Decreasing pasteurization treatment efficiency against amoeba-grown Legionella pneumophila—recognized public health risk factor

Knežević, Maša (author), Rončević, Dobrica (author), Vukić Lušić, Darija (author), Mihelčić, Mirna (author), Kogoj, Rok (author), Keše, Darja (author), Glad, Marin (author), Cenov, Arijana (author), Ožanič, Mateja (author), Glažar Ivče, Daniela (author), Šantić, Marina (author)

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.

• Language: English
• Keywords: Acanthamoeba, environment, infection, Legionella, water
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2022
• Number of pages: 19 str.
• Numbering: Vol. 19, iss. 3, art. 1099
• PID: 20.500.12556/RUL-137091
• UDC: 616.9
• ISSN on article: 1660-4601
• DOI: 10.3390/ijerph19031099
• COBISS.SI-ID: 94193155
• Publication date in RUL: 01.06.2022

Record is a part of a journal

• Title: International journal of environmental research and public health
• Shortened title: Int. j. environ. res. public health
• Publisher: MDPI
• ISSN: 1660-4601
• COBISS.SI-ID: 1818965

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 01.02.2022

Secondary language

• Language: Slovenian
• Keywords: Acanthamoeba, okolje, okužba, legionela, voda

Projects

• Funder: Other - Other funder or multiple funders
• Funding programme: University of Rijeka
• Project number: UNIRI-BIOMED-18-128

• Funder: HRZZ - Croatian Science Foundation
• Project number: HRZZ-IP-2016-06-9003