Escherichia Coli 0157 H7

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Angelique and Ethan's infectious disease presentation.

Transcript of Escherichia Coli 0157 H7

  • 1. Escherichia Coli 0157:H7 Angelique and Ethan

2. E. Coli 0157:H7

    • large and diverse group of bacteria
    • most strains are harmless but others cause disease by making a toxin called Shiga toxin
      • "Shiga toxin-producing" E. coli - STEC
    • when you hear news reports about E.coli infections they're usually about 0157:H7

3. Epidemiology

    • first recognized by the Centers for Disease Control as a pathogen in 1982
    • during an outbreak of Hemolytic-uremic Syndrome in Oregon and Michigan
    • associated with eating hamburgers at the restaurants of one national chain
    • reported to cause large outbreaks as well as isolated sporadic infections in small numbers

4. Shiga Toxin

    • released into the intestinal tract
    • inhibits protein synthesis in target cells
      • cuts off several neucleobases from RNA compromising the ribosomes
    • structure has two units
      • B subunit binds to specific glyco-lipids on the host cell
      • A subunit is internalised and divided
        • A1 binds to ribosomes
    • toxin requires specific receptors on the cell surface
      • cattle, swine, and deer do not have these receptors
        • harbor the bacteria and excrete it in their feces
    • damages red blood cells as they pass through the intestinal tract

5. STEC E. Coli

    • STEC strains can survive for long periods of time on little sustenance
      • several weeks on a countertop
      • up to a year in materials such as compost
    • takes a very small amount of bacteria to infect a human
      • as few as 10 cells can be infected and still cause the symptoms
    • toxin classified as a potential biochemical terrorist agent by the CDC

6. How's It Spread ?

    • ingesting tiny amounts of human or animal feces
      • consumption of contaminated food
      • unpasteurized (raw) milk
      • water that has not been disinfected
    • contact with cattle
    • contact with the feces of infected people

7. 8. Signs and Symptoms

    • bloody diarrhea
    • severe abdominal pain and tenderness without fever
    • colitis - swelling of the large intestines
    • an acute infection
      • recovery in 5-10 days without any specific treatment
    • more serious in children under 5 yrs old and the elderly
      • Hemolytic-uremic Syndrome (HUS)
      • Thrombotic Thrombocytopenic Purpura (TTP)

9. Hemolytic-uremic Syndrome

    • caused in young children
    • most worrisome complication - potentially fatal
    • "hemolytic" refers to the breakup of red blood cells
      • leads to anemia
      • destruction of platelets
        • leads to thrombocytopenia - low blood levels of platelets
        • promotes abdominal bleeding
    • "uremic" refers to kidney failure
    • problems with the brain - seizures
    • coma may occur

10. Thrombotic Thrombocytopenic Purpura

    • caused in the elderly
    • clotting of blood within small blood vessels
    • fragmentation of red blood cells
      • leads to anemia
    • shortage of platelets
      • causes easy bruising
    • neurologic abnormalities
    • impaired kidney functions
    • fever

11. Diagnosis

    • 2 methods of testing stool specimens
      • growing bacteria in culture dishes
      • testing for Shiga Toxin produced by the bacteria
    • Blood Tests
      • performed periodically to look for the development of HUS
        • CBC - complete blood count
        • Blood levels of electrolytes
        • BUN - blood urea nitrogen
        • Creatinine - measure the function of the kidney

12. Prognosis

    • generally good
    • most patients recover within 10 days just by treating the symptoms
    • becomes more serious if HUS develops
      • high survival rate but possibly fatal
      • most patients are under 5 yrs old so their body might not be not strong enough to fight

13. Treatment

    • antibiotics not proven useful
      • studies have shown they may increase chances of developing HUS
    • replacement of fluids and electrolytes to prevent dehydration
    • HUS and TTP require otherwise specific care
      • may need dialysis

14. Activity

  • Break up into groups of three and create one skit. Each skit should demonstrate one way in which the spread of E. coli can be prevented. You have 3 minutes to discuss and 2 minutes to perform.
  • Example: McDonalds employee does not wash his hands and patron gets sick. Re-do shows employee washing his hands after using the restroom.

15. Prevention

    • WASH YOUR HANDS
    • COOK meats thoroughly
    • AVOID raw milk, unpasteurized dairy products and juices
    • AVOID swallowing water while swimming

16. History

    • from 1982 to 2002 - 350 outbreaks in the US
      • 52 % foodborne
      • 21% unknown
      • 6% recreational water
      • 3% animal contact
      • 3 % drinking water
    • 40 deaths
    • despite regulations outbreaks remain common
    • food transmission still the highest percentage
    • person-to-person transmission happening most commonly in daycare centers
    • total recall when source identified
      • approximately 25 million pounds of beef recalled

17. History II

    • outbreaks provided information about the inadequacy of processing methods
      • U.S. Department of Agriculture created regulations for processed meats
    • U.S. Food and Drug Administration revised Model Food Code for restaurants
    • prevention methods targeting food preparers