DETECTION OF LEGIONELLA PNEUMOPHILA AND REDUCING THE RISK OF
LEGIONNAIRES’ DISEASE Dangers of Legionella pneumophila
Legionnaires’ disease is caused by Legionella bacteria that can thrive in both potable and non-potable, water systems, such as evaporative cooling systems, taps, showers, ice machines, humidifiers, water features and pools. Although there are approximately 60 species of Legionella, official statistics from Public Health England, published December 2017, note that more than 99% of confirmed cases of Legionnaires’ disease were caused by a single species, Legionella pneumophila.
For facilities managers, the threat of Legionella within a water system is magnified by its ability to form and grow rapidly in biofilm. Biofilm can build up at outlets such as taps and showers, and in older buildings, with pipework that has seen many changes and alterations in plumbing, dead- legs and blind ends. As biofilm forms, the microorganisms proliferate, with sections able to break off and potentially seed new biofilm colonies elsewhere in a water system, or to emerge from the system in a potentially infectious aerosol.
Although the UK guidelines HSG274 Parts 1, 2 and 3, “Legionnaires’ disease: Technical guidance”, published by the HSE do not specify individual species of Legionella, in practice, Legionella pneumophila should be considered the main concern, because this is the primary causative agent of Legionnaires’ disease.
By accurately monitoring the condition of water systems as a component of a comprehensive water management plan, facilities managers can minimise Legionella
risk, particularly in buildings such as hospitals, where unaddressed Legionella can lead to either patient infection, or prolonged closure of wards, which can reduce the efficiency and capabilities of a facility, and has an associated financial cost.
Testing for Legionella
For years, the only method available for testing for Legionella was a traditional spread plate culture. This method suffers from several drawbacks, including low sensitivity and a high rate of false negative results. To address these issues, the IDEXX Legiolert test was introduced in 2016, which is a liquid culture method designed to be highly sensitive for Legionella pneumophila. The Legiolert test delivers confirmed results up to seven days faster than traditional plate culture testing and confirmation methods.
Legiolert has been extensively compared to traditional spread plate methods and there are currently 11 peer-reviewed comparison studies that have evaluated over 2,000 environmental samples taken from all over the world. Nineteen different laboratories across seven countries
were involved in these studies, including the Italian Istituto Superiore di Sanità, the U.S. Environmental Protection Agency, as well as public and private laboratories.
All of the peer-reviewed research showed Legiolert to be at least as sensitive as the standard culture methods, with nine of the 11 studies showing it to be statistically more sensitive. All of the studies showed Legiolert to be highly specific for the detection of Legionella pneumophila.
This independent research is supported by a number of certification and regulatory bodies: for example, the method has been published by ASTM International as “ASTM D8429-21: Standard Test Method for Legionella pneumophila in Water Samples Using Legiolert”; is specified as a recommended method in the by the UK’s Standing Committee of Analysts’ ‘blue book’ publication, “The determination of Legionella bacteria in waters and other environmental samples (2020) – Part 2 – Culture Methods for their detection and enumeration”; and Legiolert is also recognised with AFNOR certification for hot and cold sanitary water and cooling tower water (Reference No IDX 33/06 06/19).
For facilities managers, having confidence in the results of microbiology testing is vital. Rapid, targeted testing can put them in control and promote the safety of buildings’ water systems and inhabitants.
For more information on the studies, click here, and to find out more about Legiolert and IDEXX Water, use the contact details below.
Call: 01638 676800 Email:
wateruk@idexx.com
www.idexx.co.uk/water
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