Preventing nosocomial infections.

Preventing nosocomial infections.

Preventing nosocomial infections.

Why people are at risk for nosocomial infections?


According to the WHO, a nosocomial infection, also known as “hospital-acquired infection”, is:

“[a]n infection acquired in hospital by a patient who was admitted for a reason other than that infection. An infection occurring in a patient in a hospital or other health care facility in whom the infection was not present or incubating at the time of admission. This includes infections acquired in the hospital but appearing after discharge, and also occupational infections among staff of the facility.”

On the other hand, there is a similar term “healthcare-associated infections (“HAIs”)” which refers to infections people get as they receive health care for another condition in any healthcare settings, including hospitals, clinics and long-term care facilities.

During hospitalization, a patient is exposed to various microorganisms. An infection occurs when viruses, bacteria, fungi or other microorganisms (collectively referred to as “germs”) enter the human body, multiply and cause bodily reactions. These germs can be found in many places in the healthcare environment, including dry surfaces in patient care areas and moist environments, such as faucets and sinks, and indwelling medical devices (eg catheters and intravenous lines). Patients, healthcare workers and visitors can also be the carrier of germs.

Normally, human skin and immune system can effectively prevent germs from entering our body and causing infections. Hospitalized patients, however, are often immunocompromised people who need invasive examinations and treatments. These factors make them more susceptible to nosocomial infections. Moreover, patient care practices (eg frequent transfers of patients from one unit to another) and the hospital environment (eg patients with high susceptibility to infections all in one area such as the ICU) also facilitate the transmission of germs among patients.

Nosocomial infections occur in both developed and developing countries regardless of available resources. They rank among the major causes of death and increased morbidity in hospitalized patients. The economic costs resulted from prolonged stay of infected patients can be considerable.


Who is at risk of nosocomial infections?

Nosocomial infections not only affect hospitalized patients, but it may also affect hospital staff. For an infection to occur, pathogens and other harmful organisms must have access to a susceptible person’s body, invade their skin barrier, multiply and then cause a reaction. Normal immune system can help fight the invasion of germs. Nevertheless, patients with certain conditions are more susceptible to infections. Below are some factors which increase their susceptibility, including:

  • age: infants or the elderly are often associated with a decreased resistance to infection;
  • immune status:
    • patients with chronic diseases or other underlying medical conditions, eg cancer, diabetes and AIDS, are more susceptible because their immune system are compromised; and
    • immunosuppressive drugs or irradiation also lower patients’ resistance to infection;
  • injuries to skin or mucous membranes;
  • malnutrition; and
  • certain medications, such as antibiotics, steroids.


Risk factors in hospitals

Hospitals are crowded places where both infected people and those who are susceptible to infections gather together. Healthcare workers, patients and visitors are all possible sources of infection. They can be colonized with germs without exhibiting any symptoms but, in the meantime, are able to pass the germs to others. As patients receive lots of hands-on care in hospitals, their risks of getting infections increase due to higher possibility of contacting germs.

Generally, germs in hospitals can spread through the following ways:

  • physical contact: for example, healthcare workers’ hands become contaminated by touching germs which present on medical equipment or other surfaces, and then pass the germs to a susceptible person when proper hand hygiene is not performed
  • sprays and splashes: when an infected person coughs or sneezes, germs in their respiratory droplets can land on a susceptible person’s eyes, nose, or mouth and cause an infection
  • airborne transmission: it occurs when a susceptible person inhales fine respiratory droplets or aerosol particles that contain germs released from infected patients when they cough, talk or sneeze. Some medical devices can also generate aerosolized germs
  • sharps injuries: for example, an infection occurs when bloodborne pathogens enter a person through a skin puncture by a used needle or sharp instrument

The increasing variety of medical procedures and invasive techniques also create potential routes of infection. For example, modern procedures such as injections, biopsies, endoscopic examinations, catheterization, intubation/ventilation, suction and surgery increase the risk of infection because contaminated objects or substances may be introduced directly into human body.

On the other hand, most antibiotic-resistant germs are more common in hospitals than in the community. The possible transmission of antibiotic-resistant bacteria in hospitals, which are very difficult to treat, also increase patients’ risk of getting infections.

Additional risks emerge if hospitals have poor infection control practices and are not properly cleaned and disinfected. This issue is particularly common in developing countries.


How to identify nosocomial infections?

The Centers for Diseases Control and Prevention (CDC) in the United States have published definitions for nosocomial infections based on clinical and biological criteria. Some modifications were made over the years after the first set of definitions were published. Still, these definitions are used to identify nosocomial infections at specific body area(s) (eg urinary or pulmonary) or sites (eg surgical site infection).

Common nosocomial infections include:

  • central-line associated bloodstream infections (CLABSI);
  • clostridium difficile infections;
  • pneumonia;
  • methicillin-resistant Staphylococcus aureus (MRSA) infections;
  • surgical site infections;
  • urinary tract infections; and
  • catheter-associated urinary tract infections (CAUTI).


How to deal with nosocomial infections?

While it is impossible to completely eliminate nosocomial infections, there are some measures which can be taken to reduce the rate of infection in patients.

The CDC suggests the following standard precautions for all patient care:

  • Perform hand hygiene.
  • Use personal protective equipment (PPE) whenever there is an expectation of possible exposure to infectious material.
  • Follow respiratory hygiene/cough etiquette principles.
  • Ensure appropriate patient placement.
  • Properly handle and properly clean and disinfect patient care equipment and instruments/devices.
  • Clean and disinfect the environment appropriately.
  • Handle textiles and laundry carefully.
  • Follow safe injection practices.
  • Wear a surgical mask when performing lumbar punctures.
  • Ensure healthcare worker safety including proper handling of needles and other sharps.

Details of these precautions can be found here.


Who is responsible for nosocomial infections?

Preventing nosocomial infections is the responsibility of all individuals providing healthcare services. At the national level, the responsible health authority should develop a regime to support hospitals in reducing the risk of infection for patients and staff.

At the hospital level, the management should support infection control programs and provide resources. It is important to establish an infection control committee and an infection control team. The infection control committee should include wide representation from relevant hospital departments and provide a forum for multidisciplinary input, cooperation and information sharing. The infection control team is responsible for the day-to-day surveillance of infection rate, as well as preparing the yearly work plan for review by the infection control committee and the management. This team should include specialists in infection control, epidemiology and infectious diseases (ie infection control physicians and infection control practitioners – usually nurses).

Personnel providing direct patient care (eg doctors and nurses) and other healthcare workers should follow appropriate practice of hygiene (eg handwashing, isolation) and use personal protective equipment (PPE) such as gloves, gowns, face shields or masks whenever it is necessary.

Overall, the infection control programs should include surveillance, prevention activities and staff training so that the risk of nosocomial infections can be effectively reduced.

For more information, the WHO published a detailed report outlining the responsibility of each role in infection control programs.



Nosocomial infections are a significant cause of morbidity and mortality that should not be overlooked. They can lead to serious medical consequences and economic costs. The rate of infection is an indicator of quality and safety of hospitals.

There is an inherent risk of infection in hospitals as infected people and those who are susceptible to infections congregate in one place. The increased use of invasive diagnostic and therapeutic procedures may create potential routes of infection. In addition, the emergence of antibiotic-resistant bacteria in hospitals also increases patients’ risk of getting infections.

It is important to recognize relevant factors that increase patients’ susceptibility so that necessary precautions can be taken. In order to keep nosocomial infection rates under control, there must be a comprehensive infection control program and clear guidance for everyone involved in hospitals and healthcare services to follow. Infection control is the responsibility of all healthcare professionals, including doctors, nurses, therapists, pharmacists and other service providers.



  1. Antibiotic Resistant Germs in Hospitals: Information for Patients and their Families. (2019). US Centers for Disease Control and Prevention.
  2. Health Care-Associated Infections. (n.d.). Health.Gov | US Department of Health and Human Services.
  3. Health Care-Associated Infections Overview. (n.d.). Health.Gov | US Department of Health and Human Services.
  4. How Infections Spread. (2016). US Centers for Disease Control and Prevention.
  5. Standard Precautions for All Patient Care. (2016). US Centers for Disease Control and Prevention.

World Health Organization. (2002). Prevention of hospital-acquired infections: A practical guide. 2nd edition.

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