New Test Enables Rapid Detection of Legionella

Severn Trent Laboratories in Coventry (UK) has recently introduced a new method, Polymerase Chain Reaction, for the rapid detection of Legionella, with the ability to generate results within 24 hours

In July 1976, a mysterious illness struck attendees at an American Legion convention being held at a hotel in Philadelphia.

Within a few days, 221 Legionnaires and other hotel guests were sickened and 34 had died.

Thought at first to be the beginning of an influenza epidemic known as the swine flu, the illness was eventually traced to bacteria in the hotel water cooling tower, which supplied the air conditioning system.

Following an investigation by the Centers for Disease Control in Atlanta, Legionella pneumophila was isolated in 1977.

Since then, federal agencies all over the world have required more stringent cleaning and hygiene provisions for cooling towers and large scale air conditioning systems.

Nevertheless, various outbreaks have occurred with recent, well-documented cases in the United Kingdom - including a 2002 outbreak in North West England that resulted in the deaths of seven people - and a number of outbreaks in Europe.

Today, improvements in the detection of Legionnaires disease, or Legionella, continue.

Severn Trent Laboratories in Coventry, United Kingdom, has recently introduced a new method for the rapid detection of Legionella.

With the ability to generate results within 24 hours, the new Legionella PCR (Polymerase Chain Reaction) method is a key tool in establishing risk in emergency or outbreak situations and offers real-time analysis of a water system.

The introduction of the new method complements the company's existing Legionella analysis, detection by standard culture.

The test indicates the number of viable Legionella bacteria in a water sample, generating results for Legionella pneumophila (predominantly linked to Legionnaires disease) and Legionella spp (predominantly linked to milder and variant forms of the disease such as Pontiac fever).

It is an ideal investigative tool for monitoring the effectiveness of water treatment where positive Legionella results have previously been found.

The study of Legionella has found the infection to be a commonly occurring bacterium found in both natural and artificial water systems.

These bacteria can multiply rapidly in favorable conditions of between 68F and 113F (20C and 45C), where nutrients such as biofilm, sediment and sludge are present -- common in man-made water systems.

All employers and commercial property owners in the United Kingdom are required to monitor their water systems for the presence of Legionella bacteria, in line with the Health and Safety Executive Approved Code of Practice and Guidance Document, "L8 Legionnaires Disease - The Control of Legionella Bacteria in Water Systems".

Rapid Detection by Polymerase Chain Reaction.

The PCR method may be used in conjunction with the standard methodology or as an investigational tool to monitor water treatment following a positive result using the standard method, particularly if early indication on the effectiveness of treatment is required.

The results can be available in 24 hours or within five hours for emergency analysis.

The method relies on the capture of the target organism via membrane filtration followed by extraction of DNA from intact bacterial/protozoan/algal cells.

Then, a PCR run is carried out of the purified DNA to amplify the target DNA to a threshold level in order for it to be detected by the instrument.

The target DNA is specific to the organisms being isolated (i.e, Legionella pneumophila or Legionella species).

The ability of this method to rapidly assess contamination levels has several benefits:.

* Response times are considerably reduced - essential when monitoring high-risk water systems, the application of effective treatment regimes or the effectiveness of remedial actions.

* Timely day-to-day monitoring of treatment performance and 'fine-tuning' of chemical applications.

* Rapid assessment of the cleanliness of a water system, for example, during pre-commissioning investigations or where water systems have previously failed L8 guidelines, which are key governmental health and safety rules referenced above.

* Real-time results demonstrating the Legionella status of the water system at the time of sampling.

For more information on the Legionella PCR method, please contact Carla Hall at Severn Trent Services.

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