Infectious Diarrhea

Question 1

global health context of infectious diarrhea

Answer 1

*diarrheal diseases contribute to significant global mortality in children under age of 5 (~500,000 kids per year)
*increasing mortality in the elderly
*more prevalent in low and middle income countries such as Africa

Question 2

reasons for improvement in mortality rates due to diarrhea

Answer 2

*improved sanitation
*improved nutrition
*rotavirus vaccination
*hydration strategies
*additional treatments (antibiotics, zinc)

Question 3

top pathogen for child deaths from diarrheal diseases

Answer 3

rotavirus

Question 4

definition of diarrhea

Answer 4

1. increase in the volume & frequency of bowel movements as well as a change in the consistency of the stools
   OR
2. passage of 3 or more loose stools per day that conform to the shape of their container

Question 5

risk factors for acquisition of infectious diarrhea

Answer 5

*typically acquired via a fecal-oral route, usually by ingestion of contaminated food or water
*overcrowding, inadequate public sanitation, & poor personal hygiene are major risk factors for acquisition
*host factors: age, gastric acidity, intestinal motility, specific immunity/immunodeficiency, intestinal receptors

Question 6

categories of clinical presentations of infectious diarrhea

Answer 6

*toxin “food poisoning”
*watery diarrhea
*dysentery or invasive diarrhea (inflammatory)
*enteric fever

Question 7

pre-formed toxin: “food poisoning” diarrhea

Answer 7

*MOA: preformed toxins
*clinical sx:
-nausea & vomiting within 1-8 hours after ingestion
-diarrhea common
-rarely fever
-usually resolves within 12-14 hours

*pathogens: Staph aureus, Bacillus cereus, Clostridium perfringens

Question 8

non-inflammatory (“watery”) diarrhea

Answer 8

*site = proximal small bowel
*MOA: enterotoxin/adherence/superficial invasion
*features: watery diarrhea (usually 1-3 days later)
*labs: no fecal WBC; minimal or no lactoferrin
*pathogens: salmonella, E. coli, rotavirus, etc

Question 9

inflammatory diarrhea: dysentery / invasive diarrhea

Answer 9

*site = colon
*MOA: invasion and/or cytotoxin
*features: dysentery (blood in stool), fever, abdominal pain
*labs: (+) fecal WBC, high lactoferrin
*pathogens: campylobacter, shigella, yersinia, enteroinvasive E. coli, Entamoeba histolytica

Question 10

mucosal penetrating diarrhea: “enteric fever”

Answer 10

*site = distal small bowel
*MOA: mucosal penetration
*features: enteric fever; high fever, weakness, abdominal pain headaches
*labs: fecal mononuclear leukocytes, anemia, thrombocytopenia
*pathogens: salmonella typhi, yersinia, campylobacter

Question 11

most frequent cause of Travelers’ Diarrhea

Answer 11

enterotoxigenic E. coli (ETEC)

Question 12

predominant etiologic agents of diarrhea in the US and developed settings

Answer 12

viruses (rotaviruses & noroviruses)

Question 13

primary bacteria causing inflammatory diarrhea

Answer 13

*shigella
*note - must distinguish from EHEC

Question 14

most frequent causes of bacterial foodborne infections in US

Answer 14

salmonella & campylobacter

Question 15

cause of epidemic watery diarrhea (global)

Answer 15

Vibrio cholera

Question 16

infectious dose of shigella

Answer 16

LOW ID50 (does not take much of the organism to cause an outbreak)

Question 17

post-infectious complications of infectious diarrhea

Answer 17

*campylobacter & Guillain-Barre
*post-dysenteric reactive arthritis after infection with shigella, salmonella, and campy

Question 18

differential for blood in stool in diarrhea

Answer 18

*EHEC (toxin) do NOT give antibiotics (no fever)
*shigella (invasion) GIVE antibiotics (fever)

Question 19

stool studies - infectious diarrhea

Answer 19

1. gross inspection (watery, mucoid, bloody)
2. microscopic exam (presence of fecal WBCs, ova, parasites)
3. culture
4. PCR !!! (best option)

Question 20

infectious diarrhea - principles of management

Answer 20

1. replace fluid/electrolytes aggressively (orally if possible) !!!
2. reserve empiric antibiotics for patients with:
   -fever & moderate to severe diarrhea
   -fecal WBCs or lactoferrin
   -blood in stool (WITH fever)
3. avoid anti-motility agents unless or until bacterial disease is excluded
4. assess public health implications

Question 21

treatment recs for Traveler’s diarrhea

Answer 21

*oral rehydration & loperamide
*if diarrhea is severe, persistent, or interfering with activities: ciprofloxacin or azithromycin

Question 22

treatment recs for severe inflammatory diarrhea (fever & bloody)

Answer 22

azithromycin or ciprofloxacin

Question 23

treatment recs for C diff

Answer 23

vancomycin or fidaxomicin