Bacterial GI Infections Flashcards
differentiate 3 classes of enteric bacterial pathogens
enteroinvasive: facultative intracellular
enterotoxic- bacteria produce enterotoxin, not invasive
enteropathogenic- bacteria destroy epithelium, invasion does not play a role
signs for inflammatory damage
pus, PMNs in feces
causes of inflammatory damage
baterial invasion and intracellular replication
bacterial toxins
secretory diarrhea, causes
high volume, caused by bacterial toxins
main tx for diarrhea
rehydration
sx of enteroinvasive infection
painful cramping, stools containing blood and pus
5 examples of enteroinvasive
salmonella enterica, shigella, campylobacter jejuni, listeria monocytogenes, EIEC
lactose macconkey use
only G- grow
pink means Lac+, yellow is Lac-
differentiate 4 outcomes for TSI slants, examples of microbes for each
K/K- ferment no lactose, sucrose, or glucose
-pseudomonas
A/A- ferments all 3
-E coli, Klebsiella, enterobacter
K/A-glucose only
-salmonella, shigella
black precipitate- H2S production, salmonella and proteus
identifying salmonella enterica
G- rod, facultative anaerobe
lac- on macconkey
K/A w/ H2S on TSI
salmonella e location
lower intestine in animals, acid tolerant and can survive stomach
relevant serovars for humans of salmonella enterica
typhoid group (humans only)
non typhoid; enteridis, typhimurium, cholerasuis (zoonotic)
sx of typhoid fever
gastroenteritis
slow progressing fever
profuse sweating
spread of typhoid fever
asymptomatic carriers shed lots of infectious material
often spread via food
low infectious dose, starts as GI infection then disseminates
tx for typhoid fever
antibiotics: cipro, ceftriaxone
(resistance to chloramphenicol, bactrim, ampicillin)
vaccines recommended for travelers
non typhoid salmonella disease
larger infectious dose, GI sx and fever
antibiotics not recommended, rare disseminations
shigella identification
G- non motile rod, facultative rod
lac-
shigella colonization
lower intestine of humans, acid resistant so low infectious dose
shigellosis transmission and sx
person to person only,
mild diarrhea to dysentrery
can lead to HUS
shiga toxin
enterotoxic- blocks absorption and can cause HUS
A+B toxin, receptor on intestine, kidney, brain
antibiotics like cipro increase risk of HUS
identifying campylobacter jejuni
G- motile cork screw rod
requires charcoal agar
campylobacter jejuni infection
most common cause of diarrhea, usually from animal products
low infectious dose, lasts about a week but not tx w/ antibiotics
listeria ID
G+ motile rod, grows at cold temps (refrigerated foods)
large host range
listeria transmission
foodborne, mother to child
