Biosafety in Pathology Laboratories

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Biosafety in Pathology Laboratories

The application of safety precautions to reduce the risk of a laboratory worker to a potentially infectious microorganism is called Biosafety. It also involves limiting the contamination of the laboratory environment and the community. Biosafety can be achieved by various methods and there are four levels. Each level has specific controls for limiting the microorganism and biological agents. Bio-containment is classified by the relative danger to the surrounding atmosphere as biological safety levels.


This level is suitable for laboratories involving well-characterized agents that present low risk to personnel and the environment. These organisms are highly unlikely to cause infection in healthy laboratory workers, animals or plants, e.g. non-pathogenic Escherichia coli, Agrobacterium radiobacter, Aspergillus niger. An open bench or fumed hood is used for practical work. Decontamination is accomplished by treating with chemical disinfectants or by moist heat autoclaving.


This group consists of organisms that offer a moderate risk to personnel and the environment. In case, there is any exposure within the laboratory, the risk of transmission is minimal and it hardly ever cause infection that would lead to serious disease. Effective treatment and preventive procedures are available. The microbes require Biosafety Level 2 containment. Examples of BSL-2 organisms are: Mycobacterium, Streptococcus pneumonia, C. difficile, Salmonella, Staphylococcus aureus. Right to use the laboratory is restricted. Biological safety cabinets are required.


This level is appropriate when dealing with infectious microbes which may cause serious or potentially fatal disease or can even result in serious economic consequences. These microbes are usually not transmitted by casual contact. The examples include: Mycobacterium tuberculosis, SARS corona virus, L. donovani, West Nile virus and virus of yellow fever.  It is essential that laboratory is placed in an isolated area with a double door entry and air flow with inward direction.


This level includes those microbial agents which cause deadly diseases and which are usually not treatable. These microbes are spread from one person to another, from animal to human or vice-versa, either directly or indirectly, or by casual contact. The example of these microbes include, Ebola virus, marburg virus, Lassa virus and Crimean-Congo haemorrhagic fever virus. This type of laboratory either is located in a separate building or in a controlled area within a building, which is completely isolated from all other areas of the building.  The laboratory must have dedicated supply and exhaust air, and in addition vacuum lines and decontamination systems. There are only limited laboratories across the globe as can be seen from the figure.