Enterobacteriaceae Identification Quiz
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Questions and Answers

What characteristic differentiates coliform bacteria from non-coliform bacteria?

  • Coliform bacteria ferment lactose to produce acid and gas (correct)
  • Coliform bacteria can produce gas from glucose
  • Coliform bacteria are always pathogenic
  • Coliform bacteria do not ferment lactose

Which of the following organisms is classified as a non-coliform?

  • Salmonella (correct)
  • Escherichia coli
  • Enterobacter spp.
  • Klebsiella spp.

What is the primary purpose of serological testing in pathogen detection?

  • To identify specific antigens in a sample (correct)
  • To culture bacteria from urine samples
  • To determine lactose fermentation ability
  • To classify bacteria based on morphology

Which test is commonly used to differentiate among Enterobacteriaceae species?

<p>Triple Sugar Iron (TSI) test (C)</p> Signup and view all the answers

In the fermentation process, what compounds do coliform bacteria primarily produce?

<p>Acid and gas (B)</p> Signup and view all the answers

What is typically the first step in urine formation?

<p>Filtration (B)</p> Signup and view all the answers

What characteristic of Pseudomonas aeruginosa makes it a common pathogen in hospital settings?

<p>It is resistant to many antibiotics (D)</p> Signup and view all the answers

What type of culture media is used primarily for isolating Pseudomonas aeruginosa?

<p>Cetrimide agar (A)</p> Signup and view all the answers

What characteristic of Eosin Methylene Blue (EMB) Agar distinguishes lactose fermenters?

<p>Blue-black or metallic sheen colonies (B)</p> Signup and view all the answers

Which of the following accurately describes the function of MacConkey Agar?

<p>Contains bile salts and crystal violet to inhibit Gram positive bacteria (B)</p> Signup and view all the answers

What does a positive result in the Triple Sugar Iron (TSI) test indicate?

<p>Production of hydrogen sulfide (C)</p> Signup and view all the answers

Which group of bacteria is characterized as coliform?

<p>Lactose fermenting Gram negative bacteria (A)</p> Signup and view all the answers

What is the primary aim of serological testing for pathogens?

<p>To detect specific antibodies or antigens in a sample (B)</p> Signup and view all the answers

What growth characteristic is associated with Pseudomonas aeruginosa on Cetrimide Agar?

<p>Production of a greenish pigment (B)</p> Signup and view all the answers

Which biochemical test is incorporated in the IMVIC series?

<p>Methyl Red test (B)</p> Signup and view all the answers

Which statement accurately compares coliform and non-coliform bacteria?

<p>Coliform can ferment lactose, while non-coliform bacteria cannot. (D)</p> Signup and view all the answers

What characteristic coloration indicates the presence of Pseudomonas aeruginosa on Cetrimide Agar?

<p>Yellow-green to blue color colonies (C)</p> Signup and view all the answers

What does the IMVIC test 'V' suggest about a bacterium?

<p>Presence of acetoin (A)</p> Signup and view all the answers

Which test is used to assess a bacterium's ability to ferment sugars and produce hydrogen sulfide?

<p>Triple Sugar Iron (TSI) Test (D)</p> Signup and view all the answers

Which of the following describes a feature that differentiates lactose fermenters from non-lactose fermenters on agar plates?

<p>Red colonies indicate lactose fermenters (A)</p> Signup and view all the answers

What limitation might be observed with Cetrimide Agar when testing for Pseudomonas aeruginosa?

<p>Some enterics may exhibit slight yellowing of the medium (B)</p> Signup and view all the answers

Which IMVIC biochemical test is specifically used to detect the enzyme tryptophanase?

<p>Indole Test (D)</p> Signup and view all the answers

What type of bacteria would likely produce a pink pigmentation on Cetrimide Agar?

<p>Serratia species (D)</p> Signup and view all the answers

What is a common application of serological testing in microbiology?

<p>Identifying pathogen-specific antigens (D)</p> Signup and view all the answers

Flashcards

Enterobacteriaceae

A family of gram-negative bacteria commonly found in the intestines of warm-blooded animals, including humans.

Coliforms

A group of lactose-fermenting enterobacteriaceae used as indicators of fecal contamination in water and food.

Escherichia coli (E. coli)

A type of coliform bacteria, often found in the intestines of humans and animals.

Klebsiella spp.

A genus of coliforms, often associated with urinary tract infections.

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Enterobacter spp.

A genus of coliforms, often found in the environment and can cause opportunistic infections.

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Non-Coliform enterobacteriaceae

Enterobacteriaceae that do not ferment lactose to produce gas.

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Salmonella

A genus of non-coliform enterobacteriaceae, known for causing food poisoning.

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Shigella

A genus of non-coliform enterobacteriaceae, known for causing dysentery.

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Yersinia

A genus of non-coliform enterobacteriaceae, known for causing plague and other diseases.

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EMB (Eosin Methylene Blue) Agar

A selective medium used to isolate and differentiate gram-negative bacteria based on lactose fermentation.

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MacConkey Agar

A type of agar used to differentiate lactose fermenters and non-lactose fermenters among gram-negative bacteria.

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Salmonella-Shigella Agar

A selective medium used for isolating Salmonella and Shigella.

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Cetrimide Agar

A selective medium used to isolate Pseudomonas aeruginosa.

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IMVIC

A series of four biochemical tests used to identify enterobacteriaceae.

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Indole test

A test in the IMVIC series that tests for the presence of tryptophanase.

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Methyl Red (MR) test

A test in the IMVIC series that tests for the production of mixed acids from glucose fermentation.

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Voges-Proskauer (VP) test

A test in the IMVIC series that tests for the presence of acetoin.

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Citrate test

A test in the IMVIC series that tests for the ability to utilize citrate as a carbon source.

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Triple Sugar Iron (TSI) Agar

A medium used to test for the fermentation of sugars (glucose, lactose, sucrose), production of gas, and the presence of hydrogen sulfide.

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Urea Agar

A medium used to test for the presence of urease, an enzyme that hydrolyzes urea.

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Urinary Tract Infection (UTI)

A type of infection affecting the urinary tract.

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Escherichia coli (E. coli)

A bacterium commonly associated with UTIs, especially in women.

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Klebsiella pneumoniae

A bacterium often responsible for UTIs, particularly hospital-acquired infections.

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Proteus mirabilis

A bacterium commonly associated with UTIs, particularly in people with urinary catheters.

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Study Notes

Enterobacteriaceae and Gram-Negative Intestinal Pathogens

  • Enterobacteriaceae are a family of gram-negative bacteria commonly found in the intestines of warm-blooded animals, including humans.
  • Coliforms are lactose fermenting enterobacteriaceae and are used as indicators of fecal contamination in water and food.
  • Coliform examples include Escherichia coli, Klebsiella spp., and Enterobacter spp.
  • Non-Coliform enterobacteriaceae are gram-negative but do not ferment lactose to produce gas.
  • Non-Coliform examples include Salmonella, Shigella, and Yersinia and are often pathogenic, causing gastrointestinal diseases.

Enterobacteriaceae Identification

  • EMB (Eosin Methylene Blue) Agar is used to isolate and differentiate gram-negative bacteria.
    • Metallic sheen/blue-black colonies: Lactose fermenters
    • Dark purple colonies: Slow lactose fermenters
    • Pink colonies: Non-lactose fermenters
  • MacConkey Agar is used to isolate and differentiate gram-negative bacteria.
    • Pink colonies: Lactose fermenters
    • Colorless colonies: Non-lactose fermenters
  • Salmonella-Shigella Agar is used to isolate Salmonella and Shigella.
    • Red colonies: Lactose fermenters
    • Colorless colonies: Non-lactose fermenters
  • Cetrimide Agar is used to isolate Pseudomonas aeruginosa.
    • Yellow-green to blue color colonies: Indicate the production of pyocyanin by P. aeruginosa

Biochemical Testing for Enterobacteriaceae

  • IMVIC is a series of four biochemical tests used to identify enterobacteriaceae.
    • Indole: Tests for the presence of tryptophanase, an enzyme that cleaves tryptophan to produce indole.
    • Methyl Red (MR): Tests for the production of mixed acids from glucose fermentation.
    • Voges-Proskauer (VP): Tests for the presence of acetoin, suggesting the bacterium follows the 2,3-butanediol fermentation pathway.
    • Citrate: Tests for the ability to use citrate as the only carbon source.
  • Triple Sugar Iron (TSI) Agar: Tests for the fermentation of sugars (glucose, lactose, and sucrose), production of gas, and the presence of hydrogen sulfide (H2S).
  • Urea Agar: Tests for the presence of urease, an enzyme that hydrolyzes urea into ammonia and carbon dioxide.

Urine Culture Techniques and Urinary Tract Pathogens

  • Urine is a sterile waste product formed in the kidneys, stored in the bladder, and excreted through the urethra.
  • Urine culture techniques are used to diagnose urinary tract infections (UTIs).
  • Common urinary tract pathogens include Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Staphylococcus saprophyticus.
  • Causes of UTIs in Females: Shorter urethra, closer proximity to the anus, and sexual activity.

Disease Outbreaks Associated with Enterobacteriaceae

  • Food and Waterborne Diseases/Intoxication
  • Animal Contact Disease Outbreaks
  • Antibiotic-Associated Diarrhea
  • Antimicrobial Resistance Pathogens
  • Cases with Immunocompromised Individuals

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Description

Test your knowledge on the Enterobacteriaceae family and the identification of gram-negative intestinal pathogens. Learn about the characteristics of coliforms and non-coliforms, as well as the significance of EMB and MacConkey agar in microbiology. This quiz will challenge your understanding of these critical microorganisms.

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