Biology: Enterobacteriaceae and Salmonella
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Questions and Answers

What is the optimal temperature for STEC growth?

  • 25 °C
  • 60 °C
  • 37 °C (correct)
  • 50 °C
  • Which E. coli is responsible for most foodborne infections resulting in death?

  • EIEC
  • STEC
  • ETEC
  • EHEC (correct)
  • What is the minimum pH level at which some STEC can grow?

  • 4.4 (correct)
  • 6.5
  • 5.5
  • 3.5
  • What is the minimum water activity (aw) at which some STEC can grow?

    <p>0.95</p> Signup and view all the answers

    What is the recommended internal temperature for cooking meats to prevent STEC infection?

    <p>70 °C</p> Signup and view all the answers

    What is the characteristic of Salmonella that makes it a primary cause of food infections?

    <p>Its high resistance to environmental conditions</p> Signup and view all the answers

    What is the typical duration of untreated Salmonella infection?

    <p>4-7 days</p> Signup and view all the answers

    What is the primary cause of diarrhea in newborns and children under 2 years of age?

    <p>EPEC</p> Signup and view all the answers

    What is the characteristic of Escherichia coli that causes dysentery-like bloody diarrhea?

    <p>EIEC</p> Signup and view all the answers

    What is the minimum infectious dose of Salmonella reported in the literature?

    <p>10^8-10^9 cfu/g</p> Signup and view all the answers

    Study Notes

    E. coli

    • Infection is more common in hot summer months
    • EIEC produces heat-sensitive (LT) or heat-stable (ST) toxins
    • ETEC is associated with children's diarrhea and tourist diarrhea
    • EHEC is responsible for most foodborne infections resulting in death
    • STEC can cause severe foodborne disease and produces Shiga-toxins
    • STEC can grow in temperatures ranging from 7 °C to 50 °C, with an optimum temperature of 37 °C
    • Some STEC can grow in acidic foods, down to a pH of 4.4, and in foods with a minimum water activity (aw) of 0.95
    • High virulence and low Minimum Infective Dose (MID) of 10-100

    Prevention

    • Cook meats thoroughly to at least 70 °C
    • Regular hand washing, particularly before food preparation or consumption, and after toilet contact
    • Wash fruits and vegetables carefully, especially if they are eaten raw

    Enterobacteriaceae

    • Gram negative
    • Motile
    • Facultative anaerobes
    • Surface antigens: O, H, and Vi
    • More than 2500 strains

    Salmonella

    • Widely distributed in the intestinal tract of domestic and wild animals
    • Can pass through the entire food chain from animal feed and primary production
    • High resistance to environmental conditions and long-term viability in food
    • One of the most important reasons for food infections

    Salmonella Infections

    • Caused by fecal contamination by ill or asymptomatic chronic carriers
    • Fever is documented at presentation in more than 75% of cases
    • Gastroenteritis is the most common clinical presentation of non-typhoidal Salmonella infection
    • Illness usually lasts 4-7 days, and most people recover without treatment
    • Minimal infection dose is reported to be 10^8-10^9 cfu/g

    E. coli Outbreak

    • 855 cases of HUS and 2,987 cases of acute gastroenteritis attributed to the outbreak
    • Death was reported for 35 (4.1%) of the patients identified with HUS and 18 (0.6%) of the patients with EHEC gastroenteritis
    • Total 53 deaths

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    Description

    Learn about the characteristics of Enterobacteriaceae, a family of Gram-negative bacteria, and Salmonella, a type of bacteria found in the intestinal tract of animals.

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