Microbial Identification Methods
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Questions and Answers

What is the primary purpose of serotyping in microbiology?

  • To visualize antigen-antibody reactions
  • To determine the antibiotic resistance of bacteria
  • To amplify DNA or RNA segments
  • To identify and classify bacterial species and strains (correct)

    • Which test is specifically designed to detect HIV antibodies?

  • Polymerase Chain Reaction (PCR)
  • Serotyping
  • Western Blot Test (correct)
  • Enzyme-Linked Immunosorbent Assay (ELISA)

    • What characteristic does specificity in immune testing refer to?

  • The detection of a broad range of antigens
  • Identifying multiple pathogens at once
  • The ability to differentiate between closely related antigens (correct)
  • Detecting even small quantities of antigens or antibodies

    • What is the main function of probes in hybridization techniques?

    <p>To identify microbes by targeting specific genetic sequences (B)</p> Signup and view all the answers

    What is a key benefit of using the Polymerase Chain Reaction (PCR)?

    <p>It allows for the amplification of specific DNA or RNA sequences rapidly (D)</p> Signup and view all the answers

    What does phenotypic methods focus on when identifying microorganisms?

    <p>Traits expressed in appearance and behavior (A)</p> Signup and view all the answers

    Which of the following statements is true regarding immunologic methods?

    <p>They test for the presence of antibodies to suspected pathogens. (C)</p> Signup and view all the answers

    Which advantage does genotypic methods have over phenotypic methods?

    <p>They do not always require growing the microorganism. (C)</p> Signup and view all the answers

    Which sampling method is best suited for analyzing spinal fluid?

    <p>Spinal tab (D)</p> Signup and view all the answers

    What is a crucial factor in the success of specimen collection for microbial identification?

    <p>Using aseptic techniques to keep tools sterile (B)</p> Signup and view all the answers

    Viable non-culturable (VNC) organisms are identified through which method?

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

    Which of the following is NOT a typical sampling site for microbial identification?

    <p>Hair follicles (D)</p> Signup and view all the answers

    What is the primary goal of using direct microscopic examination in phenotypic methods?

    <p>To observe traits and characteristics of microorganisms (C)</p> Signup and view all the answers

    Which type of media is specifically used to encourage the growth of only the suspected pathogen?

    <p>Selective media (D)</p> Signup and view all the answers

    What does the Mycobacterial growth indicator tube (MGIT) primarily detect?

    <p>Slow-growing mycobacterium tuberculosis (D)</p> Signup and view all the answers

    Antibody titers are used to measure what aspect of a patient's serum?

    <p>Concentration of antibodies (D)</p> Signup and view all the answers

    What characterizes differential media?

    <p>It visually distinguishes between different types of microbes. (A)</p> Signup and view all the answers

    In immunochromatography, what happens if the sample contains the correct antigen?

    <p>It binds to antibodies and moves to the next testing location. (B)</p> Signup and view all the answers

    What is the main purpose of phage typing in microbiology?

    <p>To detect and identify specific bacteria using bacteriophages. (B)</p> Signup and view all the answers

    Which of the following best describes immunologic methods?

    <p>They involve testing fluids for specific antibodies. (B)</p> Signup and view all the answers

    What type of key is used to separate primary genera of various cocci based on staining and growth results?

    <p>Dichotomous key (A)</p> Signup and view all the answers

    Flashcards

    Phenotypic methods

    Identifying microbes based on observable characteristics like enzyme activities, growth conditions, and antibiotic susceptibility.

    Immunologic methods

    Identifying microbes by detecting specific antibodies against the suspected pathogen in a patient sample.

    Genotypic methods

    Identifying microbes by analyzing their genetic material (DNA or RNA).

    Viable Non-Culturable (VNC) microbes

    Microbes that cannot be grown in a lab but can be identified using genotypic methods.

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    Specimen collection

    Collecting a sample of infected tissue or fluid for testing.

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    Aseptic technique

    Methods used to prevent contamination during specimen collection.

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    Sampling sites

    Different body locations from which samples can be collected for analysis.

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    Microscopic observation

    Directly viewing microbes under a microscope to aid in identifying them.

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    Gram Stain

    A staining technique used to categorize bacteria based on their cell wall structure.

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    Selective Media

    Growth media that favors the growth of specific types of bacteria.

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    Differential Media

    Growth media that allows for the visual differentiation of different types of bacteria.

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    Dichotomous Key

    A flowchart-style tool for identifying bacteria by combining observable characteristics like gram staining, growth, and enzymatic tests.

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    Biochemical Testing

    Tests that observe how bacteria respond to different nutrients to identify their metabolic abilities.

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    Antibody Titer

    The concentration of antibodies in a patient's sample.

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    Immunochromatography

    A rapid, visual test used to detect antigens or antibodies.

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    Serology

    Lab tests on body fluids (serum, urine) to detect antibodies or antigens.

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    Serotyping

    Antigen-antibody technique for identifying, classifying, and subgrouping bacteria into categories (serotypes).

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    Western Blot Test

    Uses electrophoresis to detect antigens or antibodies. A specific type of antibody or antigen of interest can be detected in samples.

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    ELISA

    Enzyme-linked immune assay that uses enzymes to visualize antigen-antibody reactions on a surface (plate).

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    Specificity (diagnostic test)

    A diagnostic test's ability to target only the specific antibody or antigen of interest, not unrelated ones.

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    Sensitivity (diagnostic test)

    A diagnostic test's ability to detect even small amounts of antibodies or antigens.

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    Study Notes

    Microbial Identification Methods

    • Phenotypic Methods: Observe organism appearance and behavior. Examples include enzymatic activities, environmental conditions for growth, and susceptibility to antibiotics.

    • Immunologic Methods: Detect specific antibodies to a suspected pathogen in a patient sample. This often involves faster laboratory kits for identification.

    • Genotypic Methods: Examine genetic material for identification. These methods are often more precise and automated, and don't always require growth of the microorganism. They can identify viable, non-culturable microbes.

    Specimen Collection

    • Specimen collection success depends on proper techniques. Aseptic techniques (free of microbes) are crucial, such as keeping containers and tools sterile. Sample only the infected site, avoiding surrounding areas.

    Phenotypic Methods (Detailed)

    • Immediate Direct Examination: Microscopic observation is a rapid method for determining characteristics. Common stains include Gram stain and acid-fast stain.

    • Selective and Differential Growth: Specialized media can encourage growth of specific pathogens present in small numbers. Selective media allows only target bacteria to grow, while differential media visually distinguishes microbes.

    Biochemical Testing

    • Physiological reactions to nutrients & substrates of bacteria provide evidence of the enzyme systems present in a species. The Mycobacterial Growth Indicator Tube (MGIT) detects slow-growing mycobacteria (like Mycobacterium tuberculosis).

    Immunologic Methods (Serology)

    • In vitro testing of serum, urine, cerebrospinal fluid, or tissue samples for specific antibodies.

    • Immunochromatography (Lateral Flow Test): Used for rapid tests, like pregnancy tests and COVID-19 tests, as they detect antigens or antibodies in a sample.

    • Antibody Titers: Determine the concentration of antibodies in a sample. Used to diagnose autoimmune disorders, determine past exposures, and identify specific bacterial strains. Methods including titration to dilutions.

    Genotypic Methods (PCR)

    • Polymerase Chain Reaction (PCR): Creates many copies of DNA or RNA to identify microbes quickly.

    • Hybridization: Analyzes genetic material segments for identification. Probes (segments of DNA or RNA) can be used in a process called Fluorescence in situ hybridization (FISH) to identify a microbe.

    Additional Methods

    • Electrophoresis: Separating antibodies and antigens using electrophoresis to detect their presence.

    • Enzyme-Linked Immunosorbent Assay (ELISA): Visualizes antigen-antibody reactions, commonly used in clinical laboratory diagnosis. Relies on solid supports (like microtiter plates).

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    Related Documents

    Chapter 15-Diagnosing Infections PDF

    Description

    This quiz covers various methods for identifying microbes, including phenotypic, immunologic, and genotypic techniques. It also emphasizes the importance of proper specimen collection and aseptic techniques for successful identification. Enhance your knowledge of microbial taxonomy and laboratory practices with this informative quiz.

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