ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
@#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.
ABSTRACT
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.
Subject(s)
Humans , Male , Middle Aged , Legionnaires' Disease/complications , Coinfection , COVID-19/complications , Legionella pneumophila , Reinfection , SARS-CoV-2ABSTRACT
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.
Subject(s)
Humans , Legionnaires' Disease/prevention & control , Legionnaires' Disease/transmission , Water Storage , Bacterial Growth/prevention & controlABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Background & objectives: Legionella pneumophila, a ubiquitous aquatic organism is found to be associated with the development of the community as well as hospital-acquired pneumonia. Diagnosing Legionella infection is difficult unless supplemented with, diagnostic laboratory testing and established evidence for its presence in the hospital environment. Hence, the present study was undertaken to screen the hospital water supplies for the presence of L. pneumophila to show its presence in the hospital environment further facilitating early diagnosis and prevention of hospital-acquired legionellosis. Methods: Water samples and swabs from the inner side of the same water taps were collected from 30 distal water outlets present in patient care areas of a tertiary care hospital. The filtrate obtained from water samples as well as swabs were inoculated directly and after acid buffer treatment on plain and selective (with polymyxin B, cycloheximide and vancomycin) buffered charcoal yeast extract medium. The colonies grown were identified using standard methods and confirmed for L. pneumophila by latex agglutination test. Results: About 6.66 per cent (2/30) distal water outlets sampled were found to be contaminated with L. pneumophila serotype 2-15. Isolation was better with swabs compared to water samples. Interpretation & conclusions: The study showed the presence of L. pneumophila colonization of hospital water outlets at low levels. Periodic water sampling and active clinical surveillance in positive areas may be done to substantiate the evidence, to confirm or reject its role as a potential nosocomial pathogen in hospital environment.
ABSTRACT
ABSTRACT Nine Legionella pneumophila strains isolated from cooling towers and a standard strain (L. pneumophila serogroup 1, ATCC 33152, Philadelphia 1) were analyzed and compared in terms of motility, flagella structure, ability to form biofilms, enzymatic activities (hemolysin, nucleases, protease, phospholipase A, phospholipase C, acid phosphatase, alkaline phosphatase and lipase), hemagglutination capabilities, and pathogenicity in various host cells (Acanthamoeba castellanii ATCC 30234, mouse peritoneal macrophages and human peripheral monocytes). All the isolates of bacteria appeared to be motile and polar-flagellated and possessed the type-IV fimbria. Upon the evaluation of virulence factors, isolate 4 was found to be the most pathogenic strain, while 6 out of the 9 isolates (the isolates 1, 2, 3, 4, 5, and 7) were more virulent than the ATCC 33152 strain. The different bacterial strains exhibited differences in properties such as adhesion, penetration and reproduction in the hosts, and preferred host type. To our knowledge, this is the first study to compare the virulence of environmental L. pneumophila strains isolated in Turkey, and it provides important information relevant for understanding the epidemiology of L. pneumophila.
Subject(s)
Humans , Animals , Female , Mice , Bacterial Proteins/metabolism , Legionella pneumophila/metabolism , Virulence Factors/metabolism , Bacterial Proteins/genetics , Turkey/epidemiology , Legionnaires' Disease/microbiology , Legionella pneumophila/isolation & purification , Legionella pneumophila/genetics , Virulence Factors/genetics , Environmental Microbiology , Macrophages/microbiology , Mice, Inbred BALB CABSTRACT
Objective:To investigate the prevalence,isolation,identification,characterization,antibiotic profile and pathogenicity of Legionellae isolated from various set of waters.Methods:A total of 400 water samples were collected from different water sources.Water samples were pretreated using acid treatment followed by concentration and culture on buffered charcoal yeast extract agar.Parameters like ability of Legionella isolates to grow in various pH range,effect of different concentrations of chlorine and effect of different temperature optima were set up.Biochemical tests were performed to separate Legionellae into species.Antibiotic sensitivity tests and test for pathogenicity were also conducted on isolated strains.Results:The rates of isolation of Legionella pneumophila (L.pneumophila) in different water sources were found to be 20％ (lakes),10％ (ponds),8％ (water-tanks) and 1％(rivers).Most of the isolates could grow in variable pH 6-8 and it could also survive the normal level of chlorination and even at temperature of 42 ℃.Isolated species of Legionellae resulted in identification of 5 different species,L.pneumophila being the dominant one.Strains of L.pneumophila were resistant to many antibiotics.Inoculation of Legionellae into intracerebral route of suckling mice revealed that L.pneumophila was the most virulent.Conclusions:Serious and fatal L.pneumophila infections may be transmitted through water.Legionella can survive under various conditions in various water sources.L.pneumophila is the important pathogen causing human disease.Great challenge prevails to health care professionals because these Le gionellae acquired antibiotic resistance to many routinely prescribed antibiotics.
ABSTRACT
BACKGROUND: Infection by the intracellular bacteria Mycoplasma pneumoniae, Chamydophila pneumoniae, and Legionella pneumophila are common causes of community-acquired pneumonia (CAP). This study describes the evaluation of a new multiplex real-time PCR test, EuDx™-PN MLC Detection Kit (EUDIPIA), which allows the simultaneous detection of M. pneumoniae, C. pneumoniae, and L. pneumophila in respiratory samples. METHODS: A total of 353 samples were tested using three PCR kits: multiplex PCR (Seeplex PneumoBacter ACE Detection Kit) and two multiplex real-time PCR (EuDx™-PN MLC Detection Kit and Anyplex™ II RB5 Detection Kit). The results were considered true positives (expanded standard) for M. pneumoniae, C. pneumoniae, and L. pneumophila if they were positive according to any of the three tests. RESULTS: The sensitivity and specificity of EuDx™-PN MLC Detection Kit were 93.3–100% and 100%, respectively. The agreement rate and Cohen's kappa coefficient (value) between EuDx™-PN MLC Detection Kit and Anyplex™ II RB5 Detection Kit for M. pneumoniae, C. pneumoniae, and L. pneumophila were 70–100% and 0.82–1, respectively. CONCLUSION: These results demonstrate that the EuDx™-PN MLC Detection Kit is a sensitive, specific, and useful screening tool for the detection of atypical pathogens in respiratory samples and can be helpful in selecting appropriate antimicrobial therapy for patients with respiratory infection.
Subject(s)
Humans , Bacteria , Chlamydial Pneumonia , Chlamydophila pneumoniae , Chlamydophila , Legionella pneumophila , Legionella , Mass Screening , Multiplex Polymerase Chain Reaction , Mycoplasma pneumoniae , Mycoplasma , Pneumonia , Pneumonia, Mycoplasma , Polymerase Chain Reaction , Real-Time Polymerase Chain Reaction , Respiratory Tract Infections , Sensitivity and SpecificityABSTRACT
Objective To establish a accurate and rapid method of loop-mediated isothermal amplification(LAMP) for detecting Legionella Pneumophila(LP) .Methods The strains of LP ,Staphylococcus aureus ,Pseudomonas aeruginosa ,Escherichia coli ,Enterobacter sakazakii ,Listeria monocytogenes ,Salmonella typhimurium ,shigella flexneri and Vibrio parahaemolyticus were selected . According to six special domains of toxicity-related mip gene on LP ,the LAMP primers(mip-1 ,mip-2 ,mip-3) were designed by using the Primer Explorer Version 4 .0 .The genomic DNA was extracted for conducting LAMP .Then its specificity ,lowest detectable limit and stability were evaluated .Results The screened primer mip-3 appeared the peak after amplification for about 10 min in the LAMP reaction system for detecting LP ,moreover the peak value was higher ;while the strains of non-LP had no amplification reaction ;the LAMP detection limit could reach 100 fg/μL .The primer mip-3 appeared the peak almost at the same time in 20 times of duplicated detection ,and its stability was good .Conclusion The established LAMP detection method has the advantages of strong specificity and high stability ,can rapidly and accurately detect LP and has large prospect of promotion and application .
ABSTRACT
Objective To investigate the prevalence, isolation, identification, characterization, antibiotic profile and pathogenicity of Legionellae isolated from various set of waters. Methods A total of 400 water samples were collected from different water sources. Water samples were pretreated using acid treatment followed by concentration and culture on buffered charcoal yeast extract agar. Parameters like ability of Legionella isolates to grow in various pH range, effect of different concentrations of chlorine and effect of different temperature optima were set up. Biochemical tests were performed to separate Legionellae into species. Antibiotic sensitivity tests and test for pathogenicity were also conducted on isolated strains. Results The rates of isolation of Legionella pneumophila (L. pneumophila) in different water sources were found to be 20% (lakes), 10% (ponds), 8% (water-tanks) and 1% (rivers). Most of the isolates could grow in variable pH 6–8 and it could also survive the normal level of chlorination and even at temperature of 42 °C. Isolated species of Legionellae resulted in identification of 5 different species, L. pneumophila being the dominant one. Strains of L. pneumophila were resistant to many antibiotics. Inoculation of Legionellae into intracerebral route of suckling mice revealed that L. pneumophila was the most virulent. Conclusions Serious and fatal L. pneumophila infections may be transmitted through water. Legionella can survive under various conditions in various water sources. L. pneumophila is the important pathogen causing human disease. Great challenge prevails to health care professionals because these Legionellae acquired antibiotic resistance to many routinely prescribed antibiotics.
ABSTRACT
The aim of the research is to investigate the genetic characteristics of Legionella pneumophila serogroup1 (LP1)in Sichuan Province.The sequence-based typing (SBT) and multiple-locus VNTR analysis (MLVA) were used to describe the genetic polymorphism of 42 strains which were isolated from 1989-2016 in Sichuan Province,China.According to the reference,PCR was used to detect the 8-VNTR loci and 7 housekeeping genes respectively.The VNTR results were determined by using capillary electrophoresis,and the SBT results were sequenced and compared with the database of EWGLI.Results showed that totally 42 stains were divided into 8 MLVA types with the advantage types were M08 (47.6 ％) and M07 (23.8 ％).Twelve ST types were obtained with 3 main clonal complex and 2 singleton,including 2 novel ST types,among those,ST1 was the predominant type,accounting for 52.3 ％,following by ST630 (14.2 ％).In conclusion,our results demonstrated MLVA and SBT were both applied to the research for molecular epidemiological investigation of LP1 and showed the high genetic polymorphism and the regional specificity.The results also suggest that the isolates are a potential threat to the public,effective control and prevention strategies are urgently needed.
ABSTRACT
The aim of the research is to investigate the genetic characteristics of Legionella pneumophila serogroup1 (LP1)in Sichuan Province.The sequence-based typing (SBT) and multiple-locus VNTR analysis (MLVA) were used to describe the genetic polymorphism of 42 strains which were isolated from 1989-2016 in Sichuan Province,China.According to the reference,PCR was used to detect the 8-VNTR loci and 7 housekeeping genes respectively.The VNTR results were determined by using capillary electrophoresis,and the SBT results were sequenced and compared with the database of EWGLI.Results showed that totally 42 stains were divided into 8 MLVA types with the advantage types were M08 (47.6 ％) and M07 (23.8 ％).Twelve ST types were obtained with 3 main clonal complex and 2 singleton,including 2 novel ST types,among those,ST1 was the predominant type,accounting for 52.3 ％,following by ST630 (14.2 ％).In conclusion,our results demonstrated MLVA and SBT were both applied to the research for molecular epidemiological investigation of LP1 and showed the high genetic polymorphism and the regional specificity.The results also suggest that the isolates are a potential threat to the public,effective control and prevention strategies are urgently needed.
ABSTRACT
Legionella pneumophila is one of the important pathogen responsible for community –acquired pneumonia attributing for 1-5% of cases. Since early and accurate therapy reduces mortality, rapid and reliable diagnostic methods are needed. A total of 134 samples of blood, urine and respiratory tract fluids were collected. Blood was tested for IgG, IgM and IgA antibodies using commercially available kits. A total of 8 (6%) samples were found to be positive for L. pneumophila by quantitative reverse transcription polymerase chain reaction (qRT‑PCR), compared to conventional PCR where 6 (4.4%) samples were positive. Serology was positive in a total of 32 (23%) cases though only 3 (2.2%) of the PCR‑positive cases were positive by serology as well. These results suggest that real‑time PCR can detect Legionella infection early in the course of the disease before serological response develops.