Before further discussion of Category A and Category B, it is important to define two additional terms that are used in the classification process.

Culture

An infectious substance containing a pathogen that is intentionally propagated, for example a bacterium grown on bacteriological medium as seen in the image below.

Culture does not include a human or animal patient specimen.

Patient specimen

Human or animal materials collected directly from humans or animals and transported for research, diagnosis, investigational acitivities, or disease treatment or prevention. Patient specimen includes excreta, secreta, blood and its components, tissue and tissue swabs, body parts, and specimens in transport media (e.g., transwabs, culture media, and blood culture bottles).*

*It is important to note that this means specimens that have been collected into these transport media, but have not yet been incubated and are not actively growing in the media.