Food Microbiology

Legionella pneumophila is an opportunistic pathogen of major concern, being the cause of severe respiratory diseases including Legionnaires’ disease. Monitoring of at-risk water systems, particularly in hospitals and similar environments, is key to the control of this pathogen. This presentation will outline the results of a comparison of the performance of a novel and simple most probable number (MPN) method (Legiolert™/Quanti-Tray®) with the widelyused ISO 11731-2 membrane filtration method for the enumeration of L. pneumophila from water. Data from a multi-laboratory study which were analysed according to ISO 17994 showed that Legiolert™/Quanti-Tray® yielded on average higher counts of L. pneumophila, with results being available within seven days compared to the 10 or more days required for the ISO method. The Legiolert™ medium also had a high specificity for L. pneumophila of 96.4%. This new method represents a significant  improvement in the efficiency and simplicity of testing for the enumeration of L. pneumophila from water samples.