Exam 4: gram - rods

Question 1

The bacterial group of gram negative rods are also known as ___

Answer 1

the enteric, because they cause digestion issues

Question 2

The enterobacteriacae family contains what bacteria?

Answer 2

E. coli
k. pneumoniae
enterobacter
serratia
proteus
salmonella
shigella

Question 3

What three gram negative rods are considered coliforms?

Answer 3

E coli
K pneumoniae
enterobacter

Question 4

How are coliform bacteria defined?

Answer 4

• facultative anaerobes
• ferment lactose
• gram negative
• non-endospore forming
• rod shaped

Question 5

What is the pathogenesis of E-coli?

Answer 5

septicemia, UTI, meningitis, gastroenteritis

severity is dependent on which strain of E. coli

Question 6

Why is there such great serological variation in E coli?

Answer 6

they transfer DNA via conjugation and transposons.

lysogenic conversion allows “swapping” of virulence factors

Question 7

How is E-coli diagnosed?

Answer 7

produces green metallic sheen on EMB agar, use IMViC to distinguish from enterobacter

Question 8

There are 4 different strains of E coli that cause gastroenteritis. what are they?

Answer 8

• enterotoxin producing E. coli (ETEC)
• enteroinvasive E. coli (EIEC)
• enteropathogenic E. coli (EPEC)
• enterohemorrhagic E. coli (EHEC)

Question 9

Which strain of E. coli causes “traveller’s diarrhea”?

Answer 9

enterotoxin producing E. coli

Question 10

Which strain of E. coli invades the intestinal cells and has its main virulence factor encoded on plasmid that is shared by Shigella and E. coli?

Answer 10

enteroinvasive E. coli

Question 11

Which strain of E. coli does NOT invade intestinal cells but rather adheres to them by adhesins coded on plasmid that destroy microvilli on intestinal cells where microbe attaches?

Answer 11

enteropathogenic E. coli

Question 12

Which strain of E. coli produces verotoxin which blocks the protein that functions to prevent the cell from undergoing apoptosis which causes severe abdominal pain, bloody diarrhea and can lead to hemolytic uremic syndrome (HUS)?

Answer 12

enterohemorrhagic E. coli

Question 13

How are strains of Klebsiella pneumoniae classified?

Answer 13

by their capsule proteins

Question 14

Klebsiella penumoniae is the second most common cause of ____ in hospitalized patients and _____ in infants?

Answer 14

sepsis, septicemia

Question 15

What is the most common species of enterobacter and what does it cause?

Answer 15

enterobacter aeruginosa causes UTI

Question 16

What is unique about enterobacter aeruginosa?

Answer 16

it produces ornithine decarboxylase

Question 17

What common opportunistic pathogen in hospitalized patients causes pneumonia, bacteremia and endocarditis and is characterized by a red pigment?

Answer 17

serratia

Question 18

What opportunistic pathogen is characterized by a swarming behavior on agar and presence of urease enzyme that breaks urea to produce a sherry red color?

Answer 18

proteus

Question 19

What pathogen most commonly causes typhoid (AKA enteric) fever?

Answer 19

salmonella typhi

Question 20

After recovering from typhoid fever, humans can harbor the bacteria where?

Answer 20

gallbladder

Question 21

How is salmonella transmitted?

Answer 21

oral-focal route, food/water contaminated with feces

Question 22

What does it mean to say that salmonella bacteria are facultative intracellular parasites.

Answer 22

during invasion, the bacteria are phagocytize by monocytes but survive and divide inside the monocyte

Question 23

salmonellosis starts ______ after exposure and only a low infective due is required to cause disease.

Answer 23

1-3 weeks

Question 24

In typhoid fever, salmonella initially invades intestinal cells and then moves to _____ and other organs, especially _____.

Answer 24

lymph nodes, spleen

Question 25

How is salmonella diagnosed?

Answer 25

blood, urine or feces culture and serotyping. Does not ferment lactose

Question 26

What is the treatment for typhoid fever caused by salmonella?

Answer 26

• antibiotics: chloramphenicol, Cipro, ampicillin
• IV fluids and electrolytes
• if reservoir, remove gallbladder
• travel vaccines recommended

Question 27

What are the animal reservoirs for salmonella?

Answer 27

chickens (eggs), reptiles, cows

Question 28

What is the most common type of salmonella infection?

Answer 28

gastroenteritis (but typhoid fever can occur)

Question 29

What is the pathogenesis of gastroenteritis from salmonella?

Answer 29

salmonella posses endotoxin and enterotoxin. The enterotoxin causes watery (cholera-like) diarrhea

Question 30

What is the treatment for gastroenteritis caused by salmonella?

Answer 30

• IV fluids and electrolytes

- antibiotics do not shorten course so are typically not given

Question 31

Which gram negative rods are not part of normal flora?

Answer 31

salmonella and shigella (all others are: E. coli, K, pneumonia, enterobacter, serrate, proteus)

Question 32

There are 4 species of shigella and all are always pathogenic and do not ferment lactose. Which species is the most pathogenic?

Answer 32

Shigella dysenteriae

Question 33

What is the only reservoir for shigella dysenteriae?

Answer 33

humans

Question 34

How is shigella dysenteriae transmitted?

Answer 34

oral-fecal route

Question 35

What bacteria is not easily killed by stomach acid and therefore has a low infective dose and produces a potent toxin which kills epithelial cells but rarely invades blood stream?

Answer 35

shigella dysenteriae

Question 36

What bacteria causes a severe gastric inflammatory response that produces bloody diarrhea and can cause hemolytic uremic syndrome which is often fatal?

Answer 36

shigella dysenteriae

Question 37

How is shigella dysenteriae diagnosed?

Answer 37

SS agar to distinguish from Salmonella