Hospital Acquired Infections

Hospital acquired infections (or healthcare-associated infections aka HAIs) encompass almost all clinically evident infections that do not originate from patient's original admitting diagnosis. Within hours after admission, a patient's flora begins to acquire characteristics of the surrounding bacterial pool. Most infections that become clinically evident after 48 hours of hospitalization are considered hospital-acquired. Infections that occur after the patient's discharge from the hospital can be considered to have a nosocomial origin if the organisms were acquired during the hospital stay.

Within hours of admission, colonies of hospital strains of bacteria develop in the patient's skin, respiratory tract, and genitourinary tract. Risks factors for the invasion of colonizing pathogens can be categorized into 3 areas: iatrogenic, organizational, and patient related.

Iatrogenic risk factors include pathogens that are present on medical personnel hands, invasive procedures (eg, intubation, indwelling vascular lines, urine catheterization), and antibiotic use and prophylaxis.

Organizational risk factors include contaminated air-conditioning systems, contaminated water systems, and staffing and physical layout of the facility (eg, nurse-to-patient ratio, open beds close together).

Patient risk factors include the severity of illness, underlying immunocompromised state, and length of stay.

In the US, nosocomial infections (HAIs) are estimated to occur in more than 2 million cases per year, resulting in an added expenditure in excess of $20+ billion annually. Internationally, HAI impact on the health care systems of developed countries is significant and proportionate to that of the United States. Nosocomial infections are estimated to more than double the mortality and morbidity risks of any admitted patient, and they result in at least 90,000 deaths a year in the United States.