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Knežević M, Rončević D, Vukić Lušić D, Mihelčić M, Kogoj R, Keše D, Glad M, Cenov A, Ožanič M, Glažar Ivče D, Šantić M. Decreasing Pasteurization Treatment Efficiency against Amoeba-Grown Legionella pneumophila—Recognized Public Health Risk Factor. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19031099. [PMID: 35162120 PMCID: PMC8834526 DOI: 10.3390/ijerph19031099] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/12/2022] [Accepted: 01/15/2022] [Indexed: 11/16/2022]
Abstract
Legionellae are gram-negative bacteria most commonly found in freshwater ecosystems and purpose-built water systems. In humans, the bacterium causes Legionnaires’ disease (LD) or a Pontiac fever. In this study, the different waters (drinking water, pool water, cooling towers) in which Legionella pneumophila has been isolated were studied to assess the possible risk of bacterial spreading in the population. The influence of physical and chemical parameters, and interactions with Acanthamoeba castellanii on L. pneumophila, were analyzed by Heterotrophic Plate Count, the Colony-forming units (CFU) methods, transmission electron microscopy (TEM), and Sequence-Based Typing (SBT) analysis. During the study period (2013–2019), a total of 1932 water samples were analyzed, with the average annual rate of Legionella-positive water samples of 8.9%, showing an increasing trend. The largest proportion of Legionella-positive samples was found in cooling towers and rehabilitation centers (33.9% and 33.3%, respectively). Among the isolates, L. pneumophila SGs 2–14 was the most commonly identified strain (76%). The survival of Legionella was enhanced in the samples with higher pH values, while higher electrical conductivity, nitrate, and free residual chlorine concentration significantly reduced the survival of Legionella. Our results show that growth in amoeba does not affect the allelic profile, phenotype, and morphology of the bacterium but environmental L. pneumophila becomes more resistant to pasteurization treatment.
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Affiliation(s)
- Maša Knežević
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia; (M.K.); (M.M.); (M.O.); (M.Š.)
| | - Dobrica Rončević
- Department of Epidemiology, Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia;
- Department of Public Health, Faculty of Health Studies, Viktora Cara Emina 5, 51000 Rijeka, Croatia
| | - Darija Vukić Lušić
- Department of Environmental Health, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
- Department of Environmental Health, Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia; (M.G.); (A.C.)
- Center for Advanced Computing and Modeling, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia
- Correspondence: ; Tel.: +385-(0)51-358-755
| | - Mirna Mihelčić
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia; (M.K.); (M.M.); (M.O.); (M.Š.)
| | - Rok Kogoj
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Zaloska 4, 1000 Ljubljana, Slovenia; (R.K.); (D.K.)
| | - Darja Keše
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Zaloska 4, 1000 Ljubljana, Slovenia; (R.K.); (D.K.)
| | - Marin Glad
- Department of Environmental Health, Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia; (M.G.); (A.C.)
| | - Arijana Cenov
- Department of Environmental Health, Teaching Institute of Public Health of Primorje-Gorski Kotar County, Krešimirova 52a, 51000 Rijeka, Croatia; (M.G.); (A.C.)
| | - Mateja Ožanič
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia; (M.K.); (M.M.); (M.O.); (M.Š.)
| | - Daniela Glažar Ivče
- Branch Office Rab, Teaching Institute of Public Health of Primorje-Gorski Kotar County, Palit 143a, 51280 Rab, Croatia;
| | - Marina Šantić
- Department of Microbiology and Parasitology, Faculty of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia; (M.K.); (M.M.); (M.O.); (M.Š.)
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