Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems

Nisar, Muhammad Atif; Ross, Kirstin; Brown, Melissa H.; Bentham, Richard; Whiley, Harriet

doi:10.3390/pathogens9040286

Cited by 37 publications

(35 citation statements)

References 107 publications

(103 reference statements)

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“…Although the study of Legionella is still very recent (the disease raised up around the last quarter of the 20th century) [22], some aspects seem to consistently characterize and be relevant for Legionella prevalence in water systems and for further infection in human beings [35]. Legionellosis has been linked to different water systems, such as cooling towers (CT) [36,37], hospital [38,39] and hotel [40,41], water supply lines, or whirlpool spas [42,43].…”

Section: Common Roots Of Research From Legionella Field-based Studiesmentioning

confidence: 99%

“…Apart from the complex and often unknown architectures of interconnected pipelines, equipment, pumps, and other hydraulic settings [35] that can potentially disseminate the bacteria by aerosolization, they also have very diverse conditions of the system. Warm temperatures, hydrodynamic patterns (specially stagnation) [35], water quality (pH and hardness) [44][45][46][47], corrosion and scaling (as nutrient sources) [48], and surface materials [49,50] have been linked to Legionella prevalence. Additionally, biocidal programs that are not properly set or managed may promote Legionella colonization in several installations [51][52][53][54].…”

Section: Common Roots Of Research From Legionella Field-based Studiesmentioning

confidence: 99%

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Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

2021

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Legionella is responsible for the life-threatening pneumonia commonly known as Legionnaires’ disease or legionellosis. Legionellosis is known to be preventable if proper measures are put into practice. Despite the efforts to improve preventive approaches, Legionella control remains one of the most challenging issues in the water treatment industry. Legionellosis incidence is on the rise and is expected to keep increasing as global challenges become a reality. This puts great emphasis on prevention, which must be grounded in strengthened Legionella management practices. Herein, an overview of field-based studies (the system as a test rig) is provided to unravel the common roots of research and the main contributions to Legionella’s understanding. The perpetuation of a water-focused monitoring approach and the importance of protozoa and biofilms will then be discussed as bottom-line questions for reliable Legionella real-field surveillance. Finally, an integrated monitoring model is proposed to study and control Legionella in water systems by combining discrete and continuous information about water and biofilm. Although the successful implementation of such a model requires a broader discussion across the scientific community and practitioners, this might be a starting point to build more consistent Legionella management strategies that can effectively mitigate legionellosis risks by reinforcing a pro-active Legionella prevention philosophy.

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Section: Common Roots Of Research From Legionella Field-based Studiesmentioning

confidence: 99%

Section: Common Roots Of Research From Legionella Field-based Studiesmentioning

confidence: 99%

Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

2021

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“…In the USA, the reported cases of Legionnaires’ disease increased from 2.301 in 2005 to 7.104 in 2018. In Europe, the number of known cases of Legionnaires’ disease has almost doubled (from 1.3/100,000 people in 2014 to 2.3/100,000 people in 2018) [ 94 ]. The increase in cases may be related to the changing environmental conditions, which favour the growth of Legionella bacteria, as well as the increasing number of people susceptible to infection, such as the elderly and immunocompromised subjects.…”

Section: Structure and Significance Of Legionella mentioning

confidence: 99%

The Role of Lipids in Legionella-Host Interaction

Kowalczyk

Chmiel

Palusińska-Szysz

2021

IJMS

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Legionella are Gram-stain-negative rods associated with water environments: either natural or man-made systems. The inhalation of aerosols containing Legionella bacteria leads to the development of a severe pneumonia termed Legionnaires’ disease. To establish an infection, these bacteria adapt to growth in the hostile environment of the host through the unusual structures of macromolecules that build the cell surface. The outer membrane of the cell envelope is a lipid bilayer with an asymmetric composition mostly of phospholipids in the inner leaflet and lipopolysaccharides (LPS) in the outer leaflet. The major membrane-forming phospholipid of Legionella spp. is phosphatidylcholine (PC)—a typical eukaryotic glycerophospholipid. PC synthesis in Legionella cells occurs via two independent pathways: the N-methylation (Pmt) pathway and the Pcs pathway. The utilisation of exogenous choline by Legionella spp. leads to changes in the composition of lipids and proteins, which influences the physicochemical properties of the cell surface. This phenotypic plasticity of the Legionella cell envelope determines the mode of interaction with the macrophages, which results in a decrease in the production of proinflammatory cytokines and modulates the interaction with antimicrobial peptides and proteins. The surface-exposed O-chain of Legionella pneumophila sg1 LPS consisting of a homopolymer of 5-acetamidino-7-acetamido-8-O-acetyl-3,5,7,9-tetradeoxy-l-glycero-d-galacto-non-2-ulosonic acid is probably the first component in contact with the host cell that anchors the bacteria in the host membrane. Unusual in terms of the structure and function of individual LPS regions, it makes an important contribution to the antigenicity and pathogenicity of Legionella bacteria.

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“…Several factors that enhance the colonization of Legionella bacteria in the water systems include lukewarm water temperature, obstruction and stagnation of water flow, plumbing materials, biofilm formation and presence of amoeba, which support the growth of Legionella sp. These risk factors are commonly present in the water distribution system of antiquated buildings, especially in old hospitals [30] . In fact, half of the sporadic cases of hospital-acquired pneumonia are attributed to Legionella bacteria, where patients are infected via inhalation of Legionella sp.…”

Section: Sources Of Legionella Bacteriamentioning

confidence: 99%

Legionella pneumophila — The causative agent of Legionnaires’ disease

Tan¹,

Tee²,

Khan³

et al. 2021

Prog Micobes Mol Biol

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Over the years, Legionella pneumophila has increasingly become a public health threat that causes sporadic and epidemic community-acquired and nosocomial-acquired pneumonia. Thus, this review aims to discuss the current knowledge of L. pneumophila, focusing on the global epidemiology, clinical features, diagnosis and treatment of Legionnaires’ disease (LD). Legionella bacteria are Gram-negative rod-shaped bacteria that are ubiquitous in aquatic environments. L. pneumophila was first discovered in 1976 and recognized as the causative agent of LD. L. pneumophila is a facultative intracellular pathogen that infects and replicates within eukaryotic host cells such as macrophages and protozoan. Diagnosis of LD remains a significant challenge as the clinical manifestation of LD is hardly distinguishable from pneumonia caused by other respiratory pathogens. Therefore, early testing and appropriate treatment are keys to alleviating the rising morbidity and mortality caused by LD.

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Legionella pneumophila and Protozoan Hosts: Implications for the Control of Hospital and Potable Water Systems

Cited by 37 publications

References 107 publications

Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

The Role of Lipids in Legionella-Host Interaction

Legionella pneumophila — The causative agent of Legionnaires’ disease

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