Mycology lab safety

• Refer to Public Health Agency of Canada site list of PSDS sheets

Biosafety levels

• Biosafety risk groups
  • RG1: low individual risk and low community risk; e.g. Saccharomyces, Lactobacillus
    • Essentially non-pathogenic microbes
  • RG2: moderate individual risk and low community risk; e.g. Listeria, Campylobacter
  • RG3: high individual risk and low community risk; e.g. TB, Yersinia pestis, SARS
  • RG4: high individual risk and high community risk; e.g. Marburg virus, Ebola virus
• Containment levels essentially correspond to the risk groups
  • CL1 through CL4
  • CL2-Ag for agriculture
  • CL2-P for prion
• HRLMP has a CL2 microbiology lab at HGH.
• Mycology laboratory
  • Class II B2 BSCs to eliminate puff-back during failure of ventilation. Ducts 100% HEPA-filtered air to the outside (no exhaust back into the laboratory). Toxic, volatile or radioactive chemicals can be used in this cabinet.
  • Examine all culture media in a BSC. All work/subculture must always be done in the BSC.
  • Seal all plates with Parafilm for: systemic specimens (respiratory, blood, tissue, body fluid).
  • Place all discarded plates into a tied up biological hazard bag before placing in discard bin.

Risk Group 3 fungi

• Risk Group 3 fungi:
  • Blastomyces dermatitidis
  • Cladophialophora spp. including Clado. Bantiana (black mold that causes CNS disease)
  • Coccidioides immitis and Cocci. posadasii
  • Cryptococcus spp. including Crypto. gattii
  • Histoplasma spp. including H. capsulatum var. capsulatum, H. capsulatum var. farciminosum, and H. duboisii
  • Loboa loboi
  • Paracoccidioides brasiliensis
  • Rhinocladiella mackenziei (common cause of human cerebral phaeohyphomycosis)
• Additional RG3 precautions:
  • Sealed windows
  • Use of a BSC for all work with open vessels
  • Inward-directional airflow
  • HEPA filtration of exhaust air
  • Strictly controlled lab access
• CL2 laboratory management of RG3 organisms:
  • Perform all procedures with an organism that could be RG-3 in a BSC
    • Including all fungal culture media. Only open plates (including bacterial plates) that have a white or grey mold inside the Mycology BSC.
    • If KOH prep suggests dimorphic fungus:
      • Use lab gowns with elasticized wrists, gloves, and an N95 mask while examining plates in the BSC.
      • Place a warning note in LIS.
      • Notify the Manager/Supervisor and Microbiologist if plates grow white mold.
  • Notify the Microbiologist and Supervisor if suspect dimorphic fungi based on KOH-Calcofluor or plate growth.
  • All specimens are referred to the Toronto Public Health Lab following Transportation of Dangerous Goods regulations.
    • Follow all patient samples that went to other lab benches.

Laboratory-associated Coccidioides exposure

• Review CID 2009;49:919–23.

Risk assessment

• There is a broad range of risk, and it may be difficult to assess. A small dose of arthroconidia may cause disease in humans, and attack rates in lab exposure are generally higher than natural exposure.
• Risk increases with the quantity of arthroconidia and the duration of exposure.
• Arthroconidia in culture develop after a few days, and reach very large numbers by 7 to 10 days, at which point they may be dispersed by simply opening the plate.

Managing exposed personnel

• Obtain baseline Coccidioides serology for IgM and IgG to help determine prior exposure. Travel history may also be helpful.
• All exposed personnel should be given itraconazole or fluconazole orally (400 mg daily, for adults) for 6 weeks, as prophylaxis.
  • If pregnant, avoid azoles, monitor closely, and start amphotericin if she develops infection. Can alternatively prophylax with once-weekly amphotericin for 6 weeks or until the end of pregnancy.
• If any exposed personnel develops cough or fever during the 6 week period of prophylaxis, they should be assessed by a physician. Repeat serology may be helpful.
• Repeat serology before completion of prophylaxis. If negative, stop prophylaxis; if positive, follow-up closely for up to 1 year.