A hospital-acquired infection is usually one that first appears three days after a patient is admitted to a hospital or other health care facility. Infections acquired in a hospital are also called nosocomial infections.
About 5-10% of patients admitted to hospitals in the United States develop a nosocomial infection. The Centers for Disease Control and Prevention (CDC) estimate that more than two million patients develop hospital-acquired infections in the United States each year. About 90,000 of these patients die as a result of their infections. Hospital-acquired infections usually are related to a procedure or treatment used to diagnose or treat the patient’s illness or injury. About 25% of these infections can be prevented by healthcare workers taking proper precautions when caring for patients.
Hospital-acquired infections may develop from surgical procedures, catheters placed in the urinary tract or blood vessels, or from material from the nose or mouth that is inhaled into the lungs. The most common types of hospital-acquired infections are urinary tract infections (UTIs), pneumonia, and surgical wound infections.
Causes and symptoms
Any type of invasive procedure can expose a patient to the possibility of infection. Common causes of hospital-acquired infections include:
- urinary bladder catheterization
- respiratory procedures
- surgery and wounds
- intravenous (IV) procedures
Urinary tract infection (UTI) is the most common type of hospital-acquired infection. Most hospital-acquired UTIs happen after urinary catheterization. Catheterization is the placement of a catheter through the urethra into the urinary bladder. This procedure is done to empty urine from the bladder, relieve pressure in the bladder, measure urine in the bladder, put medicine into the bladder, or for other medical reasons.
The healthy urinary bladder is sterile, which means it doesn’t have any bacteria or other microorganisms in it. There may be bacteria in or around the urethra but they normally cannot enter the bladder. A catheter can pick up bacteria from the urethra and allow them into the bladder, causing an infection to start.
Bacteria from the intestinal tract are the most common type to cause UTIs. Patients with poorly functioning immune systems or who are taking antibiotics are also at risk for infection by a fungus called Candida.
Surgical procedures increase a patient’s risk of getting an infection in the hospital. Surgery directly invades the patient’s body, giving bacteria a way into normally sterile parts of the body. An infection can be acquired from contaminated surgical equipment or from healthcare workers. Following surgery, the surgical wound can become infected. Other wounds from trauma, burns, and ulcers may also become infected.
Many hospitalized patients need a steady supply of medications or nutrients delivered to their bloodstream. An intravenous (IV) catheter is placed in a vein and the medication or other substance is infused into the vein. Bacteria transmitted from the surroundings, contaminated equipment, or healthcare workers’ hands can invade the site where the catheter is inserted. A local infection may develop in the skin around the catheter. The bacteria also can enter the blood through the vein and cause a generalized infection. The longer a catheter is in place, the greater the risk of infection.
Other hospital procedures that put patients at risk for nosocomial infection are gastrointestinal procedures, obstetric procedures, and kidney dialysis.
Fever is often the first sign of infection. Other symptoms and signs of infection are rapid breathing, mental confusion, low blood pressure, reduced urine output, and a high white blood cell count.
An infection is suspected any time a hospitalized patient develops a fever that cannot be explained by a known illness. Some patients, especially the elderly, may not develop a fever. In these patients, the first signs of infection may be rapid breathing or mental confusion.
Diagnosis of a hospital-acquired infection is based on:
- symptoms and signs of infection
- examination of wounds and catheter entry sites
- review of procedures that might have led to infection
- laboratory test results
Cultures of blood, urine, sputum, other body fluids, or tissue are done to look for infectious microorganisms. If an infection is present, it is necessary to identify the microorganism so the patient can be treated with the correct medication. A sample of the fluid or tissue is placed in a special medium that bacteria will grow in. Other tests can also be done on blood and body fluids to look for and identify bacteria, fungi, viruses, or other microorganisms responsible for an infection.
If a patient has symptoms suggestive of pneumonia, a chest x ray is done to look for infiltrates of white blood cells and other inflammatory substances in the lung tissue. Samples of sputum can be studied with a microscope or cultured to look for bacteria or fungi.
Fungal infections are treated with antifungal medications. Examples of these are amphotericin B, nystatin, ketoconazole, itraconazole, and fluconazole.
Antibiotics should be used only when necessary. Use of antibiotics creates favorable conditions for infection with the fungal organism Candida. Overuse of antibiotics is also responsible for the development of bacteria that are resistant to antibiotics.
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“Hospital-Acquired Infections are Being Underreported.” RN March 2003: 16.
“Nosocomial Infection (From the Editor).” Health Care Food & Nutrition Focus June 2003: 2.