MYCOLOGY

• What is the field of study that focuses on fungi called?

  Mycology
• What are the two phases that fungi can exhibit?

  A multicellular mold phase and a unicellular yeast phase
• What is the appearance of the mold phase of fungi?

  A cottony, mycelial mass
• How does the yeast phase of fungi appear?

  It is creamy and resembles a bacterial colony
• What temperature does the mold phase of dimorphic fungi grow at?

  Room temperature
• At what temperature does the yeast phase of dimorphic fungi grow?

  37°C
• What are the general guidelines for specimen collection, handling, and transport for fungi?

  • Specimens processed in Class 2 biosafety cabinet
  • Transport in leak-proof sterile containers at room temperature
  • Anaerobic transport media should not be used
  • Specimens with normal bacterial flora must be transported immediately
  • Process specimens as soon as possible
  • Swabs are not optimal for collection
• What should be done to disinfect surfaces before specimen collection?

  Disinfect with 70% alcohol
• How should blood specimens be collected for fungal culture?

  Aseptically
• What is the recommended volume of blood to collect from adults for fungal culture?

  20-30 mL
• What is the recommended volume of blood to collect from pediatric patients for fungal culture?

  Based on the weight of the patient
• What should be used to disinfect the skin before blood collection?

  Iodine or chlorhexidine
• What blood culture bottles are recommended for detecting fungemia?

  Bactec, BacT/Alert3D, and Versatrek
• What is the more sensitive method for recovering molds and dimorphic fungi from bone marrow?

  Lysis centrifugation
• How should cutaneous specimens be collected from hair?

  Pluck 10 strands of hair from infected areas
• How should skin specimens be collected?

  Scrape with a dull edge of a scalpel or glass slide
• How should nail specimens be collected?

  Clip or scrape with a scalpel
• What is the recommended transport time for specimens collected from skin, nails, and hair?

  Transport at room temperature within 72 hours
• How should corneal scrapings be collected?

  Done by a physician and inoculated directly
• How should vitreous humor be collected?

  By needle aspiration
• How should medical devices be collected for fungal culture?

  Collected surgically
• What is the recommended transport time for prostate fluid?

  Transport at room temperature
• How should lower respiratory tract specimens be collected?

  First morning sputum, brushings, and BAL fluid collected surgically
• What is the recommended transport time for lower respiratory tract specimens?

  If ≤ 2 hours, transport at room temperature; if longer, at 4°C
• How should upper respiratory tract specimens be collected?

  Swab oral lesions avoiding the tongue and collect sinus contents surgically
• How should body fluids be collected for fungal culture?

  Collected as for bacteriology and concentrated by centrifugation
• How should tissue specimens be collected?

  Collected surgically
• How should urine specimens be collected for fungal culture?

  First morning clean catch, suprapubic, or catheterized specimen
• What is the recommended method for the initial isolation of Histoplasma capsulatum?

  Promote the mold-to-yeast conversion of Blastomyces
• What are the characteristics of primary media used for fungal culture?

  • BHI: Supports growth of all fungi
  • SDA: Good for dermatophytes but overgrows with bacteria
  • Littman Oxgall Agar: Prevents spreading of colonies
• What is the purpose of Bromcresol Purple Milk Solids Glucose medium?

  It is a differential medium used for the identification of Trichophyton species
• What does the Canavine-Glycine- Bromthymol Blue Agar differentiate between?

  It distinguishes C. neoformans from C. gattii
• What happens to the medium when C. gattii is present?

  It turns cobalt blue
• What happens to the medium when C. neoformans is present?

  It leaves the medium greenish yellow
• What is the purpose of Leeming and Notman medium?

  Isolation and growth of lipodependent Malassezia species
• What is the function of KOH in staining techniques?

  To distinguish fungi in thick mucoid specimens or in specimens that contain keratinous material
• What does the Ascospores stain do?

  It stains Ascospores green, while the vegetative portion of the fungus stains red
• What is the purpose of the Alcian Blue stain?

  It stains mucopolysaccharides
• What does Calcofluor White visualize?

  nonspecific, non- immunological fluorochromes
• What is the purpose of colloidal carbon wet mounts?


  Visualization of encapsulated organisms like Cryptococcus neoformans