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living organisms too small to be seen with the naked eye


Microbes that cause disease


microorganisms that are part of the normal flora of the body and are beneficial in maintaining certain body processes.


requires oxygen to live


no oxygen is required


absence of pathogens


the process of inhibiting the growth and multiplication of microorganisms


free of all microorganisms, pathogenic and nonpathogenic


organisms and pathogens are present


this is a process that destroys or kills pathogenic organisms (example: bleach)


a process that destroys all microorganisms, including spores and viruses (example: chemicals, radiation, gas)

nosocomical infection

one acquired by an individual in a health-care facility such as hospital

opportunistic infection

Infections that occur when the body's defenses are weakened


one-celled microorganisms, some of which are beneficial and some of which cause disease (tuberculosis, pertussis, strep throat)


These are one-celled animal-like organisms often found in decayed materials animal or bird feces, insect bites and contaminated water, pathogenic and cause diseases such as malaria and aftrican sleeping sickness


These are simple, plant-like organisms that live on dead organic matter. Yeast and mold are two common forms that can be pathogenic. They cause diseases such as ringworm, athletes foot and thrush


These are parasitic microorganisms, which means they cannot live outside the cells of another living organism . They are found in fleas , lice, ticks and mites.


These are the smallest microorganisms, visible only using an electron microscope.
They cannot reproduce unless they are inside another living cell. They are spread by blood and body secretions.
They are difficult to kill by disinfectants and they are not affected by antibiotics. They may cause diseases such as chicken pox, herpes, influenza

PPE (Personal Protective Equipment)

A barrier between a person and pathogens; includes gloves, gowns, masks, goggles, and face shields.

standard precautions

practices used in health care facilities to prevent the spread of infection

chain of infection

Factors that must be present for disease to occur

causative agent

The pathogen responsible for causing an infection; also called the infectious agent.


anything (a person or animal or plant or substance) in which an infectious agent normally lives and multiplies

portal of exit

a way for the causative agent to be released from the reservoir (urine, feces, saliva, blood, tears, mucous discharge, draining wounds: in the body)

mode of transmission

way in which it can be transmitted to another reservoir or host where it can live

portal of entry

a way for the causative agent to enter a new reservoir or host

susceptible host

A person likely to get an infection or disease.

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