Chip detects Legionella in minutes

Scientists have created the LegioTyper, a chip that detects the dangerous pathogen and identifies which of the approximately 20 subtypes is present

TUM scientist Catharina Kober with the LegioTyper-chip. Photo: Jonas Bemetz / TUM

Scientists at the Technical University of Munich have developed a microarray rapid test to speeds up detection in case of a Legionella pneumophila outbreak.

A typical test for Legionella involves putting a water sample in a Petri dish, then waiting 10 to 14 days to check if bacterial cultures grow. Finding the source of the Legionnaires' disease outbreak is crucial to preventing further infections.

To speed up detection, the team of researchers developed a measuring chip in the context of the "LegioTyper" project funded by the German Federal Ministry of Education and Research.

This chip not only detects the pathogen Legionella pneumophila but also identifies which of the approximately 20 subtypes is present. The results are delivered in about 35 minutes.

Dangerous pathogen

Legionella is rod-shaped bacteria that can cause life-threatening pneumonia in humans. They multiply in warm water and can be dispersed into the air via cooling towers, evaporative recooling systems and hot water systems.

The most dangerous among the almost 50 species of Legionella is Legionella pneumophila. It is responsible for 80% of all infections. When an outbreak occurs, the source of the germs must be identified as soon as possible to prevent further infections.

Similar to a paternity test, the origin of the outbreak is confirmed when the germs in the process water of a technical system exactly match those identified in the patient. However, often numerous systems must be tested in the process, and the requisite cultivation for the test takes around ten days.

There is a rapid test for detecting the Legionella pathogen in the clinic. It identifies compounds of Legionella in the urine of patients. "Unfortunately, this quick test serves only as a first indication and is not suitable for screening the water of technical systems," commented Michael Seidel, head of the research group at the chair of analytical chemistry and water chemistry of the Technical University of Munich.

Microarray

The LegioTyper is a foil-based measuring chip. It uses the microarray analysis platform MCR of the Munich-based company GWK GmbH. Using 20 different antibodies, the system provides a complete analysis within 34 minutes.

Seidel explained: “Compared to previous measurements, the new method not only provides a huge speed advantage but is also so cheap that we can use the chip in one-time applications.”

According to a statement on the TUM website, the system can be deployed for environmental hygiene as well as clinical diagnostics. In combination with a second, DNA-based method, the rapid test can even distinguish between dead and living Legionella pathogens. This allows the success of disinfection measures to be monitored.

The project participants will present their system to the public for the first time at the Analytica 2018 trade fair in Munich (Hall 3, Booth 315; April 10–13, 2018).

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