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Legionella pneumophila: A Microorganism with a Thousand Faces

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

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 24296

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Dr. Teresa Fasciana

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Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties, University of Palermo, 90133 Palermo, Italy
Interests: Gram positive and negative microorganisms; multi drug resistance; H. pylori; natural components and their antibiofilm actions
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Anna Giammanco

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Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialities, University of Palermo, 90127 Palermo, Italy
Interests: MDR; rapid method of diagnosis; H. pylori; L. pneumophila
Special Issues, Collections and Topics in MDPI journals

Dr. Mario Palermo

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Co-Guest Editor

Sicilian Health Department, Public Health and Environmental Risks Service, 90127 Palermo, Italy
Interests: legionella; sexually transmitted infections; multidrug resistance; epidemiology

Special Issue Information

Dear Colleagues,

Legionella pneumophila is naturally found in fresh water where bacteria parasitize within protozoa. It also lives planctonically in water or biofilms. The pathogenesis of Legionnaires’ disease is largely due to the ability of L. pneumophila to invade and grow within macrophages. In recent times, a prodigious number of bacterial virulence factors which affect the growth of L. pneumophila in both macrophages and protozoa have been recognized. While L. pneumophila replicates within environmental protozoa, colonization and persistence in its natural environment are also mediated by biofilm formation and colonization within multispecies microbial communities. There is now evidence that some legionellosis outbreaks are correlated with the presence of biofilms. Thus, preventing biofilm formation appears as one of the strategies to reduce water system contamination. This Special Issue has the goal to focus on epidemiological data and experimental evidence as well as possible mechanisms of L. pneumophila and host factors involved in Legionnaires’ disease. Finally, it will review the known mechanisms of biofilm formation and old and new anti-biofilm substances.

Dr. Teresa Fasciana
Dr. Anna Giammanco
Guest Editors

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Keywords

Legionella pneumophila
virulence factors
biofilm
disinfection strategy

Published Papers (9 papers)

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Editorial

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4 pages, 209 KiB

Open AccessEditorial

Editorial: Special Issue: “Legionella pneumophila: A Microorganism with a Thousand Faces”

by Teresa Fasciana, Mario Palermo, Ignazio Arrigo, Maria Rita Tricoli, Orazia Diquattro and Anna Giammanco

Microorganisms 2023, 11(10), 2392; https://doi.org/10.3390/microorganisms11102392 - 25 Sep 2023

Viewed by 813

Abstract

Legionella pneumophila is a microorganism that is able to contaminate the freshwater environment and, consequently, human-made water systems [...] Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

Research

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12 pages, 2154 KiB

Open AccessArticle

Innovative Antibiofilm Smart Surface against Legionella for Water Systems

by Simona Filice, Emanuele Luigi Sciuto, Silvia Scalese, Giuseppina Faro, Sebania Libertino, Domenico Corso, Rosario Manuel Timpanaro, Pasqualina Laganà and Maria Anna Coniglio

Microorganisms 2022, 10(5), 870; https://doi.org/10.3390/microorganisms10050870 - 21 Apr 2022

Cited by 10 | Viewed by 2012

Abstract

Legionella pneumophila contamination of water systems is a crucial issue for public health. The pathogen is able to persist in water as free-living planktonic bacteria or to grow within biofilms that adhere to and clog filters and pipes in a water system, reducing its lifespan and, in the case of hospital buildings, increasing the risk of nosocomial infections. The implementation of water management is considered to be the main prevention measure and can be achieved from the optimization of water system architecture, notably introducing new materials and strategies to contrast Legionella biofilm proliferation and so prolong the water system functionality. In this research, we propose a new smart surface against L. pneumophila biofilm formation. This is based on an innovative type of coating consisting of a sulfonated pentablock copolymer (s-PBC, commercially named Nexar™) deposited on top of a polypropylene (PP) coupon in a sandwich filter model. The covering of PP with s-PBC results in a more hydrophilic, acid, and negatively charged surface that induces microbial physiological inhibition thereby preventing adhesion and/or proliferation attempts of L. pneumophila prior to the biofilm formation. The antibiofilm property has been investigated by a Zone of Inhibition test and an in vitro biofilm formation analysis. Filtration tests have been performed as representative of possible applications for s-PBC coating. Results are reported and discussed. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

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9 pages, 780 KiB

Open AccessArticle

Four-Year Environmental Surveillance Program of Legionella spp. in One of Palermo’s Largest Hospitals

by Ignazio Arrigo, Elena Galia, Teresa Fasciana, Orazia Diquattro, Maria Rita Tricoli, Nicola Serra, Mario Palermo and Anna Giammanco

Microorganisms 2022, 10(4), 764; https://doi.org/10.3390/microorganisms10040764 - 01 Apr 2022

Cited by 9 | Viewed by 2276

Abstract

Legionella is a ubiquitous bacterium that lives in freshwater environments and colonizes human-made water systems. Legionella pneumophila is the most virulent species, and risk factors for Legionnaires’ disease include increasing age, smoking, chronic diseases, and immunodeficiency. For this reason, it is very important to assess and monitor hospital water systems in order to prevent legionellosis. We have monitored a large hospital in Palermo for four years. To determine the presence of microorganisms, according to national guidelines, we used the culture method, which is considered the gold standard for Legionella detection. Sampling was divided into five macro-areas, and a total of 251 samples were collected during the period of investigation, 49% of which were Legionella spp.-positive and 51% were Legionella spp.-negative. Positive samples with L. pneumophila. sgr 2-15 were most frequent in the Underground (55.6%, p = 0.0184), Medicine (42.9%, p = 0.0184) and Other (63.2%, p = 0.002) areas; while positive samples for L. pneumophila sgr 1 were less frequent in the Underground (0.0%, p = 0.0184) and Surgery areas (4.5%, p = 0.033), and for Legionella anisa, were less frequent in the Medicine (4.1%, p = 0.021), Oncohematology (0.0%, p = 0.0282), and Other (0.0%, p = 0.016) areas. Finally, no significant differences were observed among the areas for each isolate considered. The surveillance carried out in these years demonstrates the importance of monitoring, which allows us to analyze the conditions of hospital facilities and, therefore, prevent Legionella spp. infections. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

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18 pages, 20019 KiB

Open AccessArticle

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

by William J. Rhoads, Meril Sindelar, Céline Margot, Nadine Graf and Frederik Hammes

Microorganisms 2022, 10(3), 555; https://doi.org/10.3390/microorganisms10030555 - 03 Mar 2022

Cited by 15 | Viewed by 3882

Abstract

When stay-at-home orders were issued to slow the spread of COVID-19, building occupancy (and water demand) was drastically decreased in many buildings. There was concern that widespread low water demand may cause unprecedented Legionella occurrence and Legionnaires’ disease incidence. In lieu of evidenced-based guidance, many people flushed their water systems as a preventative measure, using highly variable practices. Here, we present field-scale research from a building before, during, and after periods of low occupancy, and controlled stagnation experiments. We document no change, a > 4-log increase, and a > 1.5-log decrease of L. pneumophila during 3- to 7-week periods of low water demand. L. pneumophila increased by > 1-log after precautionary flushing prior to reoccupancy, which was repeated in controlled boiler flushing experiments. These results demonstrate that the impact of low water demand (colloquially called stagnation) is not as straight forward as is generally assumed, and that some flushing practices have potential unintended consequences. In particular, stagnation must be considered in context with other Legionella growth factors like temperature and flow profiles. Boiler flushing practices that dramatically increase the flow rate and rapidly deplete boiler temperature may mobilize Legionella present in biofilms and sediment. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

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16 pages, 605 KiB

Open AccessArticle

Water Age Effects on the Occurrence and Concentration of Legionella Species in the Distribution System, Premise Plumbing, and the Cooling Towers

by Alshae R. Logan-Jackson and Joan B. Rose

Microorganisms 2022, 10(1), 81; https://doi.org/10.3390/microorganisms10010081 - 31 Dec 2021

Cited by 12 | Viewed by 3520

Abstract

In this study, droplet digital PCR^TM (ddPCR^TM) was used to characterize total Legionella spp. and five specific Legionella species from source (groundwater) to exposure sites (taps and cooling towers). A total of 42–10 L volume water samples were analyzed during this study: 12 from a reservoir (untreated groundwater and treated water storage tanks), 24 from two buildings (influents and taps), and six from cooling towers, all part of the same water system. The approximate water age (time in the system) for all sample locations are as follows: ~4.5, 3.4, 9.2, 20.8, and 23.2 h (h) for the groundwater to the reservoir influent, reservoir influent to the reservoir effluent, reservoir effluent to building Fa (building names are abbreviated to protect the privacy of site location), building ERC and the cooling towers, respectively. Results demonstrated that gene copies of Legionella spp. (23S rRNA) were significantly higher in the cooling towers and ERC building (p < 0.05) relative to the reservoir and building Fa (closest to reservoir). Legionella spp. (23S rRNA) were found in 100% (42/42) of water samples at concentrations ranging from 2.2 to 4.5 Log10 GC/100 mL. More specifically, L. pneumophila was found in 57% (24/42) of the water samples, followed by L. bozemanii 52% (22/42), L. longbeachae 36% (15/42), L. micdadei 23% (10/42) and L. anisa 21% (9/42) with geometric mean concentrations of 1.7, 1.7, 1.4, 1.6 and 1.7 Log₁₀ GC/100 mL, respectively. Based on this study, it is hypothesized that water age in the distribution system and the premise-plumbing system as well as building management plays a major role in the increase of Legionella spp., (23S rRNA) and the diversity of pathogenic species found as seen in the influent, and at the taps in the ERC building—where the building water quality was most comparable to the industrial cooling towers. Other pathogenic Legionella species besides L.pneumophila are also likely amplifying in the system; thus, it is important to consider other disease relevant species in the whole water supply system—to subsequently control the growth of pathogenic Legionella in the built water environment. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

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Review

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20 pages, 2101 KiB

Open AccessReview

SARS-CoV-2–Legionella Co-Infections: A Systematic Review and Meta-Analysis (2020–2021)

by Matteo Riccò, Pietro Ferraro, Simona Peruzzi, Alessandro Zaniboni and Silvia Ranzieri

Microorganisms 2022, 10(3), 499; https://doi.org/10.3390/microorganisms10030499 - 23 Feb 2022

Cited by 11 | Viewed by 2176

Abstract

Legionnaires’ Disease (LD) is a severe, sometimes fatal interstitial pneumonia due to Legionella pneumophila. Since the inception of the SARS-CoV-2 pandemic, some contradictory reports about the effects of lockdown measures on its epidemiology have been published, but no summary evidence has been collected to date. Therefore, we searched two different databases (PubMed and EMBASE) focusing on studies that reported the occurrence of LD among SARS-CoV-2 cases. Data were extracted using a standardized assessment form, and the results of such analyses were systematically reported, summarized, and compared. We identified a total of 38 articles, including 27 observational studies (either prospective or retrospective ones), 10 case reports, and 1 case series. Overall, data on 10,936 SARS-CoV-2 cases were included in the analyses. Of them, 5035 (46.0%) were tested for Legionella either through urinary antigen test or PCR, with 18 positive cases (0.4%). A pooled prevalence of 0.288% (95% Confidence Interval (95% CI) 0.129–0.641), was eventually calculated. Moreover, detailed data on 19 co-infections LD + SARS-CoV-2 were obtained (males: 84.2%; mean age: 61.9 years, range 35 to 83; 78.9% with 1 or more underlying comorbidities), including 16 (84.2%) admissions to the ICU, with a Case Fatality Ratio of 26.3%. In summary, our analyses suggest that the occurrence of SARS-CoV-2–Legionella infections may represent a relatively rare but not irrelevant event, and incident cases are characterized by a dismal prognosis. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

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19 pages, 339 KiB

Open AccessReview

Legionella Occurrence beyond Cooling Towers and Premise Plumbing

by David Otto Schwake, Absar Alum and Morteza Abbaszadegan

Microorganisms 2021, 9(12), 2543; https://doi.org/10.3390/microorganisms9122543 - 09 Dec 2021

Cited by 12 | Viewed by 3041

Abstract

Legionella is an environmental pathogen that is responsible for respiratory disease and is a common causative agent of water-related outbreaks. Due to their ability to survive in a broad range of environments, transmission of legionellosis is possible from a variety of sources. Unfortunately, a disproportionate amount of research that is devoted to studying the occurrence of Legionella in environmental reservoirs is aimed toward cooling towers and premise plumbing. As confirmed transmission of Legionella has been linked to many other sources, an over-emphasis on the most common sources may be detrimental to increasing understanding of the spread of legionellosis. This review aims to address this issue by cataloguing studies which have examined the occurrence of Legionella in less commonly investigated environments. By summarizing and discussing reports of Legionella in fresh water, ground water, saltwater, and distribution system drinking water, future environmental and public health researchers will have a resource to aid in investigating these pathogens in relevant sources. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

21 pages, 4593 KiB

Open AccessReview

Epidemiology of Legionnaires’ Disease in Italy, 2004–2019: A Summary of Available Evidence

by Matteo Riccò, Simona Peruzzi, Silvia Ranzieri and Pasquale Gianluca Giuri

Microorganisms 2021, 9(11), 2180; https://doi.org/10.3390/microorganisms9112180 - 20 Oct 2021

Cited by 10 | Viewed by 2441

Abstract

Legionnaires’ disease (LD) incidence has been increasing in several European countries since 2011. Currently, Italy is experiencing high notification rates for LD, whose cause still remains scarcely understood. We sought to summarize the available evidence on the epidemiology of LD in Italy (2004–2019), characterizing the risk of LD by region, sex, age group, and settings of the case (i.e., community, healthcare, or travel-associated cases). Environmental factors (e.g., average air temperatures and relative humidity) were also included in a Poisson regression model in order to assess their potential role on the annual incidence of new LD cases. National surveillance data included a total of 23,554 LD cases occurring between 2004 and 2019 (70.4% of them were of male gender, 94.1% were aged 40 years and older), with age-adjusted incidence rates increasing from 1.053 cases per 100,000 in 2004 to 4.559 per 100,000 in 2019. The majority of incident cases came from northern Italy (43.2% from northwestern Italy, 25.6% from northeastern Italy). Of these, 5.9% were healthcare-related, and 21.1% were travel-associated. A case-fatality ratio of 5.2% was calculated for the whole of the assessed timeframe, with a pooled estimate for mortality of 0.122 events per 100,000 population per year. Poisson regression analysis was associated with conflicting results, as any increase in average air temperature resulted in reduced risk for LD cases (Incidence Rate Ratio [IRR] 0.807, 95% Confidence Interval [95% CI] 0.744–0.874), while higher annual income in older individuals was associated with an increased IRR (1.238, 95% CI 1.134–1.351). The relative differences in incidence between Italian regions could not be explained by demographic factors (i.e., age and sex distribution of the population), and also a critical reappraisal of environmental factors failed to substantiate both the varying incidence across the country and the decennial trend we were able to identify. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

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Other

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17 pages, 626 KiB

Open AccessSystematic Review

Knowledge to Predict Pathogens: Legionella pneumophila Lifecycle Systematic Review Part II Growth within and Egress from a Host Cell

by Alexis L. Mraz and Mark H. Weir

Microorganisms 2022, 10(1), 141; https://doi.org/10.3390/microorganisms10010141 - 11 Jan 2022

Cited by 6 | Viewed by 2366

Abstract

Legionella pneumophila (L. pneumophila) is a pathogenic bacterium of increasing concern, due to its ability to cause a severe pneumonia, Legionnaires’ Disease (LD), and the challenges in controlling the bacteria within premise plumbing systems. L. pneumophila can thrive within the biofilm of premise plumbing systems, utilizing protozoan hosts for protection from environmental stressors and to increase its growth rate, which increases the bacteria’s infectivity to human host cells. Typical disinfectant techniques have proven to be inadequate in controlling L. pneumophila in the premise plumbing system, exposing users to LD risks. As the bacteria have limited infectivity to human macrophages without replicating within a host protozoan cell, the replication within, and egress from, a protozoan host cell is an integral part of the bacteria’s lifecycle. While there is a great deal of information regarding how L. pneumophila interacts with protozoa, the ability to use this data in a model to attempt to predict a concentration of L. pneumophila in a water system is not known. This systematic review summarizes the information in the literature regarding L. pneumophila’s growth within and egress from the host cell, summarizes the genes which affect these processes, and calculates how oxidative stress can downregulate those genes. Full article

(This article belongs to the Special Issue Legionella pneumophila: A Microorganism with a Thousand Faces)

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