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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]

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

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]

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]

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]

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]

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]

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]

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]

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.

We determined whether the incidence rates of travel-associated Legionnaires’ disease (TALD) in hotels in Germany increased after a previous occurrence and whether control measures required by the European Legionnaires’ Disease Surveillance Network after a cluster (>2 cases within 2 years) restored the rate to baseline. We analyzed TALD surveillance data from Germany during 2015–2019; a total of 307 TALD cases (163 domestic, 144 nondomestic) in hotels were reported. The incidence rate ratio was 5.5 (95% CI 3.6–7.9) for a second case and 25 (95% CI 11–50) for a third case after a cluster had occurred, suggesting that control measures initiated after the occurrence of TALD clusters might be inadequate to restore the incidence rate to baseline. Our findings indicate that substantial LD preventive measures should be explored by hotels or other accommodations after the first TALD case occurs to reduce the risk for future infections.

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]

Fundamental to effective Legionnaires’ disease outbreak control is the ability to rapidly identify the environmental source(s) of the causative agent, Legionella pneumophila. Genomics has revolutionized pathogen surveillance, but L. pneumophila has a complex ecology and population structure that can limit source inference based on standard core genome phylogenetics. Here, we present a powerful machine learning approach that assigns the geographical source of Legionnaires’ disease outbreaks more accurately than current core genome comparisons. Models were developed upon 534 L. pneumophila genome sequences, including 149 genomes linked to 20 previously reported Legionnaires’ disease outbreaks through detailed case investigations. Our classification models were developed in a cross-validation framework using only environmental L. pneumophila genomes. Assignments of clinical isolate geographic origins demonstrated high predictive sensitivity and specificity of the models, with no false positives or false negatives for 13 out of 20 outbreak groups, despite the presence of within-outbreak polyclonal population structure. Analysis of the same 534-genome panel with a conventional phylogenomic tree and a core genome multi-locus sequence type allelic distance-based classification approach revealed that our machine learning method had the highest overall classification performance—agreement with epidemiological information. Our multivariate statistical learning approach maximizes the use of genomic variation data and is thus well-suited for supporting Legionnaires’ disease outbreak investigations. IMPORTANCE Identifying the sources of Legionnaires’ disease outbreaks is crucial for effective control. Current genomic methods, while useful, often fall short due to the complex ecology and population structure of Legionella pneumophila, the causative agent. Our study introduces a high-performing machine learning approach for more accurate geographical source attribution of Legionnaires’ disease outbreaks. Developed using cross-validation on environmental L. pneumophila genomes, our models demonstrate excellent predictive sensitivity and specificity. Importantly, this new approach outperforms traditional methods like phylogenomic trees and core genome multi-locus sequence typing, proving more efficient at leveraging genomic variation data to infer outbreak sources. Our machine learning algorithms, harnessing both core and accessory genomic variation, offer significant promise in public health settings. By enabling rapid and precise source identification in Legionnaires’ disease outbreaks, such approaches have the potential to expedite intervention efforts and curtail disease transmission. [ABSTRACT FROM AUTHOR]

Legionella pneumophila is a gram‐negative bacteria found in natural and anthropogenic aquatic environments such as evaporative cooling towers, where it reproduces as an intracellular parasite of cohabiting protozoa. If L. pneumophila is aerosolized and inhaled by a susceptible person, bacteria may colonize their alveolar macrophages causing the opportunistic pneumonia Legionnaires' disease. L. pneumophila utilizes an elaborate regulatory network to control virulence processes such as the Dot/Icm Type IV secretion system and effector repertoire, responding to changing nutritional cues as their host becomes depleted. The bacteria subsequently differentiate to a transmissive state that can survive in the environment until a replacement host is encountered and colonized. In this review, we discuss the lifecycle of L. pneumophila and the molecular regulatory network that senses nutritional depletion via the stringent response, a link to stationary phase‐like metabolic changes via alternative sigma factors, and two‐component systems that are homologous to stress sensors in other pathogens, to regulate differentiation between the intracellular replicative phase and more transmissible states. Together, we highlight how this prototypic intracellular pathogen offers enormous potential in understanding how molecular mechanisms enable intracellular parasitism and pathogenicity. [ABSTRACT FROM AUTHOR]

Legionnaires' disease is caused by Legionella (L.) pneumophila. Inhaling aerosolized water containing this bacteria is the most common transmission route. Shower heads used in the catering industry's dishwashing units are also potential amplifying systems for bacteria and possible sources of infection by generating droplets and aerosols. Therefore, these systems should not contain pathogenic bacteria. This study aims to monitor the microbial quality, Legionnaires' disease risk and L. pneumophila presence in tap water samples from the water outlet of the shower‐type dishwashing unit of mass catering establishments for a year. Seventy‐two tap water samples were microbiologically tested for total mesophilic aerobic bacteria count, coliform, Escherichia (E.) coli and L. pneumophila. DNA was isolated from L. pneumophila‐positive samples, and their serogroup was characterized by real‐time PCR. The correlation between seasonal variation and prevalence of L. pneumophila serogroup and L. pneumophila and other indicator bacteria were statistically tested by Spearman rank test (p < 0.05). Findings showed that 17 (24%) samples had microbial growth, 14 (19.4%) were positive for L. pneumophila and 13 isolates were characterized as L. pneumophila serogroup 1. The statistical analysis showed no significant correlation between seasonal variation (p = 0.491) and L. pneumophila and total mesophilic aerobic bacteria count, coliform and E. coli (p = 0.923). Overall, Legionella spp. is an essential indicator of the microbial quality in the tap water from mass catering establishments and should be regularly monitored for public health independently from seasonal variation and other indicator bacteria. [ABSTRACT FROM AUTHOR]

Background and Objectives: Legionnaires' disease (LD) is an acute respiratory disease with increasing annual numbers of reported domestic and global cases. This study aimed to establish foundational data for the prevention and control of LD by investigating the occurrence and infection routes of reported and suspected cases of LD in Gyeonggi Province, Korea, from January 2016 to December 2022, and by and analyzing the risk factors for death. Materials and Methods: A sex-and-age standardization was performed on LD patients and suspected cases reported in Gyeonggi Province. The monthly average number of confirmed cases was visualized using graphs, and a survival analysis was performed using Kaplan–Meier survival curves. The mortality risk ratio was estimated using the Cox proportional hazards model. Results: The incidence of LD in Gyeonggi Province mirrored the national trend, peaking in July with the highest number of confirmed and suspected cases. While there was no significant difference in survival rates by age, the survival rate was higher for suspected cases when analyzed separately. Comparing the death ratio by infection route, nosocomial infections showed the highest death ratio, and intensive care unit (ICU) admission and the presence of coinfections were significantly correlated with mortality. Factors such as nosocomial infection, admission within 1 to 3 days following diagnosis, and the development of complications were factors contributing to a higher risk of death. Conclusions: The general characteristics of patients with LD were similar to those suggested by previous studies. The proportion of community-acquired infections was lower than in previous studies, but the length of hospital stay was similar for survivors and the deceased, and the mortality rate within 30 days after diagnosis was higher for nosocomial infections. In conclusion, nosocomial infection, a period of up to 3 days from admission to diagnosis, and complications were significantly related to the mortality rate of LD. [ABSTRACT FROM AUTHOR]

Objectives: On September 23, 2019, the North Carolina Division of Public Health identified a legionellosis increase in western North Carolina; most patients had recently attended the North Carolina Mountain State Fair. We conducted a source investigation. Methods: Cases were fair attendees with laboratory-confirmed legionellosis and symptom onset within 2 to 14 days (Legionnaires' disease) or ≤3 days (Pontiac fever). We conducted a case-control study matching cases to non-ill fair attendees as control participants and an environmental investigation, and we performed laboratory testing (Legionella bacteria culture and polymerase chain reaction) of 27 environmental samples from fairgrounds and hot tubs and 14 specimens from case patients. We used multivariable unconditional logistic regression models to calculate adjusted odds ratios for potential Legionella exposure sources and risk factors. Results: Of 136 people identified with fair-associated legionellosis, 98 (72%) were hospitalized and 4 (3%) died. Case patients were more likely than control participants to report walking by hot tub displays (adjusted odds ratio = 10.0; 95% CI, 4.2-24.1). Complete hot tub water treatment records were not kept, precluding evaluation of water maintenance conducted on display hot tubs. Legionella pneumophila sequence types (STs) were consistent among 10 typed clinical specimens (ST224) but distinct from the only positive environmental sample from the fair (ST7 and ST8). Conclusions: Hot tub displays were identified as the most likely outbreak source, making this the largest hot tub–associated Legionnaires' disease outbreak worldwide. Following the investigation, the North Carolina Division of Public Health and the Centers for Disease Control and Prevention released guidance on mitigating risk of Legionella exposure from hot tub displays. Results highlight the importance of properly maintaining equipment that aerosolizes water, including hot tubs intended for display purposes only. [ABSTRACT FROM AUTHOR]

We determined whether the incidence rates of travelassociated Legionnaires' disease (TALD) in hotels in Germany increased after a previous occurrence and whether control measures required by the European Legionnaires' Disease Surveillance Network after a cluster (>2 cases within 2 years) restored the rate to baseline. We analyzed TALD surveillance data from Germany during 2015-2019; a total of 307 TALD cases (163 domestic, 144 nondomestic) in hotels were reported. The incidence rate ratio was 5.5 (95% CI 3.6-7.9) for a second case and 25 (95% CI 11-50) for a third case after a cluster had occurred, suggesting that control measures initiated after the occurrence of TALD clusters might be inadequate to restore the incidence rate to baseline. Our findings indicate that substantial LD preventive measures should be explored by hotels or other accommodations after the first TALD case occurs to reduce the risk for future infections. [ABSTRACT FROM AUTHOR]

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Legionella is the causative agent of Legionnaires’ disease, and its prevalence in potable water is a significant public health issue. Water stagnation within buildings increases the risk of Legionella. However, there are limited studies investigating how stagnation arising through intermittent usage affects Legionella proliferation and the studies that are available do not consider viable but non culturable (VBNC) Legionella. This study used a model plumbing system to examine how intermittent water stagnation affects both VBNC and culturable Legionella. The model plumbing system contained a water tank supplying two biofilm reactors. The model was initially left stagnant for ≈5 months (147 days), after which one reactor was flushed daily, and the other weekly. Biofilm coupons, and water samples were collected for analysis at days 0, 14 and 28. These samples were analysed for culturable and VBNC Legionella, free-living amoebae, and heterotrophic bacteria. After 28 days, once-a-day flushing significantly (p

Objectives: The effectiveness of monotherapy and combination therapy with quinolones and macrolides for treating Legionnaires’ disease remains uncertain; this study aimed to assess the comparative effectiveness of three treatment approaches. Methods: Using a nationwide inpatient database, we analyzed 3560 eligible patients hospitalized for Legionnaires’ disease between April 1, 2014, and March 31, 2021; patients were divided into combination therapy, quinolone monotherapy, and macrolide monotherapy groups according to the antibiotics administered within 2 days of admission. We compared in-hospital mortality, total hospitalization costs, and length of stay across these groups using multiple propensity score analysis with inverse probability of treatment weighting. Results: Of the 3560 patients, there were 564 (15.8%), 2221 (62.4%), and 775 (21.8%) patients in the combination therapy, quinolone monotherapy, and macrolide monotherapy groups, respectively. No significant differences were observed in in-hospital mortality between combination therapy and quinolone monotherapy groups, and between combination therapy and macrolide monotherapy groups. There were no significant differences in total hospitalization costs or length of stay among the three groups. Conclusion: The study suggests that there may not be a significant advantage in using a combination of quinolones and macrolides over monotherapy for the treatment of Legionnaires’ disease. Given the potential for increased side effects, careful consideration is advised when choosing this combination therapy.

This article presents a case report of a 35-year-old Chinese woman who initially presented with symptoms resembling idiopathic inflammatory myopathy (IIM), a rare autoimmune disorder affecting muscles. However, further investigation revealed that she had legionnaire's disease (LD), a bacterial infection that mimicked the symptoms of IIM. The patient's diagnosis was confirmed through pathogen screening, and she was successfully treated with antibiotics. The case highlights the importance of considering infectious etiologies when diagnosing conditions that mimic IIM and emphasizes the need for a comprehensive diagnostic approach. [Extracted from the article]

The article discusses the importance of maintaining water quality in buildings and the role that water utilities can play in this process. While utilities are not responsible for water quality within buildings, they can implement measures such as secondary disinfection and corrosion control strategies to help building owners and operators maintain water quality. The article also highlights the efforts of the American Water Works Association's Premise Plumbing Committee (PPC) in synthesizing industry knowledge and providing guidance on topics such as controlling microbial growth and managing lead and copper in building plumbing systems. The PPC is also working towards creating a training and certification program for building water system (BWS) operators to ensure adequate management of BWSs and the control of microbial pathogens and other contaminants. [Extracted from the article]

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 FROM AUTHOR]

This document, titled "Clinical and Environmental Surveillance for the Prevention of Legionellosis," provides an overview of Legionella, a Gram-negative bacterium that can colonize water systems in various types of buildings and cause infections in humans. Legionella pneumophila is the most common species associated with human disease, causing Legionnaire's disease and Pontiac fever. The isolation and identification of Legionella from the environment are crucial for prevention and outbreak investigations. The COVID-19 pandemic has affected the epidemiology of legionellosis, with a decrease in travel-associated cases but an increase in hospital-acquired cases. Environmental testing for Legionella is important for safeguarding public health and preventing outbreaks. New approaches, such as water management programs and sequencing technologies, can provide valuable insights for prevention and surveillance. This document is part of a Special Issue that highlights recent advances in environmental surveillance, clinical diagnosis, and innovative monitoring methods for Legionellosis. [Extracted from the article]

This article discusses a case of Q fever, a rare zoonotic disease, in a 39-year-old male traveler who had recently returned from a family visit to Goiania, Brazil. The patient initially presented with fever and headache, followed by the onset of a dry cough. Diagnostic tests revealed lung consolidation and elevated inflammatory markers. The patient's condition worsened, but improved after treatment with antibiotics. The diagnosis of acute Q fever was confirmed retrospectively, and the patient did not experience any long-term complications. The article emphasizes the importance of recognizing and diagnosing Q fever promptly to ensure appropriate treatment and prevent complications. [Extracted from the article]

Abstract Background Legionnaires’ Disease (LD) rarely evolves into pulmonary abscesses. The current systematic review has been designed to explore therapeutical strategies in pulmonary cavitary LD. Methods A research strategy was developed and applied to the databases Embase, Pubmed, and Web of Science from the 1st of January 2000 to the 1st of November 2022. Original articles, case series, case reports, and guidelines written in English, French, German, Italian, and Dutch were considered. Furthermore, medical records of patients treated at the University Hospital UZ Brussel for LD cavitary pneumonia, between the 1st of January 2016 to the 1st of January 2022, were reviewed. Results Two patients were found by the UZ Brussel’s medical records investigation. Through the literature review, 23 reports describing 29 patients, and seven guidelines were identified. The overall evidence level was low. Result of synthesis (case reports) The median age was 48 years and 65% were male. A polymicrobial infection was detected in 11 patients (44%) with other aerobic bacteria being the most commonly found. At diagnosis, 52% of patients received combination therapy, and fluoroquinolones were the preferred antimicrobial class. Anaerobic coverage was neglected in 33% of patients. Result of synthesis (guidelines) Three guidelines favor monotherapy with fluoroquinolones or macrolides, while one suggested an antimicrobial combination in case of severe LD. Four guidelines recommended anaerobic coverage in case of lung abscesses. Conclusion To date, the evidence supporting cavitary LD treatment is low. Monotherapy lowers toxicity and might be as effective as combination therapy. Finally, anaerobes should not be neglected. Graphical Abstract

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.