E. Coli, Shigella, And Salmonella

Front 1

What is the gram stain, oxygen requirements and shape of the enterobacteriaceae?

Back 1

They are gram negative rods with rapid growth under both aerobic and anaerobic conditions

Front 2

Describe the abilities of E. coli, shigella, and salmonella to ferment lactose and glucose

Back 2

All of the three can ferment glucose, but only escherichia can ferment lactose

Front 3

What are the antigens commonly found with the enterobacteriaceae?

Back 3

O antigen, H antigen (flagella), K antigen (polysaccharide capsule)

Front 4

What are the major cellular antigens of E. coli?

Back 4

LPS (O antigen), capsule (K antigen), flagella, pili/fimbriae

Front 5

What capsule antigen is most important for disseminated E. coli infections?

Back 5

The K1 antigen

Front 6

What role does the pili of E. coli play in it's virulence?

Back 6

It aides in the adherence to the mucosal surfaces

Front 7

What type of fimbriae are associated with enterotoxigenic E. coli?

Back 7

CFA fimbriae

Front 8

What type of fimbriae is found in all normal flora intestinal isolates and UTI isolates of E. coli?

Back 8

Type 1 fimbriae

Front 9

What are the types of exotoxins secreted by E. coli?

Back 9

1) Enterotoxins 2) Shiga-like toxins 3) hemolysin

Front 10

What are the two types of enterotoxins produced by E. coli and what strains produce them?

Back 10

The enterotoxins are the heat-labile toxin (LT) and the heat-stable toxin (ST); they are NOT found in normal flora E. coli but instead are produced by the enterotoxigenic E. coli (ETEC)

Front 11

What exotoxin of E. coli has the same mechanism of action as the cholera toxin? What is the MOA?

Back 11

The heat-labile enterotoxin has the same mechanism of action as cholera toxin - it activates adenylate cyclase and causes fluid secretion

Front 12

What type of E. coli produce the Shiga-like toxin?

Back 12

The shiga-like toxin is produced by enterohemorrhagic E. coli EHEC); it is NOT produced by normal flora E. coli

Front 13

What symptoms are produced by the entertoxin?

Back 13

Watery diarrhea (such as traveler's diarrhea)

Front 14

What is the disease caused by the shiga-like toxin?

Back 14

Enterohemorrhagic colitis

Front 15

What sort of disease is caused by the shiga-like toxin?

Back 15

The shiga-like toxin has activity identical to the shiga toxin from Shigella and inhibits protein synthesis in target cells; it causes hemolytic uremic syndrome with a bloody diarrhea and destruction of renal endothelium

Front 16

What is the normal habitat of E. coli?

Back 16

The intestinal tract of animals and humans

Front 17

How does E. coli cause urinary tract infections and invasive disease?

Back 17

One's own normal intestinal flora spreads to these body areas

Front 18

How does E. coli cause intestinal infections?

Back 18

These are caused by the fecal-oral spread of new unique strains of E. coli that have acquired additional virulence factors on plasmids of phage

Front 19

Describe the transmission of the enterohemorrhagic E. coli. What kind of toxin does it produce?

Back 19

The transmission of the EHEC is via animal-to-human transmission; it makes the shiga-like toxin

Front 20

Describe the transmission of the enterotoxigenic E. coli. What kind of toxin does it produce?

Back 20

The transmission of the ETEC is via human-to-human transmission; it produces the enterotoxins

Front 21

What strain or E. coli is responsible for bloody diarrhea and kidney failure?

Back 21

O157:H7

Front 22

What are the clinical manifestations of enterohemorrhagic E. coli?

Back 22

It begins as a watery diarrhea followed by bloody diarrhea; children may develop HUS (kidney failure and hemolytic anemia)

Front 23

What is the difference between the diarrhea of EHEC and dysentery of Shigella species?

Back 23

Shigella dysentery shows pus in the stools and fever, both of which are NOT seen in EHEC hemorrhagic colitis

Front 24

Describe the pathogenesis of enterohemorrhagic colitis

Back 24

The shiga-like toxin causes destruction of the epithelial cells in the colon leading to bloody diarrhea and shiga-like toxin circulation into the bloodstream which allows for destruction of renal endothelial and glomeruli (local infection with systemic toxemia)

Front 25

What is important about the treatment of enterohemorrhagic e. coli?

Back 25

It should NOT be treated with an antibiotic because it will enhance the Shiga-toxin release, making the HUS worse

Front 26

What populations usually see enterotoxigenic E. coli infections?

Back 26

Infants and children in developing countries or tourists to those countries

Front 27

Describe the clinical manifestations of enterotoxigenic E. coli infection (ETEC)

Back 27

A watery diarrhea that may produce a severe cholera-like disease with absent fever

Front 28

Describe the pathogenesis of ETEC

Back 28

It is similar to cholera toxin and shows production of one or both of the enterotoxins (LT or ST) with no invasion (bacteria remain localized in the small intestines)

Front 29

What are the two main species of shigella?

Back 29

S. dysenteriae and S. sonnei

Front 30

What are the major cellular antigens of Shigella?

Back 30

The major cellular antigens are LPS (O-antigen), and invasion plasmid antigens that are essential for the entry into intestinal epithelial cells

Front 31

Describe the toxin produced by Shigella

Back 31

The Shiga toxin is a lethal toxin which kills target cells by inhibiting protein synthesis causing a bloody diarrhea with local infection and a killing of renal endothelial cells with a systemic infection

Front 32

Why is S. dysenteriae more pathogenic than S. sonnei?

Back 32

It produces nearly 1000 times more shiga toxin

Front 33

Where is shigella commonly found?

Back 33

It is commonly found in the intestinal tract of humans with disease but is NOT NORMAL FLORA and has no animal carriers

Front 34

How is Shigella transmitted?

Back 34

It is transmitted by the fecal-oral route and is largely a pediatric disease (caused by S. sonnei)

Front 35

Describe the clinical manifestations of Shigellosis including which species is the cause

Back 35

Shigellosis is generally caused by S. sonnei, flexneri and boydii and produces a watery diarrhea that is NOT the classical dysentery

Front 36

Describe the pathogenesis of shigellosis

Back 36

The bacteria invade the colonic epithelial cells and reproduce intracellularly, small amounts of Shiga toxin are produced

Front 37

Describe the clinical manifestations of bacterial dysentery and name the causative species

Back 37

Bacterial dysentery is caused by S. dysenteriae with symptoms of small volume bloody diarrhea and mucoid discharge with fever as well as hemolytic uremic syndrome and extensive ulceration in severe cases

Front 38

Describe the pathogenesis of bacterial dysentery

Back 38

The bacteria invade the colonic epithelium and replicate intracellularly with production of large amounts of the Shiga toxin; large amounts of leukocytes and red cells appear in the stools

Front 39

How is shigella diagnosed and what is important to consider when treating?

Back 39

It is diagnosed based on stool cultures and should NOT be treated with antibiotics when showing signs of HUS

Front 40

Which serotypes of Salmonella cause food poisoning (gastroenteritis)

Back 40

S. typhimurium and S. enteritidis

Front 41

What serotypes of Salmonella cause typhoid fever?

Back 41

S. typhi and a. paratyphi

Front 42

What are the major cellular antigens of shigella?

Back 42

LPS endotoxin (O antigen) and adhesion and invasion antigens required for growth inside macrophages

Front 43

What type of salmonella has enterotoxins?

Back 43

S. enteritidis

Front 44

What is the primary reservoir for salmonella and how do humans become infected?

Back 44

The major reservoir is the intestinal tract of animals, with humans becoming infected through the ingestion of contaminated water or food and high rate of secondary spread via human to human contact

Front 45

What are the most common sources of salmonella?

Back 45

Poultry and eggs (salmonella inside the yolk and egg white) as well as pet reptiles

Front 46

Describe the gastroenteritis caused by salmonella

Back 46

It has an incubation period following infection and shows a nausea and vomiting that progresses to abdominal pain and diarrhea with fever

Front 47

Describe the pathogenesis of a salmonella infection

Back 47

The ingested bacteria invade and replicate in epithelial cells of the small and large intestines, as well as the macrophages; there is NO bloodstream invasion except in compromised patients

Front 48

What is Reiter's Syndrome?

Back 48

An autoimmune linked syndrome which is a response to an infection in another part of the body with symptoms of arthritis of large joints, inflammation of the eyes, and urethritis; associated with chlamydia trachomatis, salmonella, shigella, yersinia, or campylobacter

Front 49

What is the distinctive antigen of salmonella typhi?

Back 49

The Vi capsular antigen which aids in bloodstream spread

Front 50

What causes typhoid fever?

Back 50

Salmonella typhi

Front 51

Describe the pathogenesis of typhoid fever

Back 51

The bacteria invade the submucosa via M cells and multiply within the macrophages and spread to the bloodstream, liver, spleen and bone marrow all the while asymptomatic!

Front 52

What happens in the pathogenesis of typhoid after the bacteria spread to the liver?

Back 52

Increased numbers in the liver lead to a sustained bacteremia with high fever spreading to the kidney, gallbladder, peyers patches and skin

Front 53

How does the carrier state of typhoid occur?

Back 53

A chronic infection in the gallbladder with the bacteria constantly shed in the bile/feces

Front 54

What are the two vaccines for typhoid fever and who should receive them?

Back 54

Travelers to developing countries should receive them; one is a purified Vi capsular polysaccharide and the other is a live attenuated S. typhi strain