Identification and isolation of homoserine lactones (HSLs) produced by Pseudomonas aeruginosa and the effects on Legionella pneumophila growth

Risk for infections from Legionella pneumophila represents a critical issue for immunocompromised individuals, especially when this species is present within the biofilm of the water distribution systems of hospitals or other health facilities where the complex ancient water network creates environmental conditions that are suitable for Legionella persistence and multiplication. The shock hyperchlorination and subsequent systemic continuous chlorination is a disinfection treatment reported in the Italian Guideline for prevention and control of nosocomial legionellosis as an effective procedure to reduce L. pneumophila colonization of hospital water sources. Although this disinfection strategy has been proven to be effective in the short-term, eradication of Legionella from water networks is usually not achieved. The objective of this study is the identification and purification of P. aeruginosa bacteriocins, such as homoserine lactones (HSLs), by the development of an experimental method by High performance-liquid chromatography (HPLC), coupled to diode array detection (DAD) and the evaluation of the effectiveness of these molecules in the managing of the persistence of L. pneumophila in experimental cocultures.