Gram - Rods: Enteric bacteria like E. coli

Question 1

What bacteria is great for studying mutants?

Answer 1

E. coli because they define biochemical pathways

Question 2

T/F: E. coli grow slowly

Answer 2

False!
They actually grow rapidly and easily aerobically and anaerobically on most lab media. Have a 20 min doubling time

Question 3

What are the major pathogens of E.coli?

Answer 3

Escherichia, Shigella, Salmonella, and Vibrio

Question 4

What are the types of infections involved with E. coli?

Answer 4

intestinal, urinary, respiratory, wound, bloodstream, and meningeal infections

Question 5

What is the O antigen in E.coli?

Answer 5

carbohydrate LPS repeat

Question 6

T/F: E. coli is not normal intestinal flora

Answer 6

False!
It IS normal intestinal flora but this can cause some diseases/infections

Question 7

How does E. coli get in the bloodstream?

Answer 7

if capsule present
Can happen when E.coli ends up in the wrong place (e.g. puncture wound)

Question 8

What is the potent trigger of inflammation?

Answer 8

LPS- endotoxin (which is important in sepsis and meningitis)

Question 9

What does heat liable toxin do (involved in the enterotoxin of E. coli)?

Answer 9

activate adenylate cyclase which leads to fluid secretion/diarrhea

Question 10

How does E. coli cause 85-90% of UTI’s?

Answer 10

• intestines -> vagina -> urethra
• adhere to uroepithelial cells via fimbriae and ascend to bladder which then colonize and cause inflammation

Question 11

How does E. coli cause invasive infections neonatal meningitis?

Answer 11

vaginal normal flora colonize the infant at birth during the passage through the birth canal which then travel through intestines then blood and finally to meninges

Question 12

How common is a capsule on E. coli in neonatal meningitis?

Answer 12

90%

Question 13

How does E. coli cause bacteremia/septic shock?

Answer 13

in patients with immune impairment of mechanical damage, intestinal E. coli invade blood stream and large amounts of endotoxin stimulate systemic inflammation and septic shock

Question 14

What makes Shigella different from E. coli?

Answer 14

it has a virulence plasmid that allows cell invasions and intracellular growth
AND not normal flora

Question 15

What does shigella cause?

Answer 15

mild disease= shigellosis… diarrhea without blood

severe disease= dysentery… blood in stool cause specifically by S. dysenteriae

Question 16

How does the Virulence plasmid in Shigella work?

Answer 16

encodes proteins for attachment/entry into intestinal epithelial cells

Question 17

How does Shigella dysenteriae work?

Answer 17

cause erosion of large intestine epithelia

Question 18

What is only found in diseased humans aka not normal flora?

Answer 18

salmonella

Question 19

What are the 2 different serotypes of salmonella?

Answer 19

S. e. Typhimurium (causes food poisoning)
S. e. Typhi (causes typhoid fever)

Question 20

What is the most common salmonella infection?

Answer 20

gastroenteritis due to improper food handling

Question 21

Which is the invasive serotype of salmonella that can get in the bloodstream?

Answer 21

S. typhi
- due to the Vi capsule giving typhoid fever

Question 22

Is there a vaccine for typhoid fever (S.typhi) ?

Answer 22

Yes!
2 current vaccines. a purified Vi capsule polysaccharide or a live attenuated Ty21a strain

Question 23

Which is the curved, gram - rod?

Answer 23

vibrio cholera

Question 24

Where does Vibrio live?

Answer 24

common in surface waters worldwide with fecal pollution
- oysters are common to have this

Question 25

What is exotoxin involved in V. cholerae?

Answer 25

cholera enterotoxin which chemically modifies adenylate cyclase and stimulates fluid secretion

Question 26

T/F: Cholera invades tissue

Answer 26

False!
It does not invade in tissue

Question 27

What is the pathology associated with cholera?

Answer 27

dehydration and electrolyte imbalance

Question 28

What’s the treatment for cholerae?

Answer 28

fluid replacement is critical

Question 29

What is the vaccine for cholera?

Answer 29

Vaxchora- live V. cholerae 01
which triggers protective mucosal Ab to whole bacterium and to toxin B subunit

Question 30

Is E. coli gram- or gram +?

Answer 30

gram -

Question 31

What is the number one medical infection?

Answer 31

Staph aureus
- E.coli is the next one

Question 32

Which don’t have the LPS but the LOS?

Answer 32

Haemophilus meningitis and bordetella pertussis
which helps hide the bacteria is an important virulence factor

Question 33

How is E. coli transmitted?

Answer 33

fecal-oral spread of unique strains

Question 34

What is an important relative to E. coli worth knowing that has a thick mucous layer that prevents drugs from getting into it?

Answer 34

Klebsiella

Question 35

What allows for Shigella to cause dysentary?

Answer 35

shiga toxins

Question 36

Where is the normal reservoir of salmonella?

Answer 36

intestinal tract of animals especially reptiles

Question 37

What are the 2 vaccines for that are live strains?

Answer 37

for typhoid fever and cholera enterotoxin