Water plays a vital role in countless aspects of daily life—drinking, cooling, recreation and more. However, the same systems that deliver these benefits can also harbor Legionella, a waterborne bacteria responsible for Legionnaires’ disease, a severe form of pneumonia¹. Legionella thrives in stagnant aquatic environments, many of which are human-made and common in modern infrastructure, like in cooling towers, hot tubs and complex building water systems. In this blog, we explore the risks posed by Legionella, the limitations of traditional detection methods and how advanced tools at Promega are transforming water safety monitoring. 

Legionella Detection: Challenges and Emerging Solutions 

In 1976, a pneumonia outbreak at a Philadelphia convention led to the discovery of Legionella pneumophila, the bacterium behind Legionnaires’ disease. The pathogen was traced to aerosolized water from the air conditioning system, infecting 182 people and causing 29 deaths². This incident highlighted the far-reaching consequences of contaminated water systems, which threaten public health and impose significant financial and operational burdens on businesses and institutions. Cooling towers, decorative water features, and even hospital water systems can become sources of infection if proper precautions aren’t taken. For vulnerable populations—including older adults and those with weakened immune systems—exposure to Legionella can lead to life-threatening illness. 

In addition to being time-intensive, culture-based detection can be unreliable in mixed microbial populations. Faster-growing, non-Legionella bacteria can overgrow culture plates, obscuring the presence of Legionella and leading to underreporting of contamination³. Culture methods are also unable to detect viable-but-non-culturable (VBNC) cells—bacteria that remain infectious but cannot grow under standard laboratory conditions. These hidden risks are a critical gap in traditional culture methods and highlight the need for more comprehensive detection approaches. 

To address the limitations of culture-based methods, many facilities have turned to polymerase chain reaction (PCR) for faster and more sensitive results. PCR can detect Legionella DNA in as little as a few hours, offering same-day conformation of water quality. However, traditional PCR methods don’t differentiate between live, infectious bacteria and dead cells, which can lead to false positives and complicate risk assessments. This limitation underscores the importance of innovations like a viability PCR, which offers enhanced accuracy by focusing on live-cell detection. 

Advanced Detection with Viability PCR  

To overcome the challenges of traditional detection methods, Promega has developed a novel viability PCR workflow that sets a new standard for Legionella testing. At the heart of this solution is a dye that selectively inactivates DNA from dead cells, allowing for the detection of live versus dead Legionella cells. This innovation eliminates false positives caused by residual DNA from non-viable bacteria, providing highly accurate and informed results. 

The Viability PCR workflow integrates seamlessly into water testing protocols, offering flexibility for both manual and automated DNA extraction methods. The Wizard® PureWater Kit provides an efficient, hands-on solution for labs processing smaller sample volumes, while the Maxwell® RSC PureWater System delivers automated, high-throughput DNA purification for larger-scale operations. These options allow water quality professionals, public health laboratories, and environmental monitoring teams to customize workflows based on the unique needs of their facility. 

By combining selective viability detection with multiplex qPCR technology, the Viability PCR solution enables the simultaneous identification of multiple Legionella species, including Legionella pneumophila and its most pathogenic serogroup, SG1, which are linked to outbreaks of Legionnaire’s disease. This comprehensive approach ensures that water safety monitoring is not only faster but also more precise, providing institutions with the tools they need to protect public health. 

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To learn more about Legionella detection solutions at Promega, check out this page.

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References

1. “Legionella (Legionnaires’ Disease and Pontiac Fever): About.” Centers for Disease Control and Prevention, www.cdc.gov/legionella/about/index.html. Accessed 16 Jan. 2025. ↩︎
2. “Legionella Pneumophila.” National Center for Biotechnology Information, U.S. National Library of Medicine, 23 July 2018, www.ncbi.nlm.nih.gov/books/NBK430807/. Accessed 16 Jan. 2025. ↩︎
3. Miskowski, Diane. “An Overview of Legionella.” EMSL Analytical, Inc., www.legionellatesting.com/legionella-article/?utm_source=chatgpt.com. Accessed 16 Jan. 2025. ↩︎

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