Bio-safety in Microbiologic and Biomedical Laboratories · laboratory environment where they are...
Transcript of Bio-safety in Microbiologic and Biomedical Laboratories · laboratory environment where they are...
BIO-SAFETY IN
MICROBIOLOGIC AND
BIOMEDICAL LABORATORIES
Dr. K. P. Narkhede
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
PRINCIPLES OF BIOSAFETY
Containment
The term containment describes safe methodsfor managing infectious materials in thelaboratory environment where they are beinghandled or maintained.
The purpose of containment is to reduce oreliminate exposure to potentially hazardousagents.
Exposure could involve not only laboratoryworkers but other individuals working close byand the outside environment.
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.
PRINCIPLES OF BIOSAFETY: PRIMARY
CONTAINMENT
Primary containment is the protection of personnel and theimmediate laboratory environment from exposure to infectiousagents.
Primary containment is provided by both good microbiologicaltechnique and the use of appropriate safety equipment.
For example, the use of vaccines may provide an increased level ofpersonal protection. Personal protective equipment such asgowns, masks, and gloves and biological safety cabinets offerprotection when used properly in conjunction with goodlaboratory techniques.
Sharps are a frequent cause of exposure to personnel. View somerecommendations on working with sharps on the AALASLearning Library site.
PRINCIPLES OF BIOSAFETY:
SECONDARY CONTAINMENT
Secondary containmentis 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.
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
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.
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.
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
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.
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.
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.
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.
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
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
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.
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.
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.
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.
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.
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
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.
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.
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.
RISK ASSESSMENT
Infectious Dose
Infectious dose can vary from one to hundreds of
thousands of units.
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.
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.
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).