Culture Media in Mycology Laboratory
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Culture Media in Mycology Laboratory

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Questions and Answers

What must be done before opening the autoclave to avoid explosion?

  • Increase the temperature rapidly
  • Wait for pressure and temperature to lower (correct)
  • Open the autoclave immediately
  • Remove all contents from the autoclave

    • At what temperature should the agar be cooled to before dispensing?

  • 45 to 50°C (correct)
  • 10 to 15°C
  • 30 to 35°C
  • 60 to 65°C

    • Which agar medium requires the use of an alcohol lamp for disinfection?

  • Brain-heart infusion agar
  • Littman oxgall agar
  • Mycosel / mycobiotic agar
  • Sabouraud Dextrose Agar (correct)

    • How much agar is required to prepare 1000mL of Sabouraud Dextrose Agar?

    <p>65 grams</p> Signup and view all the answers

    Which of the following media is specifically designed for Candida?

    <p>Chromogenic agar</p> Signup and view all the answers

    When preparing agar, what is the first step to take?

    <p>Weigh the appropriate amount of agar</p> Signup and view all the answers

    What type of agar medium is BHI agar classified as?

    <p>Nutrient-rich medium</p> Signup and view all the answers

    What is a crucial practice when working in a mycology laboratory?

    <p>Practice aseptic technique</p> Signup and view all the answers

    What is the purpose of using Periodic Acid-Schiff (PAS) stain?

    <p>To identify disorders of pigmentation</p> Signup and view all the answers

    Which technique is NOT mentioned as a type of culture method?

    <p>Liquid culture technique</p> Signup and view all the answers

    What should be done prior to using Wood’s lamp on a patient?

    <p>Remove deodorant or cream from the armpits</p> Signup and view all the answers

    How far should Wood’s lamp be placed from the infected skin area?

    <p>10 – 30 cm</p> Signup and view all the answers

    What is the recommended incubation period for most fungi detection?

    <p>10 to 14 days</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the biphasic culture system?

    <p>Requires a direct culture method</p> Signup and view all the answers

    In what conditions should Wood’s lamp be used for optimal results?

    <p>In a dark room</p> Signup and view all the answers

    Which of the following is included in the final diagnosis when assessing skin, hair, and nails?

    <p>Candida spp.</p> Signup and view all the answers

    What temperature should Sabouraud's dextrose agar be incubated at for culture maintenance?

    <p>26C</p> Signup and view all the answers

    Which staining method is NOT mentioned for examining tissue sections?

    <p>Gram Stain</p> Signup and view all the answers

    How long should cultures be maintained for Brain Heart Infusion Agar (BHIA)?

    <p>4 weeks</p> Signup and view all the answers

    What agent is used as a mucolytic for viscous specimens?

    <p>N-acetyl-L-cysteine</p> Signup and view all the answers

    What is the initial step to process urine specimens for culture?

    <p>Centrifuge it at 2000 rpm</p> Signup and view all the answers

    For direct microscopy examination of sediment, which solution is used to prepare the smear?

    <p>KOH solution</p> Signup and view all the answers

    When inoculating viscous specimens, which type of swab is used?

    <p>Dacron swab</p> Signup and view all the answers

    Which of the following media is NOT mentioned for culture maintenance?

    <p>Luria-Bertani agar</p> Signup and view all the answers

    Which type of tinea infection is located on the scalp?

    <p>Tinea capitis</p> Signup and view all the answers

    What type of medium is typically used for the initial isolation of pathogens and saprobes?

    <p>Sabouraud dextrose agar (SDA)</p> Signup and view all the answers

    Which fungal infection is commonly associated with the groin area?

    <p>Tinea cruris</p> Signup and view all the answers

    Which of the following types of tinea is known to affect the nails?

    <p>Tinea ungulum</p> Signup and view all the answers

    What is the main characteristic of dimorphic fungi when grown on SDA at 22°C?

    <p>Exhibit their mycelial phase</p> Signup and view all the answers

    What is the growth rate for slow growers?

    <p>up to 2 weeks</p> Signup and view all the answers

    Which colony texture is characterized by irregular strands?

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

    What does the elevation of a mold colony refer to?

    <p>The height of the colony when the plate is tilted</p> Signup and view all the answers

    Which shape describes colonies that have a raised or bulging center?

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

    How long must fungi cultures be maintained before disposal?

    <p>4-6 weeks</p> Signup and view all the answers

    What does opacity of a colony indicate?

    <p>The light permeability</p> Signup and view all the answers

    Which term describes colonies that are colored on the surface but have a different pigmentation underneath?

    <p>Reverse pigment colonies</p> Signup and view all the answers

    What characteristic of a colony helps microbiologists identify it?

    <p>Colony morphology</p> Signup and view all the answers

    Which type of colony has a smooth margin?

    <p>Entire colony</p> Signup and view all the answers

    What type of colony is described as having a concave or 'innie' center?

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

    What is the characteristic of colonies that are opaque?

    <p>No light can pass through</p> Signup and view all the answers

    Which colony surface texture resembles cotton and has irregularities?

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

    Which characteristic does not vary among species of the same genus?

    <p>All characteristics vary</p> Signup and view all the answers

    Study Notes

    Culture Media Used in Mycology Laboratory

    • Various culture media for fungal growth:

      • Birdseed Agar
      • Brain-Heart Infusion Agar
      • Canavanine-Glycine-Bromthymol Blue Agar
      • Chromogenic Agar for Candida
      • Cornmeal Agar
      • Littman Oxgall Agar
      • Mycosel / Mycobiotic Agar
      • Potato Dextrose Agar/Broth
      • Rice Grains Medium
      • Sabouraud Dextrose Agar/Broth

    • Autoclave Procedure:

      • Start timing when pressure and temperature reach desired levels.
      • Allow pressure and temperature to lower before opening to prevent explosion.

    • Preparation of Sabouraud Dextrose Agar (SDA):

      • Weigh 65 grams of agar per 1000 mL of purified water, or 32.5 grams per 500 mL.
      • Heat to boiling for dissolution.

    Wood's Lamp Usage

    • Clean skin to remove products before use.
    • Wait 60 seconds after turning on.
    • Use in a dark room, 10-30 cm from the skin.
    • Patient should close their eyes during examination.

    Primary Fungal Culture Medium

    • Expected growth outcomes at 22°C on SDA:

      • Initial isolation of pathogens and saprobes.
      • Dimorphic fungi may show mycelial phase.

    • Inhibitory Medium:

      • SDA with antibiotics inhibits saprobes for accurate isolation.

    Tissue Biopsies and Direct Microscopy

    • Essential stains for biopsy examination:

      • Hematoxylin and Eosin (H&E)
      • Grocott's Methenamine Silver (GMS)
      • Periodic Acid-Schiff (PAS)

    • Examination of cultured samples must occur after 4 weeks.

    Urine and Respiratory Specimens

    • For urine: Centrifuge sediment, prepare a direct smear in KOH.
    • For respiratory specimens: Use Dacron swabs and N-acetyl-L-cysteine for inoculation.

    Fungal Growth Rates

    • Rapid growers: Appear within 1-3 days.
    • Intermediate growers: Appear within 5-9 days.
    • Slow growers: Appear up to 2 weeks.

    Mold Colony Morphology

    • Colony characteristics aid in identifying species:

      • Variability in color, shape, and growth form.

    • Elevation and Margin Types:

      • Raised, flat, umbilicate, and umbonate elevations.
      • Entire, undulate, and lobate margins.

    Colonies' Surface Texture and Opacity

    • Texture descriptions: Smooth, glistening, rough, wrinkled, cottony, velvety, granular.
    • Opacity assessments: Transparent, translucent, opaque.
    • Color: Surface and reverse pigmentation indicating type and health of the colony.

    Common Fungal Locations and Types

    • Tinea infections:
      • Capitis: Scalp
      • Faciei: Face
      • Barbae: Beard
      • Corporis: Body
      • Manuum: Hands
      • Ungulum: Nails
      • Cruris: Groin
      • Pedis: Feet

    Identification Techniques

    • Biphasic culture systems utilize both agar and broth for growth assessment.
    • Culture incubations generally maintained for a minimum of 4 weeks before disposal.

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    Description

    This quiz focuses on the various culture media used in mycology. It covers important aspects such as the preparation and requirements for optimal pressure and temperature settings necessary for successful fungal cultivation. Test your knowledge about laboratory procedures specific to mycology!

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