Yersinia enterocolitica is a species of gram-negative coccobacillus-shaped bacterium, belonging to the family Enterobacteriaceae. Infection from Yersinia enterocolitica causes the zoonotic disease yersiniosis. Most infected animals recover from the disease and become asymptomatic carriers.
Acute infections lead to mild self-limiting entero-colitis or terminal ileitis in humans. Symptoms include watery or bloody diarrhea and fever. After oral uptake it replicates in the terminal ileum and invade Peyer’s patches. From there it can disseminate further to mesenteric lymph nodes causing lymphadenopathy which can be confused with appendicitis. In immunosuppressed individuals, yersiniae can disseminate from the gut to liver and spleen and form abscesses. People with hereditary hemochromatosis are more susceptible to infection. It is usually transmitted to humans by insufficiently cooked pork or through contaminated water.
Normally no treatment is required, but in severe cases doxycycline in combination with an aminoglycoside is used. There are other antibiotics that can be used to treat it although Y. enterocolitica is normally resistant to penicillin G, ampicillin and cephalotin due to beta-lactamase production. Sometimes infection is followed by chronic inflammatory diseases such as arthritis.
It is associated with autoimmune Graves-Basedow thyroiditis. There is indirect evidence, however, direct evidence is limited thus Y. enterocolitica is probably not a major cause of this disease. It is also not the cause but an associated condition of auto-immune thyroid disease.