Food-borne Illness

Question 1

Probiotics

Answer 1

• Alter microecology: reduce harmful organisms, stimulate immune response
• Examples: lactobacillus, bifidobacterium
• Sources: yogurt, supplements
• Uses: diarrheal dx, ulcerative colitis, crohn’s, IBS, ABX
• Prebiotics: non-digestible, stimulate growth or activity of beneficial organisms

Question 2

Incubation Period - Important in food-borne illness

Answer 2

• Toxin-mediated: <8hrs
• Virus: 24-48 hrs
• Bacteria: 1-5 days
• Parasite: >5 days

Question 3

Top 5 Pathogens Causing Domestically Acquired Food-borne Illness

Answer 3

1. Norovirus
2. Salmonella, nontyphoidal
3. Clostridium perfringens
4. Campylobacter spp.
5. Staphylococcus aureus

Question 4

Top 5 Pathogens Requiring Hospitalization

Answer 4

1. Salmonella, nontyphoidal
2. Norovirus
3. Campylobacter spp
4. Toxoplasma gondii
5. E. coli O157

Question 5

Top 5 Pathogens Causing Death in the U.S.

Answer 5

1. Salmonella, nontyphoidal
2. Toxoplasma gondii
3. Listeria monocytogenes
4. Norovirus
5. Campylobacter spp.

Question 6

Foodborne Illness Risk Groups

Answer 6

• Infants and children
• Pregnant women
• Older adults (>65)
• Chronic disease (liver disease, diabetes, cancer)
• Immunocompromised (HIV, chemo, steroids, other immunosuppressive drugs)
• Decreased gastic acidity (achlorhydria)

Question 7

What is the most common bacterial cause of foodborne illness in the U.S?

Answer 7

Salmonella

Question 8

Samlonella Etiology

Answer 8

• Gram negative bacilli
• S. enterica three serotypes - typhi, typhimurium, and enterica

Question 9

Salmonella Sources of Infection

Answer 9

• Raw meat - poultry, eggs, fish, raw milk, water
• Feces of pets (reptiles and birds)
• Common cross-contamination - drippings, utensils, surfaces, and other foods
• Multiples rapidly at room temperature

Question 10

Salmonella: Gastroenteritis

Answer 10

• Incubation Period: 8-48 hours
• Signs & Symptoms:
  
  • N/V/D (maybe bloody), headache, fever and chills, abdominal cramps
  • Self-limited: usually resolves in 3-5 days
• Diagnosis: stool culture
• Treatment: symptomatically and supportive generally
  
  • Non-pharm: oral fluids
  • may require IV fluids
• Abx recommended for: severe cases, high-risk patients (bacteremia can occur)

Question 11

Salmonella: Bacteremia

Answer 11

• Potential complications:
  
  • Septicemia - blood cultures
  • Local bone or joint infections
  • Rare: mycotic AAA (patients with HIV)
• Abx options:
  
  • Fluoroquinolones (Ciprofloxacin or Lexofloxacin)
  • Third-generation cephalosporins (Ceftriaxone and Cefixime)
  • Seeing growing drug resistance

Question 12

Salmonella: Enteric Fever

Answer 12

• Caused by serotype typhi
• Signs & symptoms:
  
  • Gradual onset of N/V, abdominal pain, headache, and malaise
  • Bradycardia, splenomegaly, abd distention
  • Rose spots - second week of disease. Salmon-colored, blanching, 2-3mm in diameter
  • Stepladder rise of fever (103-104 F), then normal
  • Leukopenia
  • Positive stool, blood, and urine cultures
• Several complications, including death
• Other issues: carrier state and immunization

Question 13

Campylobacter jejuni

Answer 13

• Etiology: gram-negative spiral shaped bacteria
• Source of infection: raw meat, poultry, raw milk, shellfish, water contaminated with animal feces
• Incubation Period: onset 2-4 days, duration 2-7 days
• Signs and symptoms:
  
  • Diarrhea (frequently bloody) - 1/3 of cases, abdominal pain, fever - 2/3 of cases, occasionally N/V
  • Invasive dysentery - small intestine and colon

Question 14

Campylobacter jejuni - Diagnosis, Treatment, Complications

Answer 14

• Diagnosis: stool culture
• Treatment:
  
  • usually self-limiting
  • prolonged cases may need abx:
    
    • Fluoroquinolone (cipro or levo) or Azithromycin (preferred)
    • Growing abx resistance
• Complications:
  
  • Guillan-Barre syndrome: 2-3 weeks after illness
  • Sepsis: immunocompromised patients
  • Death

Question 15

Shigella

Answer 15

• Etiology: 4 species
• Sources of infection:
  
  • Fecal-oral route (including fomites, contaminated food or water)
  • Passed by food handlers or foods from contaminated soil
  • Daycare settings
  • Multiplies in small intestine then progresses to colon/colitis
• Incubation period: onset 1-3 days
• Typical duration: 4-7 days
• Signs & Symptoms: Diarrhea with blood and mucous, crampy abdominal pain, fever, tender abdomen
• Labs: fecal leukocytes with red blood cells, positive stool culture
• Treatment: supportive, abx if indicated
• Complications: reactive arthritis (HLA-B27), Hemolytic Uremic Syndrome

Question 16

E. Coli 0157:H7

Answer 16

• Enterohemorrhagic E. coli
• Incubation Period: 1-8 days
• Source: undercooked beef, unpasturized milk and juice, raw fruits and vegetables
• Reservoir: found in feces of warm blooded animals
• Person-to-person is feasible
• Signs & Symptoms: bloody watery diarrhea (>5 stools daily), hemorrhagic colitis, abdominal pain
  
  • Usually resolves in 1 week
• Diagnosis: stool culture
• Treatment: NO abx or antiperistalic agents, supportive treatment

Question 17

Hemolytic Uremic Syndrome (HUS)

Answer 17

• Affects 6-9% of those infected with EHEC. 15% in children <10 years old
• Triad of HUS:
  
  • Acute renal failure
  • Microangiopathic hemolytic anemia
  • Thrombocytopenia
• Patients with fever and neurological symptoms can have TTP

Question 18

Enterotoxogenic E. Coli (ETEC)

Answer 18

• Most common form of traveler’s diarrhea
• Source: water, contaminated food (salads, fruit, vegetables)
• Incubation: 1-3 days
• Duration: 3-7 days
• Signs & symptoms: profuse, watery diarrhea, nausea with or without vomiting, abdominal cramping. Rarely life-threatening; self-limiting
• Antibiotics only if prolonged course (FQ, Azithromycin, Rifaximin)
• Prevention: peel it, cook it, boil it - or forget it!

Question 19

Vibrio Vulnificus

Answer 19

• Incubation: 1-4 days
• Source: undercooked or raw seafood (oysters)
• Signs & symptoms: watery diarrhea, N/V, abdominal pain and cramping
• Testing: stool culture on special medium
• Treat suspected cases immediately!
  
  • Doxycycline or 3rd generation cephalosporin
• Complications:
  
  • Immunocompromised (especially chronic liver disease) - sever sepsis and/or bullous cellulitis. 50% mortality rate
  • Causes skin infections through open wounds exposed to seawater

Question 20

Vibrio cholera

Answer 20

• Incubation: 1-3 days
• Source: contaminated water, food (fish, shellfish)
• Signs & symptoms: asymptomatic or acute onset of vomiting, profuse watery diarrhea, dehydration
• Treatment:
  
  • Oral rehydration
  • IV fluids and electrolytes
  • Abx in severe or moderate disease: doxycycline

Question 21

Listeria Monocytogenes

Answer 21

• Etiology: gram-negative rod
• Source:
  
  • soft cheeses, deli meats, hot dogs, smoked seafood, unpasturized dairy
  • soil, leafy vegetables, strawberries, raspberries, juices
  • food processing environments
• Difficult to kill (survives cold temperatures)
• Commonly affects: older adults, pregnant women, newborns, and adults with weakened immune systems
• Incubation period: GI symptoms wtihin 24 hours
• Signs & symptoms: vary; fever, watery diarrhea, N/V, headache, joint/muscle pain
  
  • Older adults & immunocompromised: septicemia and meningitis
  • Preg. women: fever and nonspecific sxs. may result in fetal loss or severe illness in newborn
• Diagnosis: blood cultures
• Treatment: ampicillin

Question 22

Staphylococcus aureus

Answer 22

• Common bacteria found on the skin
• Etiology: preformed toxin produced when contaminated foods are stored at room temperature
• Sources: meat, poultry, eggs, tuna; potato and macaroni salads; bakery items
• Incubation period: 1-8 hours (rapid onset)
• Duration: 2-3 days
• Signs and symptoms: intense N/V, fever is NOT common, usually self-limiting

Question 23

Clostridium perfringens

Answer 23

• “cafeteria germ”
• Etiology: spore forming gram-positive bacilli, toxin produced in the intestines
• Source: beef, poultry, gravies, and dried or precooked foods, soil
• Incubation period: 8-16 hours
• Duration: self-limited (24-48 hours), up to 2 weeks in high-risk groups
• Signs & symptoms: abrupt onset of profuse watery diarrhea, abdominal cramps, nausea, vomiting - little to none
• Treatment: supportive, IV fluid and abx if indicated

Question 24

Clostridium botulinum

Answer 24

• Source: home canned beans, mushrooms, olives, spinach, and beef, honey and corn syrup
• Incubation period: 18-36 hours
• Signs & symptoms: N/V/D followed by constipation
  
  • classic sxs of botulism (descending paralysis)
  • can be fatal
• Antibiotics are not recommended
• Antitoxin plays a role - slows progress

Question 25

Trichinosis

Answer 25

• Parasite
• Source: undercooked meat (pork and wild game)
• Incubation period: varies; 1-2 weeks (enteral phase), 2-8 weeks (parenteral phase)
• Signs & Symptoms:
  
  • Early: asymptomatic (majority), N/V/D, abdominal pain, muscle weakness
  • Later: fever, myalgias, periorbital edema, splinter hemorrhages, eosinophilia
• Diagnosis: history, signs and symptoms, labs (serology, muscle biopsy)
• Treatment: antiparasitic

Question 26

Hepatitis A

Answer 26

• Virus
• Transmission: fecal-oral
• Sources: shell fish, fruits, vegetables, water, ice
• Incubation period: 30 days
• Symptoms: mild, but may last for several months
  
  • dark urine, fatigue, low-grade fever, poor appetite, N/V, jaundice, pale or clay-colored stools
  • young children may be asymptomatic
• Treatment: supportive

Question 27

Norovirus (norwalk virus)

Answer 27

• Common source: infected food handlers contaminate food
  
  • person-to-person
  • fecal-oral with contaminated food or water
• Incubation: 12-48 hours
• Signs & Symptoms: N/V, watery diarrhea, abdominal pain
• Treatment: self-limiting