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.