Nosocomial Transmission

The spread of infections within healthcare settings.

What is Nosocomial Transmission?

Nosocomial transmission refers to the spread of an infectious disease within a healthcare setting, like a hospital, clinic, nursing home, or other facility where patients receive medical care. The term “nosocomial” comes from the Greek nosokomeion, meaning hospital. Today, most people use the more modern term healthcare-associated infection (HAI), but nosocomial transmission is still widely used, especially in outbreak investigations.

Nosocomial transmission happens when infections pass from patient to patient, from healthcare worker to patient (or vice versa), or through contaminated equipment, surfaces, or the healthcare environment.

Preventing nosocomial transmission is one of the most critical and challenging problems in public health. Hospitals exist to heal the sick, but they also bring vulnerable people together in confined spaces where pathogens can emerge, spread readily, and kill both patients and staff. Many patients in healthcare settings have weakened immune systems, making them particularly susceptible to infections.

Understanding Nosocomial Transmission

Nosocomial transmission can take multiple pathways, each requiring targeted control strategies.

Common routes of nosocomial transmission

Transmission often occurs through:

• Direct patient-to-patient contact
• Healthcare worker-to-patient contact (hands, respiratory droplets)
• Contaminated medical devices (like catheters, ventilators)
• Contaminated surfaces (bed rails, doorknobs, medical charts)
• Airborne transmission in poorly ventilated settings
• Unsafe injection practices or shared medical equipment

Pathogens frequently involved in healthcare outbreaks

• MRSA (Methicillin-resistant Staphylococcus aureus)
• CRE (Carbapenem-resistant Enterobacteriaceae)
• Clostridioides difficile (C. diff)
• SARS-CoV-2 (COVID-19)
• Measles virus

These pathogens highlight why infection control in healthcare settings must be comprehensive and sustained.

Preventing Nosocomial Transmission

• Hand hygiene by all staff and visitors
• Use of personal protective equipment (PPE)
• Environmental cleaning and disinfection
• Isolation of infected or colonized patients
• Safe injection practices and sterile procedures
• Antimicrobial stewardship to reduce resistance

Real-World Examples

• Ebola outbreaks in West Africa and the Democratic Republic of Congo were amplified in hospitals lacking adequate PPE and isolation capacity.
• COVID-19 spread rapidly in nursing homes and hospitals early in the pandemic, often before universal masking and PPE policies were in place.
• Measles outbreaks in under-vaccinated communities have repeatedly spread through hospital emergency departments before diagnosis.

Why Nosocomial Transmission Matters

• Threatens patient safety and quality of care
• Places healthcare workers at high risk
• Can seed wider community transmission

Strengthening Infection Prevention and Control (IPC)

• Investing in healthcare worker training
• Ensuring access to PPE and cleaning supplies
• Improving facility ventilation
• Monitoring healthcare-associated infection rates
• Rapidly identifying and isolating cases