Food-borne agents of watery diarrhea

Question 1

common characteristics

Answer 1

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

Question 2

Staphylococcal FBI

Answer 2

acute emetic and diarrheal illness from eating heat-stable, preformed toxin in food

Question 3

S. aureus

little tidbit

Answer 3

G+ coag+ coccus, produces entereotoxin

multilocus seq. type/MLST strains ST398 or NT-MRSA spreading across Europe, etc. (animals and humans)

Question 4

S. aureus prevalence ??
resevoir ?
transmission ?

assoc???

Answer 4

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

Question 5

S. aureus enterotoxin

self-limited??

Answer 5

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

Question 6

S. aureus immunity

Answer 6

make Ab to specific Ag type

Question 7

S. aureus onset??
presents with…

pertinent negatives??

Answer 7

1-6 hour incubation post-ingestion (ACUTE!)
nausea, salivation, vomiting
may have diarrhea, abdominal cramps
NO neurological signs or fever

Question 8

S. aureus dx

Answer 8

the SHORT incubation period, pres. of enterotoxin in food, vomitus
epi investigation: phage typing to trace strain source

Question 9

S. aureus ddx

Answer 9

B. cereus (emetic form), metal toxemia (1 hr or less)

Question 10

Bacillus cereus

Answer 10

G+ aerobic, spore-forming rod

produces 2 enterotoxins

Question 11

B. cereus causes ??
transmitted through ??

assoc??

risk??

Answer 11

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

Question 12

B. cereus immunity??

Answer 12

unknown

Question 13

B. cereus: emetic form
onset?
also have??

Answer 13

upper GI symps: vomiting, abd. cramps
1-5 hours post ingestion
diarrhea in 33%

Question 14

B. cereus: diarrheal form:

onset??

Answer 14

lower GI symps: and. pain, profuse watery diarrhea

10-12 hrs post ingestion (longer incubation!)

Question 15

B. cereus dx

Answer 15

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

Question 16

B. cereus ddx

Answer 16

emetic: S. aureus
diarrheal: all other agents of acute onset afebrile diarrhea

Question 17

B. cereus tx

Answer 17

rehydration

Question 18

Clostridium perfringens, type A

Answer 18

FBI, self-limited, rarely fatal

anaerobic G+ non-motile rod, heat-stable SPORES

Question 19

C. perfringens, type C causes…

impairs ??
from what?

Answer 19

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)

Question 20

C. perfringens occurs how
reservoir?
what foods?

Answer 20

microepidemic patterns
human/animal gut
meat, gravy improperly handled
no assoc. with gender, age, season

Question 21

C. perfringens produces ??

has what effect??

Answer 21

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

Question 22

C. perfringens type A persists in animal’s gut (meat) even when most bacteria are killed due to ??
will germinate and proliferate if food ???

Answer 22

heat-stable spores

if left out @ room temp

Question 23

need to ingest ??? C. perfringens type A orgs for disease

Answer 23

10^8-10^9

Question 24

C. perf incubation?
causes ??
duration ?

Answer 24

14 hrs
sev. cramping abc. pain, diarrhea
complete recovery in a day

Question 25

C. perf dx

Answer 25

find >10^5 vegetative cells/gm food or
>10^4 C. perfs/gm pt feces

serology for enterotoxin presence in feces? (outbreaks)

Question 26

C. perf ddx

Answer 26

other acute afebrile diarrhea