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Public Health and Epi > Lecture 24 Biological Hazards-E. coli O157 & Salmonella spp. > Flashcards

Lecture 24 Biological Hazards-E. coli O157 & Salmonella spp. Flashcards

1
Q

What is a foodborne illness?

A
  • Any illness resulting from the
    consumption of food contaminated by
    pathogenic bacteria, viruses, parasites, as
    well as chemical or natural toxins.
  • Usually arises from improper handling,
    preparation, or food storage.
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2
Q

How do you reduce foodborne illnesses?

A

Good hygiene practices before, during, and after food preparation can reduce
the chances of contracting an illness

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3
Q

Foodborne illnesses are divided into:

A

Foodborne intoxications
Foodborne infections: noninvasive and invasive

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4
Q

What is a foodborn intoxication?

A
  • Ingestion of food containing “preformed” chemical toxicants,
    usually bacterial toxins.
  • The preformed toxin causes the illness not the bacteria itself
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5
Q

Example of foodborne intoxication?

A

E.g., Staphylococcal Food Poisoning
* Staphylococcal food intoxication is a true food poisoning caused by a toxin produced by Staphylococcus aureus.
a. Botulism
* Botulism is the most serious and most highly fatal type of
food poisoning afflicting humans.

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6
Q

What is a foodborne infection?

A
  • Pathogens in food survive the digestive processes and overcome the host’s natural defenses
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7
Q

Describe an invasive foodborne infection and give an example?

A

Organism penetrate the lining of the digestive tract and subsequently
multiply
* Characterized by dysentery (blood in feces), fecal leucocytes, fever
* E.g., EIEC, Salmonella spp, Listeria monocytogenes

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8
Q

Describe an noninvasive foodborne infection and give an example?

A

Organisms multiply in the GI tract **without ** penetrating the
digestive tract
* Characterized by watery diarrhea
* E.g., ETEC, Vibro cholarae, Clostridium perfringens

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9
Q

Foodborne intoxications present within….
& lack a?

A
  • present with 1 to 7 hours and lack a fever
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10
Q

Foodborne infections require…. & what ensues subsequently?

A
  • Typically require 8 hours to several weeks to present
  • A fever usually ensues due to the subsequent inflammatory
    response
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11
Q

What are the typical growth requirements for foodborne pathogenic bacteria?

A
  • Temperature - ranges from 40° to 140°F (4° to 60°C)
  • Also know as the “Danger
    Zone”
  • pH >4.6
  • Water activity (aw) > 0.85
  • O2 requirements - organism dependent
  • Nutrient requirements - organism dependent
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12
Q

What are the top 5 pathogens that contribute to domestically acquired foodborne illnesses resulting in hospitalization?

A
  • Salmonella, nontyphoidal
  • Norovirus
  • Campylobacter spp.
  • Toxoplasma gondii
  • E. coli O157
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13
Q

What is Escherichia coli (Colibacillosis)?

A

Gram (-) rod- Enterobacteriaceae family

Characterized by varying degrees of diarrhea

6 pathogenic strains in humans
* EHEC, ETEC, EIEC, EPEC, EAEC, DAEC

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14
Q

How is What is Escherichia coli (Colibacillosis) spread?

A

Water or food contaminated with feces (human or animal)

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15
Q

What is Enterohemorrhagic
E. coli (EHEC)?

A
  • Most virulent, severe clinical disease
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16
Q

What is the most common strain of E.coli?

A

E. coli O157:H7

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17
Q

What are the reservoir hosts of E.coli?

A

Cattle primarily and other ruminants

18
Q

Describe E. coli O157:H7.

A

Recognized first in 1993
* 1993 Jack in the box hamburger outbreak
* 4 deaths in children

Most common cause of human colibacillosis

Serotyping
* O - cell wall Ag
* H - flagellar Ag

19
Q

Describe the bacterial pathogenesis of E. coli.

A

Shiga-like toxins:
* Shigatoxins or Verotoxins
* Similar/identical to Shigella dysentariae toxin
* Neutralized by Shigatoxin antiserum
* Cytotoxic, causing fluid accumulation in the
gastrointestinal tract and hemorrhagic colitis

20
Q

What is the distribution and prevalence of E. coli?

A
  • Estimated 63,000 cases of EHEC infections in
    U.S. yearly
  • World-wide distribution
  • Cattle and humans – low infection rate
21
Q

Whats the preferred environment of E. coli?

A

45˚- 122˚F

22
Q

Who is susceptible to E. coli?

A

All ages susceptible
* Children and elderly – most common and serious affected

Children <5
* Highest incidence overall
* Highest incidence of Hemolytic
Uremic Syndrome (HUS)

23
Q

Incubation period of E. coli?

A

3-4 days, range–> 2-9

24
Q

Period of communicability of E. coli

A
  • Adults - ~1 week
  • Children – up to 3 weeks
25
Q

What is the temporal and spatial patterns of E. coli?

A

Summer/fall and rural populations

26
Q

What are the clinical signs of E. coli?

A

Mild, watery to severe, hemorrhagic diarrhea
* Average duration – 4 days
* Hemorrhagic in 50-75% of patients

Nausea, vomiting, abdominal pain – 50%
Asymptomatic disease possible

27
Q

What are some complications that can occur in E. coli infections?

A

Hemolytic Uremic Syndrome(HUS)
* Occurrence–2-10% of patients
* Thrombocytopenia, hemolytic anemia
* Main cause of acute renal failure in children
* Case fatality rate – 3-5%

Thrombocytopenic purpura
* Characterized by neurologic symptoms, thrombocytopenia, hemolytic anemia
* Mortality rate in the elderly as high as 50%

28
Q

How is E. coli transmitted?

A

Indirect:
- Fecal-oral in food–> cross contamination, improper washing, or undercooking

Direct:
- Fecal-oral –> human to human or animal to human

29
Q

What are some common sources of outbreaks of E. coli?

A
  • Raw or undercooked ground beef and beef products
  • Raw milk
  • Unpasteurized fruit juices
    a. E. coli O157:H7 can develop acid tolerance
    b. Acid foods (<pH 4.6) implicated
  • Various water sources, including well and recreational
    water
  • Contact with animals at farms or petting zoos
  • Person-to-person transmission
  • Various produce (bagged lettuce, spinach, and alfalfa sprouts)
30
Q

How can you as an individual prevent getting E. coli?

A
  • Wash hands, kitchen work surfaces, and utensils
  • Avoid cross-contaminating other foods
  • Do not eat raw or undercooked ground beef or food products
    a. Cook ground beef products to internal temperature of 1600F
  • Practice proper personal and food safety hygiene at petting zoos
31
Q

How can communities prevent E. coli?

A
  • Surveillance
  • Notification of disease to health officials
  • Pasteurization and hygienic slaughtering practices
  • Waste disposal
  • Public education and awareness
32
Q

How can you prevent/control E. coli in Livestock?

A
  • Proper animal husbandry
  • Vaccination
  • Probiotics
  • Stress reduction
  • Antemortem inspection
33
Q

What are some clinical signs of E. coli in animals?

A
  • EHEC, usually asymptomatic
  • ETEC, most common colibacillosis in animals
34
Q

What are the top 5 pathogens contributing to domestically acquired foodborne illnesses resulting in DEATH?

A
  • Salmonella, nontyphoidal
  • Toxoplasma gondii
  • Listeria monocytogenes
  • Norovirus
  • Campylobacter spp.
35
Q

What is salmonellosis?

A
  • Rod-shaped, Gram (-), non spore forming
  • > 2200 serotypes identified
  • GI tract inhabitant – usually associated with feces
36
Q

Does salmonella have to grow in food?

A

no
* Growth in food not necessary, no detectable
change in food

37
Q

Is salmonellosis zoonotic?

A

Yes
onset of symptoms 8-72 hours

38
Q

Describe the GI illness of salmonella.

A

Nausea, vomiting, diarrhea, cramps, and fever
* Symptoms persist for 4-7 days in health people

39
Q

Describe the typhoidal illness of salmonella.

A
  • High fever, diarrhea or constipation, aches, headache, and lethargy
  • 10% of people who do not get treatment may die
40
Q

How does salmonella cause GI illness?

A

Invases human beings by adhering to SI

41
Q

How can you get salmonella contamination?

A

Contaminated with fecal matter during processing

Contaminated raw foods
- Consumed raw or used in prepared foods that receive no further treatment or given insufficient heat treatment

Cooked, prepared foods contaminated from unclean equipment

Contaminations by worker with poor personal hygiene

42
Q

How do you control salmonellosis at home?

A
  • Proper hygiene
  • Separate raw foods from cooked
  • Store foods at proper temperature
  • Cook foods to proper temperature
  • Do not consume raw food products

Public Health and Epi (5 decks)

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