关注军团菌肺炎诊治中易被忽视的临床问题

军团菌肺炎常快速进展,病死率高。随着检测技术的进步,近年来军团菌的检出率较前有所增高,但仍有漏诊的病例,延误治疗是患者死亡的原因之一。因此,早期识别军团菌肺炎的临床特点、及时进行恰当的治疗至关重要。虽然军团菌肺炎某些特征已被临床所认知,但仍存在诸多被忽视的问题。本文旨在全面回顾军团菌肺炎的临床表现、辅助检查和治疗策略,提高临床医师对该病诊治的认识,以改善患者预后。

关键环境因子对嗜肺军团菌(Legionella pneumophila)在嗜热四膜虫(Tetrahymena thermophila)细胞内增殖的影响

嗜肺军团菌是一种生活在人工水环境中的条件性致病菌,环境条件对该菌的存活和胞内增殖具有重要的影响.本文用作者建立的军团菌-四膜虫模型,研究了空调水池水、Fe3+和感染温度3种关键性环境因子对嗜肺军团菌在嗜热四膜虫宿主细胞内增殖的影响.结果发现,尽管空调水中Fe3+浓度大大低于培养基中的Fe3+浓度,但适合嗜肺军团菌在嗜热四膜虫宿主胞内的存活和增殖;感染缓冲液中的Fe3+能够被嗜热四膜虫富集,并被胞内的军团菌加以利用,缓冲液中浓度0.05×10-6的Fe3+即可显著促进胞内军团菌的增殖,但0.1×10-6和0.5×10-6的Fe3+促进军团菌胞内增殖的效果差异不显著;较高的温度对军团菌的胞内增殖也有明显促进作用,35℃时,即使感染复数等于10,军团菌也可进行胞内复制扩增,并最终裂解宿主细胞.

嗜肺军团菌效应蛋白Lpg1972与CNOT7相互作用研究

嗜肺军团菌是一种寄生在真核细胞内的革兰氏阴性致病菌,其致病性主要是依靠IVB型分泌系统分泌的330多种效应蛋白,效应蛋白之间彼此协作共同干扰真核宿主细胞的各种细胞活动.嗜肺军团菌效应蛋白Lpg1972与真核细胞Ccr4-Not复合物中的CNOT7亚基存在相互作用,而Ccr4-Not复合物是真核细胞中调控mRNA降解的关键蛋白。基于此通过分子生物学的手段验证了它们之间的相互作用,设计共表达载体纯化了复合物蛋白,并利用AlphaFold2对复合物的结构和相互作用进行了预测分析,为后续研究奠定了基础。

阿奇霉素对军团菌肺炎患儿疗效、IgM抗体阳性率、肺功能及免疫功能的影响

目的:探究阿奇霉素应用于军团菌肺炎患儿对免疫球蛋白M(IgM)抗体阳性率、肺功能及免疫功能的影响。方法:选取江西省妇幼保健院2021年10月—2022年12月收治的100例军团菌肺炎患儿作为研究对象,采用随机数字表法将其分为阿奇霉素组和红霉素组,每组50例。对阿奇霉素组患儿给予阿奇霉素,对红霉素组患儿给予红霉素。观察并比较两组临床疗效、IgM抗体阳性率、肺功能指标[呼吸频率(RR)、最大呼气流量(PEF)、用力呼出25%肺活量时的平均呼气流速(FEF25)、用力呼出50%肺活量时的平均呼气流速(FEF50)]、免疫功能指标[T淋巴细胞亚群(CD3^(+)、CD4^(+)、CD8^(+))]。结果:用药后,阿奇霉素组总有效率明显低于红霉素组,差异有统计学意义(P<0.05)。用药后1个月,阿奇霉素组IgM抗体阳性率明显低于红霉素组,差异有统计学意义(P<0.05)。用药后,阿奇霉素组FEF25、FEF50及CD3^(+)、CD4^(+)均高于红霉素组,RR及CD8^(+)均低于红霉素组,差异均有统计学意义(P<0.05);两组PEF水平相近,差异无统计学意义(P>0.05)。结论:军团菌肺炎患儿应用阿奇霉素治疗效果显著,改善感染症状、呼气功能及免疫功能效果较好,可替代红霉素作为首选药物。

Rapid Identification of Legionella Pathogenicity by Surface-Enhanced Raman Spectroscopy

Objective To establish Surface-enhanced Raman Spectroscopy（SERS） can be used as a rapid and reliable method to distinguish virulent strain and mild strain of L. pneumophila. Methods We isolated and characterized of bacterial strains from ATCC and water samples strains, while we analyzed data from SERS technology using gold nanoparticles as a base and cell infections were employed to rapidly detect L. pneumophila strains. Origin 8.0 was used to collect Raman spectra, smooth and homogenize data, and to contrast spectra. Principal component analysis（PCA） was conducted to discriminate differences between groups using the multivariate analysis package Py Chem 3.0.5. Results Our results indicated that the peaks of high virulence strains reached ≥4000. This criterion was verified by subsequent cell experiments. In addition, we also conducted SERS rapid identification on the virulence of several collected clinical strains and obtained accurate results. Conclusion The present study indicates that the established SERS protocol can be used as a rapid and reliable method to distinguish virulent and mildly virulent strains of L. pneumophila, which can be further used in clinical samples.

Legionella and legionnaires' disease: An overview

Legionellosis is the generic term used to describe infections caused by different varieties of Legionella spp.,including Legionnaires'disease(LD),a severe and potentially fatal form of pneumonia,and Pontiac fever,a self-limited flu-like illness.Legionellosis is usually acquired through inhalation or aspiration of aerosols containing Legionella spp.These bacteria can cause acute consolidating pneumonia in susceptible patients who are at an advanced age,have underlying debilitating diseases,or are immunodeficient.The main natural reservoir for Legionella is water and this pathogen colonizes many different natural and man-made freshwater environments such as water networks,cooling towers,and water systems in buildings and hospitals.In recent years,various laboratory diagnostic tests for Legionella infections have changed significantly.Although the sequencing method is nowadays considered the fastest and most reliable method for differentiation and detection of different Legionella species,the isolation of these bacteria from clinical specimens is the golden standard for diagnosis of Legionnaires'disease.Today the urinary antigen test as the most rapid and inexpensive method is routinely used for diagnosis of LD caused by Legionella pneumophila serogroup 1.The macrolides and fluoroquinolones are still the mainstays for the treatment of Legionella infections.For the prevention of spreading the contaminated water aerosols and controlling Legionella infections,an effective water treatment procedure is necessary.This review describs and summarizes the latest available information about all aspects of Legionella and Legionnaires'disease.

Pneumocystis jirovecii and Legionella pneumophila coinfection in a patient with diffuse large B-cell lymphoma:A case report

BACKGROUND Diffuse large B-cell lymphoma(DLBCL)is a common non-Hodgkin's lymphoma.R-CHOP is a protocol for long-term chemotherapy for DLBCL patients.Longterm chemotherapy can lead to low immunity and increase the risk of opportunistic pathogen infections in immunocompromised patients.CASE SUMMARY We report a case of coinfection with Pneumocystis jirovecii(P.jirovecii)and Legionella pneumophila(L.pneumophila)in a patient with DLBCL.The patient was a 40-year-old female who was diagnosed with DLBCL and was admitted due to pulmonary infection.P.jirovecii and L.pneumophila were detected in her bronchoalveolar lavage fluid by hexamine silver staining,isothermal amplification and metagenomic sequencing.CONCLUSION To the best of our knowledge,this is the first case of P.jirovecii and L.pneumophila coinfection found in a DLBCL patient.Clinicians should be aware of the risk of complicated infection in patients undergoing long-term chemotherapy.

Isolation,identification,characterization and antibiotic sensitivity profile of pathogenic Legionella pneumophila isolates from different water sources

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 p H 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 p H 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.

A Case of Comorbidity of Complicated Infective Endocarditis and Severe Pneumonia Due to Legionella Pneumophila

Legionella pneumophila infection can cause Legionnaires’disease,a severe form of pneumonia.Extrapulmonary manifestations of Legionella infections include myocarditis,pericarditis,and endocarditis.We present a rare case of pneumonia caused by Legionella pneumophila with a possible etiologic link to a recently recovered culture-negative infective endocarditis.

Evaluation of the Effectiveness of a 4-Months Continuous Injection of a Gas Mixture (CO₂and Inert Gases) on <i>Legionella</i>Contamination of a Hot Water Distribution System

Within the biofilm and scales Legionella is less far susceptible to the effects of the most frequently used biocides. The objective of this study was to evaluate the effect of a 4-months continuous injection of a gas mixture (CO2 and inert gas) in the hot water distribution system of a large hotel colonized by L. pneumophila sg3 on limiting biofilm formation and scales and in turn Legionella growth. Before the continuous injection of the gas mixture, out of the 15 sampling points examined every month 60% were colonized by Legionella (mean concentrations of 102 cfu/L in the boilers and the return loop, and 104 cfu/L in taps and showers). One week after the injection of the gas mixture and daily fluxing of the distal outlets, the level of colonization decreased (3 cfu/L). When it was decided to flux all the distal outlets only 1 day per week the mean concentration of Legionella increased again (>104 cfu/L) in all the sampling points. Thus, cleaning of the boilers was performed and distal outlets were again fluxed daily. One week after the level of contamination decreased again (2 cfu/L). Nonetheless, the colonization was not eliminated and when fluxing of the distal outlets was not performed every day the mean concentrations of Legionella raised up to >104 cfu/L. Results indicate that the gas mixture was able to reduce the level of colonization by Legionella only because associated to the fluxing of the distal outlets.

Monochloramine for Remediation of <i>Legionella</i>Only in Domestic Hot Water Systems: An Iron Fist in a Velvet Glove

Monochloramine is a well-known disinfectant for drinking water with several advantages over chlorine and chlorine dioxide. With these two biocides, monochloramine is included in the US-EPA list of disinfectants for drinking water. At the beginning of XXI century, epidemiological studies demonstrated its superior ability to control Legionella in hot water health-care premises. In 2005 a research program started to set up a reliable and effective method to produce monochloramine directly in domestic hot water systems, at the safest concentration and without accumulation of by-products. Results of these researches, which has been carried out with the collaboration of Italian and American Institutions showed that monochloramine can be safely and reliably prepared and that it is the best approach to Legionella remediation in health-care facilities.

Fatal Legionella pneumophila serogroup 1 pleural empyema:A case report

BACKGROUND Legionella pneumophila(L.pneumophila)is a gram-negative intracellular bacillus composed of sixteen different serogroups.It is mostly known to cause pneumonia in individuals with known risk factors as immunocompromised status,tobacco use,chronic organ failure or age older than 50 years.Although parapneumonic pleural effusion is frequent in legionellosis,pleural empyema is very uncommon.In this study,we report a case of fatal pleural empyema caused by L.pneumophila serogroup 1 in an 81-year-old man with multiple risk factors.CASE SUMMARY An 81-year-old man presented to the emergency with a 3 wk dyspnea,fever and left chest pain.His previous medical conditions were chronic lymphocytic leukemia,diabetes mellitus,chronic kidney failure,hypertension and hyperlipidemia,without tobacco use.Chest X-ray and comouted tomographyscan confirmed a large left pleural effusion,which puncture showed a citrine exudate with negative standard bacterial cultures.Despite intravenous cefotaxime antibiotherapy,patient’s worsening condition after 10 d led to thoracocentesis and evacuation of 2 liters of pus.The patient progressively developed severe hypoxemia and multiorgan failure occurred.The patient was treated by antibiotherapy with cefepime and amikacin and with adequate symptomatic shock treatment,but died of uncontrolled sepsis.The next day,cultures of the surgical pleural liquid samples yielded L.pneumophila serogroup 1,consistent with the diagnosis of pleural legionellosis.CONCLUSION L.pneumophila should be considered in patients with multiple risk factors and undiagnosed pleural empyema unresponsive to conventional antibiotherapy.

Staphylococcus haemolyticus superinfection of legionella pneumonia during infliximab therapy

We present the case of a 42-year-old man affected by psoriasis with Staphylococcus Haemolyticus superin-fection of Legionella pneumonia during infliximab therapy. The introduction of compounds that block TNF-α has yielded great benefits for patients affected by selected autoimmune diseases that fail to respond to classic anti-inflammatory agents, but, on the other hand, has led to an increased susceptibility to infec-tions, in particular of those caused by intracellular pathogens, such as L. Pneumophila. Emerging evi-dence suggests that legionellosis can be complicated by superinfection with other agents, including sap-rophytic microorganisms, among which coagulase- negative staphylococci. To our knowledge, this is the first report of systemic legionellosis with superinfec-tion by S. Haemolyticus, an emerging nosocomial multi-resistant pathogen that commonly causes sep-ticemia, osteomyelitis or endocarditis, but has not so far been associated with necrotizing pneumonia. De-spite the optimal antimicrobial therapy for Staphylo-coccus spp. pneumonia is still controversial, evidence suggests that in patients with confirmed positivity for methicillin resistant strains, particularly if sensitivity to vancomycin is suboptimal, linezolid should be the first choice therapy, being superior to vancomycin and teicoplanin.

Three-dimensional structures of virulence proteins of Legionella establish targets for new antibacterials

Legionella pneumophila,the causative agent of Legionnaires' disease,has been recognized as a major health problem responsible for an estimated number of 15 000-30 000 cases of severe pneumonia per year in Germany alone.Despite of the high clinical relevance,many aspects of the intracellular life cycle of Legionella,especially details on interactions with host cells,are not well understood.Structural information on virulence proteins helps unravel basal pathogenicity mechanisms and is a prerequisite for the rational development of effective drug molecules.Here we discuss structures of three important virulence proteins of Legionella that have been determined in our laboratory.The structure of the macrophage infectivity potentiator(Mip) protein of Legionella pneumophila is the first of a novel subgroup within the family of FK506-binding protein(FKBP) peptidyl-prolyl cis/trans isomerases.On the basis of the Mip structure,promising antibacterial agents are being designed.Recently,structures of two equally exciting Legionella proteins have been reported.The ferrous iron transport protein FeoB is a transmembrane protein responsible for Fe2+ aquisition after entry of the pathogen into the host cell.The structure of the cytoplasmic domain of FeoB provides insights into the family of prokaryotic G proteins and allows a detailed comparison with structures of related FeoBs.Furthermore,the characterization of DegQ,a periplasmatic chaperone-protease involved in protein quality control represents an intriguing example of how enzymatic activity is regulated by oligomerization as well as by an intrinsic loop activation cascade,depending on subtle conformational rearrangements.