Infectious Substances (Division 6.2): A material known or reasonably expected to contain a pathogen. A pathogen is a microorganism (including bacteria, viruses, rickettsiae, parasites, fungi) or other agent, such as a proteinaceous infectious particle (prion) that can cause disease in humans or animals.

Category B:  An infectious substance not in a form generally capable of causing permanent disability or life-threatening or fatal disease in otherwise healthy humans or animals that are exposed to it. This includes Category B infectious substances transported for diagnostic or investigational purposes.  

Culture: An infectious substance containing a pathogen that is intentionally propagated. A culture does not include a human or animal patient specimen. Cultures may be categorized as A or B depending on the microorganism.