GI infections 4

Question 1

non inflammatory diarrhea usually involves the _____ intestine

Answer 1

small intestine; viruses and non invasive bacteria

NO mucosal destruction

Question 2

_________ toxin helps in the activity of TcdA and TcdB

Answer 2

binary toxin (CDT aka C. difficile transferase)

Question 3

what are the top 5 food borne illness pathogens

Answer 3

• norovirus
• salmonella
• clostridium perfringens
• campylobacter
• staph aureus

Question 4

describe the biology of Clostridium difficile:

Answer 4

• gram POSITIVE bacillus
• anaerobic
• endospore FORMER
• primary cause of antibiotic associated diarrhea in hospital settings

Question 5

use of __________ (antibiotic) is associated with a high risk factor for C. difficile infection

Answer 5

clindamycin (because it affects the gut microbiota the most)

Question 6

___________ is useful for initial screening for C. difficile infection

Answer 6

EIA for glutamic dehydrogenase antigen (GDH)

Question 7

________ is the primary cause of antibiotic associated diarrhea in hospital settings

Answer 7

clostridium difficile

Question 8

C. difficile has secreted ____toxins (exo/endo) which are TcdA and TcdB which cause __________ by ________

Answer 8

EXOtoxins that can cause disruption of the actin cytoskeleton by inhibiting GTPase activity by transferring glucose onto GTPases involved in regulation of the cytoskeleton

Question 9

describe course of clostridium difficile infection

Answer 9

• can be mild and be a self limiting diarrhea
• can also develop into pseduomembranous colitis
• severe cases can develop into toxic megacolon

Question 10

is C. difficile a food borne illness?

Answer 10

no, technically it is not because it is part of the normal microbiota of the gut and get infection when you alter the gut microbiota

Question 11

______ infection can regress to pseudomembranous colitis

Answer 11

clostridium difficile

Question 12

describe the biology of bacteroides fragilis

Answer 12

• GNAR: gram negative anaerobic, NON SPORE forming rod
• part of the normal flora of the large intestine
• mostly associated with opportunistic infections

Question 13

what are some risk factors that increase the chance of acquiring a C. difficile infection?

Answer 13

• antibiotic use: ↑ with days and number
• type of antibiotic use: clindamycin has the highest risk and ahminoglycosides have the lowest
• patient age: older than 65 higher risk
• history of hospitalization and length of stay

Question 14

__________ is a very common cause of intrabdominal abscesses

Answer 14

bacteroides fragilis

Question 15

a doctor orders a glutamate dehydrogenase antigen assay for a patient who has had water diarrhea for the past 4 days. What pathogen is he screening for?

Answer 15

C. difficile

Question 16

in what settings do you seen clostridium difficile infection?

Answer 16

• hospital settings

- after exposure to antibiotics which alter the gut microbiota

Question 17

routine stool culture is for : (4)

Answer 17

• campylobacter
• salmonella
• shigella
• E. coli (all types)

Question 18

describe the oxygen demands for clostridium difficile

Answer 18

obligate anaerobes

Question 19

inflammatory (blood-pus, fever) diarrhea usually invites the _________ intestine

Answer 19

large intestine; invasive bacteria and toxin producing bacteria

Question 20

what are some virulence factors of bacteroides fragilis?

Answer 20

• fimbrae for adhesion
• polysaccharide capsule: evasion of host response and triggers abscess formation
• β lactamases
• NO CONTRIBUTION OF LPS

Question 21

_______ is the form of Clostridium difficile that you seen on fomites such as health care workers hands and the environment

Answer 21

endospores

Question 22

spore forming GI microbes (2)

Answer 22

bacillus and clostridia

Question 23

which specific pathogens have incubation period more than 7 days to weeks/months?

Answer 23

• listeria monocytogenes
• parasites (will do an ova and parasite stool investigation)
• liver infections such as Hep A which is a food borne hepatitis