Serological and molecular identification of Legionella spp. isolated from water and surrounding air samples in Italian healthcare facilities

Maria Teresa Montagna, Maria Luisa Cristina, Osvalda De Giglio, Anna Maria Spagnolo, Christian Napoli, Lucia Cannova, Maria Grazia Deriu, Santi Antonino Delia, Ada Giuliano, Marco Guida, Pasqualina Laganà, Giorgio Liguori, Ida Mura, Francesca Pennino, Angelo Rossini, Stefano Tardivo, Ida Torre, Maria Valeria Torregrossa, Maria Rosaria Villafrate, Roberto AlbertiniCesira Pasquarella

Research output: Contribution to journalArticlepeer-review


Background: Legionella is an intracellular microorganism living in natural and artificial aquatic environments. Although its transmission to humans is linked to the inhalation of contaminated aerosols, there is no validated air sampling method for the control and prevention of the disease. The aim of the present study was to provide more information on the distribution of Legionella spp. in indoor environments and to determine whether the same Legionella strains are isolated from air and water samples. Methods: Ten healthcare facilities located in seven regions of Italy were enrolled. The serological typing of Legionella spp. from water samples and the surrounding air by active and passive sampling was assessed using polyvalent and monovalent antisera. Subsequently, the strains identified as Legionella pneumophila (Lpn) underwent molecular typing by sequence-based typing (SBT) using seven genes (flaA, pilE, asd, mip, mompS, proA, and neuA). The allelic profile number was assigned using the European Working Group for Legionella Infections-SBT database. Results: Lpn serogroup 6 was the most prevalent serogroup; it was found simultaneously in the air and water samples of three different healthcare facilities. In the remaining seven hospitals, Lpn serogroups 1, 6, 7, 9, and 12 were isolated exclusively from water samples. The molecular investigation showed that Lpn strains in the water and air samples of each positive healthcare facility had the same allelic profile. Strains, identified as sequence types (STs) 728 and ST 1638+ST 1324, were isolated in two respective healthcare facilities, and a new strain, identified as ST 1989, was obtained in one healthcare facility. Conclusion: The application of the SBT method allowed to verify the homology among Legionella strains from water samples and the surrounding air. The results showed that the same Lpn strains were present in the air and water samples, and a new Legionella strain was identified.

Original languageEnglish
Pages (from-to)47-50
Number of pages4
JournalEnvironmental Research
Publication statusE-pub ahead of print - Dec 21 2015


  • Bioaerosol
  • Legionella
  • Molecular investigation
  • Serological typing

ASJC Scopus subject areas

  • Environmental Science(all)
  • Biochemistry


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