HEALTHCARE-ASSOCIATED INFECTIONS (HAIs)
Healthcare‑associated infections: a documented health emergency
ECDC data, airborne microbiological contamination analysis, and the limitations of traditional hospital filtration systems.
THE SCALE OF THE PROBLEM
Healthcare‑associated infections in Italy and Europe
Data from the European Centre for Disease Prevention and Control (ECDC)
Healthcare-associated infections (HAIs) remain one of the major risks associated with hospital ventilation systems: key data from Italy (2022–2024).
How many patients are affected?
Around 8% of hospitalized patients develop at least one HAI, and many cases are linked to surgical theatres that are, or should be, contamination-controlled environments.
In numbers: approximately 500,000–700,000 patients per year are affected in Italy (ECDC estimate 2022–23), with around 11,000 direct deaths annually attributable to HAIs, and many more cases which, although not fatal, prolong length of stay and post‑discharge therapies.
Of these, up to 75% are potentially preventable.
HAI prevalence in Italian hospitals: typical point prevalence in Italian hospitals is 7–9%, and up to 10% in some regions (e.g. Lombardy). Significantly higher in intensive care units (ICUs).
Main pathogens (2024)
Enterococcus spp.
11.7% — Nosocomial infections
Staphylococcus aureus
9.0% — Including MRSA
SARS-CoV-2
9.5% — Airborne
Candida spp.
4.7% — Resistant fungi
Klebsiella pneumoniae
10.0% — Carbapenem‑resistant
Pseudomonas aeruginosa
7.9% — Multidrug‑resistant
Proteus spp.
3.2% — Urinary tract
Acinetobacter spp.
3.2% — Multidrug‑resistant, high mortality
Economic impact on the National Health Service
More than €1 billion per year in costs for the National Health Service — prolonged hospital stays, broad‑spectrum antibiotics, rehospitalizations, complications.
Source: Italian National Institute of Health (ISS) – Epicentro, Ministry of Health, ECDC, international epidemiological literature.
DANGEROUS PATHOGENS
The danger of microorganisms in the operating room
HAI (Healthcare‑Associated Infections): analysis of the main airborne pathogens contaminating healthcare environments.
| Bacterium | Percentage / Impact | Characteristics |
|---|---|---|
| Staphylococcus aureus (MRSA) | ~30% of surgical site infections | Surgical infections, resistant forms (MRSA) very severe. Critical risk |
| Escherichia coli | ~13% of nosocomial infections | Frequent urinary tract infections; increasing multidrug resistance. High risk |
| Klebsiella pneumoniae | ~10.4% of HAI infections | Multidrug-resistant (carbapenems); severe and difficult to treat. Critical risk |
| Pseudomonas aeruginosa | ~8.1% of HAI infections | Extremely persistent; affects immunocompromised and critical patients. Critical risk |
| Acinetobacter baumannii | Lethality: 17–46% sepsis, up to 70% pneumonia | Multidrug-resistant to many antibiotics; causes severe nosocomial infections. Critical risk |
| Clostridioides difficile | ~12% of nosocomial infections | Colitis and post-antibiotic diarrhea; persistent spores in the environment. High risk |
| Clostridium perfringens | Mortality up to 100% if untreated, 20–30% with therapy | Causes gas gangrene and fulminant post-surgical infections. Critical risk |
Source: Istituto Superiore di Sanità (ISS) - Epicentro, Italian Ministry of Health / National Plan for the fight against HAI and AMR, scientific literature and international epidemiological data
LIMITS OF CURRENT SYSTEMS
Why do infections persist in contamination-controlled environments?
Conventional HVAC systems rely primarily on staged filtration, from air handling unit filters to terminal HEPA and ULPA filtration near critical environments.
Viruses
Trapped viruses cannot replicate independently inside filters, but they may remain infectious for hours or even days depending on the viral species.
Bacteria and fungal spores
Bacteria can survive for longer periods and, under favourable conditions, some may reproduce. Fungal spores are particularly resistant and may germinate in humid environments.
Endotoxin production
Trapped bacteria, even when dead, can release endotoxins (cell-wall components) that are irritating and harmful if release into the air and potentially harmful when released into the airflow.
The unresolved problem
HEPA/ULPA filters effectively capture microbes, but do not automatically eliminate them. A technology is needed that actively inactivates biological contaminants.
A STRUCTURAL ISSUE
The ageing infrastructure of European hospital HVAC systems
1. Ageing systems and poor maintenance
Across Europe, a significant proportion of hospital infrastructure was built before modern HVAC and airborne contamination-control standards were introduced.
In several European countries, including Italy, many hospital facilities still rely on ageing ventilation systems and outdated duct infrastructure.
Simplified diagram of the air duct section in an ageing hospital HVAC infrastructure: air passes through worn filters and ductwork that allows dust and microorganisms to escape, resulting in non‑uniform distribution of filtered air to rooms.
2. Microbial biofilms can develop inside air ducts.
3. HVAC filtration systems are designed to capture airborne particles, but not to continuously inactivate biological contaminants accumulated within the system over time. This creates the need for continuous active decontamination technologies integrated within existing HVAC systems.
REGULATORY CONTEXT
ISO 14644‑1:2022 — New standards, same infrastructure problems
Despite increasingly stringent European regulations, including EU GMP Annex 1 and UNI EN ISO 14644 standards, infections remain highly prevalent due to numerous concomitant factors.
Current standards require controlled ventilation rates and filtration levels according to the classification of the critical environment (e.g. ISO 5, ISO 7, ISO8). However, passive filtration alone may not be sufficient to continuously neutralize biological contaminants trapped within the system or accumulated over time.
The crux of the matter
HEPA/ULPA filters effectively capture microbes, but do not automatically eliminate them. After weeks or months of operation, the filter itself becomes a potential reservoir of viable pathogens — viruses, spore‑forming bacteria, fungi — which can be re‑released into the air if in the event of filter degradation or sudden airflow disturbances
A technology is needed that not only captures but inactivates microorganisms in a continuous, continuously, safely and repeatably. SDBD cold plasma does exactly this: this, generating reactive oxygen and nitrogen species (ROS/RNS) capable of inactivating microorganisms directly within the airflow.
Simplified diagram of the air duct section in an old hospital facility: Air passes through worn filters and ductwork that allows dust and microorganisms to escape, resulting in non‑uniform distribution of filtered air to rooms.
This is the challenge PoloPlasma addresses through PLASMAir technology.