Final answer:
Salmonella typhi should be handled in a BSL-2 facility. Mycobacterium tuberculosis and Ebola virus require higher biosafety levels. Escherichia coli can fall into BSL-1 or BSL-2 depending on the strain.
Step-by-step explanation:
The appropriate biosafety level (BSL) for handling different organisms depends on their risk to human health and the environment. For organisms that pose a moderate risk, BSL-2 is recommended. This includes bacteria such as Staphylococcus aureus and Salmonella spp., and viruses like hepatitis, mumps, and measles viruses. In the context of the options provided in the student's question, Salmonella typhi, which causes typhoid fever, should be handled in a BSL-2 facility, as it is a pathogen that is indigenous and poses a moderate risk. Additional safety practices in a BSL-2 lab include using personal protective equipment (PPE), restricted access, and employing biological safety cabinets for procedures with a risk of aerosolization.
Answering the student's question, Mycobacterium tuberculosis and Ebola virus require a higher biosafety level, BSL-3, or BSL-4, respectively, due to their higher risk levels. Escherichia coli (E. coli) can be handled at either BSL-1 or BSL-2, depending on the strain and associated risk. It is important to consult with safety guidelines to ensure that the appropriate BSL is applied for each organism.