Biosafety in Microbiologic and Biomedical Laboratories

1
Biosafety in Microbiologic and Biomedical
Laboratories

• The University of Texas at Tyler
• IACUC Education and Training
• Note Content not specific to UT Tyler is from
  the American Association for Laboratory Animal
  Science (AALAS)

2
Principles of BioSafety

• This lesson will define and present information
  on methods used to provide biosafety in
  facilities where potentially infectious agents
  are used.
• These include
• Containment
• Biological safety cabinets
• Personal protection equipment
• The facility as barrier
• Secondary barriers

3
Principles of BioSafety

• Containment
• The term containment describes safe methods for
  managing infectious materials in the laboratory
  environment where they are being handled or
  maintained.
• The purpose of containment is to reduce or
  eliminate exposure to potentially hazardous
  agents.
• Exposure could involve not only laboratory
  workers but other individuals working close by
  and the outside environment.

4
Principles of BioSafety

• The three elements of containment include
• laboratory practice and technique
• safety equipment
• facility design
• The risk assessment of the work to be done with a
  specific agent will determine the appropriate
  combination of these elements.

5
Principles of BioSafety Primary Containment

• Primary containment is the protection of
  personnel and the immediate laboratory
  environment from exposure to infectious agents.
• Primary containment is provided by both good
  microbiological technique and the use of
  appropriate safety equipment.
• For example, the use of vaccines may provide an
  increased level of personal protection. Personal
  protective equipment such as gowns, masks, and
  gloves and biological safety cabinets offer
  protection when used properly in conjunction with
  good laboratory techniques.
• Sharps are a frequent cause of exposure to
  personnel. View some recommendations on working
  with sharps on the AALAS Learning Library site.

6
Principles of BioSafety Secondary Containment

• Secondary containment is the protection of the
  environment external to the laboratory from
  exposure to infectious materials.
• Secondary containment is provided by a
  combination of facility design and operational
  practices. Ventilation systems, controlled
  access, airlocks, and other facility design
  features must be part of any biosafety program.

7
Principles of BioSafety Biological Safety
Cabinets

• Safety equipment includes biological safety
  cabinets (BSCs), enclosed containers, and other
  engineering controls designed to remove or
  minimize exposures to hazardous biological
  materials.
• The biological safety cabinet (BSC) is the
  principal device used to provide containment of
  infectious splashes or aerosols generated by many
  procedures

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Principles of BioSafety Biological Safety
Cabinets

• There are three types of biological safety
  cabinets used in microbiological and biomedical
  laboratories - Class I, Class II, and Class III.
• Open-fronted Class I and Class II biological
  safety cabinets are primary barriers which offer
  significant levels of protection to laboratory
  personnel and to the environment when used with
  good laboratory techniques.

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Principles of BioSafety Biological Safety
Cabinets

• The Class II biological safety cabinet also
  provides product protection from external
  contamination of the materials (e.g., cell
  cultures, microbiological stocks) being
  manipulated inside the cabinet.
• The gas-tight Class III biological safety cabinet
  provides the highest attainable level of
  protection to personnel and the environment.

10
Principles of Biosafety Personal Protection

• Safety equipment also includes items for
  personal protection, such as gloves, coats,
  gowns, shoe covers, boots, respirators, face
  shields, safety glasses, or goggles

11
Principles of Biosafety Personal Protection

• Personal protective equipment (PPE) is often
  used in combination with biological safety
  cabinets and other devices that contain the
  agents, animals, or materials being handled. It
  may be difficult or impractical to work in
  biological safety cabinets in some situations in
  this instance, personal protective equipment may
  form the primary barrier between personnel and
  the infectious materials.

12
Principles of Biosafety The Facility as a
Barrier

• Facility design and construction contribute to
  the laboratory workers' protection, provide a
  barrier to protect persons outside the
  laboratory, and protect people and animals in the
  community from infectious agents which may be
  accidentally released from the laboratory.

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Principles of Biosafety The Facility as a Barrier

• Laboratory management is responsible for
  providing facilities that are commensurate with
  the laboratory's function and with the
  recommended biosafety level for the agents being
  manipulated.
• A variety of experts should be part of the design
  team for any new facility. These include
  biosafety professionals, HVAC engineers and
  animal care professionals.

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Principles of BioSafety Biological Safety
Cabinets

• The Biosafety in Microbiological and Biomedical
  Laboratories (BMBL) 4th Edition has additional
  details about biosafety cabinets.
• Biological safety cabinets should be
  performance-tested at least annually to validate
  proper function. It is optimal to have such
  testing done by an NSF-Accredited Biosafety
  Cabinet Field Certifier. More information is
  available in the CDC/NIH publication Primary
  Containment for Biohazards Selection,
  Installation and Use of Biological Safety
  Cabinets, 2nd Edition.

15
Principles of Biosafety Secondary Barriers

• The recommended secondary barrier(s) will depend
  on the risk of transmission of specific agents.
• When the risk of infection by exposure to an
  infectious aerosol is present, higher levels of
  primary containment and multiple secondary
  barriers may become necessary to prevent
  infectious agents from escaping into the
  environment

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Principles of Biosafety Secondary Barriers

• Such design features include
• Specialized ventilation systems to ensure
  directional air flow
• Air treatment systems to decontaminate or remove
  agents from exhaust air
• Controlled access zones
• Airlocks as laboratory entrances (as shown in
  this image)
• Separate buildings or modules to isolate the
  laboratory

17
Principles of Biosafety BioSafety Levels

• Biosafety Level 1
• BSL-1 laboratories are used to study agents not
  known to consistently cause disease in healthy
  adults.
• They follow basic safety procedures and require
  no special equipment or design features.

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Principles of Biosafety BioSafety Levels

• Biosafety Level 2
• BSL-2 laboratories are used to study
  moderate-risk agents that pose a danger if
  accidentally inhaled, swallowed or exposed to the
  skin.
• Safety measures include limited access, biohazard
  warning signs, sharps precautions, class I or II
  BSCs, the use of PPE such as gloves and eyewear
  as well as handwashing sinks and waste
  decontamination facilities such as an autoclave.

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Principles of Biosafety BioSafety Levels

• Biosafety Level 3
• BSL-3 laboratories are used to study agents that
  can be transmitted through the air and may cause
  potentially lethal infection.
• Researchers perform lab manipulations in class I
  or II BSCs or other enclosure. Other safety
  features include clothing decontamination, sealed
  windows, double-door access, and specialized
  ventilation systems.

20
Principles of Biosafety BioSafety Levels

• Biosafety Level 4
• BSL-4 laboratories are used to study agents that
  pose a high risk of life-threatening disease,
  aerosol-transmitted lab infections, or related
  agents whose risk is not known. Lab personnel are
  required to to shower when exiting the facility.
  The labs incorporate all BSL 3 features and
  occupy safe, isolated zones within a larger
  building or a separate building. Procedures are
  performed in Class III BSCs or Class II while
  wearing a positive pressure full-body suit.
• The laboratory director is specifically and
  primarily responsible for assessing the risks and
  appropriately applying the recommended biosafety
  levels.

21
Risk Assessment and Recommendations Acquiring
a Laboratory-Associated Infection

• There are risks for acquiring a
  laboratory-associated infection from job-related
  activities involving infectious or potentially
  infectious material. Assessing risks and
  identifying risk management tools are critical
  for assigning the appropriate biosafety level to
  an infectious organism and reducing the worker's
  and the environment's risk of exposure to the
  absolute minimum.

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Risk Assessment

• Assessing the risk for acquiring a laboratory
  associated infection is affected by the following
  factors
• Pathogenicity
• Route of Transmission
• Agent Stability
• Infectious Dose
• Susceptibilty
• Concentration and Volume
• Origin

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Risk Assessment

• Pathogenicity
• The greater the pathogenicity of the infectious
  or suspected infectious agent, the more severe is
  the potentially acquired disease, and so the
  higher is the risk.
• For example
• Since Staphylococcus aureus rarely causes a
  severe or life-threatening disease in a
  laboratory situation, it is assigned to BSL-2.
• Ebola, Marburg, and Lassa fever viruses cause
  diseases with high mortality rates and have no
  vaccines or treatment, so BSL-4 is the
  appropriate level to work with those viruse.
• Work with human HIV and hepatitis B virus is done
  at BSL-2 because they are not transmitted by the
  aerosol route, even though potentially lethal
  disease can result from exposure. For hepatitis
  B, there is also an effective vaccine available.

24
Risk Assessment

• Route of Transmission
• Agents transmitted by the aerosol route have
  caused the most laboratory infections, versus
  agents transmitted parenterally or by ingestion.
  When planning work with an unknown agent with an
  uncertain mode of transmission, the potential for
  aerosol transmission must be considered due to
  the higher risk.

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Risk Assessment

• Agent Stability
• Desiccation, exposure to sunlight or ultraviolet
  light, exposure to chemical disinfectants and
  other factors can affect the agent's stability in
  the environment.

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Risk Assessment

• Infectious Dose
• Infectious dose can vary from one to hundreds of
  thousands of units.

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Risk Assessment

• Susceptibilty
• The infectious dose is affected by the
  individual's resistance, so a laboratory worker's
  immune status is directly related to his/her
  susceptibility to disease when working with an
  infectious agent. Thus, susceptibility may be
  greater than in a healthy person for persons who
  are pregnant, have undergone surgery, are
  receiving immune-suppressent medications
  (including steroids), or who have systemic
  infectious diseases.

28
Risk Assessment

• Concentration and Volume
• The concentration is the number of infectious
  organisms per unit volume. Higher concentrations
  increase the risks of working with that agent.
  Working with large volumes of concentrated
  infectious material also increases the risks,
  since additional handling of the materials is
  often required.

29
Risk Assessment

• Origin
• Origin may refer to geographic location (e.g.,
  domestic or foreign) host (e.g., infected or
  uninfected human or animal) or nature of source
  (potential zoonotic or associated with a disease
  outbreak).