Salmonella and Shigella

Question 1

Gram negative rod enterobacteria: what 3 species could they be?

Answer 1

Salmonella, Shigella, E Coli

Question 2

What are some specific bacterial surface elements that differentiate serotypes?

Answer 2

O antigens, H antigens, K antigens

Question 3

Causes typhoid fever

Answer 3

Salmonella Typhi

Question 4

Salmonella strain that causes gastroenteritis

Answer 4

S. cholerasuis and S. enteriditis/typhimurium

Question 5

2 salmonella strains that cause bacteremia

Answer 5

S. Typhi and S. Cholerasuis

Question 6

1 Salmonella strain that does NOT cause bacteremia

Answer 6

S. Enteriditis/Typhimurium

Question 7

Salmonella strain that possesses Vi capsule

Answer 7

S. Typhi

Question 8

Salmonella strain that has incubation period of 7-14 days

Answer 8

S. Typhi

Question 9

Salmonella strain that is most common in US

Answer 9

S. Enteriditis/Typhimurium

Question 10

Sal strain that may be asymptomatic with a + stool culture

Answer 10

S Typhi

Question 11

Salmonella strain that can colonize the gallbladder

Answer 11

S. Typhi

Question 12

In general, LPS in the blood can cause what 2 clinical features?

Answer 12

fever, shock

Question 13

Why can S. Typhi cause a + stool culture, then a + blood culture, then a + stool culture again?

Answer 13

Intially it is found in the GI system, then it goes into the bloodstream, and it can get into the gallbladder from there and re-enter the GI system.

Question 14

SPI 1 and SPI 2 stand for what?

Answer 14

Salmonella Pathogenicity Island 1 and 2

Question 15

SPI 1 encodes genes for what?

Answer 15

Invasion of the gastric epithelial cells

Question 16

SPI 2 encodes genes for what?

Answer 16

Intracellular survival

Question 17

Describe Type 3 Secretion Systems (T3SS)

Answer 17

secretion where a protein moves across the bacterial cytoplasmic and outer membrane AND across the host cell membrane via an injection needle

Question 18

What bacterial species have T3SS?

Answer 18

Salmonella, E Coli, Shigella

Question 19

Which species of salmonella have SPI1 and SPI2?

Answer 19

S Typhi, S Cholerasuis.

Question 20

Whaty type of immune system reaction will be caused by LPS/endotoxin?

Answer 20

Innate. Macrophages will be activated, release TNF-alpha into tissue, increased plasma proteins, phagocytes and lymphocytes increase in tissue.

Question 21

What can happen when gram-negatives grow in the bloodstream? what bacteria is most likely to cause this?

Answer 21

Endotoxic shock; S typhi

Question 22

During an S Typhi infection, what tests are likely to isolate the bacterium?

Answer 22

week 1: stool. Week 2: Blood. Week 3: stool.

Question 23

For which strain of salmonella would abx be used?

Answer 23

S typhi, and S. enteriditis/typhimurium IF patient is immunocompromised.

Question 24

which Salmonella strain is primarily found in contaminated water sources?

Answer 24

s typhi

Question 25

Are there vaccines available for any strains of salmonella?

Answer 25

YES 2 vaccines for S typhi: oral attenuated and Vi capsular polysaccharide.

Question 26

what is the incubation period for S cholerasuis? what is the infectious dose?

Answer 26

6-72 hours. 1000 organisms

Question 27

what is the likely clinical course of a S cholerasuis infection?

Answer 27

gastroenteritis followed by bacteremia and high fever

Question 28

the origin of which salmonella strain is swine?

Answer 28

S cholerasuis

Question 29

what is the most common salmonella infection in the US?

Answer 29

S enteriditis / S typhimurium

Question 30

If salmonella is found on strawberries, eggs, or peanuts, what type is it likely to be?

Answer 30

S enteriditis / S typhimurium

Question 31

How long will clinical symptoms of S enteriditis / S typhimurium take to appear?

Answer 31

8-48 hours

Question 32

Do S enteriditis / S typhimurium have T3SS? Do they have SP1 and SP2?

Answer 32

Yes, No, No

Question 33

For all salmonella infections, what cultures would be most likely to yield bacteria?

Answer 33

All: feces. S typhi/S Cholerasuis: blood.

Question 34

Does salmonella ferment lactose?

Answer 34

No

Question 35

Does salmonella ferment glucose?

Answer 35

yes

Question 36

Does salmonella produce H2S?

Answer 36

yes

Question 37

Is salmonella motile?

Answer 37

yes, has a flagellum

Question 38

Salmonella: cytochrome oxidase positive or negative?

Answer 38

negative.

Question 39

How could you determine whether various salmonella outbreaks were connected?

Answer 39

comparing O and H antigens and serotyping

Question 40

How is shigella spread?

Answer 40

Food, Fingers, Feces, Flies

Question 41

Which shigella is most common in the developing world?

Answer 41

Shigella dysenteriae

Question 42

Which shigella is most common in the US?

Answer 42

Shigella sonnei

Question 43

Does shigella have an animal reservoir?

Answer 43

no

Question 44

Does shigella have LPS? how do we know?

Answer 44

YES. because it is gram-neg.

Question 45

what about shigella causes diarrhea and abd cramps?

Answer 45

Shiga toxin.

Question 46

how common is bacteremia due to Shigella?

Answer 46

rare

Question 47

what is a common clinical finding with shigella?

Answer 47

blood diarrhea with mucus

Question 48

how long will shigella be detected in feces post-recovery?

Answer 48

1-4 weeks

Question 49

Incubation period for shigella?

Answer 49

1-4 days

Question 50

What is the inoculum level for shigella?

Answer 50

100 bugs

Question 51

Describe the Shiga toxin itself

Answer 51

exotoxin with 2 subunits. Subunit A interferes with function of the 60S rRNA, inhibiting protein synthesis. Subunit B binds to the receptor on intestinal cells

Question 52

Does Shigella ferment glucose?

Answer 52

yes, does not produce gas

Question 53

does Shigella ferment lactose?

Answer 53

no

Question 54

Shigella: motile?

Answer 54

no. Shigellum no flagellum.

Question 55

what antigens does shigella have?

Answer 55

O and K only; no flagellum --> no H antigen

Question 56

Do shigella and salmonella produce H2S?

Answer 56

Salmonella yes, shigella no

Question 57

Name the members of Enterobacteriaciae.

Answer 57

E Coli, Shingella, Salmonella

Question 58

Generally, 3 clinical profiles caused by Salmonella?

Answer 58

typhoid, bacteremia, gastroenteritis

Question 59

What is the infectious dose for S Typhi?

Answer 59

10^3 to 10^5 bacteria

Question 60

How many pathogenicity islands does S typhi have?

Answer 60

2

Question 61

Features of endotoxic shock?

Answer 61

fever, diarrhea, hypotension, DIC

Question 62

Distinct diagnostic feature of typhoid fever/S typhii?

Answer 62

rose spots

Question 63

How would we prevent S typhi?

Answer 63

sanitation (access to clean water) and vaccination (2 types available)

Question 64

What does a positive cytochrome oxidase test look like?

Answer 64

purple

Question 65

Oxidase test is positive for what bacteria?

Answer 65

other common Gram negative pathogens such as Pseudomonas and Neisseria

Question 66

Salmonella: indole positive or negative? urease positive or negative?

Answer 66

Indole negative, urease negative

Question 67

shigella: indole positive or negative? urease positive or negative?

Answer 67

Indole negative, urease negative

Question 68

How does shigella lead to apoptosis of cells and ulceration? and subsequent bloody, mucusy stool?

Answer 68

Has Shiga toxin with A/B subunits. Cause cell death by preventing protein synthesis (via 60S ribosome inhibition) so cells die --> ulceration, mucous, blood.

Question 69

4 ways to distinguish Salmonella from Shigella?

Answer 69

1. Salmonella has flagellum, Shigella does not 2. Sal contains O and H antigens, Shigella only O (no flagellum) 3. Both ferment glucose, but Shigella does not produce gas with fermentation 4. Shigella does not produce H2S gas