Also known as Hospital-acquired Infection.
Cross-infection occuring between patients or hospital personnel to patient, presents a constant hazard and occurs in about 5% of hospital admissions (about 2 million people per year in the US) causing an estimated 20,000 deaths.
The cause is partly due to the prevalence of diseased patients, but is mainly due to the presence of pathogenic microorganisms which are selected by the hospital environment.
Hospitals are especially hazardous for several reasons:
- Patients may have compromised immunity, weakening their ability to fight off infection
- Hospitals must treat patients who are infected with virulent pathogens some of which may be highly contagious
- Patients are often crowded together in rooms and wards
- Hospital personnel (doctors, nurses etc.) move between patients increasing the probability of a transfer of pathogens
- Hospital procedures (venepuncture, catheterization, biopsy etc.) carry a risk of introducing pathogens to a patient
- Newborn babies are especially susceptible to certain infections because they lack a developed immune system
- Surgery presents a major hazard, as not only are highly suscepible parts of the body open to contamination, but the stress of surgical procedures often diminish a patient's ability to fight off infection
- Some drugs, especially those used to treat cancer or those used before and after organ transplants, suppress the immune system of the patient
- Antibiotic use carries the risk of selecting for antibiotic-resistant pathogens
Major types of Nosocomial Infection
- Urinary tract 41%
- Surgical 18%
- Respiratory 16%
- Septicaemia 7%
- Skin infections 6%
- Other 12%
Bacterial pathogens most often associated with nosocomial infections
Two approaches to controlling nosocomial infection have been remarkably successful.
- The Centers for Disease Control and Prevention's 1987 "Universal Blood and Body Fluid Precautions"
- Hepatitis B vaccination
Under the universal precautions, all body fluids are treated as if they are potential sources of HIV, Hepatitis B, or other blood-bourne pathogens. The precautions recommend the use of gloves and other protective barriers as well as the careful handling and disposal of used needles and other sharps.
Statistics demonstrate the impact of these two infection control measures. A 1990 study by the CDC found that cases of Hepatitis B amongst healthcare workers between 1982 and 1988 dropped 75%.
Biology of Microorganisms. Brock et al. Prentice Hall International 1994
Emerging Infections: Microbial Threats to Health in the United States. Lederberg, J. et al. Institute of Medicine. National Academy Press. 1992
Medical Microbiology. Mimms, C. et al. Mosby 1993
The changing epidemiology of hepatitis B in the United States. Alter et al. 1990 JAMA 263:1218-1222