Infectious Diarrhea Flashcards
global health context of infectious diarrhea
*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
reasons for improvement in mortality rates due to diarrhea
*improved sanitation
*improved nutrition
*rotavirus vaccination
*hydration strategies
*additional treatments (antibiotics, zinc)
top pathogen for child deaths from diarrheal diseases
rotavirus
definition of diarrhea
- increase in the volume & frequency of bowel movements as well as a change in the consistency of the stools
OR - passage of 3 or more loose stools per day that conform to the shape of their container
risk factors for acquisition of infectious diarrhea
*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
categories of clinical presentations of infectious diarrhea
*toxin “food poisoning”
*watery diarrhea
*dysentery or invasive diarrhea (inflammatory)
*enteric fever
pre-formed toxin: “food poisoning” diarrhea
*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
non-inflammatory (“watery”) diarrhea
*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
inflammatory diarrhea: dysentery / invasive diarrhea
*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
mucosal penetrating diarrhea: “enteric fever”
*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
most frequent cause of Travelers’ Diarrhea
enterotoxigenic E. coli (ETEC)
predominant etiologic agents of diarrhea in the US and developed settings
viruses (rotaviruses & noroviruses)
primary bacteria causing inflammatory diarrhea
*shigella
*note - must distinguish from EHEC
most frequent causes of bacterial foodborne infections in US
salmonella & campylobacter
cause of epidemic watery diarrhea (global)
Vibrio cholera
infectious dose of shigella
LOW ID50 (does not take much of the organism to cause an outbreak)
post-infectious complications of infectious diarrhea
*campylobacter & Guillain-Barre
*post-dysenteric reactive arthritis after infection with shigella, salmonella, and campy
differential for blood in stool in diarrhea
*EHEC (toxin) do NOT give antibiotics (no fever)
*shigella (invasion) GIVE antibiotics (fever)
stool studies - infectious diarrhea
- gross inspection (watery, mucoid, bloody)
- microscopic exam (presence of fecal WBCs, ova, parasites)
- culture
- PCR !!! (best option)
infectious diarrhea - principles of management
- replace fluid/electrolytes aggressively (orally if possible) !!!
- reserve empiric antibiotics for patients with:
-fever & moderate to severe diarrhea
-fecal WBCs or lactoferrin
-blood in stool (WITH fever) - avoid anti-motility agents unless or until bacterial disease is excluded
- assess public health implications
treatment recs for Traveler’s diarrhea
*oral rehydration & loperamide
*if diarrhea is severe, persistent, or interfering with activities: ciprofloxacin or azithromycin
treatment recs for severe inflammatory diarrhea (fever & bloody)
azithromycin or ciprofloxacin
treatment recs for C diff
vancomycin or fidaxomicin
