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| | Legionella spp. and Legionella pneumophila Testing | |
Legionella pneumophila is a bacterium that causes legionellosis, a disease that manifests as severe pneumonia (Legionnaires’ disease) or a mild flu-like illness (Pontiac fever). The bacterium is common in nature (lakes, rivers) but proliferates primarily in artificial water systems such as air conditioning systems, pipes, showers, and swimming pools, especially at temperatures between 20°C and 45°C.
Its growth in systems is facilitated by stagnant water, ideal temperatures, and the presence of biofilm. Prevention is crucial and relies on proper management and maintenance of water systems, including temperature control, elimination of stagnant water, and regular cleaning and disinfection. |
Legionellosis: Transmission, Symptoms, and Prevention
Legionellosis is an infection caused by the bacterium Legionella pneumophila (serogroup 1). Transmission occurs exclusively through the inhalation of contaminated water droplets; it is important to note that it does not spread from person to person or through drinking water. This disease can present with fever and pneumonia and, in some cases, can have serious consequences, especially for the elderly or those with weakened immune systems.
Fortunately, there are several effective preventive measures to reduce the risk of contracting Legionnaires’ disease:- Water treatment: chemical or thermal treatments to eliminate bacteria present in the water.
- Hot water production technologies: Using water heaters equipped with anti-Legionella heat exchangers or installing instantaneous water heaters (which do not store water) significantly reduces environments conducive to bacterial proliferation.
- Inspections: Regular maintenance of DHW (Domestic Hot Water) systems and air conditioning systems is essential to prevent bacterial growth.
| | Risk Management and Regulatory
Compliance To ensure the microbiological safety of systems and full legal compliance, bacteriological testing must be integrated into a proper prevention strategy. The first essential step for any apartment building, business, or hospitality facility is to prepare a Legionella Risk Assessment (DVR Legionella), which serves as a prerequisite for planning water sampling. The proper implementation of the Water Self-Monitoring Plan and the protection of workers in accordance with Legislative Decree 81/08 (Consolidated Law on Occupational Safety) fall under the responsibility of the Risk Management Officer, the individual tasked with overseeing prevention procedures. All periodic operations, sampling results, and any remediation measures—such as thermal shock, hyperchlorination, or chlorine dioxide treatment—must be promptly recorded and updated in the Sanitation and Maintenance Log.
Microbiological water analysis begins with proper and accurate sampling performed by qualified personnel at critical sampling points in the water system. To ensure the sample is as representative as possible and to promptly identify any Legionella outbreaks, it is essential to take samples at the points most at risk of stagnation and bacterial proliferation: from the hot water recirculation loop to the water heater or central storage tank, all the way to the points furthest from the system (so-called dead ends) and to high-use showerheads or those with the potential for aerosol formation. | | Target Sectors and Areas of Application
Legionella risk control and prevention do not apply only to residential settings such as apartment buildings or tourist accommodations (hotels, B&Bs, and campgrounds), but are a strict requirement for a wide range of industrial and community activities. In the healthcare and long-term care sectors (hospitals, nursing homes, private clinics, and doctors’ offices), bacteriological testing must be conducted with the utmost rigor due to the presence of frail or immunocompromised individuals. Particular attention must also be paid to the wellness and sports sector, such as sports centers, gyms, thermal pools, spas, and swimming facilities, where the heavy use of showers and hot tubs constantly generates potentially hazardous aerosols. Finally, a key component of industrial and commercial prevention concerns workplaces and industrial facilities equipped with cooling towers and evaporative condensers—structures known to be critical for the large-scale proliferation and airborne spread of bacteria.
| | Legionella Analysis Using Culture-Based Methods and Rapid Molecular
Screening As part of routine maintenance operations, it is important to schedule periodic laboratory analyses of potable water. These are crucial because they enable the early detection of problems and ensure legal compliance and safety. Furthermore, they support quality control, provide objective data for better decision-making, enable proactive risk management, and offer historical data for trend analysis. In summary, they promote a proactive rather than reactive approach—that is, anticipating and preventing risks.
C.B.A. Chimica Biologia Ambiente is an accredited laboratory for the detection of Legionella in water intended for human consumption using the ISO 11731 culture-based method. This is the standard technical specification (Accredia) for the enumeration and detection of Legionella by culture; it specifies the value of Legionella spp. present in potable water in CFU/L (Colony-Forming Units per Liter) and the identification of Legionella pneumophila (serogroup typing 1 and 2–14).
In addition, our laboratory offers an innovative, accredited rapid test for the detection of Legionella spp., based on the detection of the bacterium’s DNA using the LAMP/PCR molecular technique (Real-Time PCR / Quantitative PCR). This is a rapid screening test—also accredited—based on the amplification of bacterial DNA, ideal for an immediate diagnostic response and the preventive management of emergencies.
| | Regulatory
References The guidelines provide recommendations for the prevention and control of legionellosis, a respiratory disease caused by bacteria of the genus Legionella. They are intended for operators of tourist accommodations and spa facilities, as well as for laboratories that perform microbiological analyses and environmental testing for Legionella. The document has been updated with the latest scientific findings and technical-scientific support from the Istituto Superiore di Sanità and industry experts.
The document, approved by the State-Regions Conference at its meeting on May 7, 2015, aims to consolidate, update, and supplement all the recommendations contained in previous national guidelines and regulations: Guidelines for the Prevention and Control of Legionellosis, published in the Official Gazette on May 5, 2000; Guidelines containing recommendations on Legionnaires’ disease for operators of tourist accommodations and spa facilities, and Guidelines containing recommendations for laboratories engaged in the microbiological diagnosis and environmental monitoring of Legionnaires’ disease (Official Gazette No. 28 of February 4, 2005, and Official Gazette No. 29 of February 5, 2005).
The guidelines have been updated in light of new scientific knowledge, with technical and scientific support from the Istituto Superiore di Sanità and institutional experts in the field. | | 
Guidelines for the Prevention and Control of Legionellosis
: The first national document aimed at providing healthcare professionals with up-to-date information on Legionellosis, its various sources of infection, and diagnostic, epidemiological, and environmental investigation methods | |
LEGISLATIVE DECREE No. 18 of February 23, 2023 Implementation of Directive (EU) 2020/2184 of the European Parliament and of the Council of December 16, 2020, concerning the quality of water intended for human consumption. | |
LEGISLATIVE DECREE No. 102 of June 19, 2025 Supplementary and corrective provisions to Legislative Decree No. 18 of February 23, 2023, No. 18, implementing Directive (EU) 2020/2184 of the European Parliament and of the Council of December 16, 2020, on the quality of water intended for human consumption. | |
In addition to the hospitality sector (hotels, B&Bs, campgrounds), Italian regulations (specifically Legislative Decree 18/2023 and the 2015 Guidelines) extend the obligation to assess and manage risk to a wide range of facilities, classified as high-priority or high-risk due to the complexity of their systems or the vulnerability of their users, with the requirement to prepare a Risk Assessment Document (DVR). Here are the entities required to carry out these activities:
1. Healthcare and Social Care Facilities These are the highest-risk settings, as they house people with compromised immune systems.- Hospitals and Clinics: Both public and private.
- Nursing Homes (RSA): Facilities for the elderly and long-term care centers.
- Dental Clinics: Due to the use of water in dental unit circuits (dental chairs).
- Rehabilitation Centers: Especially those equipped with therapeutic tubs or pools.
2. Sports and Wellness Facilities Any location where water is atomized (showers, whirlpools) represents a potential source of infection.- Gyms and Sports Centers: All locker rooms with communal showers.
- Swimming Pools and Wellness Centers (SPAs): Saunas, Turkish baths, and tubs with air/water jets.
- Beach resorts.
- Thermal Baths: Due to the specific nature of the water and facilities.
3. Educational and Public- Schools and Daycare Centers: Especially after summer closures (stagnant water).
- Universities and Campuses: Large water systems with many outlets.
- Barracks and Correctional Facilities: High-traffic buildings with often outdated systems.
Facilities 4. Workplaces and the Service Sector According to Legislative Decree 81/08 (Consolidated Law on Safety), employers must protect employees’ health against biological agents.- Offices with large air-conditioning systems: Especially if equipped with cooling towers or spray humidifiers.
- Company Cafeterias and Institutional Food Service Facilities: Where water is used for food preparation and cleaning.
- Shopping Centers and Airports: Facilities with kilometers of piping and thousands of users.
5. Apartment Buildings With the introduction of the new drinking water directives, responsibility has been extended to residential complexes as well:- Condominium Managers: As Internal Water Distribution Managers (GIDI), they must monitor water quality from the meter to the faucets, especially where centralized hot water systems or storage tanks are present.
In summary, the Priority Categories according to Legislative Decree 18/2023 are:- Class A: Hospitals, clinics, nursing homes (high risk).
- Class B: Hospitality facilities (hotels), senior living facilities.
- Class C: Schools, gyms, public offices, prisons.
- Class D: Train stations, airports, large commercial buildings.
| Onboard
Water Analysis Furthermore, in the maritime sector, rigorous inspections are required to ensure the safety of onboard water. The water and sanitation systems on ships and boats are subject to specific risks due to temperature fluctuations, storage in tanks, and periods of seasonal layup. Periodic inspection is an essential requirement mandated by the Maritime Health Authority (USMAF) and international regulations (MLC 2006). Yachts and superyachts, cruise ships and ferries, commercial and cargo ships, and recreational vessels in general are subject to periodic inspections of their onboard water systems. | | | |  |  |  | | |
| ACCREDIA-Accredited Laboratory |
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