Nonpathogenic organisms are those that do not cause disease, harm or death to another organism. The term is usually used to describe bacteria. It describes a property of a bacterium – its inability to cause disease. Most bacteria are nonpathogenic. It can describe the presence of non-disease causing bacteria that normally reside on the surface of vertebrates and invertebrates as

commensals Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...

. Some nonpathogenic

microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

are commensals on and inside the body of animals and are called

microbiota Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found t ...

. Some of these same nonpathogenic microorganisms have the potential to cause disease, or being pathogenic, if they enter the body, multiply and cause

symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an disease, illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormali ...

of infection. Immunocompromised individuals are especially vulnerable to bacteria that are typically nonpathogenic; because of a compromised immune system, disease occurs when these bacteria gain access to the body's interior.

Genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

have been identified that predispose disease and infection with nonpathogenic bacteria by a small number of persons. Nonpathogenic '' Escherichia coli'' strains normally found in the

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organ (biology), organs of the digestive syste ...

have the ability to stimulate the immune response in humans, though further studies are needed to determine clinical applications. A particular strain of bacteria can be nonpathogenic in one species but pathogenic in another. One species of bacterium can have many different types or strains. One strain of a bacterium species can be nonpathogenic and another strain of the same species can be pathogenic.

References

{{portal bar, Biology Bacteriology Gram-positive bacteria Gram-negative bacteria Immune system