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Microorganisms
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Legionella pneumophila
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Legionella pneumophila

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Medical Microbiology".

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 15329

Special Issue Editors

Prof. Dr. Jean-Marc Berjeaud

E-Mail Website
Guest Editor
Laboratoire Ecologie & Biologie des Interactions, Universite de Poitiers, Poitiers, France
Interests: Legionella; biofilm; antimicrobial peptide; quorum sensing; microbiotas; bacterial virulence
Dr. Julien Verdon

E-Mail Website
Guest Editor
Laboratoire Ecologie & Biologie des Interactions, UMR CNRS 7267, Université de Poitiers, F-86000 Poitiers, France
Interests: ecology of Legionella; volatile organic compounds; antimicrobial peptides; microbial interactions; quorum sensing; Borrelia; Pseudomonas

Special Issue Information

Dear Colleagues,

Legionella pneumophila is a Gram-negative opportunistic intracellular human pathogen responsible for severe pneumonia called Legionnaires’ disease. Among over 60 Legionella species, L. pneumophila is the leading cause of Legionnaires’ disease, and the serogroup 1 is associated with almost 85–90% of cases worldwide. Within freshwater environments, L. pneumophila bacteria are ubiquitous organisms, mostly found as parasites of various phagotrophic protists such as amoebae and their natural hosts, and colonize multispecies biofilms. Since the first outbreak of pneumonia reported in 1976, many outbreaks have been linked to various water sources in hospitals, hotels, cruise ships, industrial facilities, and family residences. Transmission to humans occurs after inhalation of contaminated water droplets by exposed people. Therefore, L. pneumophila, thanks to its ability to resist phagocytosis, multiplies inside macrophages.

The aim of this Special Issue of Microorganisms is to present a collection of articles that provide a current snapshot of research in the L. pneumophila field. Manuscripts covering all aspects of research relating to L. pneumophila and its hosts are welcome, including work from an applied angle—such as novel control strategies—through to more fundamental questions relating to the intracellular lifestyle of the bacterium, quorum sensing mechanisms, immune evasion strategies, pathogenesis, and epidemiology.

Prof. Dr. Jean-Marc Berjeaud
Dr. Julien Verdon
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Microorganisms is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • biofilm
  • control strategies
  • detection and diagnosis
  • ecology of Legionella
  • host–cell interactions
  • microbial interactions
  • omics of Legionella
  • pathogenesis
  • quorum sensing
  • virulence factors

Published Papers (6 papers)

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Research

14 pages, 1991 KiB  
Article
Legionella pneumophila in Municipal Shower Systems in Stavanger, Norway; A Longitudinal Surveillance Study Using Whole Genome Sequencing in Risk Management
by Anne Vatland Krøvel, Eva Bernhoff, Elin Austerheim, Markus André Soma, Monica Regine Romstad and Iren Høyland Löhr
Microorganisms 2022, 10(3), 536; https://doi.org/10.3390/microorganisms10030536 - 28 Feb 2022
Cited by 3 | Viewed by 2247
Abstract
Following an incidence of Legionnaires disease (LD) in 2007, where a municipal shower system was the likely source of infection, Stavanger municipality initiated a surveillance program for Legionella as part of establishing internal risk evaluation and prevention routines. More than 250 shower systems [...] Read more.
Following an incidence of Legionnaires disease (LD) in 2007, where a municipal shower system was the likely source of infection, Stavanger municipality initiated a surveillance program for Legionella as part of establishing internal risk evaluation and prevention routines. More than 250 shower systems were examined for cultivatable Legionella pneumophila. The prevalence and diversity of serogroups (sg) and sequence types (STs) of L. pneumophila were mapped using available typing techniques over a period of more than 10 years (2010–2021). The surveillance showed an overall reduction in the L. pneumophila colonisation rate in municipal systems from 11 to 4.5% following prevention measures during the period, with the highest colonisation rate in complex systems (e.g., larger nursing homes and sports complexes). Further, an approximately even distribution between sg1 and 2–14 was seen. Whole genome sequencing (WGS) revealed that only a limited number of STs were detected, and they were consistent at specific locations over time. This study showed that environmental surveillance data in combination with available typing techniques and WGS can give the municipality a better tool for risk management and an overview of ST distributions that can be a valuable asset in future source investigations. Full article
(This article belongs to the Special Issue Legionella pneumophila)
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17 pages, 1700 KiB  
Article
Compromised Effectiveness of Thermal Inactivation of Legionella pneumophila in Water Heater Sediments and Water, and Influence of the Presence of Vermamoeba vermiformis
by Margot Cazals, Emilie Bédard, Margot Doberva, Sébastien Faucher and Michèle Prévost
Microorganisms 2022, 10(2), 443; https://doi.org/10.3390/microorganisms10020443 - 15 Feb 2022
Cited by 7 | Viewed by 2636
Abstract
Intermittent reduction of temperature set-points and periodic shutdowns of water heaters have been proposed to reduce energy consumption in buildings. However, the consequences of such measures on the occurrence and proliferation of Legionella pneumophila (Lp) in hot water systems have not [...] Read more.
Intermittent reduction of temperature set-points and periodic shutdowns of water heaters have been proposed to reduce energy consumption in buildings. However, the consequences of such measures on the occurrence and proliferation of Legionella pneumophila (Lp) in hot water systems have not been documented. The impact of single and repeated heat shocks was investigated using an environmental strain of L. pneumophila and a reference strain of V. vermiformis. Heat shocks at temperatures ranging from 50 °C to 70 °C were applied for 1 h and 4 h in water and water heaters loose deposits (sludge). The regrowth potential of heat-treated culturable L. pneumophila in presence of V. vermiformis in water heaters sludges was evaluated. A 2.5-log loss of culturability of L. pneumophila was observed in simulated drinking water at 60 °C while a 4-log reduction was reached in water heaters loose deposits. Persistence of Lp after 4 h at 55 °C was shown and the presence of V. vermiformis in water heater’s loose deposits resulted in a drastic amplification (5-log). Results show that thermal inactivation by heat shock is only efficient at elevated temperatures (50 °C) in both water and loose deposits. The few remaining organisms can rapidly proliferate during storage at lower temperature in the presence of hosts. Full article
(This article belongs to the Special Issue Legionella pneumophila)
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9 pages, 433 KiB  
Article
Probabilistic Analysis of a French Legionellosis Outbreak Shows Potential Role of Wastewater Basin
by France Wallet, Leila Fontenay and Pierre-André Cabanes
Microorganisms 2022, 10(2), 422; https://doi.org/10.3390/microorganisms10020422 - 11 Feb 2022
Cited by 3 | Viewed by 1732
Abstract
Based on the data from a French outbreak of legionellosis, a probabilistic approach was developed to analyze and assess the potential role of several suspected sources of contamination. Potential dates of exposure of all cases were determined using back-calculation, using two probability distribution [...] Read more.
Based on the data from a French outbreak of legionellosis, a probabilistic approach was developed to analyze and assess the potential role of several suspected sources of contamination. Potential dates of exposure of all cases were determined using back-calculation, using two probability distribution functions to model incubation period. A probabilistic analysis and risk assessment were then used to determine the most probable sources of contamination for each wave of the outbreak. The risk assessment was based on parameters representing emission and dispersion of Legionella: level and duration of emission; aerosol dispersion capacity; and probability of potential exposure for each patient. Four types of facilities containing the Legionella epidemic strain were analyzed: cooling towers, aerated wastewater basins, high pressure water cleaners, and car wash stations. The results highlighted the potential role of an aerated wastewater basin in the outbreak in addition to cooling towers. The role of high-pressure water cleaners and car wash stations appeared to be non-significant. This study also reveals the lack of knowledge on facility parameters that can be useful for microbial risk assessments. This type of probabilistic analysis can be used to quantitatively assess the risk for various facilities in order to manage a legionellosis outbreak. Full article
(This article belongs to the Special Issue Legionella pneumophila)
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13 pages, 1528 KiB  
Article
Bacterial Antagonistic Species of the Pathogenic Genus Legionella Isolated from Cooling Tower
by Kiran Paranjape, Simon Lévesque and Sébastien P. Faucher
Microorganisms 2022, 10(2), 392; https://doi.org/10.3390/microorganisms10020392 - 8 Feb 2022
Cited by 2 | Viewed by 2243
Abstract
Legionella pneumophila is the causative agent of Legionnaires’ disease, a severe pneumonia. Cooling towers are a major source of large outbreaks of the disease. The growth of L. pneumophila in these habitats is influenced by the resident microbiota. Consequently, the aim of this [...] Read more.
Legionella pneumophila is the causative agent of Legionnaires’ disease, a severe pneumonia. Cooling towers are a major source of large outbreaks of the disease. The growth of L. pneumophila in these habitats is influenced by the resident microbiota. Consequently, the aim of this study was to isolate and characterize bacterial species from cooling towers capable of inhibiting several strains of L. pneumophila and one strain of L. quinlivanii. Two cooling towers were sampled to isolate inhibiting bacterial species. Seven inhibitory isolates were isolated, through serial dilution plating and streaking on agar plates, belonging to seven distinct species. The genomes of these isolates were sequenced to identify potential genetic elements that could explain the inhibitory effect. The results showed that the bacterial isolates were taxonomically diverse and that one of the isolates may be a novel species. Genome analysis showed a high diversity of antimicrobial gene products identified in the genomes of the bacterial isolates. Finally, testing different strains of Legionella demonstrated varying degrees of susceptibility to the antimicrobial activity of the antagonistic species. This may be due to genetic variability between the Legionella strains. The results demonstrate that though cooling towers are breeding grounds for L. pneumophila, the bacteria must contend with various antagonistic species. Potentially, these species could be used to create an inhospitable environment for L. pneumophila, and thus decrease the probability of outbreaks occurring. Full article
(This article belongs to the Special Issue Legionella pneumophila)
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10 pages, 1122 KiB  
Article
Differences in UV-C LED Inactivation of Legionella pneumophila Serogroups in Drinking Water
by Helen Y. Buse, John S. Hall, Gary L. Hunter and James A. Goodrich
Microorganisms 2022, 10(2), 352; https://doi.org/10.3390/microorganisms10020352 - 3 Feb 2022
Cited by 11 | Viewed by 2544
Abstract
Legionella pneumophila (Lp) is an opportunistic pathogen that causes respiratory infections primarily through inhalation of contaminated aerosols. Lp can colonize premise plumbing systems due to favorable growth conditions (e.g., lower disinfectant residual, stagnation, warm temperatures). UV-C light-emitting diodes (UV-C LEDs) are an emerging [...] Read more.
Legionella pneumophila (Lp) is an opportunistic pathogen that causes respiratory infections primarily through inhalation of contaminated aerosols. Lp can colonize premise plumbing systems due to favorable growth conditions (e.g., lower disinfectant residual, stagnation, warm temperatures). UV-C light-emitting diodes (UV-C LEDs) are an emerging water treatment technology and have been shown to effectively inactivate waterborne pathogens. In this study, the inactivation of four Lp strains (three clinical sg1, 4, and 6; and one sg1 drinking water (DW) isolate) was evaluated using a UV-C LED collimated beam at three wavelengths (255, 265, and 280 nm) and six fluence rates (0.5–34 mJ/cm2). Exposure to 255 nm resulted in higher log reductions at the lower fluences compared to exposures at 265 and 280 nm. Efficacy testing was also performed using a UV-C LED point-of-entry (POE) flow-through device. Based on the log inactivation curves, at 255 nm, the sg4 and sg6 clinical isolates were more susceptible to inactivation compared to the two sg1 isolates. However, at 265 and 280 nm, the sg1 and sg4 clinical isolates were more resistant to inactivation compared to the sg6 clinical and sg1 DW isolates. Differential log reductions were also observed using the POE device. Results indicate that although UV-C LED disinfection is effective, variations in Lp inactivation, wavelengths, and technology applications should be considered, especially when targeting specific isolates within premise plumbing systems. Full article
(This article belongs to the Special Issue Legionella pneumophila)
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15 pages, 9234 KiB  
Article
Acute Pneumonia Caused by Clinically Isolated Legionella pneumophila Sg 1, ST 62: Host Responses and Pathologies in Mice
by Jiří Trousil, Lucia Frgelecová, Pavla Kubíčková, Kristína Řeháková, Vladimír Drašar, Jana Matějková, Petr Štěpánek and Oto Pavliš
Microorganisms 2022, 10(1), 179; https://doi.org/10.3390/microorganisms10010179 - 14 Jan 2022
Cited by 1 | Viewed by 2298
Abstract
Legionnaires’ disease is a severe form of lung infection caused by bacteria belonging to the genus Legionella. The disease severity depends on both host immunity and L. pneumophila virulence. The objective of this study was to describe the pathological spectrum of acute [...] Read more.
Legionnaires’ disease is a severe form of lung infection caused by bacteria belonging to the genus Legionella. The disease severity depends on both host immunity and L. pneumophila virulence. The objective of this study was to describe the pathological spectrum of acute pneumonia caused by a virulent clinical isolate of L. pneumophila serogroup 1, sequence type 62. In A/JOlaHsd mice, we compared two infectious doses, namely, 104 and 106 CFU, and their impact on the mouse status, bacterial clearance, lung pathology, and blood count parameters was studied. Acute pneumonia resembling Legionnaires’ disease has been described in detail. Full article
(This article belongs to the Special Issue Legionella pneumophila)
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