Quantification Of Legionella In Sanitary Water Samples By A Qpcr Method

Background: In 2014, about 7,000 cases of Legionnaires' disease were reported in the European Union and the number of unreported infections is probably much higher. Hospitals are the most likely places to contract the disease for immunocompromised patients and the elderly. Monitoring programs must be conducted to assess the infectious risks in sanitary water networks. Preventive measures include the surveillance and control of water networks and the improvement of the techniques for Legionella detection. Indeed, drawbacks of culture method can have great impact on the results, which can lead to underestimation of the risk. qPCR offers sensitive and specific detection of Legionella, especially in high risk units where the application of timely measures is needed. The aim of this study was to evaluate the efficacy of a molecular method to monitor the presence of Legionella in sanitary water samples. Methods: Hot and cold sanitary water samples were collected from cooling towers and substations from the Ospedali Riuniti of Ancona, Italy. The samples were artificiaUy inoculated with 100,000 GU/sample of L. pneumophila ATCC33152 and the robustness of the method was evaluated according to ISO/TS 12869. Briefly, after sample filtration DNA was extracted from filter and quantified with "New Legionella spp. Quantitative kit" (Diatheva, Italy). Results: Results were expressed as recovery rates, calculated as percentages of Legionella GU in the spiked samples respect to the contaminating suspension. Samples from the cooling towers showed values ranging from 33 to 19% (average 29±6.7%). Samples of the substations showed a recovery from 27 to 35% (average 29.5±3.7%). Conclusion: Preliminary results showed recovery rates >25% in almost ali samples in compliance with the ISO/TS 12869. The method is suitable for the tested water samples in which high concentrations of inhibitory substances may be expected. Further improvement will include a viability PCR protocol for live/dead cells differentiation