Infectious Diarrhea Flashcards
Leading 2 causes of death worldwide
pneumonia, diarrhea
leading cause of morbidity and death
Dehydration
important part of therapy for dehydration/diarrhea
Rehydration
Most common cause of infectious gastroenteritis in US
unknown!! (40%)
Viral (30-40%)
Bacterial/Parasitic (20-30%)
GI site implicated in non-inflammatory diarrhea
upper small bowel
GI site implicated in inflammatory diarrhea
colon
what might labs show in inflammatory diarrhea
increased T cells, WBC, RBC
pathogens causing Non-inflammatory diarrhea
vibrio cholerae, Norwalk, Rotavirus, ETEC, Giardia
Inflammatory diarrhea pathogens
C. JEJUNI, Shigella, Salmonella, E. coli O157:H7, C difficile, E. histolytica
What makes cholera infectious
Toxin (A:5B)
- similar to ETEC
symptoms of cholera
- abrupt diarrhea, vomiting
- “rice water stool” up to 24 L per day (yellowish–probably mucin)
how does cholera affect mucosa
binds epithelial cells and causes secretion – not really harming epithelium
incubation period of cholera
18h - 5 days
Blood in cholera diarrhea?
NO
Oral rehydration solution
water, a little salt, carbohydrate (sugar)
what infectious agent similar to cholera toxin?
ENEC - enterotoxic E coli
What is the leading cause of prolonged diarrhea
Rotavirus
Leading cause of dehydration from diarrhea
Rotavirus
leading cause of hospitaliziation from diarrhea
Rotavirus
Leading cause of death from diarrhea (US and world)
Rotavirus (due to prolonged diarrhea and dehydration)
Rotavirus vaccine
live attenuated vaccine;
- Efficacy in US >90%
- Efficacy in developing countries 17-65%
Incubation pd and duration of illness of rotavirus
1-3 days incubation; duration 5-8 days usually
age mostly affected by rotavirus
infants, young children
age mostly affected by norwalk virus
older children adults
Norwalk transmission
fecal-oral, contaminated.
- shellfish and water
Rotavirus transmission
fecal-oral
Epidemiology of rotavirus
sporadic cases, usually winter, occasionally epidemic
Norovirus epidemiology
family and community epidemics, often winter; comes on fast/goes away fast
incubation pd and duraiton of norovirus
1-2 days incubation and 1-2 day duration
therapy for norovirus/rotavirus
none really; vaccine work on rotavirus
giardia
eukaryote –protozoan
Giardia symptoms
diarrhea, fatigue, abdominal cramps, gas, fatty stool, stomach makes noises
cause of most hemorrhagic colitis in US
E coli O157:H7
E coli O157:H7 population affected/duration
lasts 2-4 days (
source of E coli O157:H7
mostly meat
symptoms of E coli O157:H7
- large spectrum of illness
- asymptomatic
- nonbloody diarrhea
- hemorrhageic colitis
- Hemolytic uremic syndrome (HUS)
- thrombocytic thrombocytopenic purpura (TTP)
what makes E coli O157:H7 so bad
toxin!
what happens when you give antibiotics to someone with E coli O157:H7
lyse cells so that toxin released…more toxin production?
Nosocomial diarrhea definition
-hospital-acquired; >3 days in hospital
leading cause of nosocomial diarrhea
C. difficile
reason for C difficile infection
disruption of normal microbiota– most commonly associated with antibiotic use
C difficile symptoms
mild diarrhea, watery or bloody, may have fever, leukocytosis with severe colitis
Therapy for C difficile
antibiotics, recurrence (15-26%)– bug can persist and you have knocked out all other bugs in GI–hard to get balance back
- Fecal transplant if a few rounds
- working on pills of fecal microbiota
1 cause of traveler’s diarrhea
Enterotoxic E coli
No fever suggests what kind of diarrhea?
non-inflammatory diarrhea
when diarrhea doesn’t respond to antibiotics consider what org?
Giardia
grossly bloody diarrhea without fever suggests what org
E coli O157:H7
E. coli O157H7 toxin
Verotoxin; shiga-like toxin (SLT-I/II)
- binds especially to human renal endothelial cells
- inhibits protein synthesis
Therapy of E. coli 0157H7
TMP/SMX- all sensitive
- IV Ig?
- Prevention (food, cooking)
Enteric Fever
Site: Nodes, blood, gallbladder
- Pathogens: Salmonella typhi, paratyphi, +/- Yersinia
Typhoid fever
- caused by Salmonella enteric serotype typhi
- Gram (-) rod; human only
- risks: fecal contamination, food/water (poor handling), contact with carrier
