Competitive colonization of Legionella and Pseudomonas aeruginosa in water systems of residential facilities hosting closed communities Legionella versus Pseudomonas aeruginosa in water systems of residential facilities

Gian Loreto D’Alò,1,2,* Alessandra Messina1, Cinzia Mozzetti1, Domenico Cicciarella Modica3, Patrizia De Filippis1


1 Section of Hygiene, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, via Montpellier 1, 00133 Rome, Italy
2 District 6 – Local Health Agency Rome 2, Via della Tenuta di Torrenova 138 00133, Rome, Lazio Region, Italy
3 District 4 – Local Health Agency Rome 6, Via dei Castelli Romani 2/P 00071, Pomezia (Rome), Lazio Region, Italy

Keywords: Antibiosis; Biofilm; Drinking water; Legionella; Microbial interactions; Pseudomonas aeruginosa


Legionella and Pseudomonas aeruginosa are pathogens that live and multiply in water systems and resist disinfection through biofilm formation. As suggested by some studies, we wanted to verify whether the presence of P. aeruginosa can lead to a less frequent presence of Legionella in water systems of retirement homes and group homes. We collected 123 hot water and biofilm samples from showerheads.