Legionella in water samples: How can you interpret the results obtained by quantitative PCR?. Issue 1 (February 2015)

• Record Type: Journal Article
• Authors: Ditommaso, Savina; Ricciardi, Elisa; Giacomuzzi, Monica; Arauco Rivera, Susan R.; Zotti, Carla M.
• Is Part Of: Molecular and cellular probes. Volume 29:Issue 1(2015)
• Page Start: 7
• Page End: 12
• Publication Date: 2015-02
• Subjects: Legionella spp -- PCR (polymerase chain reaction) -- Enumeration -- Environmental water; Molecular probes -- Diagnostic use -- Periodicals; Pathology, Cellular -- Technique -- Periodicals; Cell Biology -- Periodicals; Molecular Biology -- Periodicals; Sondes moléculaires -- Utilisation diagnostique -- Périodiques; Cytopathologie -- Technique -- Périodiques; 572
• DOI: 10.1016/j.mcp.2014.09.002
• Languages: English
• ISSNs: 0890-8508

Abstract

Abstract: Evaluation of the potential risk associated with Legionella has traditionally been determined from culture-based methods. Quantitative polymerase chain reaction (qPCR) is an alternative tool that offers rapid, sensitive and specific detection of Legionella in environmental water samples. In this study we compare the results obtained by conventional qPCR (iQ-Check™ Quanti Legionella spp.; Bio-Rad) and by culture method on artificial samples prepared in Page's saline by addiction of Legionella pneumophila serogroup 1 (ATCC 33152) and we analyse the selective quantification of viable Legionella cells by the qPCR-PMA method. The amount of Legionella DNA (GU) determined by qPCR was 28-fold higher than the load detected by culture (CFU). Applying the qPCR combined with PMA treatment we obtained a reduction of 98.5% of the qPCR signal from dead cells. We observed a dissimilarity in the ability of PMA to suppress the PCR signal in samples with different amounts of bacteria: the effective elimination of detection signals by PMA depended on the concentration of GU and increasing amounts of cells resulted in higher values of reduction. Using the results from this study we created an algorithm to facilitate the interpretation of viable cell level estimation with qPCR-PMA.