The potential for rust infection to cause natural selection in apomictic Arabis holboellii (Brassicaceae)

Few studies have examined the potential for pathogens with complex life cycles to cause selection on their required alternate (=intermediate) hosts. Here we examine the effects of two fungal pathogens on an herbaceous mustard, Arabis holboellii. One pathogen species uses A. holboellii as a primary host, the other uses it as an alternate host. This plant-pathogen system is especially interesting because the host, A. holboellii, is apomictic; thus individuals reproduce exact copies of themselves. Despite this mode of reproduction, A. holboellii populations are surprisingly genetically diverse. Could frequency dependent selection by pathogens be maintaining clonal diversity? This study assesses the potential for selection by pathogens. In a controlled greehouse experiment we show that there is heritable variation in A. holboellii's resistance to the rust, Puccinia monoica, and that host fitness is severely reduced by P. monoica infection in both the greenhouse and under natural conditions. Field observations indicate that host clones are also differentially susceptible to the short-cycled rust, P. thlaspeos, and that host fitness is reduced by infection to this pathogen as well. Although the preconditions for pathogen-mediated selection are present, frequency-dependent selection by pathogens is unlikely to be important in structuring populations of Arabis holboellii because multiple host genotypes are susceptible to the same inoculum and the pathogen has a long generation time.     

阴道卷曲乳酸杆菌对阴道致病菌的体外生物拮抗作用

目的研究阴道卷曲乳酸杆菌对阴道致病菌的体外生物拮抗作用。方法将阴道卷曲乳酸杆菌分别与3株阴道致病菌（金黄色葡萄球菌、大肠埃希菌、粪肠球菌）混合接种于GAM液体培养基中进行厌氧培养,通过平板菌落计数法计算阴道致病菌的菌数。结果经混合培养后阴道致病菌的菌数明显下降。结论阴道卷曲乳酸杆菌A7在体外能明显抑制3株肠道致病菌的生长繁殖。     

泌尿系统结石合并感染患者尿路病原菌分布及危险因素分析

目的 分析泌尿系统结石合并感染患者尿路病原菌分布及其危险因素,为后续研究提供参考。 方法 收集2016年1月至2019年1月我院诊治的430例泌尿系统结石患者为研究对象,根据患者是否发生感染分为感染组(n=34)和非感染组(n=396)。分析两组患者的临床特征和感染组患者病原菌分布情况,同时对影响患者感染的高危因素进行Logistic回归分析。 结果 感染组患者共计检出84株病原菌,其中革兰阳性球菌20株(23.81%),革兰阴性杆菌60株(71.43%),其他4株(4.76%)。两组患者白细胞水平、尿路梗阻情况、血肌酐水平、尿pH>7.0比例、血尿素氮水平、合并肾积水情况、结石位置、结石直径、抗菌药物使用种类差异均有统计学意义(均P9个/L)、尿pH(>7.0)、血尿素氮(≥7.15 mmol/L)、结石位置(上尿路)、抗菌药物使用种类(≥3种)均为泌尿系统结石合并尿路感染的高危因素,而血肌酐水平,结石直径与泌尿系统结石合并尿路感染无明显相关性。 结论 泌尿系统结石患者易并发尿路感染,其病原菌以革兰阴性杆菌为主。导致尿路感染的因素较多,临床上应提前制定预防措施,降低结石患者尿路感染发生率。     

血液科感染患者致病菌的临床资料分析

目的：探讨血液病患者的感染特点,为临床治疗提供病原学依据。方法：回顾性分析北京友谊医院2008年7月至2011年7月血液科住院患者临床分离出病原菌的情况。结果：原发病以血液系统恶性肿瘤为主。共培养出致病菌357株,包括革兰阴性杆菌（40.8%）;革兰阳性球菌（24.1%）;真菌（35.1%）。引起感染最常见的革兰阴性杆菌为铜绿假单胞菌,最常见的革兰阳性球菌为粪肠球菌,最常见的真菌为白色假丝酵母菌。革兰阴性杆菌来源为血29.4%,痰46.6%,尿10.3%;革兰阳性球菌来源为血14%,痰47.7%,尿10.4%;真菌来源为血8%,痰60.8%,尿4%。66.4%真菌感染患者中性粒细胞〈1.5×109/L。结论：血液病感染的致病菌以革兰阴性杆菌为主,呼吸道是主要感染部位。对于中性粒细胞减少的血液病感染患者,真菌感染的几率明显增加,经验性抗真菌治疗具有一定的意义。     

Quorum sensing inhibitors as antipathogens: biotechnological applications

The mechanisms through which microbes communicate using signal molecules has inspired a great deal of research. Microbes use this exchange of information, known as quorum sensing (QS), to initiate and perpetuate infectious diseases in eukaryotic organisms, evading the eukaryotic defense system by multiplying and expressing their pathogenicity through QS regulation. The major issue to arise from such networks is increased bacterial resistance to antibiotics, resulting from QS-dependent mediation of the formation of biofilm, the induction of efflux pumps, and the production of antibiotics. QS inhibitors (QSIs) of diverse origins have been shown to act as potential antipathogens. In this review, we focus on the use of QSIs to counter diseases in humans as well as plants and animals of economic importance. We also discuss the challenges encountered in the potential applications of QSIs.     

858例血感染患者病原菌分布及耐药情况

目的:通过对某地区中心医院收集的临床血感染患者感染病原菌的分析,了解该地区血感染患者病原菌构成、分布及耐药特点,为临床治疗提供参考和指导。方法:收集2012年6月至2013年8月期间在某院就诊的858例血感染患者血液标本,采用BACTEC9050全自动血培养仪培养,采用VITEK 2 Compack系统和K-B琼脂纸片扩散法对阳性标本进行菌种鉴定和药敏检测。结果:血培养结果显示,在858份血培养标本中共检出阳性标本109份,每份标本都只检出一种病菌,总检出率为12.7%,革兰阳性菌占64.22%(70/109),革兰阴性菌占33.03%(36/109),真菌占0.35%%(3/109);药物敏感试验结果显示:葡萄球菌对青霉素、红霉素和复方新诺明耐药率40%;肠杆菌科细菌对氨苄西林和氯霉素耐药率40%;非发酵菌科细菌对氨苄西林,头孢他啶,头孢噻肟和氯霉素耐药率40%。结论:目前本地区临床血感染患者革兰阳性菌感染率高,以金黄色葡萄球菌和凝固酶阴性葡萄球菌为主,治疗可以首选糖肽类抗菌药物;革兰阴性菌以大肠杆菌和绿脓杆菌为主,对氨苄西林、氯霉素耐药率高,大肠杆菌对头孢类抗生素的耐受较绿脓杆菌低,两种细菌感染治疗可以考虑选择单环-内酰胺类抗生素。及时准确的血培养结果及药敏试验可为临床合理选择抗菌药物提供重要依据。     

肠道微生物群在介导肠道病原体定植抗性作用的研究进展

肠道微生物群是复杂的微生态系统的组成部分, 参与机体一系列重要的生理过程。健康微生物群在稳态条件下的一个关键功能是抵抗外界病原体的定植, 称为定植抗性。抗生素和质子泵抑制剂的使用, 可引起菌群组成的改变和定植抗性的减弱, 从而为病原体在肠道定植提供了机会, 最终导致感染。细菌性肠道感染是全球疾病的主要原因。肠道微生物群提供定植抗性的机制尚未完全阐明, 但主要分为直接机制和间接机制, 包括抗菌产物的分泌、营养竞争、肠道屏障完整性和免疫反应。本文将从以上几个方面探讨肠道微生物群介导的对肠道病原体的定植抗性。

     

Multiline varieties and disease control

Summary A general model for the evolution of pathogen populations on mixtures or multilines is developed. This model is used to extend previous analyses of the effects of the widespread cultivation of multilines on the evolution of virulence in obligate parasites to mixtures of lines carrying different numbers of resistance genes. It is concluded that the composition of an equilibrium pathogen population growing on a multiline may vary within wide limits and the prinicipal determinant of its composition is the number of components in the multiline and the resistance genes they carry. Other factors of importance are (i) the relative contribution made by each host class (with different numbers of resistance genes) to the pathogen spore pool each generation; (ii) the levels of stabilizing selection against unnecessary virulence genes; and (iii) the way in which unnecessary genes for virulence combine to reduce pathogen fitness. Conditions for the fixation of avirulent biotypes in the pathogen population and the evolution of a pathogen superrace are given for multilines of various compositions.Paper No. 9246 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina. This investigation was supported in part by NIH Research Grant No. GM 11546 from the National Institute of General Medical Sciences     

系统性红斑狼疮合并感染病原菌与降钙素原的相关性分析

目的探讨降钙素原（PCT）在判断系统性红斑狼疮（SLE）合并感染病原菌中临床价值。方法采用回顾性研究,选取2011年1月至2013年6月住院的SLE合并感染患者98例。研究各种病原菌与PCT浓度的相关性,计算SLE合并感染革兰阴性菌、革兰阳性菌、真菌及支原体、病毒患者的PCT浓度。结果SLE合并感染病原体的PCT浓度：革兰阴性菌组〉革兰阳性菌组〉真菌及支原体组〉病毒组。结论SLE合并感染病原菌与降钙素原水平有一定的相关性,定量检测PCT可辅助诊断SLE合并感染病原菌种。