Contamination status and molecular typing of Legionella pneumophila in artificial water environment in Shanghai hospitals from 2019 to 2020 / 环境与职业医学

Background The incidence of Legionnaires' disease is increasing globally and artificial water environment is becoming a common source of outbreaks. Molecular typing techniques can help prevent and control Legionella. Objective To understand the molecular epidemiological characteristics of Legionella pneumophila in artificial water environment of Shanghai hospitals, and provide a scientific basis for the prevention and control of Legionnaires' disease. Methods Water samples were collected from artificial water environment in 14 hospitals from May to October each year from 2019 to 2020 in Shanghai. A total of 984 water samples were collected from 8 Grade-A tertiary hospitals and 6 non-Grade-A tertiary hospitals, including 312 samples of cooling water, 72 samples of chilled water, and 600 samples of tap water. The water samples were isolated and serotyped for Legionella pneumophila and preserved, and the positive rate of Legionella pneumophila in the samples was used as an indicator of contamination. The preserved strains were resuscitated and 81 surviving strains were obtained for pulsed field gel electrophoresis (PFGE) typing analysis. Results A total of 124 Legionella pneumophila positive water samples were detected, with a positive rate of 12.60%. The positive rate was higher in the Grade-A tertiary hospitals (16.54%, 87/526) than in the non-Grade-A tertiary hospitals (8.08%, 37/458) (χ2=15.91, P<0.001). The positive rate of cooling water (23.40%) was the highest among different types of water samples, and the difference was statistically significant (χ2=61.19, P<0.001). The difference in positive rate of tap water was statistically significant among different hospital departments (χ2=11.37, P<0.05). The positive rate in 2019 (15.06%) was higher than that in 2020 (9.84%) (χ2=6.23, P<0.05). From May to October, August had the highest annual average positive rate (16.46%) and October had the lowest (8.54%), but the difference in positive rates among months was not statistically significant (χ2=5.39, P=0.37). The difference in positive rate among districts was statistically significant (χ2=24.88, P<0.001). A total of 131 strains of Legionella pneumophila were isolated, with serotype 1 (80.15%, 105/131) predominating. Among the 81 surviving strains of Legionella pneumophila subjected to PFGE typing, the band-based similarity coefficients ranged from 41.30% to 100%. Among the 29 PFGE band types (S1-S29) recorded, each band type included 1-10 strains, and S28 was the dominant band type. Four clusters (I-IV) of PFGE band types were identified, accounting for 66.67% (54/81) of all strains and containing 13 band types. Conclusion Legionella pneumophila contamination is present in the artificial water environment of hospitals in Shanghai from 2019 to 2020, and the contamination in tap water deserves attention. The detected serotype of Legionella pneumophila is predominantly type 1, and PFGE typing reveals the presence of genetic polymorphism. Therefore, the monitoring and control of Legionella pneumophila in hospital artificial water environment should be strengthened.

Legionella pneumophila contamination in central air-conditioning systems of public places in China：a meta-analysis / 预防医学

Objective @#To systematically evaluate the detection of Legionella pneumophila in central air-conditioning systems of public places in China, so as to provide insights into the management of L. pneumophila contamination.@*Methods@#The publications pertaining to L. pneumophila contamination in central air-conditioning systems of public places in China were searched in international and national databases, including CNKI, Wanfang Data, CBM, PubMed and Web of Science from January 1, 2010 to December 31, 2022. The publication quality was evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology. A meta-analysis was performed using the software Stata version 16.0. The pooled detection of L. pneumophila and its 95%CI were estimated. The publication bias was evaluated using Begg's test, and sensitivity analysis was performed with the leave-one-out evaluation for assessment of the robustness of the outcomes.@*Results@#A total of 742 publications were initially searched, and 29 publications were finally included, all of which were cross-sectional studies. The publications included 10 high-quality and 19 moderate-quality studies covering 6 160 samples, and the pooled detection of L. pneumophila was 17.20% (95%CI: 12.80%-21.90%). Subgroup analysis showed a higher detection rate of L. pneumophila in cooling water (21.80%) than in condensed water (5.50%) (P<0.01). According to the criteria defined in Hygienic Specification of Central Air-conditioning Ventilation System in Public Buildings (2006 version), the detection of L. pneumophila was 23.30%, which was higher than the detection (13.20%) according to the Hygienic Specification of Central Air-conditioning Ventilation System in Public Buildings (WS 394-2012) (P<0.05). The detection of L. pneumophila did not vary in place, region or sample (P>0.05). Begg's test showed no significant publication bias, and sensitivity analysis showed robustness of the results. @*Conclusions@#The detection of L. pneumophila ranges from 12.80% to 21.90% in central air-conditioning systems of public places in China. Health and environmental protection sectors need to improve the monitoring of L. pneumophila contamination in central air-conditioning systems of public places.

Performance evaluation of colloidal gold test paper for Legionella pneumophila / 中国生物制品学杂志

@#ObjectiveTo prepare colloidal gold immunochromatographic test paper for rapid detection of Legionella pneumophila(LP)and test its performance to ensure that it meets the national clinical diagnostic standards.MethodsLP colloidal gold immunochromatographic test paper was prepared based on double antibody sandwich ELISA,and tested for the cross reactivity,anti-interference,sensitivity,hook effect,stability and other aspects.ResultsLP colloidal gold immunochromatography test paper showed no cross reaction with 22 common pathogens in respiratory tract such as Moraxella catarrhalis,and was not affected by internal and external interferences in respiratory tract;The minimum detection limit for LP was 2.00 × 105cfu/mL,with good sensitivity and no hook effect;Under the conditions of accelerated aging at 45 ℃,simulated high temperature transportation and frozen transportation,the repeatability and stability of test paper were not affected,and the stability was good in the same batch and between different batches.ConclusionThe prepared LP colloidal gold immunochromatographic test paper realized rapid detection of LP,which was simple to operate and had good application prospect and popularization value.

Water quality challenges in buildings during prolonged low or no occupancy: a cause for concern during COVID-19 lockdowns and related building closures

Introduction: In compliance with the COVID-19 lockdown restrictions, many nonessential workplaces and public spaces were closed or left sub-operational with no or low occupancy for several months. The abrupt and unprecedented long periods of building closures have raised concerns about the proliferation of opportunistic premise plumbing pathogens that may be a biohazard for returning occupants. Objective: In this review paper, we discuss microbiological water quality concerns during periods of no or low occupancy, as experienced during the COVID-19 lockdowns. Methods: PubMed and Google Scholar databases were searched for peer-reviewed articles using specific keywords. The literature search was extended to grey literature. The paper focuses on Legionella, as a pathogen of concern, in building water systems that are not well managed and the potential risks to workers and other occupants. Results: Most articles suggest a positive relationship between stagnation or reduced water usage and compromised microbiological quality of building water systems, but the effects are site-specific and are associated with biofilm formation and disinfectant decline. Considerations for building water risk assessment are discussed as a decision-making framework for selecting appropriate responses to anticipated changes in water quality. Conclusion: The unprecedented building closures due to COVID-19 lockdowns present a hazardous event likely to impact building water quality. Building owners and facility managers, especially in high-risk settings, should consider conducting risk assessments of water systems during low-occupancy periods to identify potential risks and apply appropriate corrective measures, where necessary.

Non-canonical Ubiquitination Mediated by the Effectors from Legionella pneumophila / 中国生物化学与分子生物学报

Ubiquitination is a unique protein post-translational modification in eukaryotic cells. It regulates a variety of physiological processes, such as protein homeostasis, cell cycle, immune response, DNA repair, and vesicle transport. In view of the importance of ubiquitin in live cells, pathogens have derived a series of effector proteins targeting the host ubiquitin process in the long-term evolutionary process, aiming to regulate the ubiquitin process in the host and render an internal environment suitable for the growth and reproduction of pathogens. Legionella pneumophila is a gram-negative bacterium that is responsible for Legionella pneumoniae pneumonia, causing fever and lung infection with a fatality rate of 15% ~ 30% in severe cases. The Dot / Icm type IV secretory system is the most important virulence system in the infection of Legionella pneumophila. In the process of infecting host cells, Legionella pneumophila uses this secretion system to secrete more than 330 effector proteins to assist bacterial survival, proliferation and escape in host cells. Several effector proteins of Legionella pneumophila regulate the host ubiquitination process directly or indirectly. Recent studies found that some effectors can mediate non-canonical ubiquitination of host proteins, which is different from the classical ubiquitination process. Here, we introduce the latest research progress of novel ubiquitination mediated by effecting proteins of Legionella pneumophila, providing a reference for understanding the important role of ubiquitination in the pathogenesis of Legionella pneumophila.

Probable caso de reinfección grave por SARS-CoV-2 con coinfección por Legionella pneumophila / Probable case of severe SARS-CoV-2 reinfection with Legionella pneumophila co-infection

Resumen La inmunidad conferida luego de una primera infección por SARS-CoV-2 y el riesgo consiguiente de infección persistente o reinfección no están completamente dilucidados. Existen reportes internacionales de casos de reinfección, incluyendo el primer caso publicado en Sudamérica. Por otra parte, las comunicaciones de casos de coinfecciones han ido en aumento, incluyendo las asociadas a Legionella pneumophila . Presentamos el caso de un varón de 47 años de edad, personal de salud, que luego de cuatro meses de una primera infección por SARS-CoV-2, presenta una neumonía grave, certificándose una nueva infección por SARS-CoV-2 y una coinfección por L. pneumophila mediante detección de antígeno urinario. Fue tratado en UCI, requiriendo ventilación mecánica, dexametaxona y moxifloxacino, con buena respuesta clínica. Actualmente se encuentra en rehabilitación respiratoria y motora.

Abstract The immunity conferred after a first SARS-CoV-2 infection and the consequent risk of persistent infection or reinfection are not fully elucidated. There are reports both in Europe and in North America of reinfection cases, recently highlighting the first case published in South America. On the other hand, reports of co-infections have been increasing, including those associated with Legionella pneumophila . We present the case of a 47-year-old male, health personnel who, after four months of a first SARS-CoV-2 infection, suffers a severe pneumonia certifying a new SARS-CoV-2 infection and a L. pneumophila co-infection by urinary antigen detection. He was treated in the ICU, requiring mechanical ventilation, dexamethasone, and moxifloxacin, with a good response. He is currently in respiratory and motor rehabilitation.

Legionella pneumophila: un patógeno emergente en Argentina / Legionella pneumophila: an emerging pathogen in Argentina

La enfermedad del Legionario es causada por bacterias pertenecientes al género Legionella, siendo la especie pneumophila el principal agente etiológico de esta patología. Esta bacteria se describió por primera vez en 1977 como causa de un brote de neumonía grave registrado en 1976 en un centro de convenciones en los Estados Unidos de América. La enfermedad se presenta como una neumonía atípica, responsable del 1 al 15 % de los casos de neumonías adquiridas en la comunidad (NAC), del 5 al 10% de neumonías del adulto y del 1% en menores de 15 años. Los miembros de la familia Legionellaceae son bacilos aeróbicos gramnegativos que crecen lentamente y se encuentran ampliamente distribuidos en cuerpos de agua. La forma más común de transmisión de Legionella spp es la inhalación de aerosoles contaminados generados a partir de fuentes de agua artificiales. Se asocian con la aparición de brotes esporádicos y epidémicos en la comunidad y en infecciones nosocomiales. Las especies pertenecientes al género Legionella se consideran patógenos emergentes transmitidos por el agua. El objetivo de este trabajo es realizar una revisión sobre las manifestaciones y presentaciones clínicas de la infección causada por L. pneumophila, en virtud de que es considerado mundialmente un patógeno emergente y por existir evidencias de su presencia en sistemas de almacenamiento de agua tratada en la región nordeste de la República Argentina, razón primordial para alertar y actualizar conocimientos al respecto

Legionnaires' disease is caused by bacteria belonging to the genus Legionella, being the pneumophila specie the main etiological agent of this pathology. This bacterium was first described in 1977 as the cause of a severe pneumonia outbreak in 1976 at a convention center in the United States of America. The disease presents as an atypical pneumonia, responsible for 1% to 15% of cases of community-acquired pneumonia (CAP), 5% to 10% of pneumonia in adults and 1% in children under 15 years of age. Members of the Legionellaceae family are aerobic, gram-negative rods that grow slowly and are widely distributed in water bodies. The most common way of transmission of Legionella spp is the inhalation of contaminated aerosols generated from artificial water sources. They are associated with the appearance of sporadic and epidemic outbreaks in the community and in nosocomial infections. Species belonging to the genus Legionella are considered emerging waterborne pathogens.The aim of this work is to carry out a review on the manifestations and clinical presentations of the infection caused by L. pneumophila, due to that it is considered an emerging pathogen worldwide and because there is evidence of its presence in storage systems of treated water in the Northeast region of the Argentine Republic, primary reason to alert and update knowledge in this regard.

Legionella surveillance in stagnant water systems during COVID-19 lockdown in Istanbul

Aim@#The aim of this study was to monitor the restricted water systems during the period of COVID-19 lockdown for the waterborne pathogen Legionella pneumophila. Selected water systems were monitored to evaluate the effect of stagnation in terms of Legionella colonization.@*Methodology and results@#A total of 160 water samples were taken from buildings which were temporarily shut down or had restricted usage between April-December 2020. None of the sampling points had Legionella positive history in the last three years. All water samples were tested using classic microbiological culture as the gold standard and rapid Vermicon ScanVIT Legionella test kit combined with epifluorescence microscopy. Sixteen (10%) out of 160 water samples were recorded as Legionella-positive by both methods, where none of them was positive before the COVID-19 lockdown. All positives were tested as L. pneumophila serogroup 1 with latex agglutination kit.@*Conclusion, significance and impact of study@#Colonization of Legionella in stagnant water systems occurs rapidly. Before reopening, routine monitoring in buildings is extremely important especially under restricted use or closure is in case. Flushing, disinfecting and testing are crucial for minimizing the health risks for the public health.

Comparison of the Legiolert enzyme-substrate method and the conventional cultivation for the detection of Legionella pneumophila in water samples from public places / 公共卫生与预防医学

Objective To compare the detection effects of Legionella pneumophila in water samples from public places by the Legiolert enzyme-substrate method and the conventional cultivation. Methods The Legiolert enzyme-substrate method and the conventional cultivation method were used to detect Legionella pneumophila in cooling water and shower water samples collected in public places. Isolated strains were verified and serotyped. Results A total of 68 samples were collected and tested. The positive rate of the conventional cultivation and the Legiolert enzyme-substrate method were 5.88%（4/68）and 35.29%（24/68）, respectively, with a significant difference （χ2=16.41，P2=16.41，P=0.000). A total of 25 strains of Legionella pneumophila were isolated，and the serum types were mainly LP1（14/25）. Conclusion The Legiolert enzyme-substrate method represente a higher detection rate of Legionella pneumophila in water samples from public places than the conventional cultivation.

Biological risk of Legionella pneumophila in irrigation systems / Riesgo biológico por Legionella pneumophila en sistemas de riego

ABSTRACT Objective The goal of this study is to determine the risk of exposure to Legionella pneumophila in hotel golf courses located in the province of Malaga (Spain). Method Spray irrigation systems were analyzed as sources for spreading the Legionella bacterium. Spanish legislation requires that irrigation systems be monitored for their water quality as well as for reasons related to health and hygiene. Based on an observational study and non-parametric tests (Goodman-Kruskal Tau and uncertainty coefficient), this study states the regulatory enforcement among the systems and contributed to announce Legionella prevention. The quality criteria for recycled water, waste water treatment plant and well water were analyzed in relationship to the hotels' categories. Results Deficiencies were found in the preventive maintenance of irrigation systems, but no relationship exists between the type of water and the risk detected. Conclusions The study suggests that aerosolized water used in golf course watering systems could pose risk to the population by exposing them to Legionella.

RESUMEN Objetivo El propósito de este trabajo es determinar el riesgo de exposición a Legionella pneumophila en campos de golf de hoteles ubicados en la provincia de Málaga (España). Método Se realizó un estudio de los sistemas de riego por aspersión como fuentes de dispersión de la bacteria Legionella. El análisis de las condiciones higiénico-sanitarias de las instalaciones y la calidad del agua es una actividad de obligado cumplimiento contemplada en la legislación sanitaria española. Mediante un estudio observacional y el empleo de pruebas no paramétricas (Tau de Goodman-Kruskal y coeficiente de incertidumbre) se expresó el cumplimiento de la reglamentación en los sistemas estudiados y la prevención de Legionella. Los criterios de calidad para el agua reciclada, procedente de la estación depuradora de agua residual y de pozo, fueron analizados en relación con la categoría de los hoteles. Resultados Se encontraron deficiencias en el mantenimiento preventivo de los sistemas de riego, pero no hubo relación entre el tipo de agua y el riesgo identificado. Conclusiones El estudio sugiere que el agua aerosolizada proveniente de los sistemas de riego de los campos de golf presenta un riesgo de infección por Legionella para la población expuesta.

A study to assess the magnitude of atypical pneumonia by serum polymerase chain reaction in children aged 3 years to 18 years at Kempegowda Institute of Medical Sciences hospital, Bengaluru, Karnataka, India

Background: Atypical organisms are a common causative agent of pneumonia in children more than 3 years of age, causing around 10-30% of the cases. Though atypical pathogens are said to cause relatively milder form of pneumonia as compared to other bacterial and viral pathogens, severe manifestations can also occur. Early identification of these pathogens can help in starting treatment with macrolides, which can reduce the length of hospital stay and mortality. Hence in this study the prevalence of atypical organisms was identified by using serum Polymerase chain reaction (PCR).Methods: This was a prospective observational study conducted in children between 3 years to 18 years of age with clinical diagnosis of pneumonia admitted in wards and PICU in KIMS hospital. Authors excluded Immunocompromised children. Detailed history and clinical examination was done. Investigations - complete hemogram, Chest Xray, blood Culture and sensitivity and serum PCR was done for a sample size of 100 children.Results: In this study among the three atypical organisms, Legionella pneumoniae was identified in 2% of the cases by serum PCR.Conclusions: In this study among the three atypical pathogens authors could only identify Legionella pneumoniae. Prevalence of Legionella pneumoniae was 2%. While treating children aged 3 years to 18 years with pneumonia, a high degree of suspicion of atypical pathogens is required, especially in Legionella because of its high mortality rate. In such circumstances adding macrolides along with other antibiotics will be beneficial to the patients outcome and duration of hospital stay.

A study to assess the prevalence of atypical organisms in pneumonia in children aged 1 month to 3 years by serum polymerase chain reaction in KIMS Hospital, Bangalore, India

Background: Atypical organisms are a common causative agent of pneumonia in children more than 3 years of age. Though atypical pathogens are said to cause relatively milder form of pneumonia severe manifestations can also occur.' Very few studies are available on the prevalence of atypical pneumonia in children less than 3 years. Hence in this study the prevalence of atypical organisms in pneumonia was identified by using serum Polymerase chain reaction (PCR).Methods: This is a prospective observational study conducted in children between 1 month to 3 years of age with clinical diagnosis of pneumonia admitted in wards and PICU in KIMS hospital. Authors excluded Immuno compromised children. Detailed history and clinical examination was done. Investigations - complete hemogram, Chest X-ray, blood Culture and sensitivity and serum PCR was done for a sample size of 50 children.Results: Among the three atypical organisms, Legionella pneumoniae was identified in 4% (2/50) cases by serum PCR.Conclusions: In this study it was found that the prevalence of 4%. Legionella pneumonia can be fatal in 10% of cases. Hence atypical pathogens like Legionella should be kept in mind even in children less than 3 years when pneumonia is not responding to beta lactam antibiotics, in such cases macrolides to be considered.

Molecular typing and distribution characteristics of Legionella pneumophila isolated from cooling water of central air conditioning system in Zhongshan, 2012-2018 / 公共卫生与预防医学

Objective To analyze the genetic characteristics of Legionella pneumophila isolated from cooling water of central air conditioning system in public places in Zhongshan from 2012 to 2018, and to understand the spatiotemporal distribution of homologous strains, in order to provide evidence for the prevention, control and traceability of Legionella pneumophila infection. Methods Eighty-five Legionella pneumophila strains were isolated for serotype identification, and the molecular typing of the 85 isolates was performed using pulsed field gel electrophoresis (PFGE). The strain location data was converted into latitude and longitude coordinates by GIS geocoding technology. The converted location data was overlaid on the map of Zhongshan City, mapping the molecular typing distribution of clusters using Qgis2.18.11 spatial processing software. Results Eighty-five strains of Legionella pneumophila included 9 serotypes, and the highest proportion was LP1, accounting for 61.18% (52/85). According to the similarity of 100%, 85 strains of Legionella pneumophila were divided into 56 patterns of PFGE bands (T1-T56), with 3 types being dominant. Same serotype of Legionella pneumophila strains showed diverse PFGE patterns. Different serotypes of Legionella pneumophila strains were basically identified as different PFGE patterns, while some were identified as same PFGE pattern. According to over 85% similarity, 8 clusters (A-H) were designated, strains of which were distributed in 12 districts. PFGE clustering clusters did not display obvious temporal and regional distribution differences, nor did they have temporal and regional clustering distributions. Conclusion Strains of Legionella pneumophila isolated from cooling water of central air conditioning system in public places in Zhongshan from 2012 to 2018 showed genetic diversity, and the main serotype was LP1. Isolates of clusters did not exist in different years or regions.

Hygienic evaluation of central air-condition ventilation system in public places in Nanshan District of Shenzhen, 2016-2019 / 公共卫生与预防医学

Objective To investigate the hygienic status of ventilation systems in centralized air-conditioning in Nanshan district of Shenzhen City, and to provide a basis for standardizing hygienic management and targeted prevention and control. Methods According to the requirements of "Hygienic Specifications for Central Air Conditioning and Ventilation Systems in Public Places" WS 394-2012, 303 public places using central air conditioning and ventilation devices in Nanshan District of Shenzhen City were sampled from 2016 to 2019 for four consecutive years. From these, 19 large public places were randomly selected for investigation of the hygienic condition of the air supply system. Results The qualified rates of central air conditioning ventilation systems from 2016-2019 were 94.56%, 96.96%, 98.33% and 95.65%, respectively, and there was no statistically significant difference among them (P>0.05). The qualified rates of accumulated dust, total bacterium and fungus counts on the inner surface of the ducts were 100%, 98.34% and 98.67%, respectively. PM10, total bacterium counts and fungus counts in the supplied air of the randomly selected 19 large public places were 100%, 63.15% and 78.94% respectively. The overall detection rate of Legionella pneumophila was 12.21%, and the detection rate of cooling water was larger than that of condensed water (P0.05). Conclusion The sanitary condition of the central air conditioning ventilation system in the public places of Nanshan district needed to be improved. Legionella pneumophila was still detected in some public places. Daily cleaning and disinfection management of central air condition systems should be strengthened.

Evaluación de la viabilidad de Legionella pneumophila en muestras de agua / Evaluation of the viability of Legionella pneumophila in water samples

Introducción: Legionella pneumophila se sitúa entre los principales agentes causales de neumonía adquirida en la comunidad y de origen nosocomial. La inhalación de aerosoles potencialmente contaminados con la bacteria, producto de la colonización de redes y otros sistemas que utilizan agua, representa un peligro para la salud de los individuos expuestos. Objetivo: evaluar la viabilidad de L. pneumophila en muestras de agua almacenadas en diferentes intervalos de tiempo para el diagnóstico por cultivo microbiológico de Legionella spp. Métodos: Se contaminaron artificialmente muestras de agua con dos cepas de L. pneumophila de serogrupos diferentes y la conformación de una mezcla de ellas, para un total de 15 muestras. Los frascos contaminados fueron procesados a las 24 h, 72 h, 7 días, 14 días y 21 días. Se realizó cultivo microbiológico según ISO 11731: 2004 y PNO 03-013: 2015. Resultados: Se demostró viabilidad de la bacteria en muestras almacenadas hasta 21 días. El método de concentración por filtración resultó tener los mayores recobrados del microorganismo. Conclusiones: El tiempo de almacenamiento de las muestras afecta la viabilidad de L. pneumophila. Sienta las bases para estudios posteriores de robustez del diagnóstico de L. pneumophila como parte del servicio que presta el Centro de Investigaciones Científicas de la Defensa Civil en los programas de prevención y control Legionella spp. en instalaciones de interés turístico e industrial(AU)

Introduction: Legionella pneumophila is one of the main causative agents of community- and hospital-acquired pneumonia. Inhalation of sprays potentially contaminated with the bacterium, due to the colonization of networks and other systems using water, is a hazard to the health of exposed individuals. Objective: Evaluate the viability of L. pneumophila in samples of water stored at various time intervals for the microbiological culture diagnosis of Legionella spp. Methods: Water samples were artificially contaminated with two strains of L. pneumophila from different serogroups and a mixture of them, for a total of 15 samples. The contaminated vessels were processed at 24 h, 72 h, 7 d, 14 d and 21 d. Microbiological culture was performed in compliance with ISO 11731: 2004 and PNO 03-013: 2015. Results: The bacterium was found to be viable in samples stored up to 21 days. The filtration concentration method obtained the greatest amount of the microorganism. Conclusions: Storage time of the samples affects the viability of L. pneumophila. The study lays the foundations for further research about the validity of L. pneumophila diagnosis as part of the service offered by the Civil Defense Scientific Research Center in Legionella spp. prevention and control programs for tourist and industrial facilities(AU)

Application of metagenomics next-generation sequencing in monitoring Legionella pneumophila infection after allogeneic hematopoietic stem cell transplantation / 白血病·淋巴瘤

Objective@#To investigate the application of metagenomic next-generation sequencing (mNGS) in detection of the rare or difficult-to-cultivate pathogens.@*Methods@#One patient with acute lymphoblastic leukemia who went through allogeneic hematopoietic stem cell transplantation (allo-HSCT) developed symptoms of infection after transplantation. Conventional microbial culture, polymerase chain reaction (PCR), and mNGS combined with biological information analysis were performed with plasma and cerebrospinal fluid samples, the anti-infective treatment was adjusted according to the test results, and the efficacy was assessed.@*Results@#No suspected pathogens were detected by microbial culture and PCR in the cerebrospinal fluid and plasma samples since the patient developed infection symptoms. However, Legionella pneumophila was analyzed by mNGS in the cerebrospinal fluid specimen on day 23 after allo-HSCT (reads count: 19 655), and it was considered as the principal pathogen after comprehensively evaluating the patient's clinical manifestations and the test results. Then the antimicrobial treatments were adjusted according to the patient's clinical manifestations and laboratory test results, and the number of gene sequences of Legionella pneumophila was monitored by mNGS method. Azithromycin, tigecycline, and other antibiotics effective for Legionella pneumophila were used after detecting this pathogen. A total of 15 mNGS analysis were performed during the 5-month period, and the highest number of Legionella pneumophila sequences monitored in the cerebrospinal fluid was 2 226, the lowest was 253 and eventually turned negative. The clinical symptoms and treatment outcomes were consistent with the mNGS monitoring results.@*Conclusions@#The mNGS technology has significant value in detection of the rare and difficult-to-cultivate pathogens. The mNGS technology provides a valuable supplement to microbial culture and PCR methods.

Epidemiology of Legionella and Climatic Variables in Seoul, Korea

Legionella species are abundant in the built environment and are increasingly recognized as a cause of Legionnaires' disease (LD). As the number of cases of Legionnaires' disease acquired by local communities in the Seoul metropolitan area in Korea has been increased, there was concern that changes in environmental factors could affect disease outbreaks. We described the association between climatic variables and occurrence of legionellosis in Korea and Legionella detection rate in Seoul area. A total of 418 cases of legionellosis were reported between 2014 and 2017. There was a seasonal peak in summer. LD continuously occurred from early spring to winter every year and rapidly increased in summer. In the regression analysis, the primary variables of interest- PM2.5 (µg/m³), NO₂ (ppb), and a number of the date of issue O₃ warning were not significant except for average temperature (R²=0.8075). The Legionella detection rate in Seoul, Korea showed a trend similar to precipitation (P=0.708, ANOVA). A relatively high proportion of Legionella detection rate was shown, especially cooling tower (17.7%) and public bath (19.3%). This finding is in line with current understanding of the ecological profile of this pathogen and supports the assertion that legionellosis occurs through contamination of water sources.

An animal experiment regarding the effect of lipopolysaccharide intervention program on Legionella pneumonia / 中华流行病学杂志

Objective@#To explore the effect of lipopolysaccharide intervention program on Legionella pneumonia.@*Methods@#C3H/HeN mice (6-8 weeks old) were used as experimental animals. The mice were randomly divided into lipopolysaccharide intervention, non-lipopolysaccharide intervention and control groups. Each group was again divided into three time points: 12 h, 24 h and 48 h. Mice in the lipopolysaccharide intervention group were intraperitoneally injected with E. coli lipopolysaccharide (100 ng per mice), and the rest groups were intraperitoneally injected with normal saline. After 24 hours, mice in the lipopolysaccharide intervention and the non-intervention groups mice were infected with Legionella by tracheal injection and the control group was given the same amount of saline. All the mice were killed at 12, 24 and 48 hours respectively. The mice were anatomized, lungs of the mice were separated and weighed. Organ coefficients (lung weight/body weight of mice) were calculated. 1 ml Orbital blood was collected. Toll-like receptor 4 (TLR4) levels of peripheral blood mononuclear cells were measured by flow cytometry. The contents of TNF-α and IL-1β in the upper left lung lobe were measured by ELISA.@*Results@#In the lung organs, the coefficients of lipopolysaccharide non-intervention group were higher than the other groups and there was no significant difference seen between the lipopolysaccharide intervention group and the controls. TLR4 peaked at 12 hours in both the lipopolysaccharide intervention and the non-intervention groups while the TLR4 level in the intervention group was higher than that in the non-intervention group. There were no significant differences appeared on the TLR4 expression levels between the two Legionella pneumonia modelled groups at 24 or 48 hours. There was no significant difference seen regarding the concentration of TNF-α and IL-1β between the intervention and the control groups. The secretion levels of TNF-α and IL-1β in the non-intervention group were higher than those in the intervention group at each time point.@*Conclusion@#The lipopolysaccharide intervention program may alleviate the inflammatory symptoms of Legionella infection.

Inhibition of the activity of methyltransferase from Legionella pneumophila by histone H3K14M mutation / 上海交通大学学报（医学版）

Objective • To investigate the effect of histone H3K14M mutation on the activity of methyltransferase RomA, a secreted effector ofLegionella pneumophila in eukaryotic cells and the underlying mechanisms. Methods • Wide-type histone H3 (H3WT) and mutant histone H3 (the lysine residue 14 was replaced by methionine, isoleucine or arginine residue, and named as H3K14M, H3K14I, and H3K14R, respectively) recombinant expression plasmids were constructed. Packaged lentiviruses with these plasmids were used to infect eukaryotic cells 293T and THP-1 with or without over-expression of RomA. The H3K14 methylation and acetylation were analyzed by Western blotting. The interaction of RomA with H3WT and H3K14 mutants was detected by co-immunoprecipitation. Results • A secreted effector of Legionella pneumophila named RomA targeted the host cell nucleus to upregulate the H3K14 methylation level and downregulate the H3K14 acetylation level for inhibiting the gene expression in host cells and promoting Legionella pneumophila's efficient intracellular replication. But histone H3K14M mutation could promote the interaction between H3K14M and RomA and thus inhibited the methyltransferase activity of RomA. Conclusion • Histone H3K14M mutation significantly inhibits the activity of Legionella pneumophilamethyltransferase RomA.