Viability of Legionella pneumophila in Water Samples: A Comparison of Propidium Monoazide (PMA) Treatment on Membrane Filters and in Liquid.
Sara Bonetta, Cristina Pignata, Silvia Bonetta, Lorenza Meucci, Donatella Giacosa, Elena Marino, Giorgio Gilli, Elisabetta Carraro
Author Information
Sara Bonetta: Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy. sara.bonetta@unito.it.
Cristina Pignata: Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy. cristina.pignata@unito.it.
Silvia Bonetta: Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy. silvia.bonetta@unito.it.
Lorenza Meucci: Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, 10152 Torino, Italy. lorenza.meucci@smatorino.it.
Donatella Giacosa: Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, 10152 Torino, Italy. donatella.giacosa@smatorino.it.
Elena Marino: Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, 10152 Torino, Italy. elena.marino@smatorino.it.
Giorgio Gilli: Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy. giorgio.gilli@unito.it.
Elisabetta Carraro: Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy. elisabetta.carraro@unito.it.
is a ubiquitous microorganism widely distributed in aquatic environments and can cause Legionellosis in humans. A promising approach to detect viable cells in water samples involves the use of quantitative polymerase chain reaction (qPCR) in combination with photoactivatable DNA intercalator propidium monoazide (PMA). However, the PMA efficiency could be different depending on the experimental conditions used. The aim of this study was to compare two PMA exposure protocols: (A) directly on the membrane filter or (B) in liquid after filter washing. The overall PMA-induced qPCR means reductions in heat-killed cells were 2.42 and 1.91 log units for exposure protocols A and B, respectively. A comparison between the results obtained reveals that filter exposure allows a higher PMA-qPCR signal reduction to be reached, mainly at low concentrations ( < 0.05). This confirms the potential use of this method to quantify in water with low contamination.
