Preventing legionellosis outbreaks by a quick detection of airborne Legionella pneumophila.

Legionellosis is a severe pneumonic infection caused by inhaling bacteria of the genus Legionella. Most cases reported in the USA and Europe are associated with the species Legionella pneumophila. This Gram-negative bacterium can survive within a wide spectrum of temperatures, and be transmitted via aerosols from multiple aquatic sources: fountains, thermal spas and other water systems. Although the PCR is one of the most popular methods to verify its presence in environmental or clinical samples, the direct application of this technique to ambient air samples is unusual because of the scarce material in the specimens. Here, we have developed a two-PCR assay, carried out over the V3 and V5 hypervariable regions of the 16S rRNA gene, to detect specifically the pathogenic bacteria Legionella pneumophila in outdoor air samples with low concentration of DNA. The application of this protocol does not require culture and retrieves quick results to activate the corresponding public alerts to prevent legionellosis outbreaks.