肺部侵袭性曲霉菌感染的诊断思路

侵袭性真菌感染(invasive fungal infection,IFI)是免疫低下患者常见的并发症之一,尤其在血液肿瘤患者和造血干细胞移植后患者中,IFI更是影响患者生存和生活质量的重要因素。随着氟康唑在高危人群中的广泛预防性应用,白念珠菌的感染较前已有所减少,而曲霉菌的感染比例则有所增[1]     

Laboratory diagnosis of invasive aspergillosis

Invasive aspergillosis is major cause of morbility and mortality in immunosuppressed patients, in part due to the inability to identify infected patients at an early stage of the disease. Diagnosis is based on a combination of imaging (high-resolution computed tomography) and a number of laboratory techniques including direct examination, culture and circulating markers (galactomannan and Aspergillus DNA) which can be detected at early stages of the infection.     

国产血清半乳甘露聚糖检测试剂对侵袭性肺曲霉菌病的诊断价值评估

目的：评估国产血清半乳甘露聚糖（Galactomannan,GM）检测试剂对侵袭性肺曲霉菌病的诊断价值。方法根据血液病/恶性肿瘤患者侵袭性真菌病的诊断标准与治疗原则（第四次修订版）[1]收集临床确诊侵袭性肺曲霉菌病（inva-sive pulmonary aspergillosis,IPA）、临床诊断IPA、拟诊IPA、排除IPA四组病例。采用天津贻诺琦公司酶联免疫吸附法（ELISA）试剂检测纳入的86例患者血清标本的GM浓度,分析其敏感性、特异性、阳性预测值（PPV）、阴性预测值（NPV）。结果86例病例中,临床诊断27例、拟诊12例、排除47例。在3种不同的阳性判断标准下,敏感性：9444%、9630%、6296%;特异性：5625%、4576%、6441%;PPV：4474%、4483%、4474%;NPV：9643%、9643%、7917%。统计学分析证实标准1（即血清GM值〉095μg/L为阳性,〈075μg/L为阴性,075~095μg/L为灰区,未将灰区加入计算）在3种判断标准中最优,故选择其为最终判断标准。结论该血清GM检测试剂盒诊断性能较好,可以用于侵袭性肺曲霉菌病的辅助诊断。     

Towards a molecular diagnosis of invasive aspergillosis and disseminated candidosis

A lot of in-house polymerase chain reaction assays have been reported for diagnosis of invasive aspergillosis and disseminated candidosis. Encouraging results have been published to anticipate the diagnosis over the conventional microbiological methods. However, the absence of standardized methods has led to diverging results. As a consequence, these tests are not recognized as consensual diagnostic criteria, in contrast with some antigenemia detection kits. The major breakthrough for improving the results of these methods is the emergence of real-time technologies. This markedly improves the reliability of the PCR results by dramatically decreasing the risk of false positive results due to PCR products carryover. Moreover, using the quantitative results provided by this technique, this allows to rapidly compare the efficiency of primers, probes, and DNA extraction methods. Therefore, the hope is to identify the more specific and sensitive parameters to implement comparative studies. Automated DNA extraction should also be useful to achieve this goal.Whatever sophisticated technology is used, we still have to define the meaning of detecting nucleic acids in a given clinical sample. This seems simple in normally sterile anatomical sites but less obvious for example in respiratory specimens for invasive aspergillosis or in blood for candidosis in heavily colonized patients. Additional studies of the kinetics of fungal DNA are needed. The development of real-time technology should improve our knowledge in order to give the clinicians informative clues for making a decision.     

Towards a molecular diagnosis of invasive aspergillosis and disseminated candidosis

A lot of in-house polymerase chain reaction assays have been reported for diagnosis of invasive aspergillosis and disseminated candidosis. Encouraging results have been published to anticipate the diagnosis over the conventional microbiological methods. However, the absence of standardized methods has led to diverging results. As a consequence, these tests are not recognized as consensual diagnostic criteria, in contrast with some antigenemia detection kits. The major breakthrough for improving the results of these methods is the emergence of real-time technologies. This markedly improves the reliability of the PCR results by dramatically decreasing the risk of false positive results due to PCR products carryover. Moreover, using the quantitative results provided by this technique, this allows to rapidly compare the efficiency of primers, probes, and DNA extraction methods. Therefore, the hope is to identify the more specific and sensitive parameters to implement comparative studies. Automated DNA extraction should also be useful to achieve this goal. Whatever sophisticated technology is used, we still have to define the meaning of detecting nucleic acids in a given clinical sample. This seems simple in normally sterile anatomical sites but less obvious for example in respiratory specimens for invasive aspergillosis or in blood for candidosis in heavily colonized patients. Additional studies of the kinetics of fungal DNA are needed. The development of real-time technology should improve our knowledge in order to give the clinicians informative clues for making a decision.     

T cell vaccination in mice with invasive pulmonary aspergillosis

Aspergillus fumigatus, an opportunistic fungal pathogen, is responsible for multiple airway diseases of an allergic and a nonallergic nature. In a murine model of invasive pulmonary aspergillosis, resistance is associated with a decreased lung inflammatory pathology and the occurrence of an IL-12-dependent Th1-type reactivity that are both impaired by IL-4. In the present study we assess the ability of Aspergillus crude culture filtrate Ags and the recombinant allergen Asp f 2 to induce protective antifungal responses in mice with invasive pulmonary aspergillosis. Similar to what occurred upon nasal exposure to viable A. fumigatus conidia, treatment of immunocompetent mice with Aspergillus crude culture filtrate Ags resulted in the development of local and peripheral protective Th1 memory responses, mediated by Ag-specific CD4+ T cells producing IFN-gamma and IL-2 capable of conferring protection upon adoptive transfer to naive recipients. Protective Th1 responses could not be observed in mice deficient of IFN-gamma or IL-12 and did not occur in response to Asp f 2, which, on the contrary, elicited high level production of inhibitory IL-4. The results show that Ags of Aspergillus exist with the ability to induce both Th1- and Th2-type reactivity during infection, a finding that suggests a possible mechanism through which potentially protective immune responses are inhibited in mice with the infection. However, the occurrence of Th1-mediated resistance upon vaccination with Aspergillus crude culture filtrate Ags, suggests the existence of fungal Ags useful as a candidate vaccine against invasive pulmonary aspergillosis.     

128例侵袭性肺曲霉病临床疗效分析

目的 通过回顾性病例分析,加强对侵袭性肺曲霉病的认识,重视对侵袭性肺曲霉病的分级诊断,从而制定合理治疗方案.方法 对四川大学华西医院201 1年1 ～12月128例诊断为侵袭性肺曲霉病患者的临床资料进行回顾性分析,重点分析基础疾病、临床表现、影像学表现、诊断及治疗方法.结果 确诊17例;依据宿主危险因素、临床表现及反复痰培养阳性拟诊111例.128例患者均伴有基础疾病.治疗方案包括伏立康唑（86例）,两性霉素B脂质体（1例）,伊曲康唑（12例）,米卡芬净（3例）,卡泊芬净（3例）,两性霉素B去氧胆酸盐（10例）,伏立康唑联合米卡芬净（1例）.治愈或好转81例（63.28％）,自动出院24例（18.75％）,死亡23例（17.97％）.结论 侵袭性肺曲霉病患者多数伴有多种感染危险因素,应当重视侵袭性肺曲霉病的分级诊断,据不同情况给予适当抗真菌治疗,以降低患者病死率.     

Bronchoalveolar lavage in an immunosuppressed rabbit model of invasive pulmonary aspergillosis

A rabbit model of invasive aspergillosis has been used to investigate the pathogenesis of Aspergillus infection in the immunosuppressed host. The animals received hydrocortisone daily and a single dose of cyclophosphamide 2 days prior to intratracheal instillation of conidia from Aspergillus fumigatus. Bronchoalveolar lavage (BAL) was performed in 3 infected and 2 control saline treated animals sacrificed on days 1, 2, 4, 7 and 10 following inoculation. Infective load within the lung was quantified using an assay for chitin which is an important component of fungal cell walls (in particular the hyphal cell wall) and is not present in vertebrate tissue. The total BAL white cell count did not discriminate between infected and saline treated animals and Aspergillus was cultured from one lavage specimen only. Infected animals developed a marked neutrophil alveolitis by day 2 in contrast to a near total absence of neutrophils in the lavages of the control animals. Phagocytosis of conidia by alveolar macrophages was prominent but did not prevent progressive infection as confirmed by measurement of lung chitin. This pattern of cellular response within the alveolar airspace reflects the complex nature of the response to Aspergillus infection in the immunosuppressed host.     

Early diagnosis of invasive aspergillosis in neutropenic patients with bi-weekly serial screening of circulating galactomannan by Platelia Aspergillus

The diagnosis of invasive aspergillosis in neutropenic individuals is difficult and lengthy since non-invasive diagnostic tests lack sensitivity and specificity. The diagnosis of invasive aspergillosis in 154 prolonged neutropenic patients was prospectively bi-weekly validated by screening circulating galactomannan. The global sensitivity was 73% and specificity was 96%. The positive and negative predictive values were 73% and 98% respectively. False positive reactions occurred at a rate of 2%. Antigenemia was detected before clinical suspicion of invasive aspergillosis (median, 6 days before) in 30% of patients and anticipated the onset of radiologic signs 9 days in 60% of patients. CONCLUSION: the prospective screening of galactomannan is a sensitive and non-invasive tool for early diagnosis of invasive aspergillosis in high-risk adult hematology patients.     

胞浆识别受体NODs及其信号通路在侵袭性肺曲霉病中的作用

【目的】研究天然免疫系统中胞浆识别受体NODs及其信号通路在小鼠侵袭性肺曲霉病(IPA)中的作用。【方法】小鼠随机分为正常对照组、正常+接种烟曲霉菌组(正常感染组)和免疫抑制+接种烟曲霉菌组(IPA组),经鼻吸入烟曲霉孢子后在不同时相点处死小鼠,无菌取肺组织分别进行病理切片,烟曲霉菌落计数,RT-PCR法、Western blot法动态检测小鼠感染烟曲霉菌过程中肺组织NOD1、NOD2、RIP2 mRNA表达,促炎细胞因子TNF-α含量的变化规律。【结果】鼻吸入烟曲霉菌后72 h时,IPA组肺组织出现严重炎症反应,并有大量的菌丝生成,同时各时相点的烟曲霉菌负荷均高于正常感染组;与正常感染组比较,IPA组NOD1、RIP2 mRNA持续低表达,而NOD2 mRNA则在感染最早期(24 h)异常高表达,而在随后的感染过程中一直处于低表达状态;正常小鼠感染烟曲霉菌后,肺组织中促炎细胞因子TNF-α在感染前期皆呈高表达,且最高表达量均出现在48 h或72 h,之后下降并恢复至正常水平。而IPA小鼠促炎症细胞因子TNF-α缓慢且低水平释放。【结论】NOD1、RIP2的表达受到长期抑制,NOD2在感染最早期的过度激活以及随后的抑制表达,引起促炎细胞因子低表达,可能导致了侵袭性肺曲霉的发生发展。     

肺部CT联合血清半乳甘露聚糖实验在白血病并发侵袭性肺曲霉菌病诊断及疗效评价中的应用

目的探讨肺部CT联合血清半乳甘露聚糖实验在白血病并发侵袭性肺曲霉菌病诊断及疗效评价中的应用价值。方法对我院2010年1月~2012年12月期间,收集临床诊断为IPA的白血病患者25例,回顾性分析其CT影像和GM实验。结果 CT表现出现结节及晕征17例,出现楔形实变影3例,弥漫分布粟粒或小结节模糊影4例;1例表现为两肺散在斑片影伴周围"卫星灶"。15例抗真菌治疗有效,治疗过程中GM值降低至正常;8例进展、GM值升高,之后调整抗真菌治疗方案有效、GM值降低;2例患者感染无法控制,GM值上升或虽有下降但一直处于阳性水平。结论肺部CT检查联合血清半乳甘露聚糖(GM)实验可监测临床诊断侵袭性肺曲霉病(IPA)的疗效。     

慢性阻塞性肺疾病急性加重期合并侵袭性肺曲霉菌病23例临床分析

目的探讨慢性阻塞性肺疾病急性加重期(AECOPD)合并侵袭性肺曲霉菌病(IPA)的危险因素及临床特点。方法回顾分析2008年5月至2010年6月浙江大学医学院附属第一医院收治的慢性阻塞性肺疾病急性加重期合并侵袭性肺曲霉菌病患者的临床资料。结果 23例患者中,确诊7例,临床诊断16例。平均年龄(68.3±4.32)岁。其中22例使用广谱抗生素和15例长期使用激素,12例1年内住院>3次,11例年龄>70岁。病灶出现在双上肺占52.1%,双肺多发占21.7%,双下肺占13.0%,位于右中叶和左舌叶共占13.0%;其中5例(21.7%)出现晕征,4例(17.3%)出现"新月"征。结论使用广谱抗生素、长期激素治疗、频繁住院等是慢性阻塞性肺疾病合并肺曲霉菌的危险因素,患者临床表现缺乏特异性,胸部CT表现有一定特征性,结合患者有危险因素及实验室检查,有助于早期诊断和早期治疗,改善患者预后。     

In vivo hypoxia and a fungal alcohol dehydrogenase influence the pathogenesis of invasive pulmonary aspergillosis

Currently, our knowledge of how pathogenic fungi grow in mammalian host environments is limited. Using a chemotherapeutic murine model of invasive pulmonary aspergillosis (IPA) and (1)H-NMR metabolomics, we detected ethanol in the lungs of mice infected with Aspergillus fumigatus. This result suggests that A. fumigatus is exposed to oxygen depleted microenvironments during infection. To test this hypothesis, we utilized a chemical hypoxia detection agent, pimonidazole hydrochloride, in three immunologically distinct murine models of IPA (chemotherapeutic, X-CGD, and corticosteroid). In all three IPA murine models, hypoxia was observed during the course of infection. We next tested the hypothesis that production of ethanol in vivo by the fungus is involved in hypoxia adaptation and fungal pathogenesis. Ethanol deficient A. fumigatus strains showed no growth defects in hypoxia and were able to cause wild type levels of mortality in all 3 murine models. However, lung immunohistopathology and flow cytometry analyses revealed an increase in the inflammatory response in mice infected with an alcohol dehydrogenase null mutant strain that corresponded with a reduction in fungal burden. Consequently, in this study we present the first in vivo observations that hypoxic microenvironments occur during a pulmonary invasive fungal infection and observe that a fungal alcohol dehydrogenase influences fungal pathogenesis in the lung. Thus, environmental conditions encountered by invading pathogenic fungi may result in substantial fungal metabolism changes that influence subsequent host immune responses.