Yersinia enterocolitica

Yersinia enterocolitica

Yersinia is a genus of Gram-negative bacteria that contains 11 known species. Among them, four are pathogenic, but only Yersinia enterocolitica and Yersinia pseudotuberculosis are commonly associated with gastroenteritis in humans.

Overview

Both Y. enterocolitica and Y. pseudotuberculosis are small, rod-shaped, facultatively anaerobic bacteria. They are significant causes of diarrheal disease and share similar mechanisms of infection and transmission.

Transmission

These bacteria are primarily transmitted through the fecal–oral route, typically via the ingestion of contaminated food or water.

Y. enterocolitica and Y. pseudotuberculosis have been isolated from a range of animal reservoirs including:

• Pigs
• Birds
• Beavers
• Cats and Dogs
• (For Y. enterocolitica): Frogs, flies, and fleas

Environmental sources such as soil and untreated water (e.g., ponds and lakes) have also been implicated in the spread of Y. enterocolitica. However, most strains isolated from these environments are considered non-pathogenic.

Pathogenesis

3D image of Yersinia enterocolitica

• Mortality: Rarely fatal.
• Infective dose: Estimated to be between 10⁴ to 10⁶ organisms.
• Incubation period: Typically 1 to 11 days, but in rare cases, it can last up to several months.
• Entry: Oral ingestion of contaminated food or water.

Once inside the host, the bacteria colonize the intestinal mucosa and release enterotoxins and cytotoxins that cause tissue damage and inflammation.

Symptoms

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Yersinia enterocolitica

Infection with Y. enterocolitica typically presents as a self-limiting diarrheal illness, most commonly in children under the age of 5.

Common symptoms include:

• Diarrhea (sometimes bloody stool)
• Vomiting
• Fever
• Abdominal pain (especially in the right lower quadrant)
• Headache
• Sore throat

The illness mimics appendicitis and mesenteric lymphadenitis. It can also manifest in other sites such as wounds, joints, and the urinary tract.

Duration: Ranges from a few days to three weeks. In chronic cases, chronic enterocolitis may persist for several months.

Complications

While the primary infection is self-limited, a small number of patients may develop:

• Reactive arthritis (especially in individuals with HLA-B27)
• Glomerulonephritis
• Endocarditis
• Erythema nodosum (more common in women)
• Uveitis
• Graves' disease, hyperthyroidism, nontoxic goiter, Hashimoto's thyroiditis
• Bacteremia (rare)

In Japan, Y. pseudotuberculosis has been associated with the development of Kawasaki disease.

Reactive Arthritis

Post-infectious arthritis occurs in 2–3% of yersiniosis cases. It may present without obvious gastrointestinal symptoms. The arthritis usually affects large joints and can be mistaken for rheumatic disease.

Diagnosis

Diagnosis is confirmed through:

• Stool culture
• Serology
• PCR
• Radiologic imaging for complications

Treatment

Most cases resolve with supportive care such as fluid and electrolyte replacement. However, in cases of sepsis or invasive infection, treatment may include:

• Gentamicin
• Cefotaxime
• Doxycycline
• Ciprofloxacin

Prevention

Preventive measures include:

• Proper food handling and cooking
• Avoidance of unpasteurized dairy products
• Handwashing after contact with animals or soil

See also

• Yersiniosis
• Zoonotic disease
• Reactive arthritis
• Enterobacteriaceae