Infectious Diarrhea

Question 1

what bacterium is found in poultry, eggs, milk, pet turtles and what are its characteristics?

Answer 1

salmonella; gram negative encapsulated bacilli

Question 2

carrier state of typhoid fever is associated with what condition?

Answer 2

gallbladder colonization by salmonella typhi

Question 3

sickle cell disease patient with osteomyelitis = what is the causative agent?

Answer 3

salmonella

Question 4

pathogenesis of non-typhoid salmonella

Answer 4

survive in phagosome and replicate (facultative intracellular) –> induce migration of neutrophils

Question 5

bloody diarrhea in daycare setting: what bacterium and what are its characteristics?

Answer 5

shigella; gram negative bacilli

Question 6

bloody diarrhea, only small inoculum required

Answer 6

shigella

Question 7

what bacterium is found in undercooked poultry, unpasteurized milk and causes bloody diarrhea?

Answer 7

campylobacter jejuni

Question 8

campylobacter is a common antecedent to what conditions? (2)

Answer 8

reactive arthritis and Guillain-Barre syndrome

Question 9

dx: diarrea, bloating, drinking from mountain streams

Answer 9

giardia lamblia

Question 10

E. coli that causes traveler’s diarrhea

Answer 10

ETEC

Question 11

dx: bloody diarrhea and thrombocytopenia

Answer 11

EHEC

Question 12

characteristics of E. coli

Answer 12

gram negative bacilli

Question 13

compare the mechanisms of heat-labile and heat-stable enterotoxins of ETEC

Answer 13

heat-labile: cause increase in cAMP

heat-stable: cause increase in cGMP

Question 14

pathogenesis of EIEC

Answer 14

EI = enteroinvasive, so it invades intestinal mucosa and causes bloody diarrhea

Question 15

Which E. coli is similar to shigella in its clinical presentation?

Answer 15

EIEC

Question 16

dx: bloody diarrhea after eating undercooked ground beef

Answer 16

EHEC

Question 17

which E. coli is associated with HUS and what are the symptoms?

Answer 17

EHEC; hemolysis/anemia, thrombocytopenia, acute renal failure

Question 18

pathogenesis of cholera toxin

Answer 18

increases intracellular cAMP –> opens CFTR –> releases Cl- into lumen –> draws water into lumen

Question 19

diarrhea after consuming seafood: what bacterium and what are its characteristics?

Answer 19

vibrio cholera; gram negative bacilli

Question 20

dx: watery diarrhea after being on a cruise ship

Answer 20

norovirus

Question 21

dx: watery diarrhea in an infant in daycare setting in the winter

Answer 21

rotavirus

Question 22

parasite that can cause intestinal infection and pneumonitis

Answer 22

ascaris lumbricoides

Question 23

diarrhea after walking barefoot in soil: causative agent and characteristic

Answer 23

strongyloides; nematode (parasite)

Question 24

dx: anemia after traveling to developing country

Answer 24

necator americanus or ancylostoma duodenale (hookworms)

Question 25

pathogenesis of necator americanus or ancylostoma duodenale

Answer 25

infection by larval penetration through the skin, intestinal infection causing anemia by sucking blood from intestinal walls

Question 26

causative agents for diarrhea seen in immunocompromised hosts (3)

Answer 26

cryptosporidium, CMV, mycobacteria avium (MAC)

Question 27

dx: diarrhea within 6 hours of eating potato salad

Answer 27

staph aureus

Question 28

dx: diarrhea within 6 hours of eating Chinese food/rice

Answer 28

bacillus cereus

Question 29

when should you order stool for O and P?

Answer 29

persistent diarrhea for over 14 days

Question 30

who is contraindicated for empiric antibiotics even though they have bloody diarrhea and leukocytes in the stool?

Answer 30

C. difficile or EHEC infection

Question 31

antimotility agents (2)

Answer 31

loperamide, diphenoxylate

Question 32

diarrhea after clindamycin: what bacterium and what are its characteristics?

Answer 32

clostridium difficile; gram positive

Question 33

treatment for C. difficile

Answer 33

metronidazole and oral vancomycin

Question 34

treatment for refractory C. difficile

Answer 34

fidaxomicin