2 Infection Transmission and Standard Precautions
Learn how infections move through linked stages, how to match protective measures to exposure risks, and how routine precautions interrupt transmission in healthcare settings.
The
Infection occurs when a disease-causing microorganism reaches a susceptible person, enters the body, and multiplies. The describes the links involved in this process; interrupting even one link can reduce transmission. Examples of ways to break a link include cleaning hands, containing secretions, and protecting a portal of entry.
The six links are:
Infectious agent: a bacterium, virus, fungus, or parasite.
Reservoir: where the agent lives or persists, such as a person, animal, surface, equipment, food, or water.
Portal of exit: how the agent leaves its reservoir, such as through respiratory secretions, blood, or wound drainage.
Mode of transmission: how the agent reaches another person.
Portal of entry: where it enters, such as the eyes, nose, mouth, broken skin, or respiratory tract.
: a person whose defenses do not prevent infection.
Routes of transmission
Infections can travel by more than one route. The likely route depends on the infectious agent and circumstances of exposure.
Contact: Direct contact with a person, or indirect contact through contaminated hands, equipment, or surfaces.
Droplet: Respiratory particles reach another person's eyes, nose, or mouth, often at close range.
Airborne: Infectious particles remain suspended in the air and may be inhaled. The route depends on the pathogen; follow applicable precautions and facility guidance.
Bloodborne or sharps exposure: Infected blood or other potentially infectious material reaches mucous membranes, nonintact skin, or the bloodstream, including through a needlestick.
Common vehicle or vector: A shared source, such as contaminated food or water, or an animal or insect, carries the infectious agent.
Assessing exposure risk
Before each care activity, consider what could be transmitted, how exposure could occur, and what protection is needed. Assess the patient's symptoms and known or suspected infection, the task, the likelihood of contact with blood or body fluids, and the possibility of a splash or spray. Also consider contaminated surfaces, contact with a mucous membrane or nonintact skin, and whether the activity involves an aerosol-generating procedure.
Choose protective measures for the anticipated exposure rather than relying only on the patient's appearance or known diagnosis. Gloves may be needed for contact with body fluids; a gown may be needed when clothing or skin could be contaminated; and a mask plus eye protection may be needed when splashes or sprays are likely. Use a respirator when required by pathogen-specific precautions and facility procedures. Remove protective equipment safely and perform at the appropriate times.
For example, wound irrigation can produce splashes, so choose protection for the hands, clothing, and face as indicated by the task, and clean hands after removing gloves. Routine contact without an expected splash or contamination risk may call for a different selection of protective equipment. If symptoms suggest a transmissible infection, alert the care team and promptly follow facility procedures for placement and additional precautions.
Standard and additional precautions
are the basic infection-prevention practices used for every patient in every healthcare setting, whether infection is suspected or confirmed. They are based on and include , appropriate protective equipment, , safe handling of potentially contaminated equipment and the care environment, and safe injection practices.
do not replace additional precautions required for a particular infection. Contact, Droplet, or Airborne Precautions may be added according to the suspected or confirmed infection and facility policy.
In the United States, CDC recommendations describe infection-prevention practices, while OSHA requirements address worker safety. OSHA's Bloodborne Pathogens standard applies to employers with employees who have reasonably anticipated occupational exposure to blood or other potentially infectious materials. It includes requirements such as an exposure control plan. Follow applicable regulations and facility procedures.
during care
Clean hands at these key points:
Immediately before touching a patient.
Before an aseptic task or handling an invasive medical device.
When moving from a soiled body site to a clean body site on the same patient.
After touching a patient or the patient's immediate surroundings.
After contact with blood, body fluids, or contaminated surfaces.
Immediately after removing gloves.
For most routine clinical situations, use an alcohol-based hand rub when hands are not visibly soiled. Apply enough to cover all hand surfaces and rub until dry, paying attention to fingertips, thumbs, and the spaces between fingers. Use soap and water when hands are visibly soiled, after using the restroom, before eating, and during care in certain C. difficile or norovirus outbreak situations, following current guidance and facility policy. Gloves do not replace .
Containing respiratory secretions
help contain infectious secretions from the first point of contact, such as reception or triage, and continue throughout the visit. When someone has respiratory symptoms:
Encourage them to cover the mouth and nose with a tissue when coughing or sneezing, then discard it in a no-touch receptacle.
If no tissue is available, cough or sneeze into the elbow rather than the hands.
Offer a mask when appropriate and tolerated, according to current guidance and facility policy.
Perform after contact with respiratory secretions.
Separate symptomatic patients from others as soon as practical when space permits.
Make tissues, disposal bins, masks, hand-hygiene supplies, and clear signs available at entrances, waiting areas, and triage points.
These measures reduce the chance that respiratory secretions reach other people or contaminate hands and surfaces.