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Legionnaires disease is a serious pneumonia caused by Legionella bacteria. During November 2022-June 2024, CDC was notified of 12 cases of Legionnaires disease among travelers on two cruise ships; eight on cruise ship A and four on cruise ship B. CDC, in collaboration with the cruise lines, initiated investigations to ascertain the potential sources of on-board exposure after notification of the second potentially associated case for each ship. Epidemiologic data collected from patient interviews and environmental assessment and sampling results identified private hot tubs on selected cabin balconies as the most likely exposure source. To minimize Legionella growth, both cruise lines modified the operation and maintenance of these devices by removing the heating elements, draining water between uses, and increasing the frequency of hyperchlorination and cleaning. Hot tubs offer favorable conditions for Legionella growth and transmission when maintained and operated inadequately, regardless of location. Private hot tubs on cruise ships are not subject to the same maintenance requirements as are public hot tubs in common areas. Given the range of hot tub-type devices offered as amenities across the cruise industry, to reduce risk for Legionella growth and transmission, it is important for cruise ship water management program staff members to inventory and assess private balcony hot tubs and adapt public hot tub maintenance and operations protocols for use on private outdoor hot tubs. [ABSTRACT FROM AUTHOR]

Introduction: Legionnaires' disease is a severe pneumonia predominantly caused by Legionella pneumophila (Lp), whose major reservoirs are artificial water systems. As most human infections are caused by L. pneumophila serogroup 1 (Lp1), a reliable method for Lp distinction can be crucial for bacterial spread prevention. As the ability to withstand in environments and to cause the waterborne disease is strongly related to specific genes, the identification of virulent strains can be of great relevance to implement water environmental monitoring and to contain harmful outbreaks to public health. We aimed to test an assay for Lp identification among different Legionella species, and to determine the serogroups. Additionally, we investigated the carriage of virulence and antimicrobial resistance genes. Methods: A total of 90 Legionella spp. isolates identified by phenotypic tests were subjected to the designed quantitative PCR assay targeting specific mip for Lp, wzm for Lp1, pvcA and ahpD for biofilm production. Eleven serogroups were investigated in all our isolates tested positive for mip gene, subsequently analyzed for 12 virulence and 8 antimicrobial resistance genes. Results: Only the 70 Lp isolates were positive for mip. Out of 27 Lp isolates belonging to serogroup 1 based on agglutination test, 23 (85.2%) carried wzm. The presence of ahpD and pvcA was found in 94.3 and 98.6% of Lp isolates, respectively. By multiplex PCR, all 23 wzm-positive strains were confirmed as serogroup 1 that was the most predominant (33%). At least one virulence gene was detected in all Lp isolates. The most frequent gene was ispE (100%), followed by issD (96%), icmK and enhC (93%), cpxA (91%), rtxA2 (74%), lvhB8-B9 (61%), and prpA (54%). The other genes were less diffused in Lp strains (rtxA1, 44%; lvhB3-B4, 47%; pvcB, 27%; lvrE, 24%). Of the macrolide resistance genes, the ereA was found in 84% of Lp strains, while only 14 (20%) harbored the lpeAB among the efflux pump genes. Conclusion: The assays validated in this study enable the simultaneous Lp and Lp1 detection. The differentiation of Lp strains according to their virulence properties could be useful to predict the bacterial ability to survive and to cause the disease. [ABSTRACT FROM AUTHOR]

Background: The incidence of Legionnaires' disease (LD) is increasing steadily in Europe. Its early diagnosis by general practitioners (GPs) is crucial for better patient outcomes. Study objectives: This study assessed Belgian GPs' knowledge about LD and the accessibility of diagnostic tests in their practices. Methods: A specifically designed questionnaire was distributed to actively practicing GPs, including primary care trainees, between 31 January 2022 and 13 March 2022. This survey targeted approximately 4200 GPs with an estimated population catchment of 30% of the actively working Belgian GPs. Results: The response rate was estimated at 3%. Over 70% of the GPs correctly identified the LD occurrence peak, major risk factors, and clinical manifestations. While 62% of participants preferred the Legionella pneumophila urinary antigen test (UAT) as a primary diagnostic method, 75% were unsure about its availability within their laboratories and 82% had not prescribed it in the last year. Finally, 76% expressed a desire for additional information on this topic. Conclusions: Belgian GPs should evaluate the possibility of conducting UAT testing in their laboratories to enhance LD case management and improve their preparedness. Furthermore, initiatives should be implemented to improve communication between specialists and GPs and develop educational programs directed at Belgian GPs. [ABSTRACT FROM AUTHOR]

Legionella is an underdiagnosed and underreported etiology of pneumonia. Legionella pneumophila serogroup 1 (LpSG1) is thought to be the most common pathogenic subgroup. This assumption is based on the frequent use of a urinary antigen test (UAT), only capable of diagnosing LpSG1. We aimed to explore the frequency of Legionella infections in individuals diagnosed with pneumonia and the performance of diagnostic methods for detecting Legionella infections. We conducted a scoping review to answer the following questions: (1) "Does nucleic acid testing (NAT) increase the detection of non-pneumophila serogroup 1 Legionella compared to non-NAT?"; and (2) "Does being immunocompromised increase the frequency of pneumonia caused by non-pneumophila serogroup 1 Legionella compared to non-immunocompromised individuals with Legionnaires' disease (LD)?". Articles reporting various diagnostic methods (both NAT and non-NAT) for pneumonia were extracted from several databases. Of the 3449 articles obtained, 31 were included in our review. The most common species were found to be L. pneumophila, L. longbeachae, and unidentified Legionella species appearing in 1.4%, 0.9%, and 0.6% of pneumonia cases. Nearly 50% of cases were caused by unspecified species or serogroups not detected by the standard UAT. NAT-based techniques were more likely to detect Legionella than non-NAT-based techniques. The identification and detection of Legionella and serogroups other than serogroup 1 is hampered by a lack of application of broader pan-Legionella or pan-serogroup diagnostics. [ABSTRACT FROM AUTHOR]

Legionella contamination in public water systems poses significant health risks, particularly in schools where vulnerable populations, including children, regularly use these facilities. This study investigates the presence of Legionella in the hot water systems from 49 primary schools across two municipalities in the Danish capital region. Water samples were collected from taps in each school, and both first-flush and stabile temperature samples were analysed for Legionella contents. The findings revealed that 97% of schools in Municipality 1 and 100% in Municipality 2 had Legionella in their hot water systems. The content of Legionella colonies was significantly higher in schools in Municipality 1, which was probably because of overall lower water temperatures. At stabile temperatures, 76% and 50% of the schools in the two municipalities exceeded the European Union's recommended limit of 1000 CFU/L. Stabile peripheral water temperatures were achieved after 3 min. Tap water temperatures above 54 °C and central tank temperatures above 59 °C were associated with Legionella contents below 1000 CFU/L. This study highlights the need for more stringent Legionella control procedures in schools, including higher water temperatures and refining Legionella reducing interventions with the addition of regular flow and draining procedures. [ABSTRACT FROM AUTHOR]

This study investigates the utility of Google Trends and Google Search data in retrospectively analyzing the Flint Water Crisis, a significant public health event. By examining keywords relevant to the crisis, such as "lead," "bottled water," "water filters," "pneumonia," and "Legionnaires' Disease," we aimed to uncover patterns in public awareness and response during a public crisis and explore how such awareness and responses could potentially aid in reducing the risk of similar crises in the future. Our analysis reveals a clear correlation between search frequencies and the crisis timeline, with spikes in search terms corresponding to key events. This suggests that such data can serve as a valuable tool for understanding public sentiment and behavior in the face of environmental disasters. The research underscores the potential of "Big Data," led by search engines and social media platforms, in shaping public policy and informed decision-making. However, it also addresses the limitations and challenges in using these data sources, including issues of data consistency, replicability, and the influence of sociocultural contexts on search behaviors. The study advocates for the combined use of Google Trends and Google Search data, complemented by other datasets, for a more comprehensive understanding of public engagement in environmental crises. This work contributes to the growing field of infodemiology, emphasizing the importance of big data analysis in environmental science and public health research. [ABSTRACT FROM AUTHOR]

Legionella infection, the causative agent of Legionnaires' disease, represents a significant threat to human health. The pathogenesis of this infection is intricately linked to the complex interactions between the bacterium and its host, resulting in profound metabolic perturbations. Central to these metabolic shifts is the bacterium's modulation of lipid metabolism, with changes in lipid synthesis and breakdown modifying membrane composition and function. These alterations can influence cellular signaling and immune responses, further contributing to disease progression. It also disrupts glucose utilization and lipid metabolism, altering cellular energy production and immune responses. Additionally, Legionella infection perturbs amino acid and protein metabolism, affecting protein synthesis and degradation, leading to changes in cellular functions and immune responses. This mini-review underscores the complexity of metabolic perturbations in Legionella infection and their significance in host-pathogen interactions. Understanding these metabolic shifts provides valuable insights into the pathogenesis of Legionnaires' disease and could lead to the development of novel therapeutic strategies. [ABSTRACT FROM AUTHOR]

Legionella longbeachae and Legionella pneumophila are the most common causative agents of Legionnaires' disease. While the clinical manifestations caused by both species are similar, species-specific differences exist in environmental niches, disease epidemiology, and genomic content. One such difference is the presence of a genomic locus predicted to encode a capsule. Here, we show that L. longbeachae indeed expresses a capsule in post-exponential growth phase as evidenced by electron microscopy analyses, and that capsule expression is abrogated when deleting a capsule transporter gene. Capsule purification and its analysis via HLPC revealed the presence of a highly anionic polysaccharide that is absent in the capsule mutant. The capsule is important for replication and virulence in vivo in a mouse model of infection and in the natural host Acanthamoeba castellanii. It has anti-phagocytic function when encountering innate immune cells such as human macrophages and it is involved in the low cytokine responses in mice and in human monocyte derived macrophages, thus dampening the innate immune response. Thus, the here characterized L. longbeachae capsule is a novel virulence factor, unique among the known Legionella species, which may aid L. longbeachae to survive in its specific niches and which partly confers L. longbeachae its unique infection characteristics. Author summary: Legionella longbeachae can cause a severe pneumonia, known as Legionnaires' disease. In Australia and New Zealand, L. longbeachae is the predominant species causing up to 50% of all infections due to Legionella. However, L. longbeachae virulence factors are nearly unknown. Here, we show that L. longbeachae expresses a capsule that is a major virulence factor of this pathogen as it is important for virulence in vivo in mice and in the environment in its natural host Acanthamoeba castellanii. It dampens the innate immune response in mice and human cells. Our study sheds light on an understudied environmental pathogen and identifies a new virulence feature of Legionellae. [ABSTRACT FROM AUTHOR]

The accidental human pathogen Legionella pneumophila (Lp) is the etiological agent for a severe atypical pneumonia known as Legionnaires' disease. In human infections and animal models of disease alveolar macrophages are the primary cellular niche that supports bacterial replication within a unique intracellular membrane-bound organelle. The Dot/Icm apparatus—a type IV secretion system that translocates ~300 bacterial proteins within the cytosol of the infected cell—is a central virulence factor required for intracellular growth. Mutant strains lacking functional Dot/Icm apparatus are transported to and degraded within the lysosomes of infected macrophages. The early foundational work from Dr. Horwitz's group unequivocally established that Legionella does not replicate extracellularly during infection—a phenomenon well supported by experimental evidence for four decades. Our data challenges this paradigm by demonstrating that macrophages and monocytes provide the necessary nutrients and support robust Legionella extracellular replication. We show that the previously reported lack of Lp extracellular replication is not a bacteria intrinsic feature but rather a result of robust restriction by serum-derived nutritional immunity factors. Specifically, the host iron-sequestering protein Transferrin is identified here as a critical suppressor of Lp extracellular replication in an iron-dependent manner. In iron-overload conditions or in the absence of Transferrin, Lp bypasses growth restriction by IFNγ-primed macrophages though extracellular replication. It is well established that certain risk factors associated with development of Legionnaires' disease, such as smoking, produce a chronic pulmonary environment of iron-overload. Our work indicates that iron-overload could be an important determinant of severe infection by allowing Lp to overcome nutritional immunity and replicate extracellularly, which in turn would circumvent intracellular cell intrinsic host defenses. Thus, we provide evidence for nutritional immunity as a key underappreciated host defense mechanism in Legionella pathogenesis. In this work, authors indicate a cooperation between nutritional immunity and interferon limits Legionella replication during infection and compromised nutritional immunity may increase severity by allowing the bacteria to replicate outside of host cells. [ABSTRACT FROM AUTHOR]

Legionella longbeachae is the leading cause of Legionnaires' disease (LD) in Australasia and has been linked to exposure to compost and potting soils. Adding antimicrobial metal ions such as copper (Cu2+), zinc (Zn2+), and manganese (Mn2+) to potting soils may reduce the load of L. longbeachae bacteria and infection risk. Baseline concentrations of metal ions in leachate from peat, bark dust, bagging base, and an all-purpose potting soil were: iron 0.40–0.99 µg/ml, Cu of 0.003–0.03 µg/ml, Zn 0.01–0.06 µg/ml and Mn 0.11–0.29 µg/ml. Addition of Cu2+ ions to leachate reduced L. longbeachae viability in a concentration dependent manner. A similar effect was seen in potting soil with Zn2+ and Mn2+ but 10-fold higher concentrations were needed. These metal ions have potential to reduce the load of L. longbeachae in potting soils but toxicity in plants needs to be determined. [ABSTRACT FROM AUTHOR]

We retrospectively reviewed 64 cases of cancer with pulmonary legionellosis (Legionella pneumophila in 73%). Nearly all patients received Legionella -active antibiotics, yet 30-day mortality was 23%. Independent predictors of 30-day mortality were hyponatremia, bilateral lung involvement, and Sequential Organ Failure Assessment score ≥5. Lung coinfections were common (31%) but did not significantly increase mortality. [ABSTRACT FROM AUTHOR]

The pandemic marked the beginning of an era of dynamic and rapid changes in the diagnosis of respiratory infections. Herein we describe Legionnaires' disease trend in the years 2016–2023 in a large Italian hospital showing how improvements in diagnostic algorithms impact on its detection. [ABSTRACT FROM AUTHOR]

Abstract The pandemic marked the beginning of an era of dynamic and rapid changes in the diagnosis of respiratory infections. Herein we describe Legionnaires’ disease trend in the years 2016–2023 in a large Italian hospital showing how improvements in diagnostic algorithms impact on its detection.

Legionella pneumophila, the bacteria responsible for Legionnaires' disease, is able to evade the host's defense mechanisms by modifying the ubiquitin landscape on the Legionella-containing vacuole (LCV). Two recent studies published in Nature Communications have revealed the cooperative action between two Legionella effectors, Sdc and Sde, in decorating the LCV with mixed ubiquitin chains. These modifications prevent the recognition of the LCV by autophagy receptors, allowing Legionella to establish a replicative niche within host cells. The findings highlight the sophisticated strategies employed by Legionella to manipulate the host ubiquitin system and evade autophagic clearance. Further research is needed to understand the temporal and spatial regulation of these effectors and their interplay with other bacterial effectors. The discovery of this mechanism opens up new avenues for studying host-pathogen interactions and developing therapeutic strategies against infections. [Extracted from the article]

Legionella pneumophila is ubiquitous and sporadically infects humans causing Legionnaire's disease (LD). Globally, reported cases of LD have risen fourfold from 2000 to 2014. In 2016, Sydney, Australia was the epicenter of an outbreak caused by L. pneumophila serogroup 1 (Lpsg1). Whole-genome sequencing was instrumental in identifying the causal clone which was found in multiple locations across the city. This study examined the epidemiology of Lpsg1 in an urban environment, assessed typing schemes to classify resident clones, and investigated the association between local climate variables and LD outbreaks. Of 223 local Lpsg1 isolates, we identified dominant clones with one clone isolated from patients in high frequency during outbreak investigations. The core genome multi-locus sequence typing scheme was the most reliable in identifying this Lpsg1 clone. While an increase in humidity and rainfall was found to coincide with a rise in LD cases, the incidence of the major L. pneumophila outbreak clone did not link to weather phenomena. These findings demonstrated the role of high-resolution typing and weather context assessment in determining source attribution for LD outbreaks in urban settings, particularly when clinical isolates remain scarce. [ABSTRACT FROM AUTHOR]

Legionella is the pathogen that causes Legionnaires' disease, an increasingly prevalent and sometimes fatal disease worldwide. In 2021, 97% of cases in Europe were caused by Legionella pneumophila. We present a mathematical model that can be used by public health officials to assess the effectiveness and efficiency of different Legionella monitoring and control strategies to inform government requirements to prevent community-acquired Legionnaires' disease in non-hospital buildings. This simulation model was built using comprehensive data from multiple scientific and field-based sources. It is a tool for estimating the relative economic and human costs of monitoring and control efforts targeting either L. pneumophila or Legionella species and was designed to analyze the potential application of each approach to specific building classes across Italy. The model results consistently showed that targeting L. pneumophila is not only sufficient but preferable in optimizing total cost (direct and economic) for similar human health benefits, even when stress-tested with extreme inputs. This cost–benefit analytical tool allows the user to run different real-life scenarios with a broad range of epidemiological and prevalence assumptions across different geographies in Italy. With appropriate modifications, this tool can be localized and applied to other countries, states, or provinces. [ABSTRACT FROM AUTHOR]

Given the recent global surge in Legionnaires' disease cases, the monitoring of Legionella pneumophila becomes increasingly crucial. Epidemiological cases often stem from local outbreaks rather than widespread dissemination, emphasizing the need to study the characteristics of this pathogen at a local level. This study focuses on isolates of L. pneumophila in the Italian region of Friuli Venezia Giulia to assess specific genotype and phenotype distribution over time and space. To this end, a total of 127 L. pneumophila strains isolated between 2005 and 2017 within national surveillance programs were analysed. Rep-PCR, RAPD, and Sau-PCR were used for genotypic characterization, while phenotypic characterization was conducted through fatty acids analysis. RAPD and Sau-PCR effectively assessed genetic characteristics, identifying different profiles for the isolates and excluding the presence of clones. Although Sau-PCR is rarely used to analyse this pathogen, it emerged as the most discriminatory technique. Phenotypically, hierarchical cluster analysis categorized strains into three groups based on varying membrane fatty acid percentages. However, both phenotypic and genotypic analyses revealed a ubiquitous profile distribution at a regional level. These results suggest an absence of correlations between strain profiles, geographical location, and isolation time, indicating instead high variability and strain dissemination within this region. [ABSTRACT FROM AUTHOR]

Background: Legionella pneumophila is a Gram-negative intracellular bacillus and is the causative agent of a severe form of pneumonia called Legionnaires' disease which accounts for 2-9% of cases of community acquired pneumonia. It produces an extremely large protein belonging to the RTX (Repeats in ToXin) family, called RtxA, and we previously reported that RtxA is transported by a dedicated type 1 secretion system (T1SS) to the cell surface. RTX proteins have been shown to participate in the virulence or biofilm formation of various bacteria, the most studied models being the pore forming hemolysin A (HlyA) of Escherichia coli and the biofilm associated protein LapA of P. fluorescens. LapA localization depends on the enzymatic release by LapD/LapG complex activity. This study aimed to elucidate the dual localization (cell surface associated or released state) of L. pneumophila RTX protein (RtxA) and whether this released versus sequestered state of RtxA plays a role in L. pneumophila virulence. Results: The hereby work reveals that, in vitro, LapG periplasmic protease cleaves RtxA N-terminus in the middle of a di-alanine motif (position 108–109). Consistently, a strain lacking LapG protease maintains RtxA on the cell surface, whereas a strain lacking the c-di-GMP receptor LapD does not exhibit cell surface RtxA because of its continuous cleavage and release, as in the LapA-D-G model of Pseudomonas fluorescens. Interestingly, our data point out a key role of RtxA in enhancing the infection process of amoeba cells, regardless of its location (embedded or released); therefore, this may be the result of a secondary role of this surface protein. Conclusions: This is the first experimental identification of the cleavage site within the RTX protein family. The primary role of RtxA in Legionella is still questionable as in many other bacterial species, hence it sounds reasonable to propose a major function in biofilm formation, promoting cell aggregation when RtxA is embedded in the outer membrane and facilitating biofilm dispersion in case of RtxA release. The role of RtxA in enhancing the infection process may be a result of its action on host cells (i.e., PDI interaction or pore-formation), and independently of its status (embedded or released). [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) are suspected reservoirs of Legionella pneumophila (Lp). The required aeration and mixing steps lead to the emission and dispersion of bioaerosols potentially harboring Lp. The aim of the project is to evaluate municipal WWTPs as a possible source of legionellosis through the statistical analysis of case clusters. A space–time scanning statistical method was implemented in SaTScan software to identify and analyze WWTPs located within and close to spatiotemporal clusters of legionellosis detected in Quebec between 2016 and 2020. In parallel, WWTPs were ranked according to their pollutant load, flow rate and treatment type. These parameters were used to evaluate the WWTP susceptibility to generate and disperse bioaerosols. Results show that 37 of the 874 WWTPs are located inside a legionellosis cluster study zone, including six of the 40 WWTPs ranked most susceptible. In addition, two susceptible WWTPs located within an extended area of 2.5 km from the study zone (2.5-km buffer) were included, for a total of 39 WWTPs. The selected 39 WWTPs were further studied to document proximity of population, dominant wind direction, and surrounding water quality. Samples collected from the influent and the effluent of six selected WWTPs revealed the presence of Legionella spp. in 92.3% of the samples. Lp and Lp serogroupg 1 (Lp sg1) were detected below the limit of quantification in 69% and 46% of the samples, respectively. The presence of Legionella in wastewater and the novel statistical approach presented here provides information to the public health authorities regarding the investigation of WWTPs as a possible source of Legionella exposure, sporadic cases, and clusters of legionellosis. [ABSTRACT FROM AUTHOR]

Backgroud: Although not fully investigated, studies show that Legionella pneumophila can develop antibiotic resistance. As there is limited data available for Portugal, we determined the antibiotic susceptibility profile of Portuguese L. pneumophila serogroup 1 (LpnSg1) isolates against antibiotics used in the clinical practice in Portugal. Methods: Minimum inhibitory concentrations (MICs) were determined for LpnSg1 clinical (n = 100) and related environmental (n = 7) isolates, collected between 2006–2022 in the context of the National Legionnaire´s Disease Surveillance Programme, against azithromycin, clarithromycin, erythromycin, levofloxacin, ciprofloxacin, moxifloxacin, rifampicin, doxycycline, tigecycline, and amoxicillin/clavulanic acid, using three different assays. Isolates were also PCR-screened for the presence of the lpeAB gene. Results: Twelve isolates had azithromycin MICs above the EUCAST tentative highest WT MIC, 9 of which were lpeAB negative; for erythromycin and clarithromycin, all isolates tested within the susceptible range. The number of isolates with MICs above the tentative highest WT MIC for the remaining antibiotics was: ciprofloxacin: 7; levofloxacin: 17; moxifloxacin: 8; rifampicin: 11; doxycycline: 82; tigecycline: 4. EUCAST breakpoints are not available for amoxicillin/clavulanic acid. We estimated the ECOFFs and one isolate had a MIC eightfold higher than the E-test ECOFF. Additionally, a clinical isolate generated three colonies growing on the E-test inhibition zone that resulted in MICs fourfold higher than for the parental isolate. Conclusions: We report, for the first time, elevated MICs against first-line and other antibiotics (including azithromycin, fluoroquinolones and amoxicillin/clavulanic acid commonly used to treat pneumonia patients in Portugal) in Portuguese L. pneumophila strains. Results point towards decreased susceptibility in circulating strains, justifying further investigation. [ABSTRACT FROM AUTHOR]

Legionella pneumophila is the waterborne pathogen primarily responsible for causing both Pontiac Fever and Legionnaire's Disease in humans. L. pneumophila is transmitted via aerosolized water droplets. The purpose of this study was to design and test primers to allow for rapid polymerase chain reaction (PCR) melt detection and identification of this infectious agent in cases of clinical or emergency response detection. New PCR primers were designed for this species of bacteria; the primer set was purchased from IDT and the target bacterial DNA was purchased from ATCC. The L. pneumophila primers targeted the macrophage infectivity potentiator gene (mip), which inhibits macrophage phagocytosis. The primers were tested for specificity, repeatability, and sensitivity using PCR–high-resolution melt (HRM) assays. The primer set was found to be specific to the designated bacteria and did not amplify the other twenty-one species from the panel. The L. pneumophila assay was able to be multiplexed. The duplex assay consists of primers for L. pneumophila and Vibrio parahaemolyticus, which are both waterborne pathogens. The triplex assay consists of primers for L. pneumophila, V. parahaemolyticus, and Campylobacter jejuni. The unique melting temperature for the L. pneumophila primer assay is 82.84 ± 0.19 °C, the C. jejuni assay is 78.10 ± 0.58 °C, and the V. parahaemolyticus assay is 86.74 ± 0.65 °C. [ABSTRACT FROM AUTHOR]

Although cases of Legionnaires' disease are notifiable, data on the phenotypic and genotypic characterisation of clinical isolates are limited. This retrospective study aims to report the results of the characterisation of Legionella clinical isolates in Spain from 2012 to 2022. Monoclonal antibodies from the Dresden panel were used for phenotypic identification of Legionella pneumophila. Genotypic characterisation and sequence type assignment were performed using the Sequence-Based Typing scheme. Of the 1184 samples, 569 were identified as Legionella by culture. Of these, 561 were identified as L. pneumophila, of which 521 were serogroup 1. The most common subgroups were Philadelphia (n = 107) and Knoxville (n = 106). The SBT analysis revealed 130 different STs, with the most common genotypes being ST1 (n = 87), ST23 (n = 57), ST20 (n = 30), and ST42 (n = 29). Knoxville has the highest variability with 32 different STs. ST23 is mainly found in Allentown/France (n = 46) and ST42 in Benidorm (n = 18), whereas ST1 is widely distributed. The results demonstrate that clinical isolates show high genetic diversity, although only a few sequence types (STs) are responsible for most cases. However, outbreaks can also occur with rare genotypes. More data on LD and associated epidemiological studies are needed to establish the risk of an isolate causing outbreak in the future. [ABSTRACT FROM AUTHOR]

This article discusses the use of rifampin in clinical drug-drug interaction (DDI) studies. Rifampin is an antibiotic that is commonly used as an inducer of drug-metabolizing enzymes and transporters. However, recent reports of a nitrosamine impurity called 1-methyl-4-nitrosopiperazine (MNP) in rifampin products have raised concerns. The FDA has set a limit for MNP in rifampin products, and this has led to the search for alternative inducers for DDI studies. The authors argue that rifampin should continue to be used in these studies due to its well-established induction effects, pleiotropic effects, and safety profile compared to alternative inducers like carbamazepine and phenytoin. [Extracted from the article]

This study introduces an innovative electrochemical aptasensor designed for the highly sensitive and rapid detection of Legionella pneumophila serogroup 1 (L. pneumophila SG1), a particularly virulent strain associated with Legionellosis. Employing a rigorous selection process utilizing cell-based systematic evolution of ligands by exponential enrichment (cell-SELEX), we identified new high-affinity aptamers specifically tailored for L. pneumophila SG1. The selection process encompassed ten rounds of cell-SELEX cycles with live L. pneumophila, including multiple counter-selection steps against the closely related Legionella sub-species. The dissociation constant (Kd) of the highest affinity sequence to L. pneumophila SG1 was measured at 14.2 nM, representing a ten-fold increase in affinity in comparison with the previously reported aptamers. For the development of electrochemical aptasensor, a gold electrode was modified with the selected aptamer through the formation of self-assembled monolayers (SAMs). The newly developed aptasensor exhibited exceptional sensitivity, and specificity in detecting and differentiating various Legionella sp., with a detection limit of 5 colony forming units (CFU)/mL and an insignificant/negligible cross-reactivity with closely related sub-species. Furthermore, the aptasensor effectively detected L. pneumophila SG1 in spiked water samples, demonstrating an appreciable recovery percentage. This study shows the potential of our aptamer-based electrochemical biosensor as a promising approach for detecting L. pneumophila SG1 in diverse environments. [ABSTRACT FROM AUTHOR]

Bacterial adhesion is a fundamental process which enables colonisation of niche environments and is key for infection. However, in Legionella pneumophila, the causative agent of Legionnaires' disease, these processes are not well understood. The Legionella collagen-like protein (Lcl) is an extracellular peripheral membrane protein that recognises sulphated glycosaminoglycans on the surface of eukaryotic cells, but also stimulates bacterial aggregation in response to divalent cations. Here we report the crystal structure of the Lcl C-terminal domain (Lcl-CTD) and present a model for intact Lcl. Our data reveal that Lcl-CTD forms an unusual trimer arrangement with a positively charged external surface and negatively charged solvent exposed internal cavity. Through molecular dynamics simulations, we show how the glycosaminoglycan chondroitin-4-sulphate associates with the Lcl-CTD surface via distinct binding modes. Our findings show that Lcl homologs are present across both the Pseudomonadota and Fibrobacterota-Chlorobiota-Bacteroidota phyla and suggest that Lcl may represent a versatile carbohydrate-binding mechanism. The Legionella collagen-like protein (Lcl) is important for host adhesion in Legionella pneumophila. Here, the authors provide structural and biochemical data, which provides insights into a distinct "fuzzy" glycosaminoglycan binding mechanism. [ABSTRACT FROM AUTHOR]

Introduction: In case of pneumonia, some biological findings are suggestive for Legionnaire's disease (LD) including C-reactive protein (CRP). A low level of CRP is predictive for negative Legionella Urinary-Antigen-Test (L-UAT). Method: Observational retrospective study in Nord-Franche‐Comté Hospital with external validation in Besançon University Hospital, France which included all adults with L-UAT performed during January 2018 to December 2022. The objective was to determine CRP optimal threshold to predict a L-UAT negative result. Results: URINELLA included 5051 patients (83 with positive L-UAT). CRP optimal threshold was 131.9 mg/L, with a negative predictive value (NPV) at 100%, sensitivity at 100% and specificity at 58.0%. The AUC of the ROC-Curve was at 88.7% (95% CI, 86.3–91.1). External validation in Besançon Hospital patients showed an AUC at 89.8% (95% CI, 85.5–94.1) and NPV, sensitivity and specificity was respectively 99.9%, 97.6% and 59.1% for a CRP threshold at 131.9 mg/L; after exclusion of immunosuppressed patients, index sensitivity and NPV reached also 100%. Conclusion: In case of pneumonia suspicion with a CRP level under 130 mg/L (independently of the severity) L-UAT is useless in immunocompetent patients with a NPV at 100%. We must remain cautious in patients with symptoms onset less than 48 h before CRP dosage. [ABSTRACT FROM AUTHOR]

In the summer of 1976, prior to the United States presidential election between Gerald Ford and Jimmy Carter, an outbreak of Legionnaires' disease occurred in Philadelphia. After an epidemiological survey, 221 people with pneumonia or similar symptoms were identified, 34 of whom died. The outbreak prompted the advancement of legislation to exempt companies that produced influenza vaccines from liability for damages, resulting in significant losses for the government. The outbreak was a major economic blow to the Bellevue Stratford Hotel, an iconic historical hotel in Philadelphia, which was forced to close 16 days after the election. Following the outbreak, media coverage was extensive, and there was frustration over the inability to determine the cause of the outbreak in Philadelphia. The critical factor was that the cause of the outbreak was not determined to be rod‐shaped bacteria, later named Legionella pneumophila, before the election date. While many aspects had an impact, it is possible that the Legionnaires' disease outbreak may have affected the outcome of the election, particularly in Pennsylvania. This study does not make definitive causal links but focuses on Legionnaires' disease and the 1976 elections. [ABSTRACT FROM AUTHOR]

Aims: Legionella bacteria cause Legionnaires' disease and Pontiac fever. It is commonly found in natural water resources and manmade water systems. Environmental conditions such as nutrient deficiency, temperature, pH, disinfectant and the presence of other bacteria can cause Legionella bacteria to pass into the viable but not-culturable (VBNC) phase. This study was aimed to determine appropriate methods to detect Legionella pneumophila bacteria living in water systems with wide temperature and pH ranges threatening human health. Methodology and results: In this study, water samples containing L. pneumophila at a concentration of 108 cell/L were exposed to different temperatures (5 °C, 50 °C, 55 °C and 60 °C) and pH (2.2, 5.8, 7.0 and 8.2) values. Conventional culture, FISH and seminested PCR methods were used to detect L. pneumophila. A comparison was made between the methods used in the study to determine the most appropriate method for detecting L. pneumophila bacteria. The results showed that the highest detection rates of L. pneumophila were at 5 °C for 24 h (100%) and at pH 2.2 for 0th min (100%) by using FISH method. All the samples could be determined by the seminested PCR method. The results of our study showed that the highest detection rates of L. pneumophila were at 5 °C for 24 h (100%) and at pH 2.2 for 0th min (100%) by FISH method. All of the samples could be determined by the seminested PCR method. It was determined that the detection rate was the lowest in the FISH method at 3 min at 60 °C and the highest was 24 h at 5 °C. The lowest detection rate was also observed by using FISH method in the samples exposed to 60 °C for 3 min. Results show that the FISH and seminested PCR methods are the most suitable for detecting L. pneumophila bacteria from water systems exposed to different environmental conditions. Conclusion, significance and impact of study: Different methods (conventional culture, FISH, seminested PCR) used to detect L. pneumophila bacteria were compared in this study. It was concluded that Legionella bacteria passed into the VBNC phase, and compared to molecular methods, the conventional culture method provides a low detection rate of these bacteria. Research findings suggest that it is insufficient to use the conventional culture method alone for the detection of Legionella bacteria from man-made water systems or human samples. This study is important as it is decisive for the determination of the most appropriate method for detecting the human pathogen L. pneumophila bacteria from water samples and the choice for a fast and effective method for the elimination of the infectious agent. [ABSTRACT FROM AUTHOR]

Background: The Flint water crisis (FWC) was a public health tragedy caused by crumbling infrastructure, subverted democracy, and indifference toward a predominantly poor and Black community that resulted in lead-in-water exposure, Legionnaires' disease, and emotional and health-related trauma. Through the cooperation of community partners, the Flint Registry (FR) was conceived to track long-term health and improve public health via service connections. Objectives: This study sought to share the FR's community-partnered, multi-tiered engagement strategy and determine the efficacy of this strategy to engage the community and reach Flint residents. Methods: Community engagement and impact were measured by collecting and describing feedback from the community engagement strategies and by comparing the demographics of the enrollees recruited through community-engaged recruitment (CER) and non-CER methods. Enroll-ees indicated how they heard about the FR; CER involved direct interaction with a community member. Results: Community engagement strategies incorporated approximately 1,200 people and 7 funded organizations, impacting 22 key areas of FR design and implementation. More than 50% of enrollees heard about the FR through CER methods. They were, on average, more likely to be younger, female, Black/African American, and living outside of Flint during the FWC. Conclusions: Community engagement elevated voices of those impacted by the FWC. CER methods were as effective as non-CER methods. Although there were no differences in screened measures of social vulnerability, there were in age, gender, and race. CER methods may increase participation and build trust in populations which historically are hesitant to participate in public health efforts. [ABSTRACT FROM AUTHOR]

Legionnaires' disease (LD) is a serious type of pneumonia, typically contracted by susceptible people through the inhalation of aerosols contaminated with Legionella pneumophila (Lp). In this report, the first case of coinfection with Lp–Bordetella bronchiseptica (Bb) is described. A possible source of the Lp infection may be the hotel in Paris (France) where the patient had stayed before developing the symptoms. The Bb infection may have been transmitted by the dog with which he had constant contact, although this has not been proven.

We report a case of Legionnaires’ disease caused by Legionella bozemanae, which is the first time that L. bozemanae has been isolated from a bronchoalveolar lavage fluid sample from an immunocompromised patient in China. The findings highlight the susceptibility of immunocompromised patients to infections caused by the rare but highly pathogenic L. bozemanae.

IntroductionLegionnaires’ disease is a severe pneumonia predominantly caused by Legionella pneumophila (Lp), whose major reservoirs are artificial water systems. As most human infections are caused by L. pneumophila serogroup 1 (Lp1), a reliable method for Lp distinction can be crucial for bacterial spread prevention. As the ability to withstand in environments and to cause the waterborne disease is strongly related to specific genes, the identification of virulent strains can be of great relevance to implement water environmental monitoring and to contain harmful outbreaks to public health. We aimed to test an assay for Lp identification among different Legionella species, and to determine the serogroups. Additionally, we investigated the carriage of virulence and antimicrobial resistance genes.MethodsA total of 90 Legionella spp. isolates identified by phenotypic tests were subjected to the designed quantitative PCR assay targeting specific mip for Lp, wzm for Lp1, pvcA and ahpD for biofilm production. Eleven serogroups were investigated in all our isolates tested positive for mip gene, subsequently analyzed for 12 virulence and 8 antimicrobial resistance genes.ResultsOnly the 70 Lp isolates were positive for mip. Out of 27 Lp isolates belonging to serogroup 1 based on agglutination test, 23 (85.2%) carried wzm. The presence of ahpD and pvcA was found in 94.3 and 98.6% of Lp isolates, respectively. By multiplex PCR, all 23 wzm-positive strains were confirmed as serogroup 1 that was the most predominant (33%). At least one virulence gene was detected in all Lp isolates. The most frequent gene was ispE (100%), followed by issD (96%), icmK and enhC (93%), cpxA (91%), rtxA2 (74%), lvhB8-B9 (61%), and prpA (54%). The other genes were less diffused in Lp strains (rtxA1, 44%; lvhB3-B4, 47%; pvcB, 27%; lvrE, 24%). Of the macrolide resistance genes, the ereA was found in 84% of Lp strains, while only 14 (20%) harbored the lpeAB among the efflux pump genes.ConclusionThe assays validated in this study enable the simultaneous Lp and Lp1 detection. The differentiation of Lp strains according to their virulence properties could be useful to predict the bacterial ability to survive and to cause the disease.

Legionellers’ desease accounts for 1–8 % of cases of severe community-acquired pneumonia (CAP). Legionella spp. Is the causative organism that can result in respiratory failure, multi-organ dysfunction, sepsis, and death. Therefore, rapid diagnosis and efficient treatment are crucial. We report the clinical and microbiology study of a patient with community-acquired pneumonia caused by Legionella pneumophila, with fatal outcome. After death, the strain causing the infection was identified as Legionella pneumophila serogroup 1, Olda OLDA phenotype and sequence-type 1. This is the first reported case of septic shock and death associated with an isolate of these characteristics.

Abstract Background Legionnaires’ disease (LD) is a common but under-diagnosed cause of community-acquired pneumonia (CAP), although rapid detection of urine antigen testing (UAT) and advances in molecular testing have improved the diagnosis. LD entails intensive care unit (ICU) admission in almost one-third of cases, and the mortality rate ranges from 4% to 40%. This review aims to discuss recent advances in the study of this condition and to provide an update on the diagnosis, pathogenesis and management of severe LD. Results The overall incidence of LD has increased worldwide in recent years due to the higher number of patients with risk factors, especially immunosuppression, and to improvements in diagnostic methods. Although LD is responsible for only around 5% of all-cause CAP, it is one of the three most common causes of CAP requiring ICU admission. Mortality in ICU patients, immunocompromised patients or patients with a nosocomial source of LD can reach 40% despite appropriate antimicrobial therapy. Regarding pathogenesis, no Legionella-specific virulence factors have been associated with severity; however, recent reports have found high pulmonary Legionella DNA loads, and impairments in immune response and lung microbiome in the most severe cases. The clinical picture includes severe lung injury requiring respiratory and/or hemodynamic support, extrapulmonary symptoms and non-specific laboratory findings. LD diagnostic methods have improved due to the broad use of UAT and the development of molecular methods allowing the detection of all Lp serogroups. Therapy is currently based on macrolides, quinolones, or a combination of the two, with prolonged treatment in severe cases. Conclusions Numerous factors influence the mortality rate of LD, such as ICU admission, the underlying immune status, and the nosocomial source of the infection. The host immune response (hyperinflammation and/or immunoparalysis) may also be associated with increased severity. Given that the incidence of LD is rising, studies on specific biomarkers of severity may be of great interest. Further assessments comparing different regimens and/or evaluating host-directed therapies are nowadays needed. Graphical Abstract

A total of 17 Legionnaires' disease cases were identified in an outbreak in a western town in New York. The cases had symptom onset dates ranging from August 1, 2019, to July 1, 2021. Staff from the New York State Department of Health and Chemung County Health Department employed numerous environmental investigation techniques. Environmental health program staff collected 74 environmental samples, including samples from cooling towers, residences, and a wastewater treatment plant. Wind direction was analyzed to determine the potential for the dispersion of aerosolized Legionella. In total, five cases were found to be genetically related by whole genome sequencing. Further testing revealed that isolates recovered from a cooling tower at an industrial facility were genetically related to four of the 2019 cases. Excessive iron was found in the tower and might have suppressed the oxidizing biocide residual and interfered with the evaluation of routine culture and other testing methods. In 2021, clinical and environmental samples from a private hot tub were found to be genetically related to the four matching cases and cooling tower samples recovered in 2019. [ABSTRACT FROM AUTHOR]

Fourier-transform infrared (FTIR) spectroscopy using the IR Biotyper and core genome single nucleotide polymorphism (cgSNP) analysis were performed on 12 Legionella isolates associated with an outbreak at a spa house in Kanagawa Prefecture, Japan, and 3 non-outbreak isolates. The discriminative power of FTIR spectroscopy for 48-h incubation conditions of L. pneumophila in this outbreak was lower than cgSNP-based typing but higher than serogroup typing. FTIR spectroscopy could screen outbreak isolates from a group of genetically related isolates and may be useful as an initial typing method in Legionella outbreak investigations. [ABSTRACT FROM AUTHOR]

This case report aims to provide up-to-date information about the conditions requiring hospitalization in primary health-care services in cases of Legionella pneumonia. This case was a 66-year-old woman with a history of smoking who admitted to the emergency department with increasing dyspnea and fatigue. On physical examination, he appeared dyspneic and tachypneic, and on auscultation, inspiratory rales and bilateral widespread expiratory rhonchi were detected. C-reactive protein was 324.3 mg/L, leukocytosis was 10980 10³ /mm³, and neutrophil-dominated (90.2%). There was a respiratory failure according to the arterial blood gas analysis (PO2: 57.3 mmHg, HCO3: 25.7 mEq/L, PCO2: 33.6 mmHg, SO²: 91.3%). Moxifloxacin (400 mg 1×1) and oseltamivir (75 mg 2×1) peroral empirically were initiated because of pneumonia, and additionally inhaler steroid and bronchodilator treatments (Salmeterol+flutikazon 50/500 mcg twice daily) for bronchitis. However, on the third day of follow-up, 40 mg methylprednisolone parenterally was added to the treatment because of bronchospasm and dyspnea continued despite bronchodilator therapy, and additionally parenteral ampicillin-sulbactam (4x1 gr.) was started to expand the spectrum of Gram-positive bacteria. Legionella was detected as the causative pathogen by viral and bacterial sampling of the airways with PCR. Low awareness about the disease may cause serious mortality and morbidity in patients presenting with a vague clinical picture in the early stages. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Legionella pneumophila ( Lp) is aerobic, non-spore forming Gram-negative bacteria, which is ubiquitous in freshwater habitats, such as rivers and hot springs, as well as colonizing artificial aquatic environments. The ability of Lp to grow intracellularly within pulmonary macrophages is a prerequisite for the development of infection. Therefore, macrolides can achieve appropriate therapeutic concentrations in eukaryotic cells, such as azithromycin. This study aimed to investigate the macrolides susceptibility of Lp. METHODS: Pre-flash water samples (n=143) were collected from the public buildings (hospitals and hotels) water system in Istanbul. Colonies were confirmed as Lp ST1, ST2-14, and non-pneumophila Lp using latex agglutination kit. RESULTS: 30 Lp were detected in hospital (n=23) and hotel (n=7) water systems using latex agglutination. Regardless of serotype and excluding strains without zone formation (≥256 mg/L), the main MIC values of azithromycin, erythromycin and clarithromycin were 0.61 mg/L (range 0.047--1 mg/L), 0.47 mg/L (range 0.047--1 mg/L) and 0.44 mg/L (range 0.047--1 mg/L), respectively. The MIC50 and MIC90 values for macrolides were 0.5 and 3 mg/L for azithromycin, respectively; 0.38 and 1 mg/L for erythromycin, respectively; and 0.5 and 1 mg/L for clarithromycin, respectively. We compared the MIC values of the strains for all antimicrobial agents tested without serotype discrimination. We did not find a significant difference between the MIC values of the antibiotics (p=0.16). CONCLUSION: Although the data obtained from our study do not fully reflect the breakpoints, further epidemiological studies are needed to standardize MIC values. [ABSTRACT FROM AUTHOR]

Legionella pneumophila is a freshwater opportunistic pathogen and the leading cause of severe pneumonia known as Legionnaires' disease. It can be found in all water systems and survives in biofilms, free-living amoebae, and a wide variety of facilities, such as air conditioning and showers in hospitals, hotels and spas. The reference cultural method allows for the isolation and identification in many days, and in addition, it does not detect viable but rather non-culturable bacteria, increasing the risk of infection. In this context, a new LAMP-based (loop-mediated isothermal amplification) kit was developed, allowing for the rapid, sensitive, and labor-saving detection of L. pneumophila. The kit, "Legionella pneumophila Glow", was validated according to ISO/TS 12869:2012, testing sensitivity, inclusivity and exclusivity, and kit robustness. Sensitivity showed that the "Legionella pneumophila Glow" kit can detect up to 28 plasmid copies/µL. Robustness tests showed consistent results, with both contamination levels and the matrices used giving reproducible results. Furthermore, real samples were evaluated to compare the performance of the two methods. The LAMP kit "Legionella pneumophila Glow" proved a useful option for the rapid, efficient, and labor-saving screening of different typologies of water samples, offering significant advantages over the traditional method, as it is characterized by a high sensitivity, ease of use for laboratory testing, and a large reduction in analysis time, making it an asset to official controls. [ABSTRACT FROM AUTHOR]

Legionella pneumophila can cause a large panel of symptoms besides the classic pneumonia presentation. Here we present a case of fatal nosocomial cellulitis in an immunocompromised patient followed, a year later, by a second case of Legionnaires' disease in the same ward. While the first case was easily assumed as nosocomial based on the date of symptom onset, the second case required clear typing results to be assigned either as nosocomial and related to the same environmental source as the first case, or community acquired. To untangle this specific question, we applied core-genome multilocus typing (MLST), whole-genome single nucleotide polymorphism and whole-genome MLST methods to a collection of 36 Belgian and 41 international sequence-type 1 (ST1) isolates using both thresholds recommended in the literature and tailored threshold based on local epidemiological data. Based on the thresholds applied to cluster isolates together, the three methods gave different results and no firm conclusion about the nosocomial setting of the second case could been drawn. Our data highlight that despite promising results in the study of outbreaks and for large-scale epidemiological investigations, next-generation sequencing typing methods applied to ST1 outbreak investigation still need standardization regarding both wet-lab protocols and bioinformatics. A deeper evaluation of the L. pneumophila evolutionary clock is also required to increase our understanding of genomic differences between isolates sampled during a clinical infection and in the environment. [ABSTRACT FROM AUTHOR]

Understanding how the infectious disease burden was affected throughout the COVID‐19 pandemic is pivotal to identifying potential hot spots and guiding future mitigation measures. Therefore, our study aimed to analyze the changes in the rate of new cases of Poland's most frequent infectious diseases during the entire COVID‐19 pandemic and after the influx of war refugees from Ukraine. We performed a registry‐based population‐wide study in Poland to analyze the changes in the rate of 24 infectious disease cases from 2020 to 2023 and compared them to the prepandemic period (2016–2019). Data were collected from publicly archived datasets of the Epimeld database published by national epidemiological authority institutions. The rate of most of the studied diseases (66.6%) revealed significantly negative correlations with the rate of SARS‐CoV‐2 infections. For the majority of infectious diseases, it substantially decreased in 2020 (in case of 83%) and 2021 (63%), following which it mostly rebounded to the prepandemic levels and, in some cases, exceeded them in 2023 when the exceptionally high annual rates of new cases of scarlet fever, Streptococcus pneumoniae infections, HIV infections, syphilis, gonococcal infections, and tick‐borne encephalitis were noted. The rate of Clostridioides difficile enterocolitis was two‐fold higher than before the pandemic from 2021 onward. The rate of Legionnaires' disease in 2023 also exceeded the prepandemic threshold, although this was due to a local outbreak unrelated to lifted COVID‐19 pandemic restrictions or migration of war refugees. The influx of war migrants from Ukraine could impact the epidemiology of sexually transmitted diseases. The present analysis indicates that continued efforts are needed to prevent COVID‐19 from overwhelming healthcare systems again and decreasing the control over the burden of other infectious diseases. It also identifies the potential tipping points that require additional mitigation measures, which are also discussed in the paper, to avoid escalation in the future. [ABSTRACT FROM AUTHOR]

The annual global incidence of legionellosis is reported between 4–20 cases per million population. Legionellosis presents two, distinct clinical entities: multisystemic Legionnaires’ disease, with severe pneumonia, and Pontiac fever, a self-limited flu-like illness. Additionally, many those who seroconvert to Legionella remain entirely asymptomatic. Although healthy individuals can contract Legionnaires’ disease, most often patients are elderly or debilitated or immunocompromised. The causative agent, Legionella pneumophila is Gram-negative, small aerobic coccoid rod, obligate or facultative intracellular. Water is the major environmental reservoir for legionellae; they can infect and multiply within amoebae and ciliated protozoa which are found in natural and manufactured water systems. Legionellae infect human macrophages and monocytes and they multiply within alveolar macrophages. Laboratory diagnosis of legionellosis is based on bacteriological, serological and molecular methods. Among them urinary antigen test, UAT, is widely used. In this article, we present the current situation of legionellosis, with the focus on consequences, recognition and treatment of the disease. [ABSTRACT FROM AUTHOR]

Climate change is having an unprecedented influence on human health. For example, increased frequency of storms with excessive precipitation may contribute to flooding, which contributes to increased water-related dermatological, gastrointestinal, and respiratory illnesses. Some of these water-related illnesses, which can be transmitted via recreational waterborne pathways, may be seen in school-age children. The purpose of this article is to raise awareness of the impact some recreational water-related illnesses have on school-age children's health and to provide school nurses with information on the signs and symptoms of these illnesses as well as prevention tips nurses may wish to share with parents. This is the third article in a series meant to inform school nurses about illnesses linked to local changes in weather that may be arising from global changes in climate and provide them with the tools they need to safeguard children's health. [ABSTRACT FROM AUTHOR]

Background: Legionnaires' disease (LD) is a common but under-diagnosed cause of community-acquired pneumonia (CAP), although rapid detection of urine antigen testing (UAT) and advances in molecular testing have improved the diagnosis. LD entails intensive care unit (ICU) admission in almost one-third of cases, and the mortality rate ranges from 4% to 40%. This review aims to discuss recent advances in the study of this condition and to provide an update on the diagnosis, pathogenesis and management of severe LD. Results: The overall incidence of LD has increased worldwide in recent years due to the higher number of patients with risk factors, especially immunosuppression, and to improvements in diagnostic methods. Although LD is responsible for only around 5% of all-cause CAP, it is one of the three most common causes of CAP requiring ICU admission. Mortality in ICU patients, immunocompromised patients or patients with a nosocomial source of LD can reach 40% despite appropriate antimicrobial therapy. Regarding pathogenesis, no Legionella-specific virulence factors have been associated with severity; however, recent reports have found high pulmonary Legionella DNA loads, and impairments in immune response and lung microbiome in the most severe cases. The clinical picture includes severe lung injury requiring respiratory and/or hemodynamic support, extrapulmonary symptoms and non-specific laboratory findings. LD diagnostic methods have improved due to the broad use of UAT and the development of molecular methods allowing the detection of all Lp serogroups. Therapy is currently based on macrolides, quinolones, or a combination of the two, with prolonged treatment in severe cases. Conclusions: Numerous factors influence the mortality rate of LD, such as ICU admission, the underlying immune status, and the nosocomial source of the infection. The host immune response (hyperinflammation and/or immunoparalysis) may also be associated with increased severity. Given that the incidence of LD is rising, studies on specific biomarkers of severity may be of great interest. Further assessments comparing different regimens and/or evaluating host-directed therapies are nowadays needed. [ABSTRACT FROM AUTHOR]

Legionella pneumophila, the leading cause of Legionnaires' disease in the United States, is found in lakes, ponds, and streams but poses a health risk when it grows in building water systems. The growth of L. pneumophila in hot water systems of healthcare facilities poses a significant risk to patients, staff, and visitors. Hospitals and long-term care facilities account for 76% of reported Legionnaires' disease cases with mortality rates of 25%. Controlling L. pneumophila growth in hot water systems serving healthcare and hospitality buildings is currently achieved primarily by adding oxidizing chemical disinfectants. Chemical oxidants generate disinfection byproducts and can accelerate corrosion of premise plumbing materials and equipment. Alternative control methods that do not generate hazardous disinfection byproducts or accelerate corrosion are needed. L. pneumophila is an obligate aerobe that cannot sustain cellular respiration, amplify, or remain culturable when dissolved oxygen (DO) concentrations are too low (< 0.3 mg/L). An alternative method of controlling L. pneumophila growth by reducing DO levels in a hot water model system using a gas transfer membrane contactor was evaluated. A hot water model system was constructed and inoculated with L. pneumophila at DO concentrations above 0.5 mg/L. Once the model system was colonized, DO levels were incrementally reduced. Water samples were collected each week to evaluate the effect of reducing dissolved oxygen levels when all other conditions favored Legionella amplification. At DO concentrations below 0.3 mg/L, L. pneumophila concentrations were reduced by 1-log over 7 days. Under conditions in the hot water model system, at favorable temperatures and with no residual chlorine disinfectant, L. pneumophila concentrations were reduced by 1-log, indicating growth inhibition by reducing DO levels as the sole control measure. In sections of the model system where DO levels were not lowered L. pneumophila continued to grow. Reducing dissolved oxygen levels in hot water systems of healthcare and other large buildings to control L. pneumophila could also lower the risk of supplemental chemical treatment methods currently in use. [ABSTRACT FROM AUTHOR]

Legionella are opportunistic pathogens in artificial water systems and can cause a severe form of pneumonia called Legionnaires' disease (LD), which is fatal in 5-50% of cases when contaminated aerosols are inhaled. LD emerged in the last half of the 20th century. Global challenges such as urbanization, aging populations, climate change, water scarcity, and circular economy approaches have led to an increase in the number of complex water systems and thus LD cases, which are expected to rise to around 2.5 billion by 2050. LD is a preventable disease if adequate measures are taken to control Legionella in water systems. Chlorine treatment and heat treatment are the methods of choice to sanitize a Legionella-contaminated water system. However, these two methods are not always effective in ensuring that the treated water is free of Legionella and safe for consumption and use. Therefore, we proposed to evaluate the efficacy of microfiltration, solar disinfection, photocatalysis, and UV-C254 irradiation on Legionella-contaminated water. Microfiltration was performed using a membrane filtration cell (SODIS). Solar disinfection and photocatalysis were performed with an experimental table consisting of six 1 L beakers, 3 for solar disinfection and 3 for photocatalysis. UV-C254 disinfection was also tested with 3 1 L beakers. For all four methods tested, the percentage of Legionella removal was over 99.99. The four disinfection systems tested provided satisfactory results and ensured that the treated water was free of Legionella and safe for consumption and use. [ABSTRACT FROM AUTHOR]

Legionnaires disease (LD) is a rare, life-threatening opportunistic bacterial infection that poses a significant risk to patients with impaired cell-mediated immunity such as solid organ transplant recipients. However, the epidemiologic features, clinical presentation, and outcomes of LD in this population are poorly described. What are the clinical manifestations, radiologic presentation, risk factors for severity, treatment, and outcome of LD in solid organ transplant recipients? In this 10-year multicenter retrospective cohort study in France, where LD notification is mandatory, patients were identified by hospital discharge databases. Diagnosis of LD relied on positive culture findings from any respiratory sample, positive urinary antigen test (UAT) results, positive specific serologic findings, or a combination thereof. Severe LD was defined as admission to the ICU. One hundred one patients from 51 transplantation centers were eligible; 64 patients (63.4%) were kidney transplant recipients. Median time between transplantation and LD was 5.6 years (interquartile range, 1.5-12 years). UAT results were positive in 92% of patients (89/97). Among 31 patients with positive culture findings in respiratory samples, Legionella pneumophila serogroup 1 was identified in 90%. Chest CT imaging showed alveolar consolidation in 98% of patients (54 of 57), ground-glass opacity in 63% of patients (36 of 57), macronodules in 21% of patients (12 of 57), and cavitation in 8.8% of patients (5 of 57). Fifty-seven patients (56%) were hospitalized in the ICU. In multivariate analysis, severe LD was associated with negative UAT findings at presentation (P =.047), lymphopenia (P =.014), respiratory symptoms (P =.010), and pleural effusion (P =.039). The 30-day and 12-month mortality rates were 8% (8 of 101) and 20% (19 of 97), respectively. In multivariate analysis, diabetes mellitus was the only factor associated with 12-month mortality (hazard ratio, 3.2; 95% OR, 1.19-8.64; P =.022). LD is a late and severe complication occurring in solid organ transplant recipients that may present as pulmonary nodules on which diabetes impacts its long-term prognosis. [Display omitted] [ABSTRACT FROM AUTHOR]

Key Clinical Message: Legionnaires' disease, often presenting as pneumonia, can uncommonly manifest with extrapulmonary symptoms such as cerebellar involvement and rhabdomyolysis. This case emphasizes the successful resolution of dysarthria and renal dysfunction with prompt Legionella treatment, underscoring the importance of vigilance for diverse manifestations in Legionella infections. Legionnaires' disease usually presents with pneumonia and a few extrapulmonary manifestations, such as neurological, musculoskeletal, and cutaneous manifestations. However, cerebellar involvement and rhabdomyolysis as an association with Legionella are not frequently encountered. We present a case of Legionella‐induced rhabdomyolysis requiring hemodialysis and dysarthria that resolved with Legionella treatment. [ABSTRACT FROM AUTHOR]