Factors Associated with Legionella Detection in the Water Systems of National Lodging Organization Facilities with Water Management Programs in the United States

A better understanding of risk factors and the predictive capability of water management program (WMP) data in detecting Legionella are needed to inform the efforts aimed at reducing Legionella growth and preventing outbreaks of Legionnaires' disease. Using WMPs and Legionella testing data from a national lodging organization in the United States, we aimed to (1) identify factors associated with Legionella detection and (2) assess the ability of WMP disinfectant and temperature metrics to predict Legionella detection. We conducted a logistic regression analysis to identify WMP metrics associated with Legionella serogroup 1 (SG1) detection. We also estimated the predictive values for each of the WMP metrics and SG1 detection. Of 5435 testing observations from 2018 to 2020, 411 (7.6%) had SG1 detection, and 1606 (29.5%) had either SG1 or non-SG1 detection. We found failures in commonly collected WMP metrics, particularly at the primary test point for total disinfectant levels in hot water, to be associated with SG1 detection. These findings highlight that establishing and regularly monitoring water quality parameters for WMPs may be important for preventing Legionella growth and subsequent disease. However, while unsuitable water quality parameter results are associated with Legionella detection, this study found that they had poor predictive value, due in part to the low prevalence of SG1 detection in this dataset. These findings suggest that Legionella testing provides critical information to validate if a WMP is working, which cannot be obtained through water quality parameter measurements alone.

Legionella-Induced Rhabdomyolysis and Acute Kidney Injury: A Case Report

Legionella pneumonia is a severe form of pneumonia caused by the bacterium Legionella pneumophila. It often presents with atypical symptoms and can lead to complications such as rhabdomyolysis and acute kidney injury (AKI). Here, we report a case of Legionella pneumonia-induced rhabdomyolysis and AKI in a 32-year-old male. Laboratory investigations revealed elevated creatinine kinase levels and acute kidney injury. Further investigation confirmed Legionella pneumonia. The patient was promptly treated with appropriate antibiotics and supportive care, resulting in clinical improvement and resolution of rhabdomyolysis and AKI. This case underscores the importance of considering Legionella pneumonia as a potential cause of rhabdomyolysis and AKI, especially in patients with atypical pneumonia presentations.

Efficacy of omadacycline in the treatment of Legionella pneumonia: a case report

Legionella, one of the main pathogens that causes community-acquired pneumonia, can lead to Legionella pneumonia, a condition characterized predominantly by severe pneumonia. This disease, caused by the bacterium Legionella pneumophila, can quickly progress to critical pneumonia and is often associated with damage to multiple organs. As a result, it requires close attention in terms of clinical diagnosis and treatment. Omadacycline, a new type of tetracycline derivative belonging to the aminomethylcycline class of antibiotics, is a semi-synthetic compound derived from minocycline. Its key structural feature, the aminomethyl modification, allows omadacycline to overcome bacterial resistance and broadens its range of effectiveness against bacteria. Clinical studies have demonstrated that omadacycline is not metabolized in the body, and patients with hepatic and renal dysfunction do not need to adjust their dosage. This paper reports a case of successful treatment of Legionella pneumonia with omadacycline in a patient who initially did not respond to empirical treatment with moxifloxacin. The patient also experienced electrolyte disturbance, as well as dysfunction in the liver and kidneys, delirium, and other related psychiatric symptoms.

Legionella pneumonia: A Case of Fever Prolonged for 10 Days

Legionnaires' disease is a potentially severe type of pneumonia most often caused by the organism Legionella pneumophila. Exposure to this bacterial pathogen typically happens in the community but may also occur in the hospital setting. This report describes the case of a patient who presented due to 10 days of fever, shortness of breath, and diarrhea, with initial imaging demonstrating multifocal pneumonia. The patient was appropriately started on empiric antibiotics for community-acquired pneumonia and admitted to the medicine floor. The patient showed no meaningful improvement in his initial hospital course on empiric antibiotics with continued oxygen requirements. Meanwhile, urine Legionella antigen testing returned positive on hospital day four, and after tailoring antibiotics accordingly, the patient's clinical status improved significantly. This case report highlights the efficacy of broad testing in the initial admission and the need for constant re-evaluation in the context of a patient not improving with appropriate therapy.

Opportunistic Pathogens in Drinking Water Distribution Systems-A Review

In contrast to "frank" pathogens, like Salmonella entrocolitica, Shigella dysenteriae, and Vibrio cholerae, that always have a probability of disease, "opportunistic" pathogens are organisms that cause an infectious disease in a host with a weakened immune system and rarely in a healthy host. Historically, drinking water treatment has focused on control of frank pathogens, particularly those from human or animal sources (like Giardia lamblia, Cryptosporidium parvum, or Hepatitis A virus), but in recent years outbreaks from drinking water have increasingly been due to opportunistic pathogens. Characteristics of opportunistic pathogens that make them problematic for water treatment include: (1) they are normally present in aquatic environments, (2) they grow in biofilms that protect the bacteria from disinfectants, and (3) under appropriate conditions in drinking water systems (e.g., warm water, stagnation, low disinfectant levels, etc.), these bacteria can amplify to levels that can pose a public health risk. The three most common opportunistic pathogens in drinking water systems are Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa. This report focuses on these organisms to provide information on their public health risk, occurrence in drinking water systems, susceptibility to various disinfectants, and other operational practices (like flushing and cleaning of pipes and storage tanks). In addition, information is provided on a group of nine other opportunistic pathogens that are less commonly found in drinking water systems, including Aeromonas hydrophila, Klebsiella pneumoniae, Serratia marcescens, Burkholderia pseudomallei, Acinetobacter baumannii, Stenotrophomonas maltophilia, Arcobacter butzleri, and several free-living amoebae including Naegleria fowleri and species of Acanthamoeba. The public health risk for these microbes in drinking water is still unclear, but in most cases, efforts to manage Legionella, mycobacteria, and Pseudomonas risks will also be effective for these other opportunistic pathogens. The approach to managing opportunistic pathogens in drinking water supplies focuses on controlling the growth of these organisms. Many of these microbes are normal inhabitants in biofilms in water, so the attention is less on eliminating these organisms from entering the system and more on managing their occurrence and concentrations in the pipe network. With anticipated warming trends associated with climate change, the factors that drive the growth of opportunistic pathogens in drinking water systems will likely increase. It is important, therefore, to evaluate treatment barriers and management activities for control of opportunistic pathogen risks. Controls for primary treatment, particularly for turbidity management and disinfection, should be reviewed to ensure adequacy for opportunistic pathogen control. However, the major focus for the utility's opportunistic pathogen risk reduction plan is the management of biological activity and biofilms in the distribution system. Factors that influence the growth of microbes (primarily in biofilms) in the distribution system include, temperature, disinfectant type and concentration, nutrient levels (measured as AOC or BDOC), stagnation, flushing of pipes and cleaning of storage tank sediments, and corrosion control. Pressure management and distribution system integrity are also important to the microbial quality of water but are related more to the intrusion of contaminants into the distribution system rather than directly related to microbial growth. Summarizing the identified risk from drinking water, the availability and quality of disinfection data for treatment, and guidelines or standards for control showed that adequate information is best available for management of L. pneumophila. For L. pneumophila, the risk for this organism has been clearly established from drinking water, cases have increased worldwide, and it is one of the most identified causes of drinking water outbreaks. Water management best practices (e.g., maintenance of a disinfectant residual throughout the distribution system, flushing and cleaning of sediments in pipelines and storage tanks, among others) have been shown to be effective for control of L. pneumophila in water supplies. In addition, there are well documented management guidelines available for the control of the organism in drinking water distribution systems. By comparison, management of risks for Mycobacteria from water are less clear than for L. pneumophila. Treatment of M. avium is difficult due to its resistance to disinfection, the tendency to form clumps, and attachment to surfaces in biofilms. Additionally, there are no guidelines for management of M. avium in drinking water, and one risk assessment study suggested a low risk of infection. The role of tap water in the transmission of the other opportunistic pathogens is less clear and, in many cases, actions to manage L. pneumophila (e.g., maintenance of a disinfectant residual, flushing, cleaning of storage tanks, etc.) will also be beneficial in helping to manage these organisms as well.

Legionnaires Disease in Solid Organ Transplant Recipients: A Decade-Long Nationwide Study in France

BACKGROUND

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.

RESEARCH QUESTION

What are the clinical manifestations, radiologic presentation, risk factors for severity, treatment, and outcome of LD in solid organ transplant recipients?

STUDY DESIGN AND METHODS

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.

RESULTS

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).

INTERPRETATION

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.

Molecular regulation of virulence in Legionella pneumophila

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.

Estimating the burden of illness caused by domestic waterborne Legionnaires' disease in Canada: 2015-2019

Legionellosis is a disease caused by the bacterium Legionella that most commonly presents as Legionnaires' disease (LD), a severe form of pneumonia. From 2015 to 2019, an average of 438 LD cases per year were reported in Canada. However, it is believed that the actual number of cases is much higher, since LD may be underdiagnosed and underreported. The purpose of this study was to develop an estimate of the true incidence of illnesses, hospitalizations, and deaths associated with LD in Canada. Values were derived using a stochastic model, based on Canadian surveillance data from 2015 to 2019, which were scaled up to account for underdiagnosis and underreporting. Overall, there were an estimated 1,113 (90% CrI: 737-1,730) illnesses, 1,008 (90% CrI: 271-2,244) hospitalizations, and 34 (90% CrI: 4-86) deaths due to domestically acquired waterborne LD annually in Canada from 2015 to 2019. It was further estimated that only 36% of illnesses and 39% of hospitalizations and deaths were captured in surveillance, and that 22% of illnesses were caused by Legionella serogroups and species other than Legionella pneumophila serogroup 1 (non-Lp1). This study highlights the true burden and areas for improvement in Canada's surveillance and detection of LD.

Association between the Timing of Urinary Antigen Testing and Outcomes in Legionella Pneumonia Patients: A Nationwide Database Study

Objective Recommendations on the timing of Legionella urinary antigen tests for community-acquired pneumonia patients differ among guidelines in Japan, the United States, and European nations. We therefore evaluated the association between the timing of urinary antigen tests and in-hospital mortality in patients with Legionella pneumonia. Methods We conducted a retrospective cohort study using the Diagnosis Procedure Combination database, a nationwide database of acute care inpatients in Japan. Patients who underwent Legionella urinary antigen tests on the day of admission formed the tested group. Patients who were tested on day 2 of admission or later or were unexamined formed the control group. We performed a propensity score matching analysis to compare in-hospital mortality, length of hospital stay and duration of antibiotics use between the two groups. Results Of the 9,254 eligible patients, 6,933 were included in the tested group. One-to-one propensity score matching generated 1,945 pairs. The tested group had a significantly lower 30-day in-hospital mortality than the control group (5.7 vs. 7.7%; odds ratio, 0.72; 95% confidence intervals, 0.55-0.95; p=0.020). The tested group also showed a significantly shorter length of stay and duration of antibiotics use than the control group. Conclusion Urine antigen testing upon admission was associated with better outcomes in patients with Legionella pneumonia. Urine antigen tests upon admission may be recommended for all patients with severe community-acquired pneumonia.

Effects of the COVID-19 Pandemic on Legionella Water Management Program Performance across a United States Lodging Organization

Legionella, the bacterium that causes Legionnaires' disease, can grow and spread in building water systems and devices. The COVID-19 pandemic impacted building water systems through reductions in water usage. Legionella growth risk factors can be mitigated through control measures, such as flushing, to address stagnation, as part of a water management program (WMP). A national lodging organization (NLO) provided WMP data, including Legionella environmental testing results for periods before and during the pandemic. The statistical analysis revealed an increased risk of water samples testing positive for Legionella during the pandemic, with the greatest increase in risk observed at the building's cold-water entry test point. Sample positivity did not vary by season, highlighting the importance of year-round Legionella control activities. The NLO's flushing requirements may have prevented an increased risk of Legionella growth during the pandemic. However, additional control measures may be needed for some facilities that experience Legionella detections. This analysis provides needed evidence for the use of flushing to mitigate the impacts of building water stagnation, as well as the value of routine Legionella testing for WMP validation. Furthermore, this report reinforces the idea that WMPs remain the optimal tool to reduce the risk of Legionella growth and spread in building water systems.

A Rare Case of Community-Acquired Pneumonia Only Presenting With Diarrhea, Abdominal Pain, and Fever: A Case Report

Legionnaires' disease is an atypical pneumonia caused by Legionella pneumophila (L. pneumophila) pneumonia that features slow onset, nonproductive cough, fatigue, headache, sore throat, myalgias, and malaise. It can be difficult to diagnose, as it presents with extrapulmonary symptoms, and delay in treatment can be fatal. Here, we present the case of a previously healthy 32-year-old Caucasian male with Legionnaires disease who only presented to the clinic with abdominal pain and diarrhea. The patient did not have any pulmonary symptoms at the initial presentation. This presentation did not fit the diagnostic tools available for Legionnaires' disease, including a validated clinical prediction rule, which ruled out L. pneumophila infection with a sensitivity of 97% and a negative predictive value of 99.4%. Due to the complaint of abdominal pain, a flat/upright abdominal X-ray was ordered, which includes a chest X-ray. Upon analyzing the chest X-ray, a right lower lobe consolidation was identified, prompting an L. pneumophila urinary test to be added to the lab orders. This case represents the difficulties in diagnosing Legionnaires' disease due to the diverse clinical complexities of presentations, which may solely involve abdominal complaints.

Legionellosis on the rise: A scoping review of sporadic, community-acquired incidence in the United States

Over the past two decades, the incidence of legionellosis has been steadily increasing in the United States though there is noclear explanation for the main factors driving the increase. While legionellosis is the leading cause of waterborne outbreaks in the US, most cases are sporadic and acquired in community settings where the environmental source is never identified. This scoping review aimed to summarise the drivers of infections in the USA and determine the magnitude of impact each potential driver may have. A total of 1,738 titles were screened, and 18 articles were identified that met the inclusion criteria. Strong evidence was found for precipitation as a major driver, and both temperature and relative humidity were found to be moderate drivers of incidence. Increased testing and improved diagnostic methods were classified as moderate drivers, and the ageing U.S. population was a minor driver of increasing incidence. Racial and socioeconomic inequities and water and housing infrastructure were found to be potential factors explaining the increasing incidence though they were largely understudied in the context of non-outbreak cases. Understanding the complex relationships between environmental, infrastructure, and population factors driving legionellosis incidence is important to optimise mitigation strategies and public policy.

Clinical Reasoning: A 47-Year-Old Man With an Upper Respiratory Infection, Acute Confusion, Dysarthria, and Ataxia

A patient presenting with acute confusion, dysarthria, and appendicular ataxia with gait instability warrants a broad differential including emergent consideration of acute ischemic or hemorrhagic stroke. Moreover, in acute to subacute presentations, a wide array of etiologies including infectious causes, toxins, or autoimmune conditions may be considered. This article features a 47-year-old man who presented acutely with confusion, severe dysarthria, left upper extremity dysmetria, and unsteady gait. In this case, these neurologic signs were preceded by symptoms of an upper respiratory infection. In addition, MRI brain without contrast demonstrated a small focus of hyperintensity on diffusion-weighted imaging in the splenium of the corpus callosum with apparent diffusion coefficient match. The article illustrates a diagnostic approach in evaluating a patient with this constellation of clinical and radiologic findings, as well as pertinent management considerations. A comprehensive overview of other potential causative factors of the imaging findings is described to augment the reader's differential diagnosis. Finally, a literature review pertaining to the revealed diagnosis highlights the epidemiologic relevance and important clinical pearls.

The Geographic Distribution of Dimorphic Mycoses in the United States for the Modern Era

BACKGROUND

The dimorphic mycoses (DMs) of the United States-Histoplasma, Coccidioides, and Blastomyces-commonly known as endemic mycoses of North America (in addition to Paracoccidioides) are increasingly being diagnosed outside their historical areas of endemicity. Despite this trend, the maps outlining their geographic distributions have not been updated in more than half a century using a large, nationwide database containing individual-patient-level data.

METHODS

This was a retrospective analysis of >45 million Medicare fee-for-service beneficiaries from 1 January 2007 through 31 December 2016. Diagnoses of histoplasmosis, coccidioidomycosis, and blastomycosis were defined by International Classification of Diseases, Ninth/10th Revision, codes. The primary outcome was the incidence of histoplasmosis, coccidioidomycosis, and blastomycosis for each US county. Clinically meaningful thresholds for incidence were defined as 100 cases/100 000 person-years for histoplasmosis and coccidioidomycosis and 50 cases/100 000 person-years for blastomycosis.

RESULTS

There were 79 749 histoplasmosis, 37 726 coccidioidomycosis, and 6109 blastomycosis diagnoses in unique persons from 2007-2016 across 3143 US counties. Considering all US states plus Washington, DC, 94% (48/51) had ≥1 county above the clinically relevant threshold for histoplasmosis, 69% (35/51) for coccidioidomycosis, and 78% (40/51) for blastomycosis.

CONCLUSIONS

Persons with histoplasmosis, coccidioidomycosis, and blastomycosis are diagnosed in significant numbers outside their historical geographic distributions established >50 years ago. Clinicians should consider DM diagnoses based on compatible clinical syndromes with less emphasis placed on patients' geographic exposure. Increased clinical suspicion leading to a subsequent increase in DM diagnostic testing would likely result in fewer missed diagnoses, fewer diagnostic delays, and improved patient outcomes.

Legionella monitoring results by water quality characteristics in a large public water system

Legionella, the causative agent of Legionnaires' disease, is an emerging concern for water utilities. Passaic Valley Water Commission (PVWC) is a public drinking water supplier, which provides treated surface water to approximately 800,000 customers in New Jersey. To evaluate the occurrence of Legionella in the PVWC distribution system, swab, first draw, and flushed cold water samples were collected from total coliform sites (n = 58) during a summer and winter sampling event. Endpoint PCR detection methods were combined with culture for Legionella detection. Among 58 total coliform sites during the summer, 17.2% (10/58) of first draw samples were positive for 16S and mip Legionella DNA markers and 15.5% (9/58) in flushed samples. Across both summer and winter sampling, a total of four out of 58 sites had low-level culture detection of Legionella spp. (0.5-1.6 CFU/mL) among first draw samples. Only one site had both a first and flush draw detection (8.5 CFU/mL and 1.1 CFU/mL) for an estimated culture detection frequency of 0% in the summer and 1.7% in the winter among flushed draw samples. No L. pneumophila was detected by culture. Legionella DNA detection was significantly greater in the summer than in the winter, and detection was greater in samples collected from areas treated with phosphate. No statistical difference was found between first draw and flush sample detection. Total organic carbon, copper, and nitrate were significantly associated with Legionella DNA detection.

Structure and Function of the Dot/Icm T4SS

The Legionella pneumophila Dot/Icm type IV secretion system (T4SS) delivers effector proteins into host cells during infection. Despite its significance as a potential drug target, our current understanding of its atomic structure is limited to isolated subcomplexes. In this study, we used subtomogram averaging and integrative modeling to construct a nearly-complete model of the Dot/Icm T4SS accounting for seventeen protein components. We locate and provide insights into the structure and function of six new components including DotI, DotJ, DotU, IcmF, IcmT, and IcmX. We find that the cytosolic N-terminal domain of IcmF, a key protein forming a central hollow cylinder, interacts with DotU, providing insight into previously uncharacterized density. Furthermore, our model, in combination with analyses of compositional heterogeneity, explains how the cytoplasmic ATPase DotO is connected to the periplasmic complex via interactions with membrane-bound DotI/DotJ proteins. Coupled with in situ infection data, our model offers new insights into the T4SS-mediated secretion mechanism.

Clinical and Laboratory Diagnosis of Legionella Pneumonia

Legionella pneumonia is a relatively rare but extremely progressive pulmonary infection with high mortality. Traditional cultural isolation remains the gold standard for the diagnosis of Legionella pneumonia. However, its harsh culture conditions, long turnaround time, and suboptimal sensitivity do not meet the clinical need for rapid and accurate diagnosis, especially for critically ill patients. So far, pathogenic detection techniques including serological assays, urinary antigen tests, and mass spectrometry, as well as nucleic acid amplification technique, have been developed, and each has its own advantages and limitations. This review summarizes the clinical characteristics and imaging findings of Legionella pneumonia, then discusses the advances, advantages, and limitations of the various pathogenetic detection techniques used for Legionella pneumonia diagnosis. The aim is to provide rapid and accurate guiding options for early identification and diagnosis of Legionella pneumonia in clinical practice, further easing healthcare burden.

New immunomagnetic separation method to analyze risk factors for Legionella colonization in health care centres

BACKGROUND

It's pivotal to control the presence of legionella in sanitary structures. So, it's important to determine the risk factors associated with Legionella colonization in health care centres. In recent years that is why new diagnostic techniques have been developed.

OBJECTIVE

To evaluate risks factors for Legionella colonization using a novel and more sensitive Legionella positivity index.

METHODS

A total of 204 one-litre water samples (102 cold water samples and 102 hot water samples), were collected from 68 different sampling sites of the hospital water system and tested for Legionella spp. by two laboratories using culture, polymerase chain reaction and a method based on immunomagnetic separation (IMS). A Legionella positivity index was defined to evaluate Legionella colonization and associated risk factors in the 68 water samples sites. We performed bivariate analyses and then logistic regression analysis with adjustment of potentially confounding variables. We compared the performance of culture and IMS methods using this index as a new gold standard to determine if rapid IMS method is an acceptable alternative to the use of slower culture method.

RESULTS

Based on the new Legionella positivity index, no statistically significant differences were found neither between laboratories nor between methods (culture, IMS). Positivity was significantly correlated with ambulatory health assistance (p = 0.05) and frequency of use of the terminal points. The logistic regression model revealed that chlorine (p = 0.009) and the frequency of use of the terminal points (p = 0.001) are predictors of Legionella colonization. Regarding this index, the IMS method proved more sensitive (69%) than culture method (65.4%) in hot water samples.

SIGNIFICANCE

We showed that the frequency of use of terminal points should be considered when examining environmental Legionella colonization, which can be better evaluated using the provided Legionella positivity index. This study has implications for the prevention of Legionnaires' disease in hospital settings.

Rutile-TiO2/PtO2 Glass Coatings Disinfects Aquatic Legionella pneumophila via Morphology Change and Endotoxin Degradation under LED Irradiation

Legionella pneumophila (L. pneumophila) is the causative agent of Legionnaires’ disease and Pontiac fever, collectively known as legionellosis. L. pneumophila infection occurs through inhalation of contaminated aerosols from water systems in workplaces and institutions. The development of disinfectants that can eliminate L. pneumophila in such water systems without evacuating people is needed to prevent the spread of L. pneumophila. Photocatalysts are attractive disinfectants that do not harm human health. In particular, the TiO2 photocatalyst kills L. pneumophila under various conditions, but its mode of action is unknown. Here, we confirmed the high performance of TiO2 photocatalyst containing PtO2 via the degradation of methylene blue (half-value period: 19.2 min) and bactericidal activity against Escherichia coli (half-value period: 15.1 min) in water. Using transmission electron microscopy, we demonstrate that the disinfection of L. pneumophila (half-value period: 6.7 min) by TiO2 photocatalyst in water is accompanied by remarkable cellular membrane and internal damage to L. pneumophila. Assays with limulus amebocyte lysate and silver staining showed the release of endotoxin from L. pneumophila due to membrane damage and photocatalytic degradation of this endotoxin. This is the first study to demonstrate the disinfection mechanisms of TiO2 photocatalyst, namely, via morphological changes and membrane damage of L. pneumophila. Our results suggest that TiO2 photocatalyst might be effective in controlling the spread of L. pneumophila.

Potential environmental and health risk when returning to normal amidst COVID-19 vaccination

Due to the SARS-CoV-2 pandemic and restricted occupancy in work and school settings, there is a heightened risk for Legionella infection. An increase of stagnation in water pipe systems with limited water usage stimulates biofilm build-up, further facilitating Legionella proliferation. Individuals can inhale infected water aerosols and develop Legionellosis that can progress into mild flu-like symptoms or severe pneumonia. While SARS-CoV-2 vaccinations have been introduced globally, there is a concern for bacterial coinfections as individuals resume normal activities. Even with new SARS-CoV-2 variants circulating, Legionella persists as a public health threat as vulnerable communities' restrictions fluctuate. Proper water monitoring and management are critical while reopening communities. This article features Legionella characteristics and novel case reports amidst the pandemic. This article encourages greater awareness for building managers to minimize water stagnancy by disinfecting water distribution systems and promotes healthcare professionals to properly diagnose other illnesses during the ongoing pandemic to reduce morbidity and mortality.

Overview of the Clinical and Molecular Features of Legionella Pneumophila: Focus on Novel Surveillance and Diagnostic Strategies

Legionella pneumophila (L. pneumophila) is one of the most threatening nosocomial pathogens. The implementation of novel and more effective surveillance and diagnostic strategies is mandatory to prevent the occurrence of legionellosis outbreaks in hospital environments. On these bases, the present review is aimed to describe the main clinical and molecular features of L. pneumophila focusing attention on the latest findings on drug resistance mechanisms. In addition, a detailed description of the current guidelines for the disinfection and surveillance of the water systems is also provided. Finally, the diagnostic strategies available for the detection of Legionella spp. were critically reviewed, paying the attention to the description of the culture, serological and molecular methods as well as on the novel high-sensitive nucleic acid amplification systems, such as droplet digital PCR.

Legionella pneumophila and Staphylococcus aureus co-infections in a patient with SARS-CoV-2

A man fully mRNA-vaccinated against COVID-19 presented to our hospital with an acute febrile illness, respiratory symptoms and a positive test for SARS-CoV-2. He was later found early into hospitalisation to have two morbid bacterial co-infections: Legionella pneumophila serogroup 1 and methicillin-resistant Staphylococcus aureus (MRSA). Although this patient was initially admitted for COVID-19 management, his initial presentation was remarkable for lobar pneumonia, hyponatraemia and rhabdomyolysis more compatible with Legionnaire's disease than severe COVID-19. On discovery of MRSA pneumonia as a second bacterial infection, immunosuppressive COVID-19 therapies were discontinued and targeted antibiotics towards both bacterial co-infections were initiated. The patient's successful recovery highlighted the need to have high suspicion for bacterial co-infections in patients presenting with community-acquired pneumonia and a positive SARS-CoV-2 test, as patients with serious bacterial co-infections may have worse outcomes with use of immunosuppressive COVID-19 therapies.

Rising Incidence of Legionnaires' Disease and Associated Epidemiologic Patterns, United States, 1992-2018

Reported Legionnaires' disease (LD) cases began increasing in the United States in 2003 after relatively stable numbers for >10 years; reasons for the rise are unclear. We compared epidemiologic patterns associated with cases reported to the Centers for Disease Control and Prevention before and during the rise. The age-standardized average incidence was 0.48 cases/100,000 population during 1992-2002 compared with 2.71 cases/100,000 in 2018. Reported LD incidence increased in nearly every demographic, but increases tended to be larger in demographic groups with higher incidence. During both periods, the largest number of cases occurred among White persons, but the highest incidence was in Black or African American persons. Incidence and increases in incidence were generally largest in the East North Central, Middle Atlantic, and New England divisions. Seasonality was more pronounced during 2003-2018, especially in the Northeast and Midwest. Rising incidence was most notably associated with increasing racial disparities, geographic focus, and seasonality.

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

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

National survey of physicians in Japan regarding their use of diagnostic tests for legionellosis

INTRODUCTION

Bacterial culture remains the gold standard for the diagnosis of legionellosis. However, past reports indicate that most physicians use the urinary antigen test (UAT) alone. Combining it with other tests is important, especially in patients with negative UAT results. The aim of this study was to investigate the current situation of legionellosis diagnostics and clarify the issues that need to be addressed.

METHODS

Between March 1, 2021 and April 30, 2021, a questionnaire survey was conducted in an anonymous manner among physicians working in Japan. Questionnaires were generated on a website and asked questions in a multiple-choice format.

RESULTS

Valid responses were received from 309 physicians during the study period. Most (92.9%) physicians reported using UAT as the initial test for patients suspected of having legionellosis, and <10% reported using other tests (e.g., culture, nucleic acid amplification test [NAAT], Gimenez staining, and serum antibody titer measurement [ATM]). When the initial test result was negative, 63% of physicians reported not conducting additional tests. Even when they chose to run additional tests, at most 27.8%, 23.6%, 12.3%, and 10.4% of all physicians used NAAT, culture, Gimenez staining, and serum ATM, respectively. The major reasons for not using tests other than UAT were "unavailability in the medical facility," "long turn-around time," and "difficult to collect sputum."

CONCLUSIONS

The present survey revealed that most physicians in Japan used UAT alone for diagnosing legionellosis. Eliminating barriers to creating a reasonable environment and edification of physicians are needed to improve the current situation.

Multidisciplinary Management of Legionella Disease in Immunocompromised Patients

Legionella pneumonia is a gram-negative bacterial infection commonly associated with aerosol transmission from contaminated water sources. Impaired immunity leads to delayed clearance of infection and further predisposes individuals with Legionella pneumonia at risk of developing complications. We present a case report on a renal transplant patient with comorbid cardiac and renal dysfunction who developed community-acquired Legionella pneumonia. The case emphasizes the importance of adopting a multidisciplinary approach when managing Legionella infection in patients with multiple comorbidities and immunosuppressive states.

Is a Proactive Approach to Controlling Legionella in the Environment Justified?

Research background

Legionella are Gram-negative bacteria that are ubiquitous in the natural environment. Contaminated water in man-made water systems is a potential source of transmission of legionnaires’ disease. The aim of this study is to explore the prevalence of Legionella pneumophila in the drinking water distribution system (DWDS) of Primorje-Gorski Kotar (PGK) County, Croatia, for the period 2013-2019, coupled with the incidence of legionnaires’ disease. A number of L. pneumophila-positive samples (>100 CFU/L), serogroup distribution and the degree of contamination of specific facilities (health and aged care, tourism, and sports) were assessed. Based on the obtained results, the reasoning for the implementation of a mandatory Legionella environmental surveillance program was assessed.

Experimental approach

Sample testing for Legionella was carried out according to the standard method for enumeration of this bacterium. A heterotrophic plate count (HPC) and Pseudomonas aeruginosa number were analysed along with the basic physicochemical indicators of drinking water quality. The research period was divided into two parts, namely, the 2013-2018 period (before implementation of the prevention program, after the outbreak of legionnaires’ disease), and the year 2019 (proactive approach, no disease cases recorded).

Results and conclusion

During the 7-year observation period in PGK County, an increase in the number of samples tested for Legionella was found. An increase in Legionella-positive samples (particularly pronounced during the warmer part of the year) was recorded, along with a growing trend in the number of reported legionnaires’ disease cases. In addition to hot water systems, the risk of Legionella colonisation also applies to cold water systems. Health and aged care facilities appear to be at highest risk. In addition to the higher proportion of positive samples and a higher degree of microbiological load in these facilities, the highest proportion of L. pneumophila SGs 2-14 was identified. Due to the diagnostic limitations of the applied tests, the number of legionnaires’ disease cases is underdiagnosed.

Novelty and scientific contribution

The introduction of a mandatory preventive approach to monitoring Legionella in DWDS water samples, along with the definition of national criteria for the interpretation of the results will create the preconditions for diagnosis and adequate treatment of larger numbers of legionnaires’ disease cases.

Hospital-acquired Legionella pneumonia outbreak at an academic medical center: Lessons learned

BACKGROUND

An outbreak of Legionella pneumonia occurred at a university hospital using copper-silver ionization for potable water disinfection. We present the epidemiological and laboratory investigation of the outbreak, and associated case-control study.

METHODS

Cases were defined by syndrome compatible with Legionella pneumonia with laboratory-confirmed Legionella infection. The water circuit and disinfection system were assessed, and water samples collected for Legionella culture. Whole genome multi-locus sequence typing (wgMLST) was used to compare the genetic similarity of patient and environmental isolates. A case-control study was conducted to identify risk factors for Legionella pneumonia.

RESULTS

We identified 13 cases of hospital-acquired Legionella. wgMLST revealed >99.9% shared allele content among strains isolated from clinical and water samples. Smoking (P= .008), steroid use (P= .007), and documented shower during hospitalization (P= .03) were risk factors for Legionella pneumonia on multivariable analysis. Environmental assessment identified modifications to the hospital water system had occurred in the month preceding the outbreak. Multiple mitigation efforts and application of point of use water filters stopped the outbreak.

CONCLUSIONS

Potable water system Legionella colonization occurs despite existing copper-silver ionization systems, particularly after structural disruptions. Multidisciplinary collaboration and direct monitoring for Legionella are important for outbreak prevention. Showering is a modifiable risk factor for nosocomial Legionella pneumonia. Shower restriction and point-of-use filters merit consideration during an outbreak.

Legionella pneumophila LegC7 effector protein drives aberrant endoplasmic reticulum:endosome contacts in yeast

Legionella pneumophila is a facultative intracellular bacterial pathogen, causing the severe form of pneumonia known as Legionnaires' disease. Legionella actively alters host organelle trafficking through the activities of "effector" proteins secreted via a type-IVB secretion system, in order to construct the bacteria-laden Legionella-containing vacuole (LCV) and prevent lysosomal degradation. The LCV is created with membrane derived from host endoplasmic reticulum (ER), secretory vesicles and phagosomes, although the precise molecular mechanisms that drive its synthesis remain poorly understood. In an effort to characterize the in vivo activity of the LegC7/YlfA SNARE-like effector protein from Legionella in the context of eukaryotic membrane trafficking in yeast, we find that LegC7 interacts with the Emp46p/Emp47p ER-to-Golgi glycoprotein cargo adapter complex, alters ER morphology and induces aberrant ER:endosome interactions, as measured by visualization of ER cargo degradation, reconstitution of split-GFP proteins and enhanced oxidation of the ER lumen. LegC7-dependent toxicity, disruption of ER morphology and ER:endosome fusion events were dependent upon endosomal VPS class C tethering complexes and the endosomal t-SNARE, Pep12p. This work establishes a model in which LegC7 functions to recruit host ER material to the bacterial phagosome during infection by driving ER:endosome contacts, potentially through interaction with host membrane tethering complexes and/or cargo adapters.

Racial Disparities in Incidence of Legionnaires' Disease and Social Determinants of Health: A Narrative Review

OBJECTIVES

Racial and socioeconomic disparities in the incidence of Legionnaires' disease have been documented for the past 2 decades; however, the social determinants of health (SDH) that contribute to these disparities are not well studied. The objective of this narrative review was to characterize SDH to inform efforts to reduce disparities in the incidence of Legionnaires' disease.

METHODS

We conducted a narrative review of articles published from January 1979 through October 2019 that focused on disparities in the incidence of Legionnaires' disease and pneumonia (inclusive of bacterial pneumonia and/or community-acquired pneumonia) among adults and children (excluding articles that were limited to people aged <18 years). We identified 220 articles, of which 19 met our criteria: original research, published in English, and examined Legionnaires' disease or pneumonia, health disparities, and SDH. We organized findings using the Healthy People 2030 SDH domains: economic stability, education access and quality, social and community context, health care access and quality, and neighborhood and built environment.

RESULTS

Of the 19 articles reviewed, multiple articles examined disparities in incidence of Legionnaires' disease and pneumonia related to economic stability/income (n = 13) and comorbidities (n = 10), and fewer articles incorporated SDH variables related to education (n = 3), social support (none), health care access (n = 1), and neighborhood and built environment (n = 6) in their analyses.

CONCLUSIONS

Neighborhood and built-environment factors such as housing, drinking water infrastructure, and pollutant exposures represent critical partnership and research opportunities. More research that incorporates SDH and multilevel, cross-sector interventions is needed to address disparities in Legionnaires' disease incidence.

Economic Burden of Legionnaires' Disease, United States, 2014

Through the use of published estimates of medical costs and new calculations of productivity losses, we estimate the lifetime economic burden of 2014 Legionnaires’ disease cases in the United States at ≈$835 million. This total includes $21 million in productivity losses caused by absenteeism and $412 million in productivity losses caused by premature deaths.

Are Fluoroquinolones or Macrolides Better for Treating Legionella Pneumonia? A Systematic Review and Meta-analysis

BACKGROUND

The Infectious Diseases Society of America recommends either a fluoroquinolone or a macrolide as a first-line antibiotic treatment for Legionella pneumonia, but it is unclear which antibiotic leads to optimal clinical outcomes. We compared the effectiveness of fluoroquinolone versus macrolide monotherapy in Legionella pneumonia using a systematic review and meta-analysis.

METHODS

We conducted a systematic search of literature in PubMed, Cochrane, Scopus, and Web of Science from inception to 1 June 2019. Randomized controlled trials and observational studies comparing macrolide with fluoroquinolone monotherapy using clinical outcomes in patients with Legionella pneumonia were included. Twenty-one publications out of an initial 2073 unique records met the selection criteria. Following PRISMA guidelines, 2 reviewers participated in data extraction. The primary outcome was mortality. Secondary outcomes included clinical cure, time to apyrexia, length of hospital stay (LOS), and the occurrence of complications. The review and meta-analysis was registered with PROSPERO (CRD42019132901).

RESULTS

Twenty-one publications with 3525 patients met inclusion criteria. The mean age of the population was 60.9 years and 67.2% were men. The mortality rate for patients treated with fluoroquinolones was 6.9% (104/1512) compared with 7.4% (133/1790) among those treated with macrolides. The pooled odds ratio assessing risk of mortality for patients treated with fluoroquinolones versus macrolides was 0.94 (95% confidence interval, .71-1.25, I2 = 0%, P = .661). Clinical cure, time to apyrexia, LOS, and the occurrence of complications did not differ for patients treated with fluoroquinolones versus macrolides.

CONCLUSIONS

We found no difference in the effectiveness of fluoroquinolones versus macrolides in reducing mortality among patients with Legionella pneumonia.

Comparison of two culture methods for the enumeration of Legionella pneumophila from potable water samples

Legionella infections have steadily increased in the United States over the last 20 years, and most of these infections have been attributed to contaminated water. The gold standard for confirmation of Legionella presence in water is culturing with Buffered Charcoal Yeast Extract (BCYE) agar. Following many modifications, this method is still time-consuming, expensive, and can take longer than 10 days for full confirmation. The Legiolert is a newer and simpler culture product that is claimed to be able to quantify Legionella pneumophila in 7 days with high sensitivity and specificity and does not need further confirmation for the presence of L. pneumophila. This study compared the culturability of L. pneumophila occurring in a simulated home plumbing system using both Legiolert and BCYE agar methods. Out of 185 water samples, Legiolert and BCYE method detected L. pneumophila in 83 and 85% of the samples, respectively. The two methods were determined to be statistically equivalent for culturability of L. pneumophila, though the detected levels by Legiolert were slightly higher than the BCYE method. The molecular confirmation of positive (n = 254) and negative wells (n = 82) with Legiolert also showed a high specificity of 96.5% (i.e., 3.5% false positives (9/254) and 0% false negatives (0/82)).

Re-opening hairdressing salons, barber shops and gyms following COVID-19 lockdown: reducing risks from Legionella species through successful domestic steam disinfection of showerheads

Given the importance of disinfecting showerheads from Legionella species and the lack of instructions as to how to successfully achieve this, the aim of this study was to examine the ability of domestic steam disinfection to successfully disinfect showerheads from Legionella species. Steam disinfection of Legionella pneumophila [n=3; L. pneumophila serogroup 2–15 (wildtype environmental water isolate); L. pneumophila serogroup 1 NCTC11192 (reference strain); L. pneumophila serogroup 1 (wildtype environmental water isolate)], L. erythra (wildtype environmental water isolate) and L. bozemanii CRM11368M (reference strain) were examined in this study. Steam disinfection employing a baby bottle steam disinfector device eradicated all Legionella organisms tested. Steam disinfection, when performed properly under the manufacturer’s instructions, offers a relatively inexpensive, simple, versatile and widely available technology for the elimination of Legionella species from contaminated showerheads. We therefore advocate the employment of such devices to regularly disinfect showerheads and shower tubing in hairdressing salons, barber shops and gyms, as a critical control in the elimination of these organisms from these sources, thereby enhancing customer/client/staff safety.

Trends in the incidence and mortality of legionellosis in Japan: a nationwide observational study, 1999-2017

This study examined temporal trend, seasonality, and geographical variations of legionellosis incidence and mortality in Japan. This nationwide observational study used the Japanese Vital Statistics and Infectious Diseases Weekly Report (1999-2017) data to calculate legionellosis crude and age-adjusted incidence and mortality rates per 100,000 population by age and sex. Incidence was compared among the 4 seasons and regional incidence among 47 prefectures. Of 13,613 (11,194 men) people with legionellosis in Japan, 725 (569 men) were fatal. Increasing incidence trend occurred from 0.0004 (1999) to 1.37 (2017) per 100,000 population. People aged ≥ 70 years accounted for 43.1% overall; men's age-adjusted incidence rate was consistently approximately five times higher than for women. Significantly higher incidence occurred in summer than in winter (p = 0.013). Geographically, highest incidence (≥ 2.0 per 100,000 population) occurred in Hokuriku District, with increasing trends in Hokkaido and middle-part of Japan. Estimated fatality rates decreased consistently at 5.9% (95% confidence interval: - 8.1, - 3.5) annually, from 1999 to 2017, with no trend change point. Increasing legionellosis incidence occurred in Japan during 1999-2017, with declining estimated fatality rates. In this aging society and warming world, disease clinical burden may further deteriorate in future due to increasing incidence trends.

Evaluation of Four Lateral Flow Assays for the Detection of Legionella Urinary Antigen

Urinary antigen tests (UATs) are often used to diagnose Legionnaires’ disease as they are rapid and easy to perform on readily obtainable urine samples without the need for specialized skills compared to conventional methods. Recently developed automated readers for UATs may provide objective results interpretation, especially in cases of weak result bands. Using 53 defined patient urine samples, we evaluated the performance of the BinaxNOW Legionella Antigen Card (Abbott), ImmuView S. pneumoniae and Legionella (SSI Diagnostica), STANDARD F Legionella Ag FIA (SD Biosensor), and Sofia Legionella FIA (Quidel) simultaneously with their respective automated readers. Automatic and visual interpretation of result bands were also compared for the immunochromatography-based BinaxNOW and ImmuView UATs. Overall sensitivity and specificity of Legionella UATs were 53.9–61.5% and 90.0–94.9%, respectively. All four UATs successfully detected all samples from L. pneumophila serogroup 1-positive patients, but most failed to detect samples for Legionella spp., or other serogroups. Automatic results interpretation of results was found to be mostly concordant with visual results reading. In conclusion, the performance of the four UATs were similar to each other in the detection of Legionella urinary antigen with no major difference between automated or visual results reading.

Community-acquired versus nosocomial Legionella pneumonia: factors associated with Legionella-related mortality

Over the past decade, changes in the diagnosis and management of Legionella pneumonia occurred and risk factors for severe infection and increased mortality were identified. Previous reports found that nosocomial infection is associated with higher mortality while others showed no differences. We aimed to evaluate the differences in the clinical course and mortality rates between hospital-acquired pneumonia (HAP) and community-acquired pneumonia (CAP) caused by Legionella pneumophila. A retrospective cohort study of patients admitted due to Legionella pneumonia between January 2012 through November 2019 was conducted in a tertiary referral center (Rambam Health Care Campus, Haifa, Israel). The primary outcome was 30-day Legionella pneumonia-related mortality. A multivariable logistic regression was performed to determine whether a nosocomial infection is an independent predictor of mortality. One hundred nine patients were included. Seventy (64.2%) had CAP and 39 (35.8%) had HAP. The groups were comparable regarding age, gender, and comorbidities. Time to diagnosis was longer and the number of patients receiving initial empiric anti-Legionella spp. treatment was smaller in the HAP group (8 days [IQR 5.5-12.5] vs. 5 days [IQR 3-8], p < 0.001 and 65.5% vs. 78.6%, p = 0.003, respectively). Patients with HAP had higher 30-day mortality, 41% vs. 18.6%, p = 0.02. In a multivariable logistic regression model, only pneumonia severity index and nosocomial source were independently associated with increased mortality. HAP caused by Legionella spp. is independently associated with increased mortality when compared to CAP caused by the same pathogen. The possible reasons for this increased mortality include late diagnosis and delayed initiation of appropriate treatment.

Legionellosis in Japan: A Self-inflicted Wound?

Legionellosis is a serious bacterial infection characterized by atypical pneumonia primarily due to infection with Legionella pneumophila, and bathing can be a potential cause of this infection. Legionellosis was first identified in 1977, and it is caused by Gram-negative bacteria belonging to the genus Legionella. Legionellosis remains an important public health threat, particularly in Japan, where the population is rapidly aging, thereby becoming more at risk of developing severe disease and accompanying life-threatening pneumonia. The bacteria are most commonly transmitted via the inhalation of contaminated aerosols produced and broadcast via water sprays, jets or mists. Infection can also occur via the aspiration of contaminated water or ice, or through inhalation of contaminated dust. Because the signs and symptoms of Legionnaires' disease (LD), as well as radiographic imaging are similar to pneumonia caused by other pathogens, a specific diagnostic test is required, such as a urine antigen detection test. Six clinical and laboratory parameters, a high body temperature, a non-productive cough, low serum sodium and platelet counts, and high lactate dehydrogenase (LDH) and c-reactive protein concentrations can be used to reliably predict the likelihood of LD. The first choices for chemotherapy are fluoroquinolone and macrolide antibiotic drugs. The main goals of LD prevention measures are 1) the prevention of microbial growth and biofilm formation, 2) the removal of all biofilm formed on equipment and in facilities, 3) minimizing aerosol splash and spread, and 4) minimizing bacterial contamination from external sources. It is apparent that, in Japan, where hot spring (onsen) bathing is common among aged people, strict regulations need to be in place - and enforced - to ensure that all Japanese onsens and spas provide a safe environment and undertake regular, effective infection control practices.

Legionella and SARS-CoV-2 Coinfection in a Patient With Pneumonia - An Outbreak in Northern Portugal

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has plagued virtually every continent and country, and Portugal is no exception. The high number of cases has caused a major burden on health services and obvious economic consequences, forcing an important reformulation in the health sectors' organization. In the past weeks, counties in the country's northern coastal region have reported an increasing number of Legionella cases, whose origin is yet to be determined. This exacerbates the already important pressure on the region's health facilities. We present a case of a patient diagnosed with Legionella pneumonia and concomitant coronavirus disease 2019 (COVID-19) pneumonia, highlighting the need for etiological investigation not only for common community agents but also for pandemic pathogens and regional outbreaks.

A Methodology for Classifying Root Causes of Outbreaks of Legionnaires' Disease: Deficiencies in Environmental Control and Water Management

We piloted a methodology for collecting and interpreting root cause—or environmental deficiency (ED)—information from Legionnaires’ disease (LD) outbreak investigation reports. The methodology included a classification framework to assess common failures observed in the implementation of water management programs (WMPs). We reviewed reports from fourteen CDC-led investigations between 1 January 2015 and 21 June 2019 to identify EDs associated with outbreaks of LD. We developed an abstraction guide to standardize data collection from outbreak reports and define relevant parameters. We categorized each ED according to three criteria: ED type, WMP-deficiency type, and source of deficiency. We calculated the prevalence of EDs among facilities and explored differences between facilities with and without WMPs. A majority of EDs identified (81%) were classified as process failures. Facilities with WMPs (n = 8) had lower prevalence of EDs attributed to plumbed devices (9.1%) and infrastructure design (0%) than facilities without WMPs (n = 6; 33.3% and 24.2%, respectively). About three quarters (72%) of LD cases and 81% of the fatalities in our sample originated at facilities without a WMP. This report highlights the importance of WMPs in preventing and mitigating outbreaks of LD. Building water system process management is a primary obstacle toward limiting the root causes of LD outbreaks. Greater emphasis on the documentation, verification, validation, and continuous program review steps will be important in maximizing the effectiveness of WMPs.

Flushing of Stagnant Premise Water Systems after the COVID-19 Shutdown Can Reduce Infection Risk by Legionella and Mycobacterium spp

There is concern about potential exposure to opportunistic pathogens when reopening buildings closed due to the COVID-19 pandemic. In this study, water samples were collected before, during, and after flushing showers in five unoccupied (i.e., for ∼2 months) university buildings with quantification of opportunists via a cultivation-based assay (Legionella pneumophila only) and quantitative PCR. L. pneumophila were not detected by either method; Legionella spp., nontuberculous mycobacteria (NTM), and Mycobacterium avium complex (MAC), however, were widespread. Using quantitative microbial risk assessment (QMRA), the estimated risks of illness from exposure to L. pneumophila and MAC via showering were generally low (i.e., less than a 10^-7 daily risk threshold), with the exception of systemic infection risk from MAC exposure in some buildings. Flushing rapidly restored the total chlorine (as chloramine) residual and decreased bacterial gene targets to building inlet concentrations within 30 min. During the postflush stagnation period, the residual chlorine dissipated within a few days and bacteria rebounded, approaching preflush concentrations after 6-7 days. These results suggest that flushing can quickly improve water quality in unoccupied buildings, but the improvement may only last a few days.

Unravelling the importance of the eukaryotic and bacterial communities and their relationship with Legionella spp. ecology in cooling towers: a complex network

BACKGROUND

Cooling towers are a major source of large community-associated outbreaks of Legionnaires' disease, a severe pneumonia. This disease is contracted when inhaling aerosols that are contaminated with bacteria from the genus Legionella, most importantly Legionella pneumophila. How cooling towers support the growth of this bacterium is still not well understood. As Legionella species are intracellular parasites of protozoa, it is assumed that protozoan community in cooling towers play an important role in Legionella ecology and outbreaks. However, the exact mechanism of how the eukaryotic community contributes to Legionella ecology is still unclear. Therefore, we used 18S rRNA gene amplicon sequencing to characterize the eukaryotic communities of 18 different cooling towers. The data from the eukaryotic community was then analysed with the bacterial community of the same towers in order to understand how each community could affect Legionella spp. ecology in cooling towers.

RESULTS

We identified several microbial groups in the cooling tower ecosystem associated with Legionella spp. that suggest the presence of a microbial loop in these systems. Dissolved organic carbon was shown to be a major factor in shaping the eukaryotic community and may be an important factor for Legionella ecology. Network analysis, based on co-occurrence, revealed that Legionella was correlated with a number of different organisms. Out of these, the bacterial genus Brevundimonas and the ciliate class Oligohymenophorea were shown, through in vitro experiments, to stimulate the growth of L. pneumophila through direct and indirect mechanisms.

CONCLUSION

Our results suggest that Legionella ecology depends on the host community, including ciliates and on several groups of organisms that contribute to its survival and growth in the cooling tower ecosystem. These findings further support the idea that some cooling tower microbiomes may promote the survival and growth of Legionella better than others. Video Abstract.

Legionella pneumophila sg1-sensing signal enhancement using a novel electrochemical immunosensor in dynamic detection mode

This work presents a comparison between static and dynamic modes of biosensing using a novel microfluidic assay for continuous and quantitative detection of Legionella pneumophila sg1 in artificial water samples. A self-assembled monolayer of 16-amino-1-hexadecanethiol (16-AHT) was covalently linked to a gold substrate, and the resulting modified surface was used to immobilize an anti-Legionella pneumophila monoclonal antibody (mAb). The modified surfaces formed during the biosensor functionalization steps were characterized using electrochemical measurements and microscopic imaging techniques. Under static conditions, the biosensor exhibited a wide linear response range from 10 to 10⁸ CFU/mL and a detection limit of 10 CFU/mL. Using a microfluidic system, the biosensor responses exhibited a linear relationship for low bacterial concentrations ranging from 10 to 10³ CFU/mL under dynamic conditions and an enhancement of sensing signals by a factor of 4.5 compared to the sensing signals obtained under static conditions with the same biosensor for the detection of Legionella cells in artificially contaminated samples.

Trends in Legionnaires' Disease-Associated Hospitalizations, United States, 2006-2010

Background

Legionella pneumophila is a waterborne cause of both healthcare-associated and community-acquired pneumonia. Legionella pneumophila serogroup 1 is responsible for 80% of infections. There is currently limited published disease burden data on Legionnaires’ disease-associated hospitalization in the United States.

Methods

In this study, we estimated the annual incidence of Legionnaires’ disease-associated hospitalizations in United States and identified demographic, temporal, and regional characteristics of individuals hospitalized for Legionnaires’ disease. A retrospective study was conducted using the National Hospital Discharge Survey (NHDS) data from 2006 to 2010. The NHDS is a nationally representative US survey, which includes estimates of inpatient stays in short-stay hospitals in the United States, excluding federal, military, and Veterans Administration hospitals. All discharges assigned with the Legionnaires’ disease International Classification of Diseases 9th Clinical Modification discharge diagnostic code (482.84) were included in this study.

Results

We observed the annual incidence and number of Legionnaires’ disease-associated hospitalizations (per 100 000 population) in the United States by year, age, sex, race, and region. Over a 5-year period, 14 574 individuals experienced Legionnaires’ disease-associated hospitalizations in the United States The annual population-adjusted incidence (per 100 000 population) of Legionnaires’ disease-associated hospitalizations was 5.37 (95% confidence interval [CI], 5.12–5.64) in 2006, 7.06 (95% CI, 6.80–7.40) in 2007, 8.77 (95% CI, 8.44–9.11) in 2008, 17.07 (95% CI, 16.62–17.54) in 2009, and 9.66 (95% CI, 9.32–10.01) in 2010. A summer peak of Legionnaires’ disease-associated hospitalizations occurred from June through September in 2006, 2007, 2008, and 2010.

Conclusions

Legionnaires’ disease-associated hospitalizations significantly increased over the 5-year study period. The increasing disease burden of Legionnaires’ disease suggests that large segments of the US population are at risk for exposure to this waterborne pathogen.

Management of patients with SARS-CoV-2 infections and of patients with chronic lung diseases during the COVID-19 pandemic (as of 9 May 2020) : Statement of the Austrian Society of Pneumology (ASP)

The coronavirus disease 2019 (COVID-19) pandemic is currently a challenge worldwide. In Austria, a crisis within the healthcare system has so far been prevented. The treatment of patients with community-acquired pneumonia (CAP), including SARS-CoV‑2 infections, should continue to be based on evidence-based CAP guidelines during the pandemic; however, COVID-19 specific adjustments are useful. The treatment of patients with chronic lung diseases has to be adapted during the pandemic but must still be guaranteed.

Population-Based Assessment of Clinical Risk Factors for Legionnaires' Disease

We used US population-based surveillance data to characterize clinical risk factors for Legionnaires' disease (LD). The LD incidence increased by age and the risk was elevated for 12 clinical conditions, when compared to healthy adults. This information can be used to guide testing, treatment, and public health prevention efforts.

[Statement of the Austrian Society of Pneumology (ASP)]

The COVID-19 pandemic is currently a challenge worldwide. In Austria, a crisis within the health care system has so far been avoided. The treatment of patients with community-acquired pneumonia (CAP), including SARS-CoV‑2 infections, should continue to be based on evidence-based CAP guidelines during the pandemic. However, COVID-19-specific adjustments are useful. The treatment of patients with chronic lung diseases must be adapted during the pandemic, but must still be guaranteed.

Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America

Background: This document provides evidence-based clinical practice guidelines on the management of adult patients with community-acquired pneumonia.

Methods: A multidisciplinary panel conducted pragmatic systematic reviews of the relevant research and applied Grading of Recommendations, Assessment, Development, and Evaluation methodology for clinical recommendations.

Results: The panel addressed 16 specific areas for recommendations spanning questions of diagnostic testing, determination of site of care, selection of initial empiric antibiotic therapy, and subsequent management decisions. Although some recommendations remain unchanged from the 2007 guideline, the availability of results from new therapeutic trials and epidemiological investigations led to revised recommendations for empiric treatment strategies and additional management decisions.

Conclusions: The panel formulated and provided the rationale for recommendations on selected diagnostic and treatment strategies for adult patients with community-acquired pneumonia.