Yersinia enterocolitica

Yersinia enterocolitica on Endo agar with biochemical slope (see here). Glucose fermenation without gas production, urea usually positive(about 75%), H₂S negative. Lactose negative (ONPG test positive), sucrose and mannnitol positive. Fig.D: Endo agar with biochemical slope before inoculation. Yersinia enterocolitica usually forms small colonies on Endo agar after 24 hour of cultivation (Fig.E). Fig.F: colonies on blood agar after prolonged cultivation at room temperature.

Yersinia enterocolitica is a species of gram-negative coccobacillus-shaped bacterium, belonging to the family Enterobacteriaceae. Yersinia enterocolitica infection causes the disease yersiniosis which is a zoonotic disease occurring in humans as well as a wide array of animals such as cattle, deer, pigs, and birds. Many of these animals recover from the disease and become asymptomatic carriers.

Acute Y. enterocolitica infections usually lead to mild self-limiting entero-colitis or terminal ileitis in humans. Symptoms may include watery or bloody diarrhea and fever. After oral uptake yersiniae replicate in the terminal ileum and invade Peyer's patches. From here yersiniae can disseminate further to mesenteric lymph nodes causing lymphadenopathy. Ths condition can be confused with appendicitis and is therefore called pseudoappendicitis. In immunosuppressed individuals, yersiniae can disseminate from the gut to liver and spleen and form abscesses. Because Yersinia is a siderophilic (iron-loving) bacteria, people with hereditary hemochromatosis (a disease resulting in high body iron levels) are more susceptible to infection with Yersinia (and other siderophilic bacteria). Yersiniae are usually transmitted to humans by insufficiently cooked pork or contaminated water.

Abbreviated from Wikipedia.