Food-borne agents of watery diarrhea Flashcards
common characteristics
toxemia don't use abx-useless symptomatic tx for cramping fluids if no salt depletion no RBCs/WBCs in feces not transmissible afebrile prevent via proper food handling
Staphylococcal FBI
acute emetic and diarrheal illness from eating heat-stable, preformed toxin in food
S. aureus
little tidbit
G+ coag+ coccus, produces entereotoxin
multilocus seq. type/MLST strains ST398 or NT-MRSA spreading across Europe, etc. (animals and humans)
S. aureus prevalence ??
resevoir ?
transmission ?
assoc???
second to salmonella for FBI
foods: custard-filled, canned, processed meat, potato salad, etc.
reservoir is HUMANS (nasophar., skin–>skin/resp infections)
no gender assoc. WARMER mos: picnics,etc
risk: improper handling/storage of food
S. aureus enterotoxin
self-limited??
acts on neural rec. in upper GIT–>stim vomiting center in brain
5 Ag types: A-E, (A,B most common)
water-sol, heat stable (100d 30 min), colorless/odorless/tasteless
IS self-limited–>recovery 1-4 days
S. aureus immunity
make Ab to specific Ag type
S. aureus onset??
presents with…
pertinent negatives??
1-6 hour incubation post-ingestion (ACUTE!)
nausea, salivation, vomiting
may have diarrhea, abdominal cramps
NO neurological signs or fever
S. aureus dx
the SHORT incubation period, pres. of enterotoxin in food, vomitus
epi investigation: phage typing to trace strain source
S. aureus ddx
B. cereus (emetic form), metal toxemia (1 hr or less)
Bacillus cereus
G+ aerobic, spore-forming rod
produces 2 enterotoxins
B. cereus causes ??
transmitted through ??
assoc??
risk??
emetic and/or diarrheal disease
spores on grains: rice, potatoes, vegetables
extensive multiplication happens on food
no age/gen assoc. happens YEAR ROUND (foods made inside)
risk: inadequate prep/storage of food: esp. rice
B. cereus immunity??
unknown
B. cereus: emetic form
onset?
also have??
upper GI symps: vomiting, abd. cramps
1-5 hours post ingestion
diarrhea in 33%
B. cereus: diarrheal form:
onset??
lower GI symps: and. pain, profuse watery diarrhea
10-12 hrs post ingestion (longer incubation!)
B. cereus dx
if upper GIT symps develops 1-5 hours after eating
or lower dev. 6-24 hrs after eating
isolate 10^5+ orgs/gram from food or pt feces
B. cereus ddx
emetic: S. aureus
diarrheal: all other agents of acute onset afebrile diarrhea
B. cereus tx
rehydration
Clostridium perfringens, type A
FBI, self-limited, rarely fatal
anaerobic G+ non-motile rod, heat-stable SPORES
C. perfringens, type C causes…
impairs ??
from what?
causes clostridial necrotizing enteritis: “pigbel”: FBI w. necr. sm. bowel inflammation from beta toxin
normal trypsin-mediated degradation of beta toxin is impaired by protein-poor diet or congestion of foods like sweet potatoes (contain trypsin inhibitors)
C. perfringens occurs how
reservoir?
what foods?
microepidemic patterns
human/animal gut
meat, gravy improperly handled
no assoc. with gender, age, season
C. perfringens produces ??
has what effect??
enterotoxin in situ
max activity in ileum: inhibits glucose and chloride ion absorption, damages intestinal epithelium by denuding (stripping) the brush border @ villus tips–>diarrhea from secretion of e-lytes and H2O into gut lumen
C. perfringens type A persists in animal’s gut (meat) even when most bacteria are killed due to ??
will germinate and proliferate if food ???
heat-stable spores
if left out @ room temp
need to ingest ??? C. perfringens type A orgs for disease
10^8-10^9
C. perf incubation?
causes ??
duration ?
14 hrs
sev. cramping abc. pain, diarrhea
complete recovery in a day
C. perf dx
find >10^5 vegetative cells/gm food or
>10^4 C. perfs/gm pt feces
serology for enterotoxin presence in feces? (outbreaks)
C. perf ddx
other acute afebrile diarrhea
