Laboratory Bio-safety Levels

May 19, 2019

There are various types of microorganisms that are to be dealt in laboratory.
Their potentiality to cause or infect the laboratories workers may differ from one another.
The level of containment used to prevent accidental infections or accidental environmental contamination in clinical, research and teaching laboratories must be adjusted.
It is done to counter the bio-hazard potential of the organism handled in the laboratory.
Laboratories may be of different levels but on the basis of containment potential or bio-safety levels, they are categorized as BL1, BL2, BL3 and BL4.
Good laboratories practices must be followed by the personnel working in the laboratories at all bio-safety levels.
It ensures basic cleanliness and limit contamination as well as decontamination of the laboratory surfaces after each work or whenever spills occur.
No food or drink should be consumed and one must wash their hands before leaving the laboratory.
Access to laboratory is to be restricted to the laboratory personnel at all times.

A)Bio-safety level 1 (BL1)

These are the lowest level of containment.
Work can be done on the open bench with organisms that present low risk of infections.
These types of organisms are not pathogens in normal individuals and include organisms such as Bacillus subtilis.
Microbiology teaching laboratory is one of the examples of BL1 as it does not use any pathogens.

B)Bio-safety level 2 (BL2)

These are designed for those organisms that present a moderate risk of infection.
Risk may be due to accidental ingestion, per-cutaneous injection or exposure to mucous membranes via aerosols.
E. coli and Streptococcous pyogenes are dealt in a BL2 laboratory or sometimes at higher containment levels.
Normal procedures may be done on bench tops, but barrier protection devices are used if necessary such as face and eye protection, gloves, lab coats or gowns, etc.
Most microbiology research, clinical and instructional laboratories falls under this category.

C)Bio-safety level 3 (BL3)

Pathogens having a very high potential for causing infections especially from aerosols, require this type of laboratories.
Mycobacterium tuberculosis, the causative agent of tuberculosis that is extremely infectious air-borne pathogens if is to be handled by the laboratory personnel, the laboratory should have special features.
Laboratory having negatively pressurized rooms and air filters that prevents the accidental release of the pathogen is preferred.
Work must not be done on the open bench for which biological safety cabinets are required.
In some cases, some organisms that can normally be handled in BL2 must be handled in BL3.
Staphylococcus aureus can be handled on culture plates normally in BL2.
But, when large quantities are grown and are to be centrifuged, work must be done in BL3 facility to contain potential infectious aerosols.
Specialized research and teaching facilities fall under this category.

D)Bio-safety level 4 (BL4)

These are designed in order to handle life threatening pathogens that have high possibility of transmission by aerosols.
For these pathogens, there may not be effective immunization, treatment or cure.
There should be provision of total isolation of the organisms such as manipulation through gloves in a sealed biological safety cabinet or by personnel wearing full body, positive pressure suits with air supplies.
Work related to hemorrhagic fever viruses (Lassa, Marburg, Ebola), variola virus, drug-resistant M. tuberculosis is done in this laboratory.
These laboratories are specially designed and equipped to handle the most dangerous and high risk group pathogens.
They are usually associated with government facilities such as Centers for Disease Control and Prevention or University laboratories that specialize in infectious disease.