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).