Nosocomial infections are infections contracted during a stay in a health care facility that was neither present nor incubating at the time of admission.
Particularly at risk are the elderly, immunocompromised, newborns, polytrauma patients and burn victims. Certain treatments such as the use of antibiotics can unbalance the bacterial flora of patients and lead to the selection of resistant bacteria (this is known as a favouring factor).
More than 72 000* in the United States of America with approximately 722,000 hospital admissions due to nosocomial infections.
It is estimated that nosocomial infections are the direct cause of 4,000 deaths each year in France. These values are two to three times higher in developing countries.
The most common nosocomial infections are urinary tract infections and lung infections. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa are the most frequently identified germs in nosocomial infections. Therefore, the hospital is a very particular place because it represents a space where healthy individuals such as caregivers and visitors meet patients with diseases or infections that may carry germs of any kind. Some patients may become infected with their own germs (endogenous infections), while others acquire an infection externally. In the latter case, germs are often carried by hospital staff or visitors. The germs spread rapidly throughout the hospital and on various surfaces, making the hospital a real « germ nest ». Germs can be found on door handles, light switches, surfaces and objects such as telephones and computers (fomites) and even in the air (aerosols).
As a result, many medical devices such as endoscopes, catheters and joint prostheses can become contaminated and colonised by microorganisms and then be a source of nosocomial infections. These infections are often linked to the formation of biofilms, clusters of microorganisms attached to a surface.