Question

Microbiology question:

What do BSL-1-4 mean? What kind of organisms fo they classify? Which signals the most dangerous organisms?

Answer 1

The Centers for Disease Control and Prevention (CDC) have specified the biosafety levels as a set of biocontainment precautions required to isolate dangerous biological agents in an enclosed laboratory facility. The levels of containment range from the lowest biosafety level 1 (BSL-1) to the highest at level 4 (BSL-4).

Biosafety level 1 (BSL-1) deals with well-characterized agents including non-pathogenic Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae and other organisms which do not cause disease in healthy humans.

At BSL-2, all precautions used at Biosafety Level 1 are followed, and some additional precautions are taken. It deals with work involving organisms that cause mild disease to humans, such as the Hepatitis A, B, and C viruses, human immunodeficiency virus (HIV), pathogenic Escherichia coli, Staphylococcus aureus, Salmonella, Plasmodium falciparum, and Toxoplasma gondii.

Biosafety level 3 is suitable for work involving microbes that can cause serious and potentially lethal disease via the inhalation route including  Francisella tularensis, Mycobacterium tuberculosis, Chlamydia psittaci, Venezuelan equine encephalitis virus, Eastern equine encephalitis virus, SARS coronavirus, Coxiella burnetii, Rift Valley fever virus, Rickettsia rickettsii, several species of Brucella, chikungunya, yellow fever virus, and West Nile virus

Biosafety level 4 (BSL-4) is the highest level of biosafety precautions, and is suitable for work with microbes or agents at could easily be aerosol-transmitted within the laboratory and cause severe to fatal disease in humans for which there are no available vaccines or treatments such as Marburg virus, Ebola virus, Lassa virus, Crimean-Congo hemorrhagic fever or  Hendra virus, Nipah virus, and some Flaviviruses.

BSL-4 are set up to be either cabinet laboratories or protective-suit laboratories as they deal with poorly characterized and most dangerous pathogens that need sufficient data to confirm continued work at this level, or to permit working with them at a lower level.