Enterobacteriaceae II

Question 1

Typhoid Fever, Enteric Fevers, and Gastroenteritis are all clinical syndromes caused by what genus?

Answer 1

Salmonella

Question 2

In Typhoid salmonella infections- how does the bacteria enter?

Answer 2

Through the cells lining the intestine- they are then engulfed by macrophages

Question 3

The symptoms of Typhoid occur in 10-14 days and correspond to what?

Answer 3

Bacteremic phase (followed by colonization of gall bladder and reinfection of intestines)

Question 4

At what sites does the organism causing Typhoid replicate?

Answer 4

liver, spleen, bone marrow

Question 5

What is the reservoir for Typhoid fever?

Answer 5

People (1-5 percent chronic carriers- most common in gallbladder)

Question 6

What is the most common syndrome caused by salmonella?

Answer 6

Gastroenteritis

Question 7

Where does the salmonella that causes gastroenteritis replicate?

Answer 7

cells lining lumen of terminal small intestine

Question 8

What gene protects salmonella from the acid of the stomach and phagosome?

Answer 8

ATR (acid tolerance response gene)

Question 9

What secretion system adheres salmonella to microvilli?

Answer 9

Type III

Question 10

What protects salmonella from intracellular killing?

Answer 10

Catalase and superoxide dismutase

Question 11

Salmonella requires a large inoculum unless:

Answer 11

immunosuppressed or underlying disease (note- a small amt can become large in improperly stored and contaminated food)

Question 12

How long does it take for salmonella gastroenteritis to resolve?

Answer 12

mild and self limited- 2 days to 1 wk

Question 13

Septicemia occurs from what species of salmonella?

Answer 13

typhi and rare serotypes of entericia

Question 14

What is the only common cause of shigellosis in the developed world?

Answer 14

Shigella sonnei

Question 15

What age group does shigella affect, and how is it transmitted?

Answer 15

pediatric- 1-10. Fecal-Oral

Question 16

Where does shigella attach and invade? What type of Secretion system?

Answer 16

M cells of Peyer’s Patches, Type 3

Question 17

What type of passage does shigella use?

Answer 17

cell to cell

Question 18

Cardinal features of Shigellosis (caused by shigella sonnei)

Answer 18

Lower abdominal cramps, tenesmus, pus and blood in stool

Question 19

Explain the exotoxin produced by shigella dysenteriae

Answer 19

Shiga Toxin: A subunit and 5 B subunits. B bind host glycolipid Gb3 and transfer A subunit into cell, where it cleaves 28SrRNA in 60S ribosomal subunit

Question 20

What Shigella species can cause hemolytic uremic syndrome (HUS)?

Answer 20

Shigella dysenteriae

Question 21

What pathogenic infection mimics appendicitis?

Answer 21

Yersinia

Question 22

What virulence genes for adherence does Yersinia carry?

Answer 22

yadA (adherence), yop (outer membrane, multi func), lcr (low calcium response regulatory)

Question 23

What does fraction I (FI) gene code for in Yersinia pestis? Plasminogen Activator (Pla)?

Answer 23

antiphagocytic proteins capsule. Degrades C3b and C5a to prevent opsonization and phagocytic migration (also degrades fibrin clots to allow yersinia pestis to spread)

Question 24

What are the two clinical types of Yersinia pestis?

Answer 24

Pneumonic (person to person pulm infection), bubonic (plague, no person to person, painful bubos in groin and axilla)

Question 25

Enteric Disease caused by Yersinia enterocolitica or Yersinia pseudotuberculosis is most often found in what climate/area?

Answer 25

Cold, Great Lakes

Question 26

What cells does Yersinia invade in enteric disease?

Answer 26

Terminal ileum

Question 27

What is responisble for the mucoid appearance and enhanced virulence of the Klebsiella genus?

Answer 27

Polysaccharide capsule

Question 28

Why are penicillins ineffective against Klebsiella?

Answer 28

produce B Lactamase

Question 29

What is a common cause of community acquired primary lobar pneumonia? What does it involve?

Answer 29

Klebsiella pneumoniae, destruction of alveolar spaces, cavity formation, blood tinged sputum

Question 30

What is the most common disease produced by Proteus?

Answer 30

UTI

Question 31

What does Proteus produce and why is it relevant?

Answer 31

Urease- raises pH of urine causing renal stones and toxicity to uroepithelium

Question 32

What hospital acquired infections are often antibiotic resistant?

Answer 32

Enterobacter, Citrobacter, Morganella, Serratia

Question 33

What type of vaccine is used for Salmonella Typhi?

Answer 33

live attenuated