Bacterial Morphology and Metabolic Assays
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Questions and Answers

What is the primary purpose of applying safety measures in the procedure?

  • To ensure accurate quantification of forming units.
  • To protect individuals from harmful bacteria. (correct)
  • To prevent contamination of the culture medium.
  • To facilitate easier counting of bacterial colonies.

    • What does a color change in the culture medium most likely indicate?

  • The age of the bacterial culture.
  • Presence or absence of a bacterial capsule. (correct)
  • Presence of bacteria only.
  • Growth of Staphylococcus species.

    • Which bacterial morphology is characterized by rod-shaped organisms?

  • Coccobacilli
  • Cocci
  • Streptococci
  • Bacilli (correct)

    • Which part of the microscope is NOT typically used for adjusting focus?

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

    What is the first step in the quantification procedure of forming units?

    <p>Applying safety measures.</p> Signup and view all the answers

    What is required for using the 100x objective of a microscope?

    <p>Immersion oil</p> Signup and view all the answers

    Which color indicates Gram-positive bacteria when observed under a microscope?

    <p>Blue/Violet</p> Signup and view all the answers

    What is the first step in the Gram staining procedure?

    <p>Prepare a smear of the sample</p> Signup and view all the answers

    What shape do Staphylococci bacteria have?

    <p>Spherical (in clusters)</p> Signup and view all the answers

    During Gram staining, after applying the primary stain, what should be done next?

    <p>Rinse with water</p> Signup and view all the answers

    What is the primary indication of bacteria using citric acid as a carbon source?

    <p>The medium turns blue</p> Signup and view all the answers

    What does a positive indole test indicate about a bacterium?

    <p>It produces indole and the medium turns red</p> Signup and view all the answers

    Which structure in bacteria allows for movement in semi-solid media?

    <p>Flagella or pseudopodia</p> Signup and view all the answers

    What color indicates a positive reaction when testing for the use of citrate in a bacterial culture?

    <p>Navy Blue</p> Signup and view all the answers

    What is the significance of using a semi-solid medium like LIA in bacterial testing?

    <p>To evaluate the use of non-carbohydrate carbon sources</p> Signup and view all the answers

    What is the purpose of using Triple Sugar Iron (TSI) in bacterial metabolic assays?

    <p>To assess if bacteria can ferment sugars or produce hydrogen sulfide and/or gas.</p> Signup and view all the answers

    What color change in the Urea test indicates a positive result for urea hydrolysis?

    <p>Pink color</p> Signup and view all the answers

    After incubating bacteria in TSI agar slant, which color change indicates fermentation of sugars?

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

    What is the role of TTC (Tetrazolium Chloride) in the metabolic assays?

    <p>It serves as a metabolic indicator to distinguish between fermentation and oxidative metabolism.</p> Signup and view all the answers

    Why might further analysis be necessary after initial testing of bacteria?

    <p>The color changes are often not reliable indicators alone.</p> Signup and view all the answers

    What indicates a positive result in the oxidative test?

    <p>A color change in the oxidase disc to grayish.</p> Signup and view all the answers

    During the oxidative test, how long should one wait to observe any color change?

    <p>1 minute</p> Signup and view all the answers

    If no change is observed in the oxidase disc after the procedure, how should this be reported?

    <p>As negative.</p> Signup and view all the answers

    What is the first step in performing the oxidative test?

    <p>Confirm bacterial growth and select a CFU.</p> Signup and view all the answers

    What should be used to pick up the oxidase disc during the procedure?

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

    What is a key component used in differentiating Salmonella?

    <p>Trisulfatate of soda</p> Signup and view all the answers

    What color change indicates a positive result for colicine in the MIO test?

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

    Which ingredient is common to both the differentiation of Salmonella and MIO tests?

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

    In the context of the MIO test, what does the presence of ornitine decarboxylase lead to?

    <p>Formation of putrescine</p> Signup and view all the answers

    What does the fluid color of bromocresol purple indicate in the MIO test?

    <p>Alkaline conditions</p> Signup and view all the answers

    Which microorganism is primarily differentiated based on urease activity?

    <p>Proteus sp.</p> Signup and view all the answers

    What color do colonies turn when urease is produced?

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

    Which ingredient is NOT used in the citrate differentiation test?

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

    Citrate permease is associated with which type of bacteria?

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

    What is produced from the fermentation of citrate by bacteria?

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

    What is the primary reaction observed in a positive catalase test?

    <p>Bubbles indicating the breakdown of hydrogen peroxide</p> Signup and view all the answers

    Which enzyme is identified by performing the catalase test?

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

    What does a negative result in the catalase test indicate?

    <p>No catalase production</p> Signup and view all the answers

    Which step occurs after selecting a colony-forming unit in the catalase test procedure?

    <p>Spread the CFU on a microscope slide</p> Signup and view all the answers

    How is a catalase-positive result typically reported?

    <p>Catalase Positive</p> Signup and view all the answers

    What is the primary use of Kligler Iron Agar?

    <p>To differentiate enterobacteria based on carbohydrate fermentation and hydrogen sulfide production.</p> Signup and view all the answers

    What does the color change of phenol red indicate in Kligler Iron Agar?

    <p>Fermentation of sugars resulting in acid production.</p> Signup and view all the answers

    Which of the following ingredients is NOT found in TSI Agar?

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

    In TSI Agar, what is the significance of sulfuric acid production?

    <p>It shows that sugars other than glucose are being fermented.</p> Signup and view all the answers

    How is hydrogen sulfide produced in Kligler Iron Agar?

    <p>By the reduction of iron sulfate to sulfide and further reactions with ferric iron.</p> Signup and view all the answers

    What does the coagulase test primarily determine in bacteria?

    <p>The capacity to form a coagulant</p> Signup and view all the answers

    Which bacteria are typically identified using the coagulase test?

    <p>Staphylococcus and Streptococcus</p> Signup and view all the answers

    What is a potential clinical outcome of bacteria producing coagulation enzymes?

    <p>Formation of blood clots in vessels</p> Signup and view all the answers

    What is the final incubation temperature for the plasma inoculated in the coagulase test?

    <p>37°C</p> Signup and view all the answers

    What indicates a negative result in the coagulase test?

    <p>No change in plasma (no clot formation)</p> Signup and view all the answers

    Study Notes

    Quantification of Forming Units of Colonies

    • Procedure involves several steps including preparing the culture plate, focusing on the colony counter, and quantifying the units.
    • Colonies can be round or circular.
    • Color varies from white to gray based on sulfuric acid production.
    • Salmonella can be distinguished by their ability to affect the medium color.
    • Bacterial Morphology can include bacilli (rod-shaped), cocci (spherical), and coccobacilli (a combination of rod and spheres).
    • Staphylococcus bacteria form clusters; streptococci form chains.

    Bacterial Metabolic Assays

    • Triple Sugar Iron (TSI) agar slant is used to determine if the bacteria can ferment sugars or produce hydrogen sulfide and gas production.
    • TTC (Tetrazolium Chloride) metabolic indicator determines if the organism uses fermentation or oxidative metabolism.
    • Urea Test is used to determine if a bacterial species uses urea as a source of carbon.
    • MIO Test (Movilidad Indol y Ornitina) determines the presence of flagella, the production of indol, and if the bacteria can use ornitine as a source of carbon.
    • Citrate Test determines whether bacteria can use citrate as a source of carbon.

    Biochemical Tests (Bacterial)

    • Kligler Iron Agar is used to differentiate enterobacteria based on carbohydrate fermentation and hydrogen sulfide production.
    • TSI Agar (Triple Sugar Iron) measures glucose, sucrose, and lactose fermentation, and sulfuric acid production.

    Differentiation of Salmonella L-30-Sep-2024

    • Ingredients include peptones of gelatin, extract of yeast, glucose, lysine, trisulfatate of soda, and agar.
    • Fundamentals include termination of glucose, acidification, and color change.

    MIO (MOVILITY, INDOLE AND O-NITRIFICATION)

    • Identify enterobacteriaceae
    • Ingredient: extract of yeast, peptones, tryptone, agar and bromocresol purple
    • Fundamentals: bromocresol purple, purple color, and color change in purple.
    • Positive Result: Colicine

    Urea

    • Procedure: Differentiate microorganisms based on urease activity.
    • Ingredients: Triple sugar, glucose, sodium chloride, and agar.
    • Fundamentals: urease, alkaline ammonia, and carbon dioxide.

    Citrate

    • Ingredients: sodium citrate, sodium chloride, dipotassium phosphate, magnesium sulfate, and agar.
    • Fundamentals: citrate permease, oxalate and pyruvate, carbonates and bicarbonates, and neutral red agar.

    PRUEBAS COMPLEMENTARIAS de Identificación Bacteriana

    • Coagulaza Test determines the bacteria’s ability to form a clot by interacting with a host’s coagulation factors.
    • Procedure involves collecting blood, centrifuging it, separating the plasma, and inoculating it with a bacterial colony.
    • Results: positive if a clot forms, negative if no change in plasma is observed.

    Oxidative Test

    • Positive Result: A visible clot formation is observed.
    • Oxidative Test Procedure involves preparing a smear on a glass slide, placing an oxidase disc on the smear, and observing any color change after one minute.
    • Results: positive if the oxidase disc turns grayish, negative if the disc remains white.

    Catalase Test

    • Purpose: Identifies bacteria based on their ability to produce the enzyme catalase, which breaks down hydrogen peroxide.
    • Procedure involves preparing a hydrogen peroxide solution, spreading a bacterial colony onto a microscope slide, adding a drop of hydrogen peroxide, and observing any reaction.
    • Results: negative if no reaction is observed, positive if bubbles form on the smear.

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    Description

    This quiz covers key concepts in bacterial morphology and metabolic assays, focusing on the quantification of colony-forming units and the use of specific tests like TSI agar and urea tests. You'll explore various bacterial shapes, colors, and their metabolic processes. Test your understanding of how these characteristics help distinguish between different types of bacteria.

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