4 Food and Waterborne Diseases

Question 1

population with the highest frequency of foodborne illness

Answer 1

children

Question 2

most common cause of foodborne disease

Answer 2

viruses
norovirus causes more than half of all cases a quarter of all admissions

Question 3

foodborne bacteria most often resulting in fatality

Answer 3

nontyphoidal salmonella
listeria

Question 4

most common foods associated with foodborne illness outbreaks from any pathogen reported in the uS

Answer 4

poultry
leafy vegetables
fruits/nuts

Question 5

etiologic agents that may cause gastroenteritis in 1-6 hours

Answer 5

S aureus
B cereus
C botulinum

astrovirus
norovirus

Ciguatoxin (barracuda)
Tetrodotoxin (pufferfish)
Scombroid toxin (tuna)

Question 6

etiologic agents that involves toxin production after ingestino

Answer 6

vibrio
shigella
STEC

Question 7

etiologic agents that involve direct invasinoof the intestinal epithelium

Answer 7

salmonella
enteroinvasive E coli
campylobacter

causes bloody stools and fever
upper and lower GI symptoms last from 24 hours to weeks

Question 8

obtain a stool test in those with:

Answer 8

watery diarrhea with signs of hypovolemia
bloody diarrhea
fever ≥38.5C
duration of illness >1 week

severe abdominal pain or tenderness
hospitalized patients or recent antibiotic use
elderly (≥70 years of age) or the immunocompromised
pregnant women or those with comorbid conditions such as inflammatory bowel disease

Question 9

how to make oral rehydration solution as per WHO

Answer 9

8 teaspoon of sugar
1 teaspoon of salt
in 1L of water

Question 10

the 2017 Infectious Diseases Sociaty of America guidlines recommend empiric treatment for patients with bloody diarrhea under the ff circumstances

Answer 10

infants less than 3 months of age
immunocompromised patients with severe illness
Ill immunocompetent people with documented fever, abdominal pain, bloody diarrhea, and bacillary dysentery presumptively due to shigella
recent international travelers with fever ≥38.5C or signs of sepsis

Question 11

remarks on STEC

Answer 11

Avoid empiric antibioitics if you believe illness is from STEC O157 and other STEC that produce Shiga toxin due to increased risk of hemolytic-uremic syndrome (HUS)

Antibiotics may promote Shiga toxin release, which increases the incidence of HUS

Treatment of HUS is supportive

Question 12

A common bacterial enteritis regimen is

Answer 12

oral ciprofloxacin 500mg BID x 3-5 days
levofloxacin 500mg BID x 3-5 days
Azithromycin 500mg OD x 3 days

Question 13

most common cause of HUS in children

Answer 13

EHEC that produces Shiga toxin (STEC)

Question 14

remarks on scombroid poisoning

Answer 14

culprit: tuna, macckerel
sx: flushing, headache, abdominal cramping, vomiting, diarrhea

tx: antihistamines

Question 15

remarks on ciguatera poisoning

Answer 15

culprit: barracuda, amberjack
sx: hyperestehsias,numbness, reversal of hot/cold sensation, bradycardia, hypotension

tx: atropine, mannitol

Question 16

remarks on puffer fish

Answer 16

toxin: tetrodotoxin
sx: paresthesias, headache, VAD, ascending paralysis
death in 4-6 hours

tx:
emergent supportive care
anticholinesterases such as neostigmine and edrophonium

Question 17

remarks on GBS

Answer 17

associated with Campylobacter infection

symptoms typically occur 7-21 days after the GI symptoms resolve

Question 18

most common bacteria associated with recreational waterborne disease outbreaks

Answer 18

Campylobacter
- found in virtually all surface waters due to contamination from wild bird feces
- most enteric bacteria, including E coli O157:H7 and Campylobacter, are susceptible to chlorination

Question 19

most common cause of recreational waterborne GI illness [in the US]

Answer 19

Cryptosporidium
- an intracellular protozoan parasite
- standard doses of chlorine and zonation used in water treatment are not effective against Cryptosporidium, which explaines its association with recreational water sources

Question 20

Vibrio vulnificus vs Aeromonas

Answer 20

Vibrio vulnificus
- seawater
- assoc’d with life- and limb-threatening necrotic wound infections

Aeromonas
- fresh and marine waters
- majority of wound infections are simple cellulitis, but necrotizing infections and septic arthritis occur

Question 21

leading cause of acute gastroenteritis across all age groups

Answer 21

Noroviruses, including the Norwalk virus

Question 22

When to use azithromycin instead of doxycyline

Answer 22

pregnant women
children
patients with travel to areas fluoroquinolone-resistant Campylobacter (Thailand)

Question 23

first priority for Cryptosporidium treatment in patients with HIV

Answer 23

initiation of highly active antiretroviral threapy

Question 24

a monoclonal antibody to complement factor C5 that blocks complement activation;

Answer 24

eculizumab
- shows promise in severe cases of STEC-related HUS

Question 25

adjunct in cryptosporidium infection

Answer 25

nitazoxanide or paromomycin
(used for patients with prolonged infections, children, and the immunocompromised)