is an important route of infection: Undercooked poultry and cross-contaminated foods are major concerns.
· It usually affects the intestine: Diarrhea, abdominal pain, and fever are typical symptoms.
· Most infections resolve: Supportive care is sufficient for many uncomplicated cases.
· Some infections cause complications: Guillain–Barré syndrome and reactive arthritis are recognized post-infectious complications.
· Laboratory testing can confirm infection: Culture and molecular tests are important diagnostic approaches.
· Antibiotic resistance matters: Resistance can affect treatment choices.
· Food hygiene is central to prevention: Cooking, separation of raw and cooked foods, hand hygiene, pasteurization, and safe water all reduce risk.
· Its biology is distinctive: It is a curved, motile, non-spore-forming, microaerophilic, Gram-negative bacterium that grows preferentially around 42°C.
Reference
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