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15 Cards in this Set

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  • Back
What are the 4 species of Shigella?
1. S. dysentariae
2. S. flexneri
3. S. boydii
4. S. sonnei
All are non-motile.
List three properties that can distinguish Shigella from E. coli?
1. Shigella has no flagella.
2. Does not ferment lactose.
3. Does not produce H2S.
Humans are the only hosts of Shigella, and it is never a part of the normal flora. It is always a pathogen. TRUE/FALSE
How is Shigella similar to E. coli/
They both invade intestinal epithelial cells and release Shiga toxin. With Shiga toxin, on colonoscopy there are shallow ulcers where cells have sloughed off. Diarrhea is the result of the colon not being able to absorb fluids.
The Shiga toxin targets the 60S ribosome, causing epithelial cell damage. TRUE/FALSE
What comprises the Shiga toxin?
There is an A subunit bound to 5 B subunits. The B subunits(b for binding), bind to the microvillus membranr in the colon, allowing the entry of the deadly A subunit(A for Action). They inactivate the 60S ribosome, inhibiting protein synthesis and killing the intestinal epithelial cell.
Salmonella is a non lactose fermenter, is motile and produces H2S. TRUE/FALSE
What is salmonells Vi antigen?
It is a polysaccharide capsule that surrounds the O antigen, protecting the bacteria from antibody attack on the O antigen. Vi is for virulence.
Though there are thousands of Salmonella serotypes, what are the three major groups?
1. S. typhi
2. S. cholerae-suis
3. S. enteritiditis
How is salmonella different from other enterics?
It lives in the GI tract of animals and infects humans when there is contamination of food or water with animal feces.
Salmonella is not a zoonotic disease. It is carried only by humans. TRUE/FALSE
Salmonella is never considered a part of normal flora. It is always a pathogen. TRUE/FALSE
What are the 4 Salmonella disease states in humans?
1. Typhoid fever
2. Carrier state
3. Sepsis
4. Gastroenteritis
What is Enteric fever?
It is Typhoid fever. After invading the intestinal epithelial cells, it invades the regional lymph nodes, finally seeding multiple organs systems. The bacteria are phagocytosed by monocytes and can survive intracellularly. It is a facultative intracellular parasite.
Salmonella starts 1-3 weeks after exposure. TRUE/FALSE