Diagnosis legionella in drinking water

Legionella in drinking water? - New diagnostic procedure developed
Germs in drinking water are always a problem. Despite strict controls and comprehensive hygiene measures, there are always contaminants. It is also possible to transmit so-called legionellae, which cause severe pneumonia and have so far been difficult to detect in drinking water. However, researchers at the Helmholtz Center for Infection Research (HZI) in Braunschweig have now developed a very accurate and rapid diagnostic procedure at the molecular level that greatly improves the diagnostics and cause research in legionella infections.

Heaters, showers, air conditioners - Legionella are widespread
Legionella are relatively common in hot water production and hot water distribution systems, swimming pools, air conditioning, showers, water tanks, but also cold water pipes with external heat. Water temperatures of 25 to 59 degrees Celsius, with a long residence time and simultaneous supply of fresh water form for Legionella optimal living conditions. Through aerosols, the finest droplets in the air, the one rod-shaped bacteria reach deep into the respiratory tract, where they can trigger Legionnaire's disease with appropriate pneumonia. Although all Legionella are potentially human pathogenic (transmissible to humans), so far only the pathogen type Legionella pneumophila as a trigger of Legionnaires' disease for humans. However, as the bacteria were difficult to isolate and cultivate, evidence of different types of pathogens has been extremely complicated.

New diagnostic procedure improves detection possibilities
To remedy this malady, researchers at the Helmholtz Center for Infection Research (HZI) in Braunschweig have now developed a new diagnostic procedure at the molecular level, which is published in the current issue of the journal „Applied and Environmental Microbiology. "On the one hand, this method detects any legionella in drinking water, and on the other hand, it can easily be determined whether it belongs to a strain that is dangerous for humans. „So far, it has often been very difficult to quickly pin down the cause of an epidemic, as it was not possible to pinpoint the bacteria, their virulence and their source of origin, "said Höfer, Manfred Höfle, a researcher at HZI. „Legionella pneumophila alone has 14 subgroups called serotypes. The distinction between these different serotypes is very complex, as it is difficult to isolate legionella: they grow very slowly or are overgrown by competing bacteria. "

Detection using repeating DNA sections
In the new diagnostic procedure, the pathogens are therefore detected via the characteristic sections of their DNA, explained Manfred Höfle. In the process, his research team succeeded for the first time in adapting the known methods for the extraction and duplication of Legionella DNA in such a way that it is possible to detect the individual bacterial strains directly from a water sample, according to the specialist of the HZI. Höfle explained that „In the past (...) the concentration and purification of DNA from drinking water was problematic (was). In addition, the necessary degree of genetic breakdown has not yet been achieved. "Together with his research colleague, who gained a great deal of experience from the analysis of water samples and the detection of germs contained therein, the difficulties were overcome by improved procedures. „We can now detect short, repeating DNA sections, so-called tandem repeats, in the Legionella genome, "Höfle explained, highlighting the tandem sections in color and producing comparable patterns for the various bacterial strains. „This means that we can not only check which germ contains the water sample, but also how unhealthy it is for humans. "According to Manfred Höfle, the new diagnostic method could in the future make a significant contribution to the risk management of drinking water systems. Not only the overall quality could be better checked, but the process also helps in the detection of biofilms (deposition of microorganisms on the water surface or at contact points to solid objects), which favor the occurrence of Legionella.

Also in Germany frequently diseases by Legionellen
Legionella were first introduced at a veterans' meeting in 1976 „American Legion“ at the Bellevue-Fort Hotel in Philadelphia. Out of 4,400 delegates, 180 and 29 died of severe lung infections. Legionnaire's disease was already well under way until the health authorities became ill with the plague. The detection of the bacterium in the lung tissue of a deceased veteran succeeded only in early 1977. Since then, Legionella have been detected worldwide and also in Germany it comes again and again to isolated infections. An outbreak of legionnaires diseases with disease character is relatively rare in this country. However, such an incident occurred at the beginning of January 2010 in the Ulm area. Here, according to official figures, 64 people fell ill with Legionnaire's disease and five people died as a result. The source of the infection is primarily the cooling towers of a combined heat and power plant near Ulm central station under suspicion. At present, Dresden University of Technology is investigating the risk posed by the cooling towers. (fp, 14.10.2010)

Also read:
Drug residues in drinking water
Microbial contamination detected in drinking water
Drinking water often contaminated with germs