New system for the detection of Legionella pneumophila in water samples

Waterborne pathogens are a global concern for public health worldwide. Despite continuing efforts to maintain water safety, water quality is still affected by deterioration and pollution. Legionella pneumophila colonizes man-made water systems and can infect humans causing Legionnaire's disease (LD), pneumonia. The prevention of LD is a public health issue and requires specific systems to control and detect these microorganisms. Culture plate is the only technique currently approved, but requires more than 10 days to obtain results. A rapid test that inform in hours about the presence of Legionella pneumophila in water samples will improve the control of this pathogen colonization. In order to control colonization by L. pneumophila we developed a membrane filter method to capture and immunodetect this microorganism in water samples. This membrane filter is used to retain the bacteria using a nitrocellulose disc inside a home-made cartridge. Subsequently we perform the immunodetection of the bacteria retained in the nitrocellulose (blocking, antibody incubation, washings and developing). On comparing our test with the gold-standard, the most important finding is the considerably reduction in time maintaining the same detection limit. This rapid test is easily automated for L. pneumophila detection allowing a comprehensive surveillance of L. pneumophila in water facilities and reducing the variability in the analyses due to the low need for manipulation. Moreover, corrective measures may be applied the same day of the analysis. This method considerably reduces the detection time compared with the conventional, gold-standard detection culture method that requires more than 10 days, being decisive to prevent outbreaks.