Yersinia enterocolitica and Yersinia pestis
The genus Yersinia belongs to the family Enterobacteriaceae and consists of Gram-negative coccobacilli named after the French scientist Alexandre Yersin. The genus has 11 species (Yersinia enterocolitica, Y. pseudotuberculosis, Y. pestis, Y. frederiksenii, Y. intermedia, Y. kristensenii, Y. mollaretii, Y. bercovieri, Y. aldovae, Y. rhodei, and Y. ruckeri). The three species are well known to cause infections in humans include: Yersinia enterocolitica, Y. pseudotuberculosis, and Y. pestis. All three are facultative intracellular pathogens, harbor a 70-kb virulence plasmid (pVY), and exhibit tropism for lymphoid tissues. Yersinia enterocolitica is associated with foodborne infections resulting in gastroenteritis, mesenteric lymphadenitis, septicemia, and emerged as a human pathogen during 1930s. The Center for Disease Control and Prevention (CDC) estimates, about 87,000 cases of human diseases occur due to Y. enterocolitica infection annually in the US and 90% of those are foodborne. A recent US foodborne outbreak survey report indicates that between 1988 and 2002, there were 8 outbreaks linked to Y. enterocolitica with 87 cases. Yersinia pseudotuberculosis also causes gastrointestinal disorders, septicemia, and mesenteric adenitis. Yersinia pestis causes bubonic or pneumonic plague and the organism can be transmitted through contact with wild rodents and their fleas. Plague is an old-world disease and often referred to as “Black Death” and occurs in the bubonic or pulmonary forms.
Yersinia species can be differentiated based on their biochemical properties (Table 13.1). Yersinia grows on MacConkey agar, is catalase positive, oxidase negative, and ferments glucose. Most Yersinia species are noncapsulated except Y. pestis, which develops an envelope at 37 °C. All three pathogenic species share common antigens (O:3, O:8, O:9). In addition, all three species also share Yersinia outer membrane proteins (YOPs), V (immunogenic protein), and W (nonprotective lipoprotein) antigens. The fraction 1 envelope antigen (F1) is produced at 37 °C and has two major components; fraction 1A, polysaccharide, and 1B, a protein. Yersinia pestis has been identified as a subspecies of Y. pseudotuberculosis based on the 16S rDNA sequence. These two species also share 11 common antigens.
KeywordsYersinia Enterocolitica Yersinia Pestis Virulence Plasmid Virulence Gene Product Yersinia Species
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