Types of Healthcare-Associated Infections

In the United States, it is estimated that approximately 1 out of every 25 hospitalized patients will contract a healthcare-associated infection (HAI). There were an estimated 722,000 infections in U.S. acute care hospitals in 2011. Additionally, about 75,000 hospital patients with HAIs died during their hospitalizations according to a recent prevalence study. More than half of all HAIs occurred outside of the intensive care unit. (citation)

The most common types of infections in U.S. acute care hospitals include: (citation)

  • Pneumonia (22%, 157,500 estimated infections in 2011)
  • Surgical site infections (22%, 157,500 estimated infections in 2011)
  • Gastrointestinal infections (17%, 123,100 estimated infections in 2011)
  • Urinary tract infections (14%, 93,300 estimated infections in 2011)
  • Primary bloodstream infections (11%, 71,900 estimated infections in 2011)

Device-associated infections (i.e., central line-associated bloodstream infections, catheter-associated urinary tract infections, and ventilator-associated pneumonia) accounted for about one-quarter (26%) of all HAIs in 2011.

It is important to understand the different types of HAIs and how they are spread to be able to effectively prevent them.

Urinary tract infections  (UTIs) occur when germs enter the urinary system and affect the bladder (which stores the urine) and/or the kidneys (which filter the blood to make urine).  These infections are often associated with the use of a catheter, which is a tube placed into the bladder to drain urine.

Surgical site infections (SSIs) occur after surgery in the part of the body where the surgery took place.  These infections may involve only the skin, or may be more serious and involve tissue under the skin, organs, or implanted material.  SSIs sometimes take days or months after surgery to develop.

Respiratory or lung infections (such as pneumonia) can also be healthcare-associated.   Ventilator-associated pneumonia (VAP) is a type of lung infection that occurs in a person who has been on a ventilator.  A ventilator is a machine that helps a person breathe by giving oxygen through a tube placed in the mouth, nose, or through a hole in the front of the neck.  Germs can enter the ventilator and get into the patient’s lungs, causing illness.

Central line-associated bloodstream infections (CLABSIs) occur when germs enter the bloodstream through a central line.  A central line is a tube that is placed in a large vein to give fluids, blood, or medications, or to do certain medical tests quickly.

Multidrug-resistant organisms (MDROs) can cause infections of the blood, skin, or organ systems.  These infections have arisen due to the overuse or misuse of antibiotics, which has resulted in the germs becoming more resistant to antibiotic therapy.  Methicillin-resistant Staphyloccocus aureus (MRSA) is an example of a MDRO.  Approximately 16% of HAIs are associated with MDROs.

Clostridium difficile (or C. difficile) is a bacterium that can cause diarrhea and other intestinal problems.  These infections are often associated with prolonged antibiotic use because antibiotics can wipe out “good” bacteria in the gut, allowing the C. difficile bacteria to grow and cause illness.

Bloodborne pathogens (BBPs) such as hepatitis B, hepatitis C, or HIV, can be spread in healthcare settings through contact with an infected individual’s blood or body fluids.

Other illnesses or infections such as influenza, norovirus, tuberculosis, and scabies can also be transmitted in healthcare settings.

For basic information on the difference between bacteria, viruses, fungi, and parasites, please see the Microbiology 101 PDF.

Magill SS, Edwards JR, Bamberg W, et al. Multistate Point-Prevalence Survey of Health Care–Associated Infections. N Engl J Med 2014;370:1198-208.