Healthcare-associated infections (HAIs) are infections patients acquire while receiving medical care in various healthcare settings, including hospitals, long-term care facilities, and outpatient clinics. These infections pose a considerable risk to patient safety, potentially leading to increased illness, prolonged hospital stays, and even death. Understanding how HAIs spread is a fundamental step toward their prevention.
Main Pathways of Transmission
Microorganisms primarily spread in healthcare settings through contact transmission. This involves direct contact, where germs transfer from an infected person to a susceptible individual, or indirect contact, via contaminated objects or surfaces. For instance, a healthcare worker’s hands can become contaminated after touching a patient and then transfer those germs to another patient if hand hygiene is not performed.
Microorganisms also spread through respiratory droplets, larger particles expelled into the air when an infected person coughs, sneezes, or talks. These droplets typically travel short distances, usually up to about six feet, before settling on surfaces or directly contacting another person’s mucous membranes. Airborne transmission occurs when smaller particles, known as droplet nuclei, remain suspended in the air for longer periods and can travel greater distances. These tiny particles can be inhaled by susceptible individuals, leading to infection.
Another route of transmission involves contaminated medical devices or equipment. Microorganisms can colonize surfaces of medical devices such as catheters or ventilators, and if proper sterilization or disinfection procedures are not followed, these devices can introduce pathogens directly into a patient’s body. Surgical procedures also present opportunities for infection if aseptic techniques are not strictly maintained.
Common HAIs and Their Specific Spread
Many common HAIs spread through direct or indirect contact. Methicillin-resistant Staphylococcus aureus (MRSA), an antibiotic-resistant bacterium, often spreads via contaminated hands or surfaces. Clostridioides difficile infection (CDI), which causes severe diarrhea, is also predominantly transmitted through contact with contaminated surfaces or healthcare workers’ hands.
Respiratory HAIs, such as pneumonia, spread via droplet transmission when an infected person coughs or sneezes. The large droplets can then be inhaled by someone nearby or land on surfaces. Some respiratory viruses can also have airborne dissemination, with smaller, lighter particles remaining suspended in the air for extended periods and traveling further distances.
Device-associated infections, like catheter-associated urinary tract infections (CAUTIs) and central line-associated bloodstream infections (CLABSIs), involve pathogens entering the body directly through medical devices. For example, bacteria can migrate into the bladder via a urinary catheter if proper sterile technique is not followed during insertion or maintenance. Mishandling a central venous line can also introduce infectious agents directly into the bloodstream.
Reducing the Risk of HAI Transmission
Preventing HAIs relies on consistent infection control practices. Hand hygiene is the most effective measure to reduce HAIs. Healthcare workers should clean hands often, using soap and water or alcohol-based hand rubs, especially before and after patient contact, after touching patient surroundings, and after removing gloves.
Proper use of personal protective equipment (PPE), such as gloves, gowns, masks, and eye protection, creates a barrier between healthcare workers and patients, preventing pathogen transfer. Gloves should be single-use and discarded after each patient. Environmental cleaning and disinfection of frequently touched surfaces and equipment are also fundamental to minimizing microorganisms in the healthcare environment.
Safe injection practices are also important, ensuring needles and syringes are used for one patient, one time. Strategies like patient screening and cohorting (grouping infected or colonized patients) can help contain the spread of multidrug-resistant organisms. Implementing these prevention measures helps protect patients and reduce HAIs.