Yersinia: A group of bacteria that appear rod-like under the microscope and include Yersinia pestis (the cause of the bubonic and pneumonic plague), Yersinia entercolitic a (the cause of a disease called yersinosis), and Yersinia pseudotuberculosis (which causes a condition called mesenteric adenitis, particularly in immunocompromised patients). Both Y. entercolitica and Y. pseudotuberculosis have also been implicated in an unusual form of arthritis. Infection with Yersinia bacteria can be treated with antibiotics.
Yersinia is named after the Swiss bacteriologist Alexandre-Emile-Jean Yersin (1863-1943) who identified it in 1894 after a trip to Hong Kong looking for the agent that was killing thousands of people in southern China. Since the bacteria was also discovered at the same time by the Japanese bacteriologist Shibasaburo Kitasako, Yersinia could well have been named after him.