Answer:
A pathogen (also called an infectious agent) is a biological agent that causes disease or illness to its host.
Pathogenic bacteria are bacteria that can cause disease.
Nonpathogenic bacteria are harmless, and, in fact, most bacteria are nonpathogenic. For example, nonpathogenic E. coli bacteria live naturally in the large intestine, but there are pathogenic varieties that can cause serious food poisoning, septic shock, meningitis, or urinary tract infections.
