Asexual sporulation facilitates adaptation: The emergence of azole resistance in Aspergillus fumigatus

Understanding the occurrence and spread of azole resistance in Aspergillus fumigatus is crucial for public health. It has been hypothesized that asexual sporulation, which is abundant in nature, is essential for phenotypic expression of azole resistance mutations in A. fumigatus facilitating subsequent spread through natural selection. Furthermore, the disease aspergilloma is associated with asexual sporulation within the lungs of patients and the emergence of azole resistance. This study assessed the evolutionary advantage of asexual sporulation by growing the fungus under pressure of one of five different azole fungicides over seven weeks and by comparing the rate of adaptation between scenarios of culturing with and without asexual sporulation. Results unequivocally show that asexual sporulation facilitates adaptation. This can be explained by the combination of more effective selection because of the transition from a multicellular to a unicellular stage, and by increased mutation supply due to the production of spores, which involves numerous mitotic divisions. Insights from this study are essential to unravel the resistance mechanisms of sporulating pathogens to chemical compounds and disease agents in general, and for designing strategies that prevent or overcome the emerging threat of azole resistance in particular.     

藜蒿提取物抑菌作用的初步研究

采用榨汁、水提、醇提等 3种不同的方法 ,提取藜蒿中的抗菌有效成分。测定了各种提取物对 14种食品腐败菌的最低抑菌浓度 ( MIC) ,结果表明 :1.藜蒿汁的 MIC:痢疾杆菌为 2 5% ,大肠杆菌为 2 5% ,巨大芽孢杆菌为 50 % ,面包酵母为 5% ;2 .藜蒿水提物的 MIC:痢疾杆菌为 2 .5% ,大肠杆菌为 5% ,巨大芽孢杆菌为 5% ,面包酵母为 10 % ;3.黎蒿醇提物的 MIC:痢疾杆菌、巨大芽孢杆菌、大肠杆菌均为 5% ,蜡状芽孢杆菌、金黄色葡萄球菌、面包酵母、黄曲霉均为 10 % ,产朊酵母、裂殖酵母、异常汉逊酵母、白地霉、桔青霉、镰刀霉均为 2 0 %     

罕见角膜炎致病真菌的体外药敏试验

目的探索角膜炎罕见致病真菌对于临床常用抗真菌药物的敏感性。方法应用美国临床实验室标准化委员会制订的标准M38-A方案进行体外药敏试验。结果束状刺盘孢对4种抗真菌药的MIC值最低,≤4.0μg/ml;茄病镰刀菌次之;淡紫拟青霉的MIC值最高;茄病镰刀菌和淡紫拟青霉对氟康唑耐药。结论束状刺盘孢对氟康唑、酮康唑、伊曲康唑和两性霉素B体外试验敏感;淡紫拟青霉对酮康唑、伊曲康唑和两性霉素B的MIC值较高;茄病镰刀菌和淡紫拟青霉对氟康唑耐药。     

天然药物对牙龈卟啉单胞菌的体外抗菌研究

目的 观察天然药物对牙龈卟啉单胞菌（Porphyromonas gingivalis,P.gingivalis）生长的影响,筛选抗菌作用最强的天然药物。方法 选用7种天然药物,采用液体稀释法,结合吸光度测定以确定7种天然药物对P.gingivalis的最小抑菌浓度（MIC）与最小杀菌浓度（MBC）。结果 黄芩、三七、白芷、大黄、五倍子、血藤和川芎对P.gingivalis的MIC值分别为1、1、0.5、0.0156、1、0.5、0.125 mg/ml;MBC值分别为1、1、0.5、0.0625、1、1、0.25mg/ml。结论 7种天然药物对P.gingivalis的生长均表现出明显的抑制作用,大黄的抑菌作用最强,川芎其次。     

十八种辛香料对五种食源性致病菌的抑菌研究(英文)

本实验研究18种辛香料对五种食源性病原菌:单增李斯特菌,大肠杆菌O157∶H7,肠炎沙门氏菌,副溶血性弧菌和金黄色葡萄球菌的抑制作用。辛香料以60℃蒸馏水浸提。研究各种辛香料的最低抑菌浓度(80~5 mg/mL)以及经100℃处理15 m in和121℃处理15 m in的稳定性。结果表明,大部分辛香料具有良好的抑菌效果,尤其是丁香和桂皮对副溶血弧菌和金黄色葡萄球菌的最低抑菌浓度为5 mg/mL。经热处理部分香料失去了抑制作用,如八角,茴香,五香粉,海南白和黑胡椒,但大多数香料保持抑菌效果。这些结果表明,香料可抑制感染海产品的病原菌,同时在加工香料的过程中应该避免高温处理。     

石荠苧精油的GC-MS分析及其抑菌活性的研究

利用水蒸汽蒸馏法提取石荠芋（Mosla scabra（Thunb．）C．Y．Wu et H．W．Li]精油,得油率为1．2％。采用GC—MS方法分析了该挥发油的化学组成,检测到125个峰,共鉴定出其中67个化学成分并测定其相对含量。占总含量的95．25％。其中,（R）侧柏酮（26．11％）、（M）侧柏酮（13．66％）、石竹烯（8．89％）、桉叶油素（7．99％）、（R）-α-石竹烯（6．45％）、芹菜脑（5．43％）和β-荜澄茄油烯（4．51％）为主要成分。体外抑菌实验表明,该精油对7种供试细菌均有抑制作用,对金黄色葡萄球菌（Staphylococcus aureus Roenbach）、普通变形杆菌（Proteasv ulgarisHauser）、甘薯青枯假单胞菌（Ralstonia soanacearum E．F．Smith）、大肠杆菌（Esckrichia coli Castellani et Chalmers）和短小芽孢杆菌（Bacillus pumilus Meyer et Gottheil）的最低抑菌浓度（MIC）为2％,对枯草芽孢杆菌（Bacillus subtilis Cohn）和藤黄八叠球菌（Sarcina lutea Schroeter）的MIC为1％。     

Aggregates of nisin with various bactoprenol-containing cell wall precursors differ in size and membrane permeation capacity

Many lantibiotics use the membrane bound cell wall precursor Lipid II as a specific target for killing Gram-positive bacteria. Binding of Lipid II usually impedes cell wall biosynthesis, however, some elongated lantibiotics such as nisin, use Lipid II also as a docking molecule for pore formation in bacterial membranes. Although the unique nisin pore formation can be analyzed in Lipid II-doped vesicles, mechanistic details remain elusive. We used optical sectioning microscopy to directly visualize the interaction of fluorescently labeled nisin with membranes of giant unilamellar vesicles containing Lipid II and its various bactoprenol precursors. We quantitatively analyzed the binding and permeation capacity of nisin when applied at nanomolar concentrations. Specific interactions with Lipid I, Lipid II and bactoprenol-diphosphate (C₅₅-PP), but not bactoprenol-phosphate (C₅₅-P), resulted in the formation of large molecular aggregates. For Lipid II, we demonstrated the presence of both nisin and Lipid II in these aggregates. Membrane permeation induced by nisin was observed in the presence of Lipid I and Lipid II, but not in the presence of C₅₅-PP. Notably, the size of the C₅₅-PP–nisin aggregates was significantly smaller than that of the aggregates formed with Lipid I and Lipid II. We conclude that the membrane permeation capacity of nisin is determined by the size of the bactoprenol-containing aggregates in the membrane. Notably, transmitted light images indicated that the formation of large aggregates led to a pinch-off of small vesicles, a mechanism, which probably limits the growth of aggregates and induces membrane leakage.     

马齿苋体外抗菌作用的实验研究

目的：研究马齿苋水浸液,醇提液对大肠埃希菌,金黄色葡萄球菌,毛霉,黑曲霉的体外抑制作用。方法：要用滤纸片法进行定性研究;采用分光光度法进行定量研究。结果：马齿醇提液的抑菌效果强于其水提液;对细菌的抑菌作用强,对黑曲霉的作用不明显。结论：马齿苋体外对细菌有较强的抑制作用。     

A beta-defensin 1-like antimicrobial peptide from the tree shrew, Tupaia belangeri

A novel beta-defensin 1-like antimicrobial peptide (β-defensin 1TB) containing 36 amino acid residues was purified and characterized from the serum of the tree shrew, Tupaia belangeri. Its amino acid sequence was determined as DHYLCVKNEGICLYSSCPSYTKIEGTCYGGKAKCCK, by Edman degradation, mass spectrometry analysis, and cDNA cloning. Evolution analysis indicated that β-defensin 1TB showed maximal similarity to the β-defensin 1 identified from cotton-top tamarin, Saguinus oedipus. β-defensin 1TB exerted potential antimicrobial activities against wide spectrum of microorganisms including Gram-negative and -positive bacteria and fungi. It showed little hemolitic activity to human or rabbit red cells. To the best of our knowledge, this is the first report of antimicrobial peptide from Tupaiidae.     

高铁酸钾对几种常见鱼类病原菌的杀菌效果测定

试验测定了高铁酸钾(K2FeO4)溶液对8种常见鱼类病原菌的MIC(最小抑菌浓度,minimal inhibitory concentration,MIC)和MBC(最低杀菌浓度,minimal bactericidal concentration,MBC),并研究了不同浓度的K2FeO4溶液对几种病原菌的杀灭效果.结果显示,K2FeO4对温和气单胞菌(Aeromonas sobria)、河弧菌(Vibrioflurialis)、弧菌Ⅰ组淡水亚组弧菌(Vibrio group Ⅰ freshwater subgroup)的抑制效果良好;当各试验菌液浓度约为105cfu/mL时,施以K2FeO4溶液作用1h后,对以上两种弧菌亦表现出最优的杀灭效果;基于以上试验结果,选取这两种最为敏感的病原菌测定其长势随消毒剂浓度和时间的变化情况.研究对于使用K2FeO4浸泡消毒鱼体或全池泼洒消毒池塘时具有指导意义,并为使用K2FeO4防治鱼类弧菌病研究工作的展开打下基础.