Microbiology: Coliforms and Fecal Coliforms in Food

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Questions and Answers

What is the primary reason why coliforms are used as indicators of contamination?

  • They are the primary pathogens in foodborne illnesses
  • They are the most common type of bacteria found in food
  • They react similarly to pathogens in the natural environment (correct)
  • They are easily cultured and identified in a laboratory setting

What is the term for all members of the coliform bacteria group?

  • Klebsiella
  • Fecal coliforms
  • Total coliforms (correct)
  • Enterobacter

Which of the following foods is a common source of coliforms?

  • Pasteurized milk
  • White brined cheese (correct)
  • Cooked poultry
  • Canned vegetables

What is the characteristic of coliforms that allows them to be used as indicators of contamination?

<p>Their ability to ferment lactose (B)</p> Signup and view all the answers

What is the primary habitat of coliforms?

<p>Soil and vegetation (C)</p> Signup and view all the answers

What is the implication of detecting coliforms in food?

<p>The food is contaminated with other pathogenic organisms (B)</p> Signup and view all the answers

What is the primary function of the tetrazolium indicator in the Petrifilm EC/Coliform Count Plate?

<p>To facilitate colony enumeration (A)</p> Signup and view all the answers

Why is it essential to perform the presumptive test before the confirmatory test in coliform detection?

<p>To ensure the statistical validity of the method (C)</p> Signup and view all the answers

What is the purpose of the 5-bromo-4-chloro-3-indolyl-D-glucuronide (BCIG) in the Petrifilm EC/Coliform Count Plate?

<p>To detect the presence of glucuronidase activity (D)</p> Signup and view all the answers

What is the primary advantage of using the Petrifilm EC/Coliform Count Plate in food and beverage industries?

<p>It reduces the time required for testing (D)</p> Signup and view all the answers

What is the significance of Modified Violet Red Bile (VRB) nutrients in the Petrifilm EC/Coliform Count Plate?

<p>It inhibits the growth of non-coliform bacteria (A)</p> Signup and view all the answers

What is the primary implication of coliform contamination in food and beverages?

<p>All of the above (D)</p> Signup and view all the answers

What is the primary habitat of Escherichia coli bacteria?

<p>Lower part of the intestines of humans and animals (A)</p> Signup and view all the answers

What is the function of 0.1% peptone water in the detection of coliforms?

<p>It is a minimal nutrient media designed to reduce multiplication of microorganisms (B)</p> Signup and view all the answers

What is the significance of detecting fecal coliforms in food and water?

<p>It indicates the presence and risk of pathogenic microorganisms (D)</p> Signup and view all the answers

What is the purpose of using Lauryl sulfate tryptose broth (LSTB) in the detection of coliforms?

<p>It is used for the presumptive testing for the presence of coliforms (D)</p> Signup and view all the answers

What is the characteristic of Escherichia coli that makes it a member of the thermotolerant coliform group?

<p>It can ferment lactose in 48 hours at 44.5ºC (B)</p> Signup and view all the answers

What is the significance of recovering fecal coliforms from processed food?

<p>It indicates post-sanitation and post-process contaminations (C)</p> Signup and view all the answers

Flashcards

Why use coliforms as indicators?

They react similarly to pathogens in the natural environment, indicating potential health risks.

What are total coliforms?

All bacteria belonging to the coliform group.

Common coliform source?

White brined cheese due to production and storage conditions.

Coliform characteristic?

Their ability to ferment lactose, producing gas and acids.

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Coliform habitat?

Soil and vegetation, making their way into water and food sources.

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Implication of detection?

Indicates contamination with other potentially pathogenic organisms, posing a health risk.

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Function of tetrazolium indicator?

To facilitate colony enumeration, making it easier to count coliform colonies.

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Why presumptive test first?

To ensure the statistical validity of the method, reducing false positives.

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Purpose of BCIG?

To detect the presence of glucuronidase activity, an enzyme specific to E. coli.

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Advantage of Petrifilm EC?

It reduces the time required for testing, providing faster results.

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Significance of VRB?

It inhibits the growth of non-coliform bacteria, allowing for selective growth of coliforms.

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Coliform contamination in food?

Indicates the presence and risk of pathogenic microorganisms, possible fecal contamination and potential foodborne illnesses.

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Habitat of Escherichia coli?

Lower part of the intestines of humans and animals.

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Function of 0.1% peptone water?

It is a minimal nutrient media designed to reduce multiplication of microorganisms.

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Significance of fecal coliforms?

It indicates the presence and risk of pathogenic microorganisms.

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Purpose of using LSTB?

It is used for the presumptive testing for the presence of coliforms.

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E. coli characteristic?

It can ferment lactose in 48 hours at 44.5ºC.

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Recovering fecal coliforms?

It indicates post-sanitation and post-process contaminations.

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