Germs are a part of everyday life. Germs live in our air, soil, water and in and on our bodies. Some germs are helpful, others are harmful.

An infection occurs when germs enter the body, increase in number and the body reacts. Only a small portion of germs can cause infection.

Terms to know Sources

Sources are places where infectious agents (germs) live (e.g., sinks, surfaces, human skin). Sources are also called reservoirs.

Transmission is a way germs move to the susceptible person. Germs depend on people, the environment and/or medical equipment to move in healthcare settings. Transmission is also called a pathway.

A susceptible person is someone who is not vaccinated or otherwise immune. For example, a person with a weakened immune system who has a way for the germs to enter the body.

Colonization is when someone has germs on or in their body but does not have symptoms of an infection. Colonized people can still transmit the germs they carry.

How it works in healthcare settings

For an infection to occur, germs must transmit to a person from a source, enter their body, invade tissues, multiply and cause a reaction.

People such as patients, healthcare workers and visitors.

Dry surfaces in patient care areas such as bed rails, medical equipment, countertops and tables).

Wet surfaces, moist environments and biofilms (collections of microorganisms that stick to each other and surfaces in moist environments, like the insides of pipes).

Cooling towers, faucets and sinks, and equipment such as ventilators.

Indwelling medical devices such as catheters and IV lines.

Dust or decaying debris such as construction dust or wet materials from water leaks.

Physical contact, like when a healthcare provider touches medical equipment that has germs on it and then touches a patient before cleaning their hands.

Sprays and splashes when an infected person coughs or sneezes. This creates droplets containing the germs, and the droplets land on a person's eyes, nose or mouth.

Inhalation when infected patients cough or talk, or construction zones kick up dirt and dust containing germs, which another person breathes in.

Sharps injuries such as when someone is accidentally stuck with a used needle.

People who have underlying medical conditions such as diabetes, cancer or organ transplantation. These can decrease the immune system's ability to fight infection.

People who take medications such as antibiotics, steroids and certain cancer fighting medications. These can decrease the body's ability to fight infection.

People who receive treatments or procedures such as urinary catheters, tubes and surgery, which can provide additional ways for germs to enter the body.

Keep Reading Infection Control in Health Care: An Overview

Recommendations Healthcare providers

Healthcare providers can perform basic infection prevention measures to prevent infection.

There are 2 tiers of recommended precautions to prevent the spread of infections in healthcare settings:

Standard Precautions, used for all patient care.

Transmission-based Precautions, used for patients who may be infected or colonized with certain germs.

There are also transmission- and germ-specific guidelines providers can follow to prevent transmission and healthcare-associated infections from happening.

Health Care Providers Guidance Library

Keep Reading Tips for Being a Safe Patient

Resources For healthcare providers and settings

About Project Firstline

Accessible infection control education for all frontline healthcare workers.

Infection Control Assessment and Response (ICAR) Tool for General Infection Prevention and Control (IPC) Across Settings

Assess and improve a healthcare facility’s infection control and prevention practices.

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Core Components to creating and sustaining clean & safe surfaces in healthcare facilities.

Considerations for Reducing Risk: Water in Healthcare Facilities

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Strategies for preventing and responding to multi-drug resistant organisms (MDROs).