Y. enterocolitica
Etiology/Bacteriology
Taxonomy
| Domain = Bacteria
| Phylum = Proteobacteria
| Class = Gammaproteobacteria
| Order = Enterobacteriales
| Family = Enterobacteriaceae
| Genus = Yersinia
| species = Y. enterocolitica
Description
Pathogenesis
Transmission
Yersinia enterocolitica is found in meats (pork, beef lamb ect) fish, and raw milk. Exact reason for food contamination is unknown (CDC). Yersinia enterocolitica infection results in yersiniosis—a zoonotic disease that occurs in humans, cattle deer, birds and pigs (CDC). Only a few strains cause infection in humans, and children are infected more often than adults. There are over 60 serotypes for Yersinia enterocolitica . The serotypes pathogenic to humans are O:3, O:5,27, O:8, O:9, and O:13.
Invasion
Y. enterocolitica can efficiently colonize the small intestine. After entering the host, bacteria colonize on the lumen and invade the epithelial lining—resulting in peyer patches. Y. enterocolitica colonization requires the transfer of the bacteria across the epithelial tissue barrier. Produces 3 invasions proteins—Ail, YadA and invasin. These proteins promote adherence and invasion of M cells, a type of antigen-sampling intestinal epithelial cells.
Infectious dose, incubation, and colonization
The infectious dose for Yersinia enterocolitica is currently unknown. Illness takes place between 24 and 48 hours after ingestion. Illness typically presents as Diarrhea—sometimes bloody—low-grade fever, abdominal pain and vomiting is present in 15-40% of cases. Yersiniosis does not often occur. Most food processing techniques eliminate the risk for infection.
Epidemiology
The most susceptible populations to Y. enterocolitica are small children, immuno-suppressed, and the elderly. 75% of patients are between the age of 5-15 years. Most isolates of the disease are type O:3 and O:9 serotypes in Canada and Europe. In the US it is estimated that approximately 5% of bacterial enteric infections for children under the age of 5.The CDC claims 17,000 cases annually in the United States. The disease is much more common in Northern Europe, Scandinavia, and Japan.
=Virulence Factors
Enterotoxicity
The enterotoxin produced by Y. enterocolitica is similar to E. coli . Nevertheless, the enterotoxin only plays a minor role in pathogenesis, because diarrheal symptoms have been observed with the absence of enterotoxin formation. The outer membrane antigens are associated with bacterial resistance to opsonization and neutrophil phagocytosis
Iron and pathogenicity
Y. enterocolitica is unable to chelate iron. Despite not being able to produce siderophores-- Y. enterocolitica can utilize siderophores produced by other bacteria.
Clinical Features
Diagnosis
Stool cultures are the best way to confirm diagnosis, and the culture is typically positive within 2 weeks of the onset of disease. Enzyme-linked immunosorbent assays, radioimmunoassay, imaging studies and a colonoscopy may also be used to diagnosis yersiniosis
Treatment
Infections by Yersinia enterocolitica are usually self-limiting and will resolve on their own in most patients who recover without any antibiotic treatment within a seven days to three weeks. Hydration is important in uncomplicated cases of diarrhea caused by the organism and will be sufficient treatment in the infection, however in severe or more complicated cases of infection antibiotic treatment may be necessary. The antibiotics commonly used are aminoglycosides, doxycycline, trimethoprim-sulfamethoxazole, or fluoroquinolones.
Prevention
Prevention of Yersinia enterocolitica infection is easy if one is aware of what to avoid. The most common mode of transmission is via poultry and livestock. Thus, avoid raw or undercooked meats. Make sure that milk products are pasteurized before consumption. If raw meat must be handled, clean hands thoroughly to avoid cross-contamination. Beware of cross-contamination in the kitchen by cleaning all surfaces and appliances with soap and hot water. Animal feces may also be contaminated so dispose of all animal waste properly.
Host Immune Response
References
Created by Emily Kurtz, Kristen Hoelscher, Dane Korber and Caitlyn Baukal, students of Tyrrell Conway at the University of Oklahoma
