20. Enteric Infections Flashcards
Features of enterobacteriaceae
Gm- rods, facultative anaerobes, ferment glucose, oxidase negative
When motile by peritrichous flagella (klebsiella and shigella non-motile)
Antigens used to subtype enterobacteriaceae
O-antigen: lipopolysaccharide
H-antigen: flagellum
K-antigen: capsule
Vi-antigen: capsule in salmonella
Which enteric bacteria are oxidase +? Which are -?
(+) = Campylobacter and vibrios (-) = ecoli, salmonella, shagilla
human are the primary reservoir for ___ (enteric bacteria)
shigella
Transmission of Shigella
- primary reservoir = humans
- low infectious dose
which infection is known as “traveler’s diarrhea”?
shigella
> 70% of shigella infections in the US are s. ____, and globally ___ are most common
sonnei = in US flexneri = global (150 mil/yr)
How does shigella dysenteriae cause damage?
shiga toxin leads to endothelial cell toxicity–> HUS
Inflammatory response damages endothelial cells.
Result: renal failure, bloody diarrhea, CNS manifestations.
Treatment of EHEC (e. coli)
Antibiotics cause more toxicity (trigger release of shiga toxins and cytotoxicity of endothelial cells)
Reservoir for e.coli? route of transmission?
cattle
contact with animal, person to person, contaminated food (beef, spinich, milk, lettuce, water).
Salmonella typhi has a mortality rate of
10-15% (due to ileal perforation and hemorrhage)
Which enteric pathogen has a high infectious dose (hard to transfer)?
non-typhoid salmonella
Which enteric infections have seasonal pattern?
salmonella (non typhoid) and campylobacter
of the salmonella typhi cases in the US, ___% is traveler’s disease
75%
incubation pd and duration of typhoid vs. non-typhoid salmonella infection
typhoid = 6-48 hrs incubation, 2-7days gastroentritis (self resolving)
non-typhoid salmonella = 10-14 day incubation, prolonged fever 3-4 weeks.
