Antibiotic Susceptibility of Environmental Legionella pneumophila Strains Isolated in Northern Italy

Clementina Elvezia Cocuzza, Marianna Martinelli, Federica Perdoni, Chiara Giubbi, Maria Erica Alessandra Vinetti, Enrico Calaresu, Sergio Frugoni, Maria Scaturro, Maria Luisa Ricci and Rosario Musumeci
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Clementina Elvezia Cocuzza: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
Marianna Martinelli: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
Federica Perdoni: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
Chiara Giubbi: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
Maria Erica Alessandra Vinetti: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
Enrico Calaresu: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
Sergio Frugoni: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy
Maria Scaturro: National Reference Laboratory for Legionella, Department of Infectious Diseases, Istituto Superiore di Sanità, 00161 Roma, Italy
Maria Luisa Ricci: National Reference Laboratory for Legionella, Department of Infectious Diseases, Istituto Superiore di Sanità, 00161 Roma, Italy
Rosario Musumeci: Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy

IJERPH, 2021, vol. 18, issue 17, 1-10

Abstract: Legionella pneumophila is ubiquitous in aquatic environments and responsible for severe pneumonia in humans through inhalation of aerosol containing Legionella spp. Macrolides and fluoroquinolones are frequently used antimicrobials, but treatment failures are increasingly being reported. As susceptibility testing is not routinely performed, this study aimed to determine the minimum inhibitory concentrations (MICs) on 58 environmental Legionella pneumophila strains (24 of serogroup 1 and 34 of non-serogroup 1) isolated in Northern Italy. MICs of azithromycin, erythromycin, ciprofloxacin, levofloxacin, and rifampicin were determined by the microdilution method using buffered yeast extract broth supplemented with ?-ketoglutarate (BYE?). Seventy-five percent of Legionella pneumophila isolates showed MIC values below the tentative highest MICs indicated by the European Committee on Antimicrobial Susceptibility Testing (EUCAST); rifampicin was the most active agent with MIC 90 values below 0.008 mg/L. Interestingly, one isolate was tested and found to be PCR-positive for the azithromycin LpeAB active efflux system, further confirmed by the reserpine/resazurin microtiter assay. In conclusion, this study has provided additional susceptibility data for environmental Legionella pneumophila isolates from Northern Italy demonstrating, in general, low MICs values for the tested antimicrobials, although one strain tested was shown to possess the LpeAB resistance determinant, indicating that future surveillance studies are warranted.

Keywords: Legionella pneumophila; antimicrobial susceptibility testing; minimum inhibitory concentrations; macrolides; fluoroquinolones; rifampicin; doxycycline; LpeAB active efflux system; reserpine coupled REMA assay (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2021
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