Micro/digestion

Front 1

Typhoid fever is so named because it bears a superficial resemblance to typhus, a rickettsial disease, despite that the two diseases are quite different. TRUE/FALSE

Back 1

TRUE.

Front 2

What causes Typhoid fever?

Back 2

It is caused by the typhi serovar of S. enterica and characterized by a progressive, invasive infection that leads eventually to septicemia.

Front 3

What are the symptoms of Typhoid fever?

Back 3

Fever, diarrhea and abdominal pain. It infiltrates the mesenteric lymphnodes and phagocytes of the liver and spleen. occasionally, the small intestine may develop ulcers and perforations.

Front 4

Does Salmonella possess a virulence factor?

Back 4

There is believed to be an island of genes in Salmonells that seems to confer virulence on the bacterium.

Front 5

How is salmonella transmitted?

Back 5

Animal products such as meat and milk can be readily contaminated during slaughter.
It has been spread via rodent feces.
There was a breakout in Colorado after visitors were exposed to the railings of the Kimodo dragon exhibit.

Front 6

is there a treatment protocol for Salmonella?

Back 6

Uncomplicated cases of Salmonella are treated with fluid and electrolyte replacement. if the disease is severe, Trimethoprim-sulfamethoxazole is recommended.
Typhoid fever is always treated with antibiotics.
Some may carry the organism unsymptomatically in their gall bladder.

Front 7

What are Shigella?

Back 7

They are Gram - straight rods, nonmotile and non spore forming. They are usually human parasites, but will infect apes.

Front 8

Stool culture is still the gold standard for identification in the case of Shigella. TRUE/FALSE

Back 8

True.

Front 9

hich serovar causes the most severe case of shigellosis?

Back 9

Shigella dysenteriae, though it is uncommon in the US.
The two most prevalent strains are S. sonnei and flexneri.

Front 10

Are nausea and vomiting common signs of Shigellosis?

Back 10

Yes. Fever and abdominal pain may accompany this as well. Diarrhea with blood from an infectious source is usually referred to as dysentery.

Front 11

What is the pathogenesis of Shigella?

Back 11

Shigella invades the villus cells of the large intestine, rather than the small. It is not as invasive as Salmonella.

Front 12

How does Shigella enter the intestinal mucosa?

Back 12

It enters the intestinal mucosa by means of lymphoid cells in Peyer's patches. Once there, it instigates an inflammatory reaction that causes extensive tissue destruction.

Front 13

Does Shigella possess an endotoxin?

Back 13

Yes. The release of endotoxin causes fever. Enterotoxin, an exotoxin that affects the enteric or GI tract damages the mucosa and villi. heavy bleeding and mucus secretion result.

Front 14

What is the Shiga toxin?

Back 14

It is a heat labile exotoxin, and appears to be responsible for the more serious damage to the intestine as well as other systemic effects, including injury to nerve cells. It is an A-B toxin.

Front 15

What is the A-B toxin?

Back 15

The B portion of the toxin attaches to host cells, and the whole toxin is internalized. Once inside, the A portion of the toxin exerts its effect. In the Shiga toxin, the A portion binds to ribosomes, interrupting protein synthesis and leading to the damage.

Front 16

How is Shigella transmitted?

Back 16

Aside from the usual oral route, it is also acquired through direct person to person contact, due to the small required dose of 10-200 bacteria. Lax sanitation appears to be a prime factor.

Front 17

Shigella can establish a chronic carrier condition in some people that lasts several months. TRUE/FALSE

Back 17

TRUE.

Front 18

What is the general treatment for Shigella?

Back 18

Trimethoprim-sulfamethoxazole.

Front 19

What is a particularly strain of E. coli?

Back 19

E. coli 0157:H7 and its close relatives are the most virulent. A particularly virulent form of E. coli is the enterohemorrhagic E. coli or EHEC.

Front 20

What are the signs of E. coli 0157:H7?

Back 20

Mild gastroenteritis with fever to bloody diarrhea.
About 10% of patients develop hemolytic uremic syndrome(HUS), a severe hemolytic anemia that causes kidney damage and possible failure.
Neurologic symptoms such as blindness, seizure and stroke are also possible. Young children are more commonly stricken.

Front 21

What is the pathogenesis of this form of E. coli?

Back 21

This bacterium owes much of its virulence to shiga toxins, because they are identical to the shiga exotoxin secreted by virulent shigella species.
Sometimes this E. coli is referred to as STEC(shiga toxin producing E. coli). The shiga toxin genes are present are present on bacteriophage in E.coli, but are on the chromosome of shigells dysenteriae.

Front 22

Are there any other virulence determinants for EHEC?

Back 22

Yes. They have an ability to efface enterocytes which are gut epithelial cells. This is done via a set of bacterial proteins, one called, intimin, used for intimate attachment to host cells.

Front 23

What is the type 111 secretion system?

Back 23

Another set of proteins enables the bacterium to construct a complex bridging system between E. coli and host cell membranes, which permits E. coli to insert its products into the host cell.

Front 24

is there a particularly interesting characteristic regarding the type 111 pipeline system?

Back 24

One of the products sent through the type 3 pipeline is a protein that the bacterium inserts into the host cell membrane so that it will become a receptor for the bacterial intimin protein.

Front 25

Ground beef is more dangerous than steaks or other cuts of meat regarding E. coli infection?

Back 25

True. The bacterium is a natural habitat of the GI tracts of cattle. When intestinal contents contact the animal carcass, so bacteria are confined to the surface of meats. Ground beef is ground up and the bacteria remain viable throughout the batch. It is important to cook hamburger meat completely through.

Front 26

Regarding culture and diagnosis, presence should be confirmed with stool culture or with newer techniques such as Elisa and PCR. TRUE/FALSE

Back 26

TRUE.

Front 27

Is the hamburger meat more dangerous today than it was 30 years ago?

Back 27

Yes. The emergence of this pathogen in the early 1980s has resulted from a regular E. coli picking upthe shiga toxin from shigella.

Front 28

Is ther treatment for this species of E. coli?

Back 28

Antibiotics are contraindicated for this infection. They may augment pathology. Antimotility drugs are contraindicated as well. Supportive therapy remains the only viable practical option.