People can acquire infections from particular settings. An infection acquired while in a hospital or health care setting is considered nosocomial. A nosocomial infection, or health care–acquired infection, can arise from exogenous (external) or endogenous (patient's microbiota) sources. The intensive care unit (ICU) is the most common ward within a hospital to acquire these infections and 1 in 10 people admitted to a hospital will contract a nosocomial infection. In order to be considered nosocomial, certain criteria must be met. The infection must occur within 48 hours of hospital admission, up to three days after discharge, or up to 30 days postsurgery, and the infection must not be present before the patient is admitted to the health care facility.
Health care–associated infections may be caused by one or a combination of factors unique to the hospital: the microorganisms in the environment of the hospital, a weakened or compromised host, and/or the chain of transmission of the hospital. The Centers for Disease Control (CDC) approximates that on a given day, 1 in 25 hospitalized patients has a nosocomial infection, and the mortality rate of nosocomial infections is 10%. The most common cause of nosocomial infections are catheters because they are foreign objects placed directly into the body. In fact, 80% of urinary tract nosocomial infections are because of catheterization.
Common types of health care–acquired infections include ventilator-associated pneumonia (pathogens enter the ventilator, or breathing machine, and then gain entry to the lungs), gastrointestinal infections, urinary tract infections (caused by indwelling, or long-term use, urinary catheters that provide a portal of entry), surgical wound infections, and central-line–associated blood infections. A central line is an intravenous catheter that delivers fluids to a major blood vessel near the center of the body. Unsterile fields, such as areas that have become contaminated with pathogens, can also pass on infections. Methicillin-resistant Staphylococcus aureus (MRSA) is a significant and dangerous nosocomial infection because the pathogen is resistant to antibiotic treatment. Risk factors for MRSA infection include recent or current hospitalization, long-term antibiotic use, and nursing-home living.
Types of Nosocomial Infections
|Organism||Infection||Method of Transmission|
|Escherichia coli||Gastrointestinal infection
Urinary tract infection
Indwelling urinary catheters
|Clostridium difficile||Gastrointestinal infection||Unwashed hands
Unsanitized medical equipment
|Candida species||Urinary tract infection
|Indwelling urinary catheters
|Methicillin-resistant Staphylococcus aureus||Blood infection