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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]

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.

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]

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]

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

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]

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]

• In a systematic review, no significant differences regarding mortality, hospital length of stay or clinical complications were identified when comparing fluoroquinolones vs macrolides administration in hospitalized patients with moderate severity Legionella pneumonia. • When data from the three cohorts with severe pneumonia were pooled together, mortality with fluoroquinolones alone was statistically superior to macrolides alone (72.8 % vs 30.7 %, p value 0.027). • A randomized controlled trial in severe pneumonia is an unmet clinical need to determine if one class of antibiotic is superior to another or whether a combination therapy regimen provides any significant clinical benefit over monotherapy. The optimal antimicrobial regimen for adults with respiratory failure due to Legionella pneumonia remains controversial. A systematic review was performed to assess the impact on outcomes comparing quinolones versus macrolides. A literature search was conducted in PubMed, Cochrane Library and Web of Science between 2012 and 2022. It yielded 124 potentially articles and ten observational studies met the inclusion criteria. A total of 4271 patients were included, 2879 (67 %) were male. A total of 1797 (42 %) subjects required intensive care unit (ICU) admission and 942 (52 %) mechanical ventilation. Fluoroquinolones and macrolides alone were administered in 1397 (33 %) and 1500 (35 %) subjects, respectively; combined therapy in 204 (4.8 %) patients. Overall mortality was 7.4 % (319 patients), with no difference between antibiotics. When data from the three studies with severe pneumonia were pooled together, mortality with fluoroquinolones alone was statistically superior to macrolides alone (72.8 % vs 30.8 %, p value 0.027). Hospital length of stay and complications were comparable. Our findings suggest that macrolides and quinolones were comparable for hospitalized Legionella pneumonia. However, in severe pneumonia, a randomized clinical trial is an unmet clinical need. PROSPERO registration number: CRD42023389308. [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]

Copyright of Epidemiological Review / Przegląd Epidemiologiczny is the property of National Institute of Public Health - National Institute of Hygiene and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Despite the growing prevalence of legionellosis in Poland and worldwide, little is known about the extent of public awareness regarding the seriousness of this disease and the appropriate preventive measures. The aim of this work is to assess the Polish adults’ knowledge, perceptions, and beliefs about legionellosis and its causative agents, risk factors, exposure, and other relevant facts. Data for this cross-sectional study were gathered via a questionnaire that was constructed and validated by the study investigators before commencing the survey, which lasted from January to March 2022. Knowledge, attitude and practice towards legionella were measured and quantified. One-way ANOVA and chi square tests were used to compare between demographic variables and the level of knowledge. Regression analysis was conducted to examine the predictors for higher knowledge among study participants. A total of 251 participants with a mean age of 28.26 ± 9.6 were enrolled in the current study. Over two thirds (74%) were females, with higher education (62%). Older age was associated with less knowledge about legionellosis (B = -0.049, p < 0.001), while higher education was associated with more knowledge (B = 1.656, p < 0.001). No significant differences were found between genders (p = 0.066). A knowledge gap was present for diagnostic tests regarding legionella. On the other hand, knowledge about prevention procedures was quite high among study participants. This study showed that overall knowledge about legionellosis in Polish adults was quite low. In particular, older age groups and the less educated are in need of more awareness of legionellosis disease. A knowledge gap was particularly present regarding how the disease is diagnosed. Awareness campaigns containing simple, easy-to-understand information could prove useful in combating the disease.

Progressive climate change holds the potential for increasing human health risks from waterborne infections and intoxications, e. g. through an increase in pathogen concentrations in water bodies, through the establishment of new pathogens or through possible changes in pathogen properties. This paper presents some examples of potential impacts of climate change in Germany. Non-cholera Vibrio occur naturally in seawater, but can proliferate significantly in shallow water at elevated temperatures. In the case of Legionella, climate change could lead to temporary or longer-term increased incidences of legionellosis due to the combination of warm and wet weather. Higher temperatures in piped cold water or lower temperatures in piped hot water may also create conditions conducive to higher Legionella concentrations. In nutrient-rich water bodies, increased concentrations of toxigenic cyanobacteria may occur as temperatures rise. Heavy rainfall following storms or prolonged periods of heat and drought can lead to increased levels of human pathogenic viruses being washed into water bodies. Rising temperatures also pose a potential threat to human health through pathogens causing mycoses and facultatively pathogenic micro-organisms: increased infection rates with non-tuberculous mycobacteria or fungi have been documented after extreme weather events.

Legionellosis, notably Legionnaires’ disease, is recognized globally and in New Zealand (Aotearoa) as a major cause of community-acquired pneumonia. We analyzed the temporal, geographic, and demographic epidemiology and microbiology of Legionnaires’ disease in New Zealand by using notification and laboratory-based surveillance data for 2000‒2020. We used Poisson regression models to estimate incidence rate ratios and 95% CIs to compare demographic and organism trends over 2 time periods (2000–2009 and 2010–2020). The mean annual incidence rate increased from 1.6 cases/100,000 population for 2000–2009 to 3.9 cases/100,000 population for 2010–2020. This increase corresponded with a change in diagnostic testing from predominantly serology with some culture to almost entirely molecular methods using PCR. There was also a marked shift in the identified dominant causative organism, from Legionella pneumophila to L. longbeachae. Surveillance for legionellosis could be further enhanced by greater use of molecular typing of isolates.

Introduction: Extrapulmonary legionella disease is rare and occasionally reported in immunocompromised patients; it includes lymphadenitis, panniculitis, hepatitis, atrio-ventricular block, arthritis, prosthetic valve endocarditis and myocarditis. In this article, we report a rare case of legionella suppurative lymphadenitis in an immunocompetent patient. Case: 53-year-old female patient from the Philippines, non-smoker, previously healthy who presented to our facility for chills and respiratory distress following a course of corticosteroid intake. She was admitted for respiratory failure and septic shock, and was diagnosed with legionella infection associated with extrapulmonary dissemination (lymphadenitis) leading to her death 72 h after admission. Discussion: Legionella is an important cause of community acquired pneumonia (CAP) and a delay in appropriate antibiotic therapy was associated with an increased mortality rate. Since legionnaire’s disease is indistinguishable from other forms of pneumonia without diagnostic testing, empiric antibiotic therapy regimen should cover legionella species. In unfortunate cases, a delay in the diagnosis and treatment may lead to extrapulmonary manifestations such as lymphadenitis and will be associated with worse patient outcomes. Conclusion: Legionella is an important cause of community acquired pneumonia which if left untreated can become complicated with extrapulmonary manifestations such as lymphadenitis and become eventually fatal to patients. A prompt early diagnosis and appropriate antimicrobial therapy covering legionella should be considered whenever treating community acquired pneumonia.

Despite the growing prevalence of legionellosis in Poland and worldwide, little is known about the extent of public awareness regarding the seriousness of this disease and the appropriate preventive measures. The aim of this work is to assess the Polish adults’ knowledge, perceptions, and beliefs about legionellosis and its causative agents, risk factors, exposure, and other relevant facts. Data for this cross-sectional study were gathered via a questionnaire that was constructed and validated by the study investigators before commencing the survey, which lasted from January to March 2022. Knowledge, attitude and practice towards legionella were measured and quantified. One-way ANOVA and chi square tests were used to compare between demographic variables and the level of knowledge. Regression analysis was conducted to examine the predictors for higher knowledge among study participants. A total of 251 participants with a mean age of 28.26 ± 9.6 were enrolled in the current study. Over two thirds (74%) were females, with higher education (62%). Older age was associated with less knowledge about legionellosis (B = -0.049, p < 0.001), while higher education was associated with more knowledge (B = 1.656, p < 0.001). No significant differences were found between genders (p = 0.066). A knowledge gap was present for diagnostic tests regarding legionella. On the other hand, knowledge about prevention procedures was quite high among study participants. This study showed that overall knowledge about legionellosis in Polish adults was quite low. In particular, older age groups and the less educated are in need of more awareness of legionellosis disease. A knowledge gap was particularly present regarding how the disease is diagnosed. Awareness campaigns containing simple, easy-to-understand information could prove useful in combating the disease. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Medicine / Medycyna Środowiskowa is the property of Witold Chodzki Institute of Rural Medicine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Legionellosis is a respiratory disease of bacterial and environmental origin that usually presents two distinct clinical entities, "Legionnaires' disease" (LD) and "Pontiac fever". LD is an important cause of hospital-acquired pneumonia (HAP). The objective of this study is to describe the epidemiology of legionellosis-associated hospitalization (L-AH) in Spain from 2002 to 2021 and the burden of hospitalization due to legionellosis. Discharge reports from the Minimum Basic Data Set (MBDS) were used to retrospectively analyze hospital discharge data with a diagnosis of legionellosis, based on the ICD-9-CM and ICD-10-CM diagnosis codes, from 2002 to 2021. 21,300 L-AH occurred throughout the year during 2002–2021. The incidence of hospitalization associated per 100,000 inhabitants by month showed a similar trend for the 2002–2011, 2012–2021, and 2002–2021 periods. In Spain, during 2002–2021, the hospitalization rate (HR) in the autonomous communities ranged from 4.57 (2002–2011) to 0.24 (2012–2021) cases per 100,000 inhabitants. The HR of legionellosis in Spain has substantially increased across the 2002–2021 period, and the estimate is consistent with available European data. It is considered that in-depth epidemiological surveillance studies of legionellosis and improvements in the prevention and control of the disease are required in Spain. [ABSTRACT FROM AUTHOR]

Type 1 secretion systems (T1SSs) are broadly distributed among bacteria and translocate effectors with diverse function across the bacterial cell membrane. Legionella pneumophila, the species most commonly associated with Legionellosis, encodes a T1SS at the lssXYZABD locus which is responsible for the secretion of the virulence factor RtxA. Many investigations have failed to detect lssD, the gene encoding the membrane fusion protein of the RtxA T1SS, in non-pneumophila Legionella, which has led to the assumption that this system is a virulence factor exclusively possessed by L. pneumophila. Here we discovered RtxA and its associated T1SS in a novel Legionella taurinensis strain, leading us to question whether this system may be more widespread than previously thought. Through a bioinformatic analysis of publicly available data, we classified and determined the distribution of four T1SSs including the RtxA T1SS and four novel T1SSs among diverse Legionella spp. The ABC transporter of the novel Legionella T1SS Legionella repeat protein secretion system shares structural similarity to those of diverse T1SS families, including the alkaline protease T1SS in Pseudomonas aeruginosa. The Legionella bacteriocin (1-3) secretion systems T1SSs are novel putative bacteriocin transporting T1SSs as their ABC transporters include C-39 peptidase domains in their N-terminal regions, with LB2SS and LB3SS likely constituting a nitrile hydratase leader peptide transport T1SSs. The LB1SS is more closely related to the colicin V T1SS in Escherichia coli. Of 45 Legionella spp. whole genomes examined, 19 (42%) were determined to possess lssB and lssD homologs. Of these 19, only 7 (37%) are known pathogens. There was no difference in the proportions of disease associated and non-disease associated species that possessed the RtxA T1SS (p = 0.4), contrary to the current consensus regarding the RtxA T1SS. These results draw into question the nature of RtxA and its T1SS as a singular virulence factor. Future studies should investigate mechanistic explanations for the association of RtxA with virulence.

In August 2021, a legionellosis outbreak involving 7 persons occurred within a 500-meter radius in the Montérégie region of Québec, Canada. Near real-time modeling of wind direction along with epidemiologic and environmental investigations identified the possible source. Modeling wind direction could help identify likely Legionella pneumophila sources during legionellosis outbreaks.

Although legionellosis represents a widely underestimated disease for various reasons, the rate of Legionella pneumophila infections has increased steadily over the past 30 years. The present study describes the characteristics of patients hospitalized due to legionellosis. The present study retrospectively reviewed 10 cases of legionellosis during the defined period and documented the epidemiological and clinical characteristics of the patients, as well as the methods used for diagnosis and therapeutic management. The majority of the patients were male (80%) with a mean age of 55.8 years. The most common comorbidities were hypertension (40%) and tumors (20%). Fever was present in all the cases (100%) and the most frequent imaging finding was lung consolidation. Half of the cases exhibited hyponatremia, 40% of them had leukocytosis, and 50% of the patients presented elevated procalcitonin levels, as well as elevated levels of transaminases. In total, 2 patients (20%) required non-invasive oxygen support. All the cases presented a positive urinary antigen test for Legionella pneumophila serogroup 1. A total of 9 patients (90%) received levofloxacin-based therapy for a mean duration of 17.7 days. All the cases described herein were successfully discharged without any complications. On the whole, the present study demonstrates that a prompt clinical diagnosis along with early testing and treatment represent the cornerstone for positive outcomes in patients affected by Legionnaire's disease. [ABSTRACT FROM AUTHOR]

Copyright of Epidemiological Review / Przegląd Epidemiologiczny is the property of National Institute of Public Health - National Institute of Hygiene and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Legionellosis is a respiratory disease related to environmental health. There have been manifold studies of pipe materials, risk installations and legionellosis without considering the type of transferred water. The objective of this study was to determine the potential development of the causative agent Legionella pneumophila regarding air–water cooling units, legislative compliance, pipe material and type of water. Forty-four hotel units in Andalusia (Spain) were analysed with respect to compliance with Spanish health legislation for the prevention of legionellosis. The chi-square test was used to explain the relationship between material–water and legislative compliance, and a biplot of the first two factors was generated. Multiple correspondence analysis (MCA) was performed on the type of equipment, legislative compliance, pipe material and type of water, and graphs of cases were constructed by adding confidence ellipses by categories of the variables. Pipe material–type of water (p value = 0.29; p < 0.05) and legislative compliance were not associated (p value = 0.15; p < 0.05). Iron, stainless steel, and recycled and well water contributed the most to the biplot. MCA showed a global pattern in which lead, iron and polyethylene were well represented. Confidence ellipses around categories indicated significant differences among categories. Compliance with Spanish health legislation regarding the prevention and control of legionellosis linked to pipe material and type of water was not observed. [ABSTRACT FROM AUTHOR]

According to current knowledge about legionella transmission, healthcare workers (HCWs) are at an increased risk of exposure. The aim of this research was to systematically review the literature about HCWs' exposure to legionella and establish whether there is an occupational risk. This was a systematic review and meta-analysis. PubMed, Scopus and Web of Science were searched to identify studies regarding the occupational risk of legionellosis for HCWs. Keywords used in the search were 'Legionella pneumophila ', 'occupational medicine', 'occupational' and 'risk'. Selected studies were reviewed to assess the quality and meta-analysed. Finally, the nine epidemiological principles of Bradford–Hill criteria were used to assess whether legionellosis could be considered an occupational risk for HCWs. The search strategy retrieved 124 studies, and 10 studies were included in the present review. The overall study quality was low. The pooled odds ratio estimate was 2.45 (95% confidence interval: 1.52–3.96). The assessment using Bradford–Hill criteria showed that only two criteria (plausibility and coherence) were met, which is insufficient to establish an occupational risk. This systematic review suggests that there is a higher risk of legionella exposure for HCWs, but there is currently no clinical evidence. Further studies with appropriate study design are needed to determine whether legionella infection is an occupational risk for HCWs. [ABSTRACT FROM AUTHOR]

This study examined 184 legionellosis outbreaks in the United States reported to the Centers for Disease Control and Prevention's Waterborne Disease and Outbreak Surveillance System, from 2001 to 2017. Drinking water characteristics examined include source water type, disinfectant type, exposure setting, geographical distribution by U.S. Census Divisions, and the public water system size (population served). This study found that most of the reported drinking water-associated legionellosis outbreaks occurred in eastern United States, including 35% in the South Atlantic, 32% in the Middle Atlantic, and 16% in the East North Central Census Divisions were linked with building water systems in healthcare and hotel settings; and were associated with buildings receiving drinking water from public water systems serving >10,000 people. Targeted evaluations and interventions may be useful to further determine the combination of factors, such as disinfectant residual type and drinking water system size that may lead to legionellosis outbreaks. HIGHLIGHTS Most of the reported legionellosis outbreaks associated with drinking water in the United States (2001–2017) have been documented in healthcare and hotel/motel settings.; Reported legionellosis outbreaks were more often associated with buildings obtaining water from large, chlorinated, surface water systems than with small systems (serving 10,000 or fewer), using disinfectants other than chlorine and ground water sources.;