A nosocomial infection, also known as a healthcare-associated infection, is an infection contracted by a patient during a stay in a healthcare establishment, such as a hospital. This infection was neither present nor incubating at the time of admission. Nosocomial infections represent a real public health issue, due to their frequency, their sometimes serious consequences and the difficulty of preventing them completely. The risk of contracting a nosocomial infection is particularly high among vulnerable patients, those undergoing surgery or invasive care.

To limit their occurrence in healthcare hospitals, it is important to understand the mechanisms of contamination, identify risk factors, and implement effective prevention measures.

What is a nosocomial infection?

Definition and context

A nosocomial infection is an infection contracted in a healthcare establishment, such as a hospital or clinic, which was neither present nor incubating at the time of the patient's admission. To qualify as nosocomial, the infection generally appears at least 48 hours after admission. It can also occur up to 30 days after surgery, or up to a year if a foreign medical device has been implanted.

This definition is based on precise epidemiological criteria, allowing for the distinction between healthcare-associated infections and community-acquired infections. These infections can be caused directly by a medical procedure or simply by exposure to the hospital environment.

Statistics and impact on healthcare

Nosocomial infections represent a significant challenge for healthcare facilities worldwide. Their prevalence varies from country to country and from facility to facility, but they affect a significant proportion of hospitalized patients. For example, some studies estimate that approximately 5 to 10% of hospitalized patients develop a nosocomial infection.

These infections lead to an increase in the length of hospital stay, a rise in healthcare costs, and a worsening of patients' health, especially when resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are involved. Rigorous monitoring of these infections is essential to improve the quality of care and implement effective prevention measures.

The main causes of nosocomial infections

Transmission of micro-organisms

The primary cause of nosocomial infections is the transmission of pathogenic micro-organisms from one source to another, often between patients, visitors, and healthcare staff. This transmission can be direct, through manual contact ("cross infections"), or indirect, via contaminated surfaces and medical equipment.

There are two origins:

• Endogenous: when the patient becomes infected with their own opportunistic germs.
• Exogenous: when it is contaminated by external agents, such as other patients or the hospital environment.

The hospital environment

The hospital environment is a significant reservoir of bacteria and other microorganisms, including resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa. Air, water, medical equipment, and surfaces can become vectors if hygiene and disinfection standards are not strictly observed.

In addition, the high density of patients and the frequency of surgical procedures significantly increase the risk of dissemination.

Medical and surgical procedures

Invasive procedures, such as surgical interventions, the placement of catheters, urinary catheters or other medical devices, create entry points for microorganisms. These procedures can disrupt the patient's natural defense barriers and promote the occurrence of healthcare-associated infections.

Contamination can also occur through inadequate hand washing or poorly sterilized medical equipment.

Antimicrobial resistance

An aggravating factor is the presence of antibiotic-resistant bacteria, such as resistant Staphylococcus aureus or certain strains of Pseudomonas aeruginosa. This resistance complicates the treatment of nosocomial infections, increases the risk of complications and prolongs hospital stays.

The selection of these resistant bacteria is often linked to inappropriate use of antibiotics within hospitals.

Factors contributing to the occurrence of nosocomial infections

The role of nursing staff

Healthcare personnel play an essential role in the prevention and spread of nosocomial infections. Insufficient hand hygiene or strict non-compliance with aseptic protocols during care can promote the transmission of bacteria between patients.

In addition, incorrect wearing of personal protective equipment exposes not only patients but also caregivers to an increased risk of infection.

Medical devices and hospital equipment

Invasive medical devices, such as catheters, urinary probes, and ventilation tubes, represent major risk factors. They constitute direct entry points for microorganisms. Prolonged use or inadequate sterilization of these devices can significantly increase the likelihood of developing a nosocomial infection.

Patient vulnerability

Some patients are particularly vulnerable to nosocomial infections, especially the elderly, newborns, immunocompromised individuals (such as those with HIV or undergoing chemotherapy), major burn victims, and polytrauma patients. Their weakened immune systems and often high comorbidity promote the occurrence of infections during hospitalizations.

Hygiene and disinfection practices

Poor application of hygiene and disinfection practices in healthcare establishments contributes to the persistence and spread of bacteria responsible for nosocomial infections. Failure to comply with rules governing surface maintenance, instrument sterilization and hospital waste management increases the risk of infection for patients.

Most frequent types of nosocomial infections and their specific causes

Surgical site infections

Surgical site infections generally appear after a surgical procedure, when micro-organisms contaminate the surgical wound. These infections are often due to bacteria present on the patient's skin or introduced by surgical instruments. Staphylococcus aureus, especially in its resistant form (MRSA), is frequently involved.

These infections can lead to delays in healing, require prolonged treatment, and increase the risk of serious complications.

Catheter-associated urinary tract infections

Urinary tract infections are the leading cause of nosocomial infections. They are mainly related to the use of urinary catheters, which create a direct access route to the urinary tract. This facilitates the penetration of bacteria such as Escherichia coli. Elderly patients or those in intensive care are particularly vulnerable.

These infections can range from a simple cystitis to serious complications, such as kidney infections.

Catheter-related bloodstream infections

Venous catheters, especially when used over long periods, are a frequent source of nosocomial bloodstream infections. Bacteria can colonize the surface of the catheter and spread into the bloodstream, leading to potentially severe septicemia.

The microorganisms responsible often include resistant bacteria, such as resistant Staphylococcus aureus. Rigorous sterilization and careful monitoring of devices are essential to limit these infections.

Pneumonia associated with mechanical ventilation

Nosocomial pneumonias frequently occur in patients on mechanical ventilation. The endotracheal tube used in this context facilitates the colonization of the respiratory tract by pathogenic bacteria, such as Pseudomonas aeruginosa.

These pneumonias often complicate hospital stays, particularly in intensive care, with high mortality if not treated quickly.

Prevention and intervention strategies

Strengthening hygiene protocols

Strengthening hygiene protocols is one of the most effective ways to combat nosocomial infections. This involves the rigorous application of standard precautions, such as hand hygiene at key moments, systematic disinfection of surfaces and equipment, as well as the appropriate wearing of effective prevention measures. These practices help prevent cross-transmission of bacteria and other pathogenic microorganisms in all hospital departments, especially in sensitive areas such as operating rooms and intensive care units.

The importance of infection monitoring and follow-up

Active surveillance of nosocomial infections is essential to accurately measure their prevalence within a healthcare facility. This approach is based on regular data collection, microbiological analysis and detailed reporting.

It enables rapid detection of infectious outbreaks, guiding appropriate prevention measures and evaluating their effectiveness. Specialized teams, as well as infection committees, play a central role in this monitoring, which is an essential pillar in the fight against these infections.

Training and education of healthcare staff

Continuing education and training of healthcare staff are key elements in ensuring compliance with best practices. Raising awareness of hygiene practices, the correct use of medical devices, and the management of risks associated with healthcare-associated infections helps to reduce the risk of transmission.

These training programs, integrated into hospital policies, are regularly updated to include the latest innovations and the results of the most recent research.

Technological innovations to reduce risk

Technological advancements are playing an increasingly important role in the prevention of nosocomial infections. These include medical devices with antibacterial surfaces, automated sterilization systems, and sensors for monitoring hand hygiene.

Moreover, digital tools facilitate infection monitoring and the steering of corrective actions in real time, thereby improving the safety of care and optimizing its effectiveness.

Conclusion

Nosocomial infections are a major issue for patient safety and quality of care within healthcare facilities. Their occurrence is mainly related to the transmission of micro-organisms, patient vulnerability, and the use of invasive medical devices. To effectively combat these infections, it is essential to strengthen prevention measures. This involves the rigorous application of hygiene protocols, continuous and adapted training of healthcare personnel, as well as increased and systematic monitoring.

By adopting these best practices and actively supporting education and innovation in healthcare initiatives, you can play a key role in reducing nosocomial infections and contribute to greater safety for all patients.

FAQ

What is the most common nosocomial illness?

The most common nosocomial infection is urinary tract infection, followed by respiratory tract infections, surgical site infections, and bloodstream infections. These infections affect approximately 5% of hospitalized patients in France, with Escherichia coli being a frequently implicated bacterium.

What are the signs of a nosocomial infection?

Signs of a nosocomial infection vary depending on its location. They include: fever, chills, pain, cough, shortness of breath, vomiting, headaches, and chest pain.

For a urinary tract infection, typical symptoms include: burning, frequent urge to urinate, pelvic heaviness, and cloudy urine. Inflammation or discharge may also be present.

How do you get rid of a nosocomial infection?

To eliminate a nosocomial infection, it is essential to identify the responsible bacterium through sampling. Subsequently, a targeted antibiotic treatment is prescribed based on the results of the antibiogram.

In some cases, removal or replacement of invasive devices may be necessary, or even surgical intervention to drain the infected area. Rigorous monitoring ensures the effectiveness of the treatment.

What are the 4 types of infection?

The 4 types of infections are:

• Viral infection: caused by viruses.
• Bacterial infection: caused by bacteria.
• Fungal infection: caused by fungi.
• Parasitic infection: resulting from parasites such as protozoa.

These classifications cover the majority of human infections.