Yersinia enterocolitica is a gram-negative bacillus shaped bacterium that causes a zoonotic disease called yersiniosis. The infection is manifested as acute diarrhea, mesenteric adenitis, terminal ileitis, and pseudoappendicitis. In rare cases, it can even cause sepsis.

In some countries, yersinia infections have overtaken shigella and salmonella species as the most common cause of bacterial gastroenteritis. While most cases are sporadic, large outbreaks are not uncommon. Humans acquire yersinia after consumption of contaminated food as well as a blood transfusion. The one key feature of yersinia is that the individual will continue to shed the organism in feces for nearly 3 months after symptoms have subsided- thus detection of yersinia in stools is critical.

The genus Yersinia includes 11 species, of which 3 are notable for causing human diseases: Yersinia pestis, Yersinia enterocolitica, and Yersinia pseudotuberculosis. Yersinioses are zoonotic infection with the human being the incidental hosts who do no contribute to the life cycle for the pathogen.

Yersinia are classified based on their biochemical features and of the 6 biotypes, subtypes 2,3, and 4 are most common in humans.

The genus Yersinia is best known for Yersinia pestis, a gram-negative rod that causes the plague. However, Y. enterocolitica and Y. pseudotuberculosis can cause gastroenteritis. The infection is generally transmitted through the fecal-oral route, with ingestion of food or water that has been contaminated by feces. Intoxication can also result because of the activity of its endotoxin and exotoxins (enterotoxin and cytotoxin necrotizing factor). The illness is normally relatively mild and self-limiting. However, severe diarrhea and dysentery can develop in infants. In adults, the infection can spread and cause complications such as reactive arthritis, thyroid disorders, endocarditis, glomerulonephritis, eye inflammation, and/or erythema nodosum. Bacteremia may develop in rare cases.

Diagnosis is generally made by detecting the bacteria in stool samples. Samples may also be obtained from other tissues or body fluids. Treatment is usually supportive, including rehydration, without antibiotics. If bacteremia or other systemic disease is present, then antibiotics such as fluoroquinolones, aminoglycosides, doxycycline, and trimethoprim-sulfamethoxazole may be used. Recovery can take up to two weeks.