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Key Terms


Usually a chemical agent (but sometimes a physical agent) that destroys disease-causing pathogens or other harmful microorganisms, but might not kill bacterial spores. It refers to substances applied to inanimate objects. EPA groups disinfectants by product label claims of limited, general, or hospital disinfection.


The removal, usually with detergent and water or enzyme cleaner and water, of adherent visible soil, blood, protein substances, microorganisms, and other debris from the surfaces, crevices, serrations, joints, and lumens of instruments, devices, and equipment by a manual or mechanical process that prepares the items for safe handling and/or further decontamination.


An organism, such as a human, animal, or plant, which harbors or accommodates a microorganism within. This relationship can be detrimental or negative for one or both, such as person that is the host of a parasite or disease-causing bacteria. It can also be mutually beneficial, such as the relationship between humans and the bacteria that inhabits our intestinal tract.

Microorganism (or microbe)

Single-celled or multicellular organisms that are too small to be viewed without the aid of a microscope. Includes bacteria, protozoans, fungi, algae, plants, and animals. Some microbiologists include viruses in this definition, and some do not.


Capable of producing or causing disease.

Phage (or bacteriophage)

Viruses that only infect bacteria and help to limit the size of bacterial populations.


The bacteria and/or yeast present in certain nutritional supplements or foods that have claimed health benefit for the one that intake them, such as improved digestion and better immunological defenses to fight illnesses.


An agent that reduces the number of bacterial contaminants to safe levels as judged by public health requirements. Commonly used with substances applied to inanimate objects. According to the protocol for the official sanitizer test, a sanitizer is a chemical that kills 99.999% of the specific test bacteria in 30 seconds under the conditions of the test.

Definitions gathered from the Centers for Disease Control and Prevention Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008.

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