Comparative genome analysis identifies few traits unique to the Escherichia coli ST131 H30Rx clade and extensive mosaicism at the capsule locus

Background

E.coli ST131 is a globally disseminated clone of multi-drug resistant E. coli responsible for that vast majority of global extra-intestinal E. coli infections. Recent global genomic epidemiological studies have highlighted the highly clonal nature of this group of bacteria, however there appears to be inconsistency in some phenotypes associated with the clone, in particular capsule types as determined by K-antigen testing both biochemically and by PCR.

Results

We performed improved quality assemblies on ten ST131 genomes previously sequenced by our group and compared them to a new reference genome sequence JJ1886 to identify the capsule loci across the drug-resistant clone H30Rx. Our data shows considerable genetic diversity within the capsule locus of H30Rx clone strains which is mirrored by classical K antigen testing. The varying capsule locus types appear to be randomly distributed across the H30Rx phylogeny suggesting multiple recombination events at this locus, but that this capsule heterogeneity has little to no effect on virulence associated phenotypes in vitro.

Conclusions

Our data provides a framework for determining the capsular genetics of E. coli ST131 and further beyond to ExPEC strains, and highlights how capsular mosaicism may be an important strategy in becoming a successful globally disseminated human pathogen.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-830) contains supplementary material, which is available to authorized users.     

地佐辛复合丙泊酚静脉麻醉应用于无痛胃肠镜检查的临床观察

目的:观察地佐辛复合丙泊酚静脉麻醉在无痛胃肠镜检查中的临床应用效果。方法:选取接受100例无痛胃肠镜检查的患者,随机分为观察组和对照组,每组50例,观察组采用地佐辛复合丙泊酚麻醉,对照组采用芬太尼复合丙泊酚静脉麻醉,比较两组患者麻醉起效时间、意识消失时间、术后睁眼时间、丙泊酚用量以及呼吸和血液动力学变化。结果:1观察组患者睁眼时间、丙泊酚用量显著低于对照组,比较差异均有统计学意义(t1=2.243,t2=69.724,t3=2.451,均P0.05);2对照组患者麻醉前、插管后1min、术中、术毕30min组内RR、SpO2比较差异有统计学意义(F1=12.442,F2=99.133,P0.05),插管后1min、术中两项指标均降低,MAP、HR组内比较差异无统计学意义(F1=15.241,F2=11.383,P0.05);而观察组患者MAP、HR、RR、SpO2组内比较差异无统计学意义(F1=9.34,F2=12.35,F3=5.34,F4=12.83,均P0.05)。3观察组患者不良反应发生率为4%,明显低于对照组的12%,比较差异有统计学意义(c2=8.452,P0.05)。结论:地佐辛复合丙泊酚麻醉应用于无痛胃肠镜检查镇痛效果好,安全性高,值得推广应用。     

Rapid methods to extract DNA and RNA from Cryptococcus neoformans

Extraction of nucleic acids from the pathogenic yeast Cryptococcus neoformans is normally hampered by a thick and resistant capsule, accounting for at least 70% of the whole cellular volume. This paper presents procedures based on mechanical cell breakage to extract DNA and RNA from C. neoformans and other capsulated species. The proposed system for DNA extraction involves capsule relaxation by means of a short urea treatment and bead beating. These two steps allow a consistent extraction even from strains resistant to other procedures. Yield and quality of DNA obtained with the proposed method were higher than those obtained with two earlier described methods. This protocol can be extended to every yeast species and particularly to those difficult to handle for the presence of a capsule. RNA purification is accomplished using an original lysing matrix and the FastPrep System (Bio101) after a preliminary bead beating treatment. Yields range around 1 mg RNA from 15 ml overnight culture (10(9) cells), RNA appears undegraded, making it suitable for molecular manipulations.     

Nrc of Streptococcus pneumoniae suppresses capsule expression and enhances anti-phagocytosis

Streptococcus pneumoniae is a major pathogen of community-acquired pneumonia and one of its major virulence factors is pneumolysin, which functions as a cholesterol-dependent cytolytic pore-forming toxin. In this study, we identified the ply-like gene spd0729 in a BLAST search. Unexpectedly, hemolytic and cytotoxic assays showed no significant differences between a Δspd0729 mutant strain and the wild-type strain, whereas the mutant strain exhibited weaker anti-phagocytic activity in human peripheral blood. In addition, real-time RT-PCR analysis revealed that four capsular biosynthesis genes in the mutant strain had expressions 7- to 432-fold greater than those of the wild type, while an enzyme-linked immunoassay showed a mean 3-fold greater amount of total capsular polysaccharide in the mutant strain. These results suggest that Spd0729 is not a cytolysin, though it plays crucial roles in anti-phagocytosis and regulation of capsule expression. Thus, we named Spd0729 as a negative regulator of capsular polysaccharide synthesis (Nrc).     

速效止泻胶囊含量测定方法的初步研究

目的：探讨速效止泻胶囊质量标准中含量测定方法的建立。方法：采用中性氧化铝柱层析-紫外分光光度法建立了盐酸小檗碱的含量测定方法。结果：线性关系r=0.99996,平均回收率为106．42％,含量限度为90mg/粒。结论：建立的含量测定方法准确可靠,可以控制产品质量。     

Unexpected link between lipooligosaccharide biosynthesis and surface protein release in Mycobacterium marinum

The mycobacterial cell envelope is characterized by the presence of a highly impermeable second membrane, which is composed of mycolic acids intercalated with different unusual free lipids, such as lipooligosaccharides (LOS). Transport across this cell envelope requires a dedicated secretion system for extracellular proteins, such as PE_PGRS proteins, which are specific mycobacterial proteins with polymorphic GC-rich sequence (PGRS). In this study, we set out to identify novel components involved in the secretion of PE_PGRS proteins by screening Mycobacterium marinum transposon mutants for secretion defects. Interestingly, most mutants were not affected in secretion but in the release of PE_PGRS proteins from the cell surface. These mutants had insertions in a gene cluster associated with LOS biosynthesis. Lipid analysis of these mutants revealed a role at different stages of LOS biosynthesis for 10 novel genes. Furthermore, we show that regulatory protein WhiB4 is involved in LOS biosynthesis. The absence of the most extended LOS molecule, i.e. LOS-IV, and a concomitant accumulation of LOS-III was already sufficient to reduce the release of PE_PGRS proteins from the mycobacterial cell surface. A similar effect was observed for major surface protein EspE. These results show that the attachment of surface proteins is strongly influenced by the glycolipid composition of the mycobacterial cell envelope. Finally, we tested the virulence of a LOS-IV-deficient mutant in our zebrafish embryo infection model. This mutant showed a marked increase in virulence as compared with the wild-type strain, suggesting that LOS-IV plays a role in the modulation of mycobacterial virulence.     

新型冠状病毒肺炎疫情防控期间内镜诊疗相关感染防控建议

针对2019年底出现在我国的新型冠状病毒肺炎疫情,全国上下拼尽全力积极抗疫。目前全国疫情在得到良好控制的同时,各大医疗机构为防控疫情纷纷暂停的各项高风险诊疗项目也陆续开诊。由此根据国家卫生健康委员会最新发布的《新型冠状病毒肺炎诊疗方案(试行第八版)》及《新型冠状病毒肺炎防控方案(第七版)》等文件,结合相关国家规范对新型冠状病毒肺炎疫情防控期间消化内镜、支气管镜及喉镜(软镜)诊疗的感染防控措施进行梳理和总结,提出相关建议以供临床医务工作者参考。     

色素内镜联合CRP和TRF在青海地区早期食管癌患者的诊断价值

摘要 目的：探讨色素内镜联合C反应蛋白(C-reactive protein,CRP)和转铁蛋白(Transferrin,TRF)在青海地区早期食管癌患者的诊断价值。方法：2018年6月至2020年3月选择在本院进行食管癌筛查的青海地区患者250例,所有患者都给予色素内镜检查,同时给予血浆CRP和TRF检查并判断诊断价值。结果：在250例患者中,病理诊断为原位癌28例,高级别上皮内瘤变10例,低级别上皮内瘤变12例,慢性炎症200例;其中早期食管癌38例。卢戈液色素内镜显示不染色47例,淡染色95例,浓染色108例。早期食管癌患者的血浆CRP值都高于非早期食管癌患者,TRF值低于(P<0.05)。Pearson相关性分析显示早期食管癌与色素内镜卢戈液不染色、CRP、TRF值存在相关性(P<0.05)。色素内镜联合CRP和TRF在青海地区早期食管癌的诊断敏感性与特异性分别为97.4 %和100.0 %。结论：色素内镜联合CRP和TRF在青海地区早期食管癌患者诊断中的应用具有很好的敏感性与特异性,能有效预测早期食管癌发生情况,对早期诊治早期食管癌具有一定的指导意义。     

In situ endoscopy: New insights to root growth in biopores

Abstract

A flexible videoscope with an outer diameter of 3.8 mm and equipped with a movable tip was used for in situ observation of roots growing in larger‐sized biopores. We were able to display root morphology and position inside of biopores and differentiate four categories of root segments.     

兽疫链球菌荚膜多糖对免疫抑制鼠的抗氧化和免疫调节活性研究

目的测定部分纯化的兽疫链球菌荚膜多糖（PCP）的抗氧化和免疫调节活性。方法以注射用环磷酰胺（CY）造成免疫抑制鼠模型。结果口服PCP诱导了免疫抑制鼠超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）和过氧化氢酶（CAT）的活性,提高了总抗氧化能力（TAOC）的水平。口服PCP后免疫抑制鼠的胸腺和脾脏指数明显增加,血清溶菌酶活性和迟发型超敏反应（DTH）引起的肿胀率也显著提高。结论 PCP对免疫抑制鼠具有免疫调节功能并改变CY诱导的氧化压力,是一种潜在的抗氧化剂和免疫调节剂。