Water Testing

The MALDI Biotyper® system accurately detects cultivated waterborne pathogens within minutes enabling water suppliers to preserve environmental and drinking water from serious contamination events.

Water is essential for life. It is part of the environment, being used in industrial processes and available as tap water. Water for human consumption does not need to be sterile but it does need to be safe. Establishing whether or not water is safe requires robust techniques to isolate and to identify potentially pathogenic bacteria. Rapid availability of testing results enables prompt action to be taken to minimize risk as early as possible.

Until now, techniques like light microscopy or biochemical tests have proved useful but have inherent limitations. The primary limitation of LM is that it cannot fully identify a bacterium and, for biochemical tests, the number of reactions which can be simultaneously performed, the extent of the associated databases and the time taken to generate a result.

MALDI Biotyper for identification of bacteria

Matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry has changed bacterial identification practices worldwide. The adaptation of the technology to generate protein ‘fingerprints’ of bacteria has provided a rapid and robust method with high discriminatory power for e.g. Legionella pneumophila.

Traditional identification of potential pathogens in water

Following primary culture of water samples, colonies which are suspected of being potential pathogens require confirmatory tests to exclude or verify the presence of specific organisms. Traditionally, such confirmatory steps have necessitated a subculture stage prior to biochemical or immunological tests. This adds up to two days to the time taken to generate a definitive result.

The process for Legionella testing (complying with ISO standards) involves preliminary steps of membrane filtration and heat/acid treatment followed by culture on selective agar. The primary agar plates are incubated for 10 days during which time they are inspected three times for suspect colonies. Presumptive colonies of Legionella species are subcultured in order to provide growth for confirmatory tests. The final result may therefore take 12 days from the time the primary culture was set up.

Molecular detection of potential pathogens offers an alternative approach, but they are laborious and costly. PCR methods are highly sensitive and rapid, yet they do not discriminate between viable and non-viable organisms.

Your benefit using MALDI-Biotyper for confirmation of Legionella species from water

Although primary culture for Legionella species still requires 10 days of incubation, the MALDI-Biotyper offers same-day confirmation once suspect colonies have been observed. Analysis requires only a small portion of one colony and can be performed directly from the primary plate. Confirmation therefore takes a matter of minutes; reducing the processing time by two days. The system can be employed for a broad range of bacteria.

The UKAS (United Kingdom Accreditation Service) accredited MALDI-TOF in September 2016 as a confirmation technique for Legionella confirmation.

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