Microbiology Quiz: Bacterial Growth Factors and Culture Media
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Questions and Answers

What factor does Haemophilus influenzae need to grow on an agar?

  • Heme and NAD (correct)
  • Xylose and yeast extract
  • Citrate and salts sucrose
  • Mannitol salt and bile
  • Why are some bacteria unable to survive in the presence of oxygen?

  • They lack catalase and superoxide dismutase (correct)
  • DNA replication is suppressed in the presence of oxygen
  • Actinomyces israelii
  • They have thin cell walls which are susceptible to free radicals
  • What medium should be used to culture sputum to confirm tuberculosis diagnosis?

  • Xylose-Lysine-Deoxycholate (XLD)
  • Bordet-Gengou
  • Cefsulodin-Irgasan-Novobiocin (CIN)
  • Middlebrook (correct)
  • What non-essential bacterial component mediates adherence to mucous membranes?

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

    Which statement is true of bacteria?

    <p>Contains DNA only</p> Signup and view all the answers

    What is the most likely organism based on the described blood culture findings?

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

    What type of flagellar arrangement does a bacterium have if it is peritrichous?

    <p>Surrounded with flagella</p> Signup and view all the answers

    What does it mean if a bacterium is aerotolerant?

    <p>Does not grow well but survives in the presence of air</p> Signup and view all the answers

    Which organism serves as the biological indicator of autoclaves?

    <p>B. stearothermophilus</p> Signup and view all the answers

    In bacterial growth stages, which phase involves no net growth of the bacterial population?

    <p>Stationary Phase</p> Signup and view all the answers

    What is NOT a cause of bacterial death?

    <p>Decreased concentration of antibiotics</p> Signup and view all the answers

    Which chemical sterilant is commonly used for sterilization purposes?

    <p>Ethylene Oxide</p> Signup and view all the answers

    What is the primary function of acetone in Gram staining?

    <p>Decolorizing agent</p> Signup and view all the answers

    In the context of bacterial survival, which of the following bacteria thrives in an oxygen-rich environment?

    <p>Pseudomonas aeruginosa</p> Signup and view all the answers

    What is the main function of glutaraldehyde in sterilization processes?

    <p>Acts as a sporicidal agent</p> Signup and view all the answers

    Which of the following best describes the growth factors required by Haemophilus influenzae?

    <p>X and V factors</p> Signup and view all the answers

    What is the mechanism of action of endotoxins in bacterial infections?

    <p>Induces overproduction of IL-1</p> Signup and view all the answers

    Which culture medium is commonly used for the diagnosis of tuberculosis?

    <p>Lowenstein-Jensen medium</p> Signup and view all the answers

    Study Notes

    Bacterial Growth and Requirements

    • Haemophilus influenzae requires heme and NAD to grow on an agar.

    Culture Media

    • Middlebrook medium is used to culture sputum to confirm a diagnosis of pulmonary tuberculosis.
    • Xylose-Lysine-Deoxycholate (XLD) medium is not used to culture Haemophilus influenzae.

    Bacterial Adherence

    • Pilus is a non-essential bacterial component that mediates adherence of bacteria to mucous membranes.

    Bacterial Survival

    • Some bacteria are unable to survive in the presence of oxygen due to lacking catalase and superoxide dismutase.

    Bacterial Identification

    • Streptococcus pneumoniae is identified by its shiny, greenish colonies on a blood agar disc, which are inhibited by optochin, and its Gram-positive spherical shape growing in chains with a positive Quellung reaction.

    Bacterial Characteristics

    • Bacteria are prokaryotic, containing DNA only, and multiply by binary fission, producing either endotoxin or exotoxin.

    Flagella

    • Monotrichous refers to a single flagellum at one end, atrichous has no flagellum, lotrichous has a tuft of flagella at one or both ends, and peritrichous has flagella surrounded around the cell.

    Bacterial Types

    • Lactobacillus is an aerotolerant bacterium, meaning it does not require oxygen for growth.

    Autoclave Sterilization

    • Geobacillus stearothermophilus is the biological indicator for autoclaves.

    Bacterial Growth Phases

    • The lag phase is also known as the adjustment phase, the log phase is when the bacteria grow exponentially, the stationary phase has no net growth of the bacterial population, and the death phase has a decline in the bacterial population.

    Causes of Bacterial Death

    • Causes of bacterial death include food shortage, decreased pH, and increased concentration of toxic products.

    Sterilization Indicators

    • Geobacillus stearothermophilus is the biological indicator for autoclaves, and Thermus aquaticus is the indicator for ovens in sterilizing glassware.

    Chemical Sterilants

    • Glutaraldehyde is a chemical sterilant commonly used for sterilizing equipment.

    Antiseptics

    • Hexachlorophene is not an antiseptic, while alcohol, chlorhexidine, and QUATS are antiseptics.

    Normal Flora

    • The most abundant normal flora in throat and nasopharyngeal swab specimens is Streptococcus pyogenes.

    Autoclave Settings

    • The settings for an effective autoclave are a temperature of 121°C, for at least 15 minutes, using 15 psi of pressure.

    Gram Staining

    • Iodine is the mordant in Gram staining, not a counterstain.

    Sterilization of Surgical Materials

    • Glutaraldehyde can effectively kill Clostridium tetani in surgical materials.

    Endotoxins

    • Endotoxins induce the overproduction of IL-1.

    Oxygen-Rich Environment

    • Nocardia will not survive in an oxygen-rich environment.

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    Description

    Test your knowledge of microbiology with questions about the factors needed for Haemophilus influenzae to grow on agar and the appropriate culture medium to confirm pulmonary tuberculosis. Answer these and more in this quiz!

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