Characterisation and expression of phospholipases B from the opportunistic fungus Aspergillus fumigatus

The phospholipase B family (PLB) are enzymes sharing phospholipase (PL), lysophospholipase (LPL) and lysophospholipase-transacylase (LPTA) activities. They have been shown to be important virulence factors in several human fungal pathogens including Candida albicans and Cryptococcus neoformans. Aspergillus fumigatus, a human opportunistic fungal pathogen leading to a high rate of mortality in immunosuppressed patients is known to possess an extracellular phospholipase B activity. In this paper, we report the molecular characterisation of three PLB genes from A. fumigatus (afplb) using degenerate primers in PCR amplification and data from the A. fumigatus genome project. They are expressed at 37 degrees C, and two of them (afplb1 and afplb3) are induced by lecithin. They encode proteins of 633, 588 and 630 amino acids, respectively, presenting together a T-Coffee score of 81. They also possess the amino acid triad responsible for enzymatic activity in the mammalian cytosolic PLA2 and other fungal PLBs. AfPLB1 and afPLB3 are secreted with a cleaved signal peptide. The complete cDNA sequences were obtained by RACE-PCR for the two secreted afPLBs and probably account for the extracellular phospholipase activity previously reported in the culture media of A. fumigatus.     

Ocurrence of the antibiotic producing bacterium Burkholderia sp. in colonies of the leaf-cutting ant Atta sexdens rubropilosa

Fungus garden material from recently established Atta sexdens rubropilosa colonies (6-12 months old) was sampled to detect antibiotic producing microorganisms that inhibited the growth of pathogens of insects and of the fungus gardens but did not affect their mutualistic fungus. A bacterium with activity against the entomopathogenic fungus Beauveria bassiana was isolated from 56% of the gardens tested (n=57) and identified from its biochemical profile and from 16S and 23S ribosomal DNA sequences as a member of the genus Burkholderia. The ant-associated Burkholderia isolates secreted a potent, anti-fungal agent that inhibited germination of conidia of the entomopathogenic fungi B. bassiana, Metarhizium anisopliae, of the saprophytic Verticillium lecanii, and also of a specialist fungus garden Escovopsis weberi. Growth of the ant's mutualist fungus was unaffected.     

Isolation of an alpha-methylene-gamma-butyrolactone derivative, a toxin from the plant pathogen Lasiodiplodia theobromae

Lasiodiplodia theobromae is known as a multi-infectious microorganism that causes considerable crop damage, particularly to tropical fruits. When the fruits are infected by L. theobromae, the typical symptom is the appearance of black spots on the surface of the infected fruit. When injected in to the peel of banana, the culture filtrate of L. theobromae induced formation of black spots. The structure of the isolated compound responsible for this effect was determined to be (3S,4R)-3-carboxy-2-methylene-heptan-4-olide on the basis of analysis of MS, IR, and 1H and 13C NMR spectroscopic data, including HMQC, HMBC, and 1H-1H COSY experiments. The active compound was not only isolated from the culture filtrate derived from potato dextrose medium, but also from the extract of infected peels of bananas.     

君子兰软腐病病原体侵染途径与致病规律的研究

本文报导了君子兰(Clivia miniata)软腐病二株病原体的分离及确定;鉴定了病原体的分类地位,一株为链球菌属的一个新种,定名为君子兰链球菌(Streptococcus miniatus Zhou,Ping et al shao sp.nov),另一株为环状芽孢杆菌(Bacillus subtilis);并对其二病原体的侵染途径与致病规律进行了研究。     

白内障患者术后感染性眼内炎的病原菌分布及CD64指数、血清sTREM1、HMGB1表达的临床意义

摘要 目的：分析白内障患者术后感染性眼内炎（IE）的病原菌分布并探讨分化簇64（CD64）指数、血清可溶性髓系细胞触发受体1（sTREM1）、高迁移率族蛋白1（HMGB1）表达的临床意义。方法：选取2018年1月～2022年7月济南市人民医院眼科收治的125例（125眼）白内障术后IE患者为IE组,选取同期150例（150眼）白内障术后无术后IE患者为非IE组。分析术后IE患者病原菌分布,计算CD64指数和检测血清sTREM1、HMGB1表达。采用多因素Logistic回归分析白内障患者术后IE的影响因素,采用受试者工作特征（ROC）曲线分析CD64指数、血清sTREM1、HMGB1表达对白内障患者术后IE的诊断价值。结果：125例术后IE患者房水或玻璃原液中检测出138株病原菌,革兰氏阳性菌、革兰氏阴性菌、真菌分别占比81.88%（113/138）、16.67%（23/138）、1.45%（2/138）。与非IE组比较,IE组糖尿病、玻璃体溢出比例、CD64指数和血清sTREM1、HMGB1水平升高,手术时间更长（P＜0.05）。多因素Logistic回归分析显示,糖尿病、玻璃体溢出、手术时间延长和CD64指数、sTREM1、HMGB1升高为白内障患者术后IE的独立危险因素（P＜0.05）。ROC曲线分析显示,CD64指数与血清sTREM1、HMGB1联合预测白内障患者术后IE的曲线下面积显著高于单独预测。结论：白内障患者术后IE的病原菌以革兰氏阳性菌为主,CD64指数和血清sTREM1、HMGB1表达与白内障患者术后IE独立相关,可能成为白内障患者术后IE的辅助诊断指标,且三指标联合具有较高的预测价值。     

Pathogenicity of Sporotrichum pruinosum and Cladosporium oxysporum,isolated from the bronchial secretions of a patient,for laboratory mice

In this study we have demonstrated the occurrence of Sporotrichum pruinosum and Cladosporium oxysporum in the bronchial secretions of a patient with a presumptive diagnosis of tuberculosis. This observation coupled with the ability of both fungi to cause infection and elicit tissue responses in experimentally infected mice supported a probable etiologic relationship with the patient which could not be confirmed in the absence of histologic evidence. In vitro some antimycotics were tested against S. pruinosum and C. oxysporum by the agar dilution method. Oxiconazole with a minimum inhibitory concentration of 0.1 g/ml^–1 after 72 h and amorolfine at a concentration of 0.001 g/ml^–1 after 72 h were the most active ones against S. pruinosum and C. oxysporum respectively. It is suggested that the isolation of S. pruinosum and C. oxysporum from patients with bronchopulmonary disorders should be viewed with caution. Clinical and laboratory evaluation of such patients should be done critically before arriving at a firm diagnosis.     

A field study using the fungicide benomyl to investigate the effect of mycorrhizal fungi on plant fitness

Summary The effect of vesicular-arbuscular mycorrhiza (VAM) on the fecundity ofVulpia ciliata ssp.ambigua was investigated at two field sites in eastern England by applying the fungicide benomyl to reduce VAM infection. The application of benomyl at the two sites produced very different results. At one site the application of the fungicide reduced the fecundity of plants whereas at the other fecundity was increased. At the first site the reduction in fecundity was linked to a significant reduction in VAM infection on the sprayed plants. The mechanism of the benefit associated with the VAM infection is however unclear: there was no treatment effect on morphology or on phosphorus inflow. At the second site, where fecundity was increased, there was only a negligible amount of VAM infection amongst the unsprayed plants and it is suggested that the increase in fecundity with the application of benomyl may have resulted from a reduction in infection by other, presumably pathogenic, fungi. The value of VAM fungi to the host plant may therefore not be restricted to physiological benefits. They may also provide protection to the plant by competing for space with other species of pathogenic fungi.     

中长期深静脉留置透析的导管相关性感染菌群分布及药敏分析

目的探讨中长期深静脉留置透析的导管相关性感染(CRI)菌群分布及药敏分析。方法回顾性分析39例导管相关性感染患者发生率及感染类型,不同置管部位的感染情况,病原菌的种类分布,药敏试验和疗效。结果 106例中长期导管透析的患者中,39例发生导管相关性感染,占36.7%。其中感染率较高的原发病为狼疮肾及糖尿病性肾病。39例标本菌培养阳性,分离出6种病原菌,41株细菌。病原菌分布:革兰阳性球菌24株,占61.5%;革兰阴性杆菌15株,占38.5%。葡萄球菌属最为敏感的抗生素为万古霉素,对于革兰阴性杆菌,亚胺培南和头孢哌酮最为敏感。结论中长期维持性血液透析患者导管相关性感染的发生率较高,只有医护人员严格进行无菌操作,加强环境卫生,积极开展健康宣教,合理使用敏感抗菌药物,防止创口的污染,才能降低CRI的发生率,最终取得良好的临床效果。     

人艰难梭菌感染的致病机制与防治策略研究进展

艰难梭菌是一种非常重要的医院感染病原菌,其感染占抗菌素相关腹泻的10．25％,占抗菌素相关肠炎的50．75％,占抗菌素相关伪膜炎的90．100％。而且越来越多的证据表明艰难梭菌的感染与其它疾病,如活性关节炎、婴儿突发性死亡、溶血性尿毒症、坏死性肠炎、希施斯普龙病等有关。更糟糕的是艰难梭菌存在着复发性感染,15—20％的病人在成功治愈后会复发。近年来,随着强毒株的出现,艰难梭菌的感染率和发病率逐年上升,病情也越来越严重,由艰难梭菌感染引起的死亡率也成倍增加。到目前为止,艰难梭菌发病率升高的原因及其致病机制还有待进一步研究。由于艰难梭菌是一种孢子产生菌,对大部分抗菌素都有抗性,目前用于艰难梭菌防治的主要抗菌素甲硝唑和万古霉素的治疗效果也在不断下降,所以正确认识艰难梭菌的感染与流行,进一步了解其致病机制,寻找新的替代疗法已是迫在眉睫。本文对艰难梭菌感染和流行的病因进行了较为全面的分析,对其致病机制进行了深入的总结,并探讨了艰难梭菌防治的最新策略和方法,将有利于更好的认识和研究艰难梭菌,为艰难梭菌的防治提供新思路。     

白内障术后感染性眼内炎的致病菌分析及影响因素研究

目的:分析白内障术后感染性眼内炎的致病菌分布情况,并对其影响因素进行分析。方法:选取2016年8月~2019年3月期间于我院行白内障手术的患者2936例,统计白内障术后感染性眼内炎的发生情况。分析术后感染性眼内炎患者的病原菌分布情况及病原菌耐药情况。单因素及多因素Logistic回归分析术后感染性眼内炎发生的影响因素。结果:本研究中,共发放2936份调查问卷,回收2931份,回收率为99.83%(2931/2936)。其中53例患者患有感染性眼内炎,发生率为1.81%(53/2931),根据患者是否患有感染性眼内炎分为感染组(n=53)和未感染组(n=2878)。感染性眼内炎的病原菌检出41株,其中革兰阳性菌37株,占90.24%;共检出4株真菌,为白色假丝酵母菌,占比9.76%。37株革兰阳性菌中,头状葡萄球菌、表皮葡萄球菌以及腐生葡萄球菌对利福平、利奈唑胺以及万古霉素的敏感度达100.00%。感染组和未感染组在性别、住院时间、玻璃体溢出方面比较差异均无统计学意义(P>0.05);两组在麻醉药时间、年龄、手术切口、手术时间、高血压、糖尿病方面比较差异均有统计学意义(P<0.05)。多因素Logistic回归分析结果显示:年龄≥66岁、手术切口为透明角膜、手术时间≥15 min、合并糖尿病均是发生感染性眼内炎的危险因素(OR=2.759、2.676、1.601、1.261,P<0.05)。结论:白内障术后感染性眼内炎的致病菌较多,以革兰阳性菌为主,革兰阳性菌对利福平、利奈唑胺、万古霉素的敏感度较高,年龄≥66岁、手术切口为透明角膜、手术时间≥15 min、合并糖尿病均会增加术后感染性眼内炎发生的风险。