What are Healthcare-Associated Infections?

What are Healthcare-Associated Infections?

What are Healthcare-Associated Infections?

Healthcare-associated infections (HAIs), also referred to as “nosocomial” or “hospital” infections, are infections acquired while hospitalized, and generally occur 48 hours after admittance. HAIs also include occupational infections among clinical staff. These infections can be transmitted in all types of clinical settings and can spread to a patient host by various means. Most HAIs ascribe to common bacteria, fungal, and viral pathogens. Due to frequent usages of antibiotics within hospitals, types of bacteria and their resistance to antibiotics are distinct from those external to the hospital. Thus, complications caused by HAIs can be severe, particularly in patients with chronic illnesses, who are immunocompromised, young children and older people.


What are the symptoms of nosocomial infections?

The most common infection sites include surgical sites, the urinary tract, and the lungs. Depending on the type of HAI, the attributed pathogen and the severity of illness, clinical manifestations may vary and encompass:

  • If the pathogen causes skin infection, signs of inflammation, such as superficial skin reddening, warmth, pain, and suppuration may occur.
  • If the pathogen infects the lungs, symptoms of pneumonia; such as cough, shortness of breathing are common.
  • If the pathogen affects the heart, symptoms could include rapid heart rate, heart failure, i.e. endocarditis, etc.
  • If the pathogen affects the gastrointestinal tract, symptoms could include inflammation, nausea, vomiting, and diarrhea
  • If the pathogen affects the urinary tract, symptoms could include fever, acute hematuria, catheter obstruction, dysuria, urgency.


What are the four most common HAIs?

The most common types of HAIs include:

1.) Bloodstream Infection (BSI):

The medical term for this type of infection is septicemia. It comes into being when an infection in any part of the body enters the bloodstream and spreads to other parts of the body. Septicemia can be potentially fatal and should be treated promptly. Catheter-related bloodstream infections (CRBSI) are common in a clinical setting.

2.) Ventilator-associated Pneumonia (VAP):

Ventilator-associated pneumonia is a lung infection that develops in a person who is on a ventilator. A ventilator is a machine used to help a patient breathe by giving oxygen through a tube placed in a patient’s mouth, nose, or through a hole in the front of the neck. An infection may occur if pathogens enter through the tube and get into the patient’s lungs.

3.) Urinary Tract Infection (UTI):

UTIs are common infections most often caused by bacteria. UTI happens when bacteria, often from the skin or rectum, enter the urethra and infect the urinary tract. It can affect several parts of the urinary tract, but the most common type is a bladder infection (cystitis).
Kidney infection (pyelonephritis) is another type of UTI. They’re less common but more serious than bladder infections.

4.) Surgical Site Infection (SSI):

A surgical site infection is an infection that occurs after surgery in the part of the body where the surgery took place. Surgical site infections can sometimes be superficial infections involving the skin only. Other surgical site infections are more severe and can involve tissues under the skin, organs, or implanted material. SSI is one of the most common types of infection in the operating room.

Other signs and symptoms may include abdominal pain, distention, cramping, fever, nausea, anorexia, and dehydration.


What causes nosocomial infections?

Various things in a hospital environment can cause nosocomial infections.

Antibiotics: Various hospital-associated infections may ascribe to the most critical antibiotic-resistant (AR) pathogens. Antibiotics often are prescribed to prevent or alleviate an existing infectious condition while a patient is in the hospital. Many types of bacteria in the body of a patient are healthy and eliminate harmful bacteria. Since antibiotics kill both healthy and unhealthy bacteria, taking them can increase the chances of nosocomial infection.‌

Urinary catheters: Urinary catheters are tubes inserted through your urethra into the bladder of a patient. It is often used during surgeries or other treatments when a patient cannot get up to use the bathroom for a long time. Leaving one inserted for too long can cause a bacterial urinary tract infection.

Mechanical Ventilation: Pathogens can live inside a ventilator and enter the body of a patient.

Central Venous Catheters: A central line is a tube that connects to a patient’s neck, chest, arm, or groin to deliver medicine straight into the bloodstream. Pathogens can pass through the tube and cause dangerous bloodstream infections. These pathogens can live on medical gloves, on the skin, where the tube is inserted, or on the external end of the tube.

Surgical Procedures: Surgical site infections occur when harmful pathogens enter the body of a patient when the skin, hair, or surgical tools are not completely clean before surgery.


Common pathogens causing HAIs include:

  • Methicillin-resistant Staphylococcus aureus (MRSA)
  • Clostridium difficile (c. diff)
  • Staphylococcus aureus
  • Vancomycin-resistant Enterococci (VRE)
  • Norovirus
  • Pseudomonas aeruginosa
  • Vancomycin-resistant Staphylococcus aureus
  • Enterobacteriaceae (carbapenem-resistance)
  • Gram-negative bacteria such as E. coli

These pathogens are responsible for central line-associated bloodstream infections (CLABSI), catheter-associated urinary tract infections (CAUTI), surgical site infections (SSI), ventilator-associated pneumonia (VAP), and many other such infections.



  • Contact transmission: Contact transmission encompasses two subgroups: direct-contact transmission and indirect-contact transmission. The most frequent mode of HAI transmission is by direct contact.
  • Direct contact transmission involves a direct surface-to-body contact and physical transfer of pathogens between a susceptible host and an infected individual such as a patient and a caretaker in a clinical setting. Direct contact transmission also can occur
    between two patients.
  • Indirect contact transmission involves contact of a susceptible host with a contaminated
    intermediate object, such as contaminated medical instruments.
  • Droplet transmission: Transmission occurs when droplets are generated from the source person mainly by coughing, sneezing, and talking, and during the performance of specific medical procedures.
  • Airborne transmission: Infections can spread by either airborne droplet nuclei or dust particles containing the infectious agent. Pathogens carried in this manner can be spread widely by air flows and may be inhaled by an affected host within the same room or over a longer distance from the source patient.
  • Common vehicle transmission: This applies to microscopic organisms transmitted to the host by contaminated items, such as food, water, medications, devices, and equipment.
  • Vector-borne transmission: This occurs when vectors such as mosquitoes, flies, rats, and other vermin transmit microorganisms.


Economic Burden from HAIs

The detrimental adversity resulting from HAIs comes at a high cost for patients and their families. Not only do HAIs extend the duration of hospital stays, they also cause chronic disability, harmfully fortifying antimicrobial resistance, creating massive financial burden for health systems, patients and their families. HAIs overall account for approximately 37,000 deaths or more in Europe each year, and they are responsible for about 99,000 deaths in the USA.

The economic impacts of HAIs differ for patients, health care providers, third-party payers, and society in general. The annual costs of the most common types of HAI occurring in acute care hospitals are estimated to be approximately $10 billion in US adult inpatient populations alone. Listed in the following order, the most high-priced HAI area along with the respective contributing percentages are Skin and Soft Tissue Infection (33.7%); Ventilator-Associated Pneumonia (31.7%), Central Line-Associated Blood Stream Infection (18.9%), Clostridioides difficile Infection (15.4%) and Catheter-Associated Urinary tract Infection (0.3%).

The CDC estimates that all HAIs cost the US healthcare system from $28 billion to $45 billion annually. In Europe, HAI-associated costs are approximately €7 billion annually.

How can we prevent HAIs?

Hand hygiene plays a crucial role in preventing skin pathogen transmission. Washing hands thoroughly with soap and using alcohol-based hand sanitizer is a significant part of infection control and isolation precautions. Studies have shown that following hand hygiene recommendations reduces the pathogen load, prevents transmission of HAIs.

Personal protective equipment (PPE) such as gloves, gowns, masks, and eye protection to protect from contacting blood and body fluids is also necessary to prevent airborne, droplet, and contact transmission.

In addition, hospital waste potentially can cause HAIs. Therefore, monitoring and enforcing sanitation protocols and appropriate cleaning regimens are recommended to ensure proper handling of medical equipment and disposal of single-use items.

Click here for more preventative measures.



To effectively reduce antimicrobial resistance in a HAI prevention program, it will not be enough to just examine and monitor antimicrobial use. We should also implement adequate infection control measures and integrated laboratory, surveillance, and administrative supports. Although the best possible strategy for controlling antibiotic-resistant organisms is different from one healthcare facility to another, the Infection Control and Prevention Plan and epidemiology professionals at each facility are valuable resources to provide educational programs and to implement targeted infection control measures, which include the use of quality PPE, hand hygiene resources, patient placement and isolation. With committed organizational support and expert recommendations adopted into daily practice routines, the morbidity and mortality attributed to HAIs should be under control.


  1. Bharati, K. (2018, March 27). Hospital Acquired Infections | Nosocomial Infections – Types,
    Causes, Symptoms, Risk Factors, Diagnosis, Treatment and Prevention. Medindia. Retrieved October 25, 2021, from http://www.medindia.net/patientinentinfo/hospital-acquired-infection s.htm
  2. Cheung, J RN, and Antonella Melani, MD, Ahaana Singh, Lisa Miklush, PhD, RN, CNS, (n.d.).
    Nosocomial Infection: What Is It, Causes, Prevention, and More. Osmosis. Retrieved No
    vember 18, 2021, from https://www.osmosis.org/answers/nosocomial-infection
  3. Collins, A. S. (2008, April). Chapter 41 Preventing Health Care–Associated Infections from
    Patient Safety and Quality: An Evidence-Based Handbook for Nurses. NCBI: National Center
    for Biotechnology Information. Retrieved October 31, 2021, from https://
  4. Hand Hygiene: Guidelines and evidence. (2010, April 29). World Health Organization. Retrieved
    October 31, 2021, from https://www.who.int/teams/integrated-health-services/infection-prevention-control/hand-hygiene/guidelines-and-evidence
  5. Scott II, PhD, Steven D. Culler, PhD, and Kimberly J. Rask, MD, PhD (2019, April). The Art
    and Science of Infusion Nursing: Understanding the Economic Impact of Health Care-Associated Infections: A Cost Perspective Analysis. CEConnection by Welters Kluwer Health, Inc. Retrieved October 31, 2021, from https://nursing.ceconnection.com/ovidfiles/00129804-201903000-00002.pdf
  6. Sikora, A. and Farah Zahra. (2021, August 10). Nosocomial Infections. NCBI: National Center
    for Biotechnology Information. Retrieved October 31, 2021, from https://
  7. Stubblefield, H. (2017, June 7). What Are Nosocomial Infections? Healthline. Retrieved October
    31, 2021, from https://www.healthline.com/health/hospital-acquired-nosocomial-infections
  8. Suffering from a urinary tract infection? (2021, October 6). Centers for Disease Control and
    Prevention. Retrieved October 26, 2021, from https://www.cdc.gov/antibiotic-use/uti.html
  9. Surgical Site Infection (SSI) | HAI | CDC. (2010, November 24). Centers for Disease Control and
    Prevention. Retrieved October 31, 2021, from https://www.cdc.gov/hai/ssi/ssi.html
  10. Ventilator-associated Pneumonia (VAP) | HAI | CDC. (2010, November 24). Centers for Disease
    Control and Prevention. Retrieved October 25, 2021, from
  11. What is a Nosocomial Infection? (2021, May 21). WebMD. Retrieved November 18, 2021, from
  12. Wikipedia contributors. (2021, August 14) Hospital-acquired infection. Wikipedia. Retrieved
    October 31, 2021, from http://en.wikipedia.org/wiki/Hospital-acquired_infection

Copyright Notice: 

You may not reproduce, modify, publish, display, transmit, or in any way exploit any content on this website, or use such content to construct any kind of database without prior express written approval by Medtecs Group. For permission to use the content, please contact: Johnnywu@medtecs.com 


The information contained in this article is for general information purposes only. The Company does not guarantee the accuracy, relevance timeliness or completeness of any information, and the Company assumes no responsibility for errors or omission in the content of this article. 


Related Articles

Scroll to Top