Remaining Bacterial Agents causing Afebrile Diarrhea (not due to food) Flashcards
ETEC Characteristics
GNR, motile by flagella (H antigen) or non-motile, non-fastidious, facultative anaerobe, Oxidase (-), Coliform!
ETEC is a coliform, meaning:
ferments lactose with acid and gas production
ETEC on MacConkey agar will grow
PINK colonies
What other organism is a coliform?
Aeromonas
Salmonella, Shigella, Yersinia would all grow what color on MacConkey agar?
White!
ETEC has what antigens
O, H, K, pili/fimbriae
Risk factors for ETEC infection
Poor sanitation, contaminated water/food
ETEC infections are commonly called
Traveler’s diarrhea, weanling diarrhea, montezuma’s revenge, etc
Transmission of ETEC is
HIGH dose: fecal-oral (not p-to-p)
Reservoir of ETEC is
human and animal GIT
What allow ETEC to attach to small intestine?
Fimbriae/Colonization Factor Antigen (CFA)
ETEC virulence factors?
CFA/fimbriae, LT toxin, and ST toxin
ETEC LT toxin mechanism
heat-labile enterotoxin w/ same mechanism as Cholera toxin CT-1/2 (binds Gm1 ganglioside, blocks GTPase, activates A.C. and cAMP, hyper secretion of Cl-, HCO3-, H2O = diarrhea)
ETEC CFA mechanism
fimbriae that allows ETEC to adhere to small bowel
ETEC ST toxin mechanism
heat-stabile enterotoxin that binds guanylate cyclase, activates cGMP, Phosphorylates Cl- channel–> Cl- secretion and blocks Na+ absorption
Immunity for ETEC is partially provided by?
O1 cholera vaccine
ETEC inhabits the
small intestines
Incubation period of ETEC
1-2 days
Duration of illness from ETEC
1-3 days; self-limiting
Main symptoms from ETEC infection
abrupt onset of mild-severe afebrile watery diarrhea
Diagnosis is made from
History; lab results of little value
Culture ETEC on what media?
Non-fastdious, ALSO a COLIFORM (lactose fermenter) –> PINK on MacConkey
Treatment for ETEC infection
Replace fluids/electrolytes, pepto bismol
Should you give abx for ETEC infection?
NO, unless severe case
Prevention of ETEC
O1 Cholera vaccine has some cross-coverage, pepto-bismol, abx protection for traveler’s
EAEC is a subgroup of
ETEC
EAEC has the ability to
adhere to epithelial cells such as Hep-2 in a “stacked-brick” pattern
EAEC symptoms
PERSISTENT diarrhea (>14 days)
Newer strains of EAEC can produce
Shiga toxins
EAEC strains have adapted
from cattle GIT pathogens to HUMAN GIT pathogens
Aeromonas hydrophila Characteristics
GNR, Mesophilic to psychrophilic (RT to cold temperatures), resistant to Cl-, Oxidase +, coliform
Aeromonas hydrophila causes up to ___% of gastritis in the world
13
Aeromonas hydrophila is also associated with what type of infections
cellulitis
Aeromonas hydrophila is found primarily in
fresh-water sources
Aeromonas hydrophila can be isolated from many environments due to
its ability to survive and proliferate in cold temperatures
Main symptoms of Aeromonas hydrophila
afebrile, watery diarrhea
Duration of symptoms of Aeromonas hydrophila
1-3 days
Virulence factors of Aeromonas hydrophila
Enterotoxin (cholera/CT-like toxin)
Transmission of Aeromonas hydrophila
fecal-oral (contaminated water/food source)
Culture of Aeromonas hydrophila is normally on
Blood agar w/ ampicillin (MDR)
Treatment of Aeromonas hydrophila
Rehydrate
Should Aeromonas hydrophila be treated w/ abx?
No, it’s usually MDR anyways
Main risk factor of Aeromonas hydrophila
ingestion of fresh-water or brackish water contaminated food/water
