BIOSAFETY LEVEL (BSL) CLASSIFICATION OF AGENTS

The agents listed by the Centers for disease Control and Prevention (CDC) are those biological agents known to infect humans as well as select animal agents that may pose theoretical risks if inoculated into humans. In general, the four biosafety levels (BSLs) correspond directly to the four risk groups of microorganisms. The agents of minimal hazard are Biosafety Level 1 (BSL-1), with the most dangerous microorganisms at Biosafety Level 4 (BSL4). The following descriptions were taken from Biosafety in Microbiological and Biomedical Laboratories 5th Edition.

The following is a list of the biological agents used at Tusculum University along with their Biosafety Level (BSL).

For new agents the BSL can be determined by using the Pathogen Safety Data Sheets for an organism here or here.

BSL 1 AGENTS

BSL 1 agents are not associated with disease in health adult humans. Examples of BSL 1 agents used on Tusculum University’s campus include the following:

  • Staphylococcus epidermis
  • Sarcina lutea
  • Penicillum notatum
  • Sacchromyce cerevisiae
  • Micrococcus luteus
  • Clostridium sporogenes
  • Enterobacter aerogenes
  • Flavobacterium capsulatus
  • Bacillus subtilis
  • Escherichia coli B
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BSL 2 AGENTS

BSL 2 agents are associated with human disease which is rarely serious and for which preventive or therapeutic interventions are often available. Examples of BSL 2 agents used on Tusculum University’s campus include the following:

  • Streptococcus pyogenes
  • Staphylococcus aureus
  • Mycobacterium smegmatis
  • Micrococcus roseus
  • Proteus mirabilis
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Each BSL has recommended practices, barriers, equipment, and facility requirements that must be in place to be able to use these organisms. A table summarizing these requirements can be found below.

A SUMMARY OF RECOMMENDED BIOSAFETY LEVELS FOR INFECTIOUS AGENTS

BSL Agents Practices Primary Barriers &
Safety Equipment		 Facilities
(Secondary Barriers)
1 Not known to consistently cause diseases in healthy adults. Standard Microbiological Practices
  • No primary barriers required
  • PPE: laboratory coats and gloves;
    eye, face protection as needed
 Laboratory bench and sink required
2
  • Agents associated with human disease
  • Routes of transmission include percutaneous injury, ingestion, mucous membrane exposure
 BSL-1 Practice Plus:

  • Limited access
  • Biohazard warning signs
  • “Sharps” precautions
  • Biosafety manual defining any needed waste decontamination or medical surveillance policies
 Primary Barriers:

  • BSCs or other physical containment devices used for all manipulations of agents that cause splashes or aerosols of infectious materials
  • PPE: laboratory coats, gloves, face and eye protection, as needed
 BSL-1 Plus:

  • Autoclave available
3 Indigenous or exotic agents that may cause serious or potentially lethal disease through the inhalation route of exposure BSL-2 Practice Plus:

  • Controlled access
  • Decontamination of all waste
  • Decontamination of laboratory clothing before laundering
 Primary Barriers:

  • BSCs or other physical containment devices used for all open manipulations of agents
  • PPE: protective laboratory clothing, gloves, face, eye and respiratory protection, as needed
 BSL-2 Plus:

  • Physical separation from access corridors
  • Self-closing, double-door access
  • Exhausted air not recirculated
  • Negative airflow into laboratory
  • Entry through airlock or anteroom
  • Hand washing sink near laboratory exit
4
  • Dangerous/exotic agents which post high individual risk of aerosol-transmitted laboratory infections that are frequently fatal, for which there are no vaccines or treatments
  • Agents with a close or identical antigenic relationship to an agent requiring BSL-4 until data are available to redesignate the level
  • Related agents with unknown risk of transmission
 BSL-3 Practice Plus:

  • Clothing change before entering
  • Shower on exit
  • All material decontaminated on exit from facility
 Primary Barriers:

  • All procedures conducted in Class III BSCs or Class I or II BSCs in combination with full-body, air-supplied, positive pressure suit
 BSL-3 Plus:

  • Separate building or isolated zone
  • Dedicated supply and exhaust, vacuum, and decontamination systems
  • Other requirements outlined in the text
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