嗜水气单胞菌对四环素类药物诱导耐药表型及机理研究

【目的】初步探讨利用四环素类药物体外诱导嗜水气单胞菌耐药后,嗜水气单胞菌对四环素类药物敏感性的变化及其耐药机制。【方法】筛选临床分离嗜水气单胞菌的四环素类敏感株,从含有1/4×MIC的强力霉素的TSA固体培养基开始,等比2倍提高诱导药物质量浓度对受试菌进行连续传代培养,以获得高耐诱导株;测定诱导菌对强力霉素和16种非诱导药物的最小抑菌浓度(MIC)及添加外排泵抑制剂N-甲基吡咯烷酮(NMP)后的MIC,分析其敏感性变化与外排作用的关系;提取诱导菌的DNA,PCR扩增其5个tet基因并测序。【结果】诱导后菌株对强力霉素的MIC显著升高,对非诱导四环素类药物也有不同程度提高,对氟喹诺酮类药物的MIC比诱导前增加几十至上千倍;对氨基糖苷类药物和利福平的MIC则有不同程度的降低;添加NMP后,所有诱导菌株对强力霉素的MIC值均有不同程度的下降;四环素类耐药基因的检测结果表明,在诱导后7号菌株中同时检测到tet A和tet E;在诱导前后的2号菌株中检测到tet C;在诱导前后的1、3、4、5、6、7号菌株中均检测到tet E。【结论】本研究表明tet E基因可能是介导气单胞菌分离株对四环素类药物耐药的优势基因,为阐明嗜水气单胞菌对四环素类药物耐药机制及耐药性与耐药基因之间的关系提供理论依据。     

产超广谱β-内酰胺酶大肠埃希菌对喹诺酮类抗菌药物的耐药性检测

目的 了解临床分离产超广谱β-内酰胺酶（ESBLs）大肠埃希菌对喹诺酮类等抗菌药物的耐药性。方法 NCCLS表型确证试验（纸片增强法）检测出临床分离大肠埃希菌中产ESBLs菌株,琼脂稀释法测定产ESBLs菌株对喹诺酮类等抗菌药物的耐药性。结果 临床分离大肠埃希菌中产ESBLs菌株的检出率为40．2％（92／229）,产ESBLs菌株以尿标本多见,对6种喹诺酮类抗菌药物的耐药率均在89％以上,哌拉西林的耐药率为100％;对头孢噻肟、头孢他啶和哌拉西林-三唑巴坦的耐药率分别为77．2％、1．1％和21．7％,对亚胺培南极其敏感,耐药率为0％。结论 产ESBLs大肠埃希菌发生率较高,对喹诺酮类抗菌药物耐药显著,临床应加强检测和监测。     

139株空肠弯曲菌耐药性分析

空肠弯曲菌(Campylobacter jejuni)是最常见的食源性病原菌之一。本研究采用微量肉汤稀释法对分离得到的139株空肠弯曲菌(117株为禽源样本分离株,22株为人源样本分离株)进行耐药性检测。通过对最小抑菌浓度(MIC)的判定结果得出:120株(86. 33%)空肠弯曲菌分离株对6类9组临床常用的抗生素表现出不同程度的耐药,其中禽源空肠弯曲菌耐药率为83. 76%,22株人源空肠弯曲菌均表现出耐药性。对喹诺酮类抗生素表现出高度耐药(环丙沙星80. 58%,萘啶酸77. 70%);对四环素类表现为中等耐药(四环素53. 24%);对部分大环内酯类、氨基糖苷类、林可酰胺类表现为低耐药(庆大霉素7. 19%,阿奇霉素5. 76%,克林霉素6. 47%);对酰胺醇类、部分大环内酯类表现为敏感(氟苯尼考0%,红霉素0%、泰利霉素0%)。139株空肠弯曲菌共产生14种耐药谱型,以TET-CIP-NAL谱型最多,占比38. 13%,耐三重及以上抗生素的多重耐药菌株占比53. 24%。禽源菌株中多重耐药占比46. 15%,人源菌株中多重耐药占比90. 91%。研究结果显示空肠弯曲菌耐药现状不容乐观,尤其对喹诺酮类与四环素类抗生素耐药性较为突出,且过半数菌株为多重耐药。本研究为食源性空肠弯曲菌的防控及临床用药提供参考。     

洋葱伯克霍尔德菌对哌拉西林/他唑巴坦MIC值变迁的4年监测

目的了解浙江地区4年分离的洋葱伯克霍尔德菌对哌拉西林-他唑巴坦的MIC值变迁,以利于临床对该抗生素在抗感染中更合理的应用。方法先用VITEK-32型配套的药敏检测卡GNS-120检测2000～2003年临床分离的洋葱伯克霍尔德菌对哌拉西林-他唑巴坦的敏感性。对不耐药的菌株进一步用哌拉西林-他唑巴坦E-试条进行MIC检测,并统计其累积的MIC值变化情况。结果2000—2003年,洋葱伯克霍尔德菌对哌拉西林．他唑巴坦的耐药率分别为：40．5％,42．9％,40．6％,41．2％。对分离到不耐哌拉西林．他唑巴坦的100株菌（2000～2003年分别为21株、21株、22株、36株）进行MIC值检测,其累积的MIC百分率,M1C值≤4分别为：47．6％,42．9％,45．5％,36．I％;MIC值≤8分别为：66．7％,52．4％,54．5％,47,2％;MIC值≤16分别为：76．2％,66．7％,63．6％,52．8％。结论4年中临床分离的洋葱伯克霍尔德菌对哌拉西林-他唑巴坦的耐药率虽然变化不大,但其不耐药菌株对哌拉西林-他唑巴坦的累积MIC百分率降低较为明显,表明洋葱伯克霍尔德菌对哌拉西林-他唑巴坦的耐药性存在有增加的趋势,应引起临床的重视。     

48例消化性溃疡患者幽门螺杆菌的耐药性调查

对幽门螺杆菌 (Helicobacterpylori ,Hp)临床分离株进行药物敏感性试验及耐药性分析 ,为探求幽门螺杆菌感染的根除疗法提供依据。运用微需氧培养方法 ,从胃镜活检标本中分离幽门螺杆菌 ,利用琼脂稀释法测定幽门螺杆菌对抗生素的敏感性试验 ,将 2 1株Hp临床分离株进行 7种抗菌药物的敏感性及耐药性调查。从 4 8例消化性溃疡患者胃镜活检标本中分离出 2 1株幽门螺杆菌。 2 1株幽门螺杆菌对阿莫西林MIC范围 0 .5～ 8mg/L ,无耐药菌株 ;克拉霉素、替硝唑的MIC范围分别为 0 .12 5～ 0 .5mg/L和 4～ 8mg/L ,耐药率均为 4 .76 % ;四环素、利福平的MIC范围分别为 0 .5～ 1mg/L和 1～ 6 4mg/L ,耐药率分别为 4 .76 % ,9.5 2 % ;甲硝唑的MIC为 16～ 12 8mg/L ,红霉素的MIC为 0 .5～ 12 8mg/L ,耐药率较高 ,分别为 2 3.89%和5 7.15 %。此次分离的Hp对阿莫西林、克拉霉素、替硝唑有较高的敏感性 ;而对甲硝唑及红霉素耐药率高 ,应避免应用 ;阿莫西林、克拉霉素可作为本地区治疗Hp感染的主要药物 ;四环素、利福平可用于一线治疗失败后二线治疗 ;替硝唑可替代甲硝唑用于Hp的根除治疗。     

PCR-RFLP检测猪源致病性沙门氏菌gyrA基因点突变

四川农业大学谭炳乾、王红宁和叶如俊等先生利用PCR-RFLP法检测猪源致病性沙门氏菌gyrA基因点的突变。他们测定了16株猪源致病性沙门氏菌对5种常用氟喹诺酮类药物的最低抑菌浓度（MIC）。结果表明对此5种药物的耐药率在31．2％～56．2％。分别以质粒和染色体为模板,应用PCR扩增16株沙门氏菌的gyrA基因,以后所有菌株均获得以染色体为模板的扩增产物,还从1株鼠伤寒沙门氏菌获得了以质粒为模板的扩增产物。     

无乳链球菌临床株对四环素类的敏感性研究

为探讨无乳链球菌对四环素类的敏感性及其与耐药基因、多位点序列分型(multilocus sequence typing,MLST)之间的关系,本研究收集2014-2017年深圳市南山区人民医院分离自患者的136株无乳链球菌临床分离株,采用琼脂平板稀释法分析四环素类最低抑菌浓度(minimum inhibitory concentration,MIC)。采用聚合酶链反应检测菌株四环素类耐药基因(tetM、tetK、tetO),MLST测定ST型别,并分析四环素类敏感性与其耐药基因及ST型别之间的关系。结果显示,无乳链球菌对四环素类的耐药率为46.32%,耐四环素类菌株主要携带tetM基因,主要为ST17型和ST19型,且ST17型菌株对四环素类的耐药率显著高于ST19型(P<0.05)。结果提示,无乳链球菌的主要四环素类耐药基因为tetM,ST17型、ST19型是主要流行型别,且ST17型菌株对四环素类的敏感性低于ST19型。     

深圳市儿童社区获得性肺炎细菌病原学及其耐药性

目的研究儿童社区获得性肺炎细菌病原学及其耐药性特征,指导临床合理应用抗菌药物。方法对2006年2月至2007年3月1年期间住院的5岁及5岁以下社区获得性肺炎病人,进行深部呼吸道吸引物细菌培养,并且检测分离菌株对常用抗菌药物的耐药性。结果1441例病人中,722例检出细菌共761株,分离阳性率为50．1％,分离菌依次为肺炎克雷伯菌170株（22．3％）、大肠埃希菌130株（17．1％）、肺炎链球菌89株（11．7％）、金黄色葡萄球菌63株（8．3％）及流感和副流感嗜血杆菌60株（7．9％）。耐甲氧西林金黄色葡萄球菌（MRSA）检出率为15．9％;对青霉素不敏感的肺炎链球菌（包括PISP和PRSP）检出率为84．3％;肺炎克雷伯菌、大肠埃希菌、粘质沙雷菌和阴沟肠杆菌产ESBLs的检出率分别为31．2％、46．2％、94．8％和16．8％;流感嗜血杆菌和副流感嗜血杆菌对氨苄西林的耐药率为36％和40％;铜绿假单胞菌和鲍曼复合不动杆菌对亚胺培南的耐药率分别为10．7％和13．2％。结论在深圳儿童社区获得性肺炎的分离菌中,革兰阴性菌明显多于革兰阳性菌,分离菌依次为肺炎克雷伯菌、大肠埃希菌、肺炎链球菌、金黄色葡萄球菌及流感和副流感嗜血杆菌。分离细菌对常用抗菌药物的耐药性较为严重。     

不同来源株香港海鸥形菌药敏试验结果分析

目的对分离自社区获得性胃肠炎患者及淡水鱼肠道内的香港海鸥形菌(Laribacter hongkongensis,LH)进行药敏试验,为临床合理使用抗菌药物提供依据。方法2005年至2006年杭州市第一人民医院肠道门诊从社区获得性胃肠炎患者中分离到4株及2种淡水鱼体内10株LH菌株,计14株,按美国CLSI推荐的纸片扩散法进行药敏试验。结果药敏结果显示,14株LH菌株对24种常用抗菌药物中的15种药物,分别表现出不同程度的耐药性,耐药率达62.5%;尤其对青霉素、头孢唑啉和头孢哌酮等3种药物,14株LH菌株均为耐药,耐药率为100.0%;其中人体株LHHZ26,对12种药物耐药、1种为中介。LH对3代头孢表现为较高的耐药性,3种头孢药物的耐药率为71.43%~100%;14株LH株对头孢吡肟及头孢哌酮/舒巴坦均为敏感。对氨曲南(14.29%)、庆大霉素(7.14%)、复方新诺明(7.14%)的耐药率较低;喹诺酮类、氯霉素、阿米卡星、美罗培南、亚胺培南等药物均敏感。结论LH菌株对β-内酰胺类药物表现出耐药性,对青霉素类、头孢菌素类药物广泛耐药。建议对LH感染患者喹诺酮类为首选治疗用药。     

纳米银的抗菌特性及对多重耐药菌株的抗菌作用

【目的】利用革兰氏阴性细菌、革兰氏阳性细菌和真菌的模式菌株分析纳米银的抗菌特性,并评价纳米银对多重耐药菌株的抗菌作用。【方法】利用生物法合成的纳米银,以微量肉汤法测定3种标准菌株的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),并计算MBC/MIC比值。用系列浓度的纳米银处理3株标准菌株后经平板计数法绘制时间-杀菌曲线。采用菌落平板计数法测定了纳米银对3种标准菌株的"抗生素后效应"(post-antibiotic effect,PAE),最后在生物安全II级实验室测定纳米银对临床分离的多重耐药菌株的抗菌作用。【结果】用生物法合成了粒径5–30 nm的纳米银,zeta电位为–19.5 m V。该纳米银制剂对3种标准菌株的时间-杀菌曲线均表现为时间依赖型抗菌作用。纳米银对大肠杆菌和白色念珠菌"抗生素后效应"随着浓度增加而增加,对金黄色葡萄球菌无明显"抗生素后效应"。纳米银对3种标准菌株的MIC值和MBC值均在1.00–4.00μg/m L之间;对3株人源性多重耐药菌MIC值在6.00–26.00μg/m L之间,MBC值在1.00–32.00μg/m L之间;对14株动物源性多重耐药菌MIC值在4.00–10.00μg/m L之间,MBC值在8.00–16.00μg/m L之间。纳米银对所有测试菌株的MBC/MIC值均小于2。【结论】纳米银是一种时间依赖型的抗菌剂,有不同程度的"抗生素后效应",对人源和动物源性多重耐药菌有杀菌作用。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

2017年中国植物科学若干领域重要研究进展

2017年中国植物科学继续保持高速发展态势, 重大成果频出, 具体表现在中国植物学家在国际顶级学术期刊发表的文章数量平稳上升。中国植物科学领域的研究工作者成果精彩纷呈, 如新型广谱抗病机制的发现、水稻广谱抗病遗传基础及机制和疫霉菌诱发病害成灾机制研究等。2017年中国生命科学领域十大进展评选中, 有两项植物科学领域的研究成果入选。水稻生物学、进化与基因组学和激素生物学等领域学科发展突出。另外, 值得一提的是, 长期从事高等植物与代谢途径调控分子网络研究和水稻品种设计育种的李家洋院士的研究成果“水稻高产优质性状形成的分子机理及品种设计”荣获2017年国家自然科学一等奖。这一具有重大国际影响的开创性贡献标志着中国植物科学在该领域的国际科学前沿居于引领和卓越地位。该文对2017年中国本土科学家在植物科学若干领域取得的重要研究成果进行了系统梳理, 旨在全面追踪和报道当前中国植物科学领域发展的最新前沿动态, 与广大读者共同分享我国科学家所取得的辉煌成就。     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义.综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望.     

Changes in aquatic vegetation in Rhine floodplain streams in Alsace in relation to disturbance

Abstract. Changes are described in aquatic vegetation in oligotrophic, groundwater-fed Rhine floodplain streams in Alsace (eastern France), resulting from disturbance. Disturbance factors include changes in nutrients, either permanent ones - effluent from a waste water treatment plant or trout hatcheries - or periodic ones: flooding. Regular inputs of high levels of phosphate and ammonia modified the macrophyte vegetation in these streams. The floristic composition, which was characteristic of oligotrophic waters upstream of the eutrophicated sector, changed to that of a eutrophic situation as originally found downstream. Periodic disturbance by floods which normally occur once a year, irregularly eutrophicates the small streams, causing the development of a mixture of eutrophic and oligotrophic species. Six macrophyte communities are distinguished, indicating different trophic levels. The aquatic vegetation is adapted to the variations of phosphate and ammonia levels. Hence, aquatic macrophytes can be used as bio-indicators of fluctuations in water nutrient levels in relation to the type of disturbance.     

Morphine-potentiated platelet aggregation in in vitro and platelet plug formation in in vivo experiments

The detailed mechanisms underlying morphine-signaling pathways in platelets remain obscure. Therefore, we systematically examined the influence of morphine on washed human platelets. In this study, washed human platelet suspensions were used for in vitro studies. Furthermore, platelet thrombus formation induced by irradiation of mesenteric venules with filtered light in mice pretreated with fluorescein sodium was used for an in vivo thrombotic study. Morphine concentration dependently (0.6, 1, and 5 microM) potentiated platelet aggregation and the ATP release reaction stimulated by agonists (i.e., collagen and U46619) in washed human platelets. Yohimbine (0.1 microM), a specific alpha(2)-adrenoceptor antagonist, markedly abolished the potentiation of morphine in platelet aggregation stimulated by agonists. Morphine also potentiated phosphoinositide breakdown and intracellular Ca(2+) mobilization in human platelets stimulated by collagen (1 microg/ml). Moreover, morphine (0.6-5 microM) markedly inhibited prostaglandin E(1) (10 microM)-induced cyclic AMP formation in human platelets, while yohimbine (0.1 microM) significantly reversed the inhibition of cyclic AMP by morphine (0.6 and 1 microM) in this study. The thrombin-evoked increase in pH(i) was markedly potentiated in the presence of morphine (1 and 5 microM). Morphine (2 and 5 mg/g) significantly shortened the time require to induce platelet plug formation in mesenteric venules. We concluded that morphine may exert its potentiation in platelet aggregation by binding to alpha(2)-adrenoceptors in human platelets, with a resulting inhibition of adenylate cyclase, thereby reducing intracellular cyclic AMP formation followed by increased activation of phospholipase C and the Na(+)/H(+) exchanger. This leads to increased intracellular Ca(2+) mobilization, and finally potentiation of platelet aggregation and of the ATP release reaction.     

Apoptosis in experimental myocardial infarction in situ and in the perfused heart in vitro

We report the appearance of apoptotic cells in experimental myocardial infarction (rabbit heart) in in situ and in vitro preparations. Apoptosis was recognized by intravital staining with Hoechst 33342 (Ho342), by nick-end labeling (TUNEL) and by DNA laddering. A steady rise in the relative number of apoptotic cardiomyocytes (apoptotic index) was noted in in situ preparations. Apoptosis was first noted 6 h after the onset of ischemia with its highest value occurring after 72 h. Apoptotic nuclei were absent in remote areas of the left and right ventricles. Apoptotic nuclei within the infarcted area showed diminished intensity of Ho342 fluorescence. Three days after ischemia, a border zone adjacent to the infarcted area consisting of apoptotic macrophages was recognized. A novel finding was the appearance of apoptotic cardiomyocytes in the isolated perfused ischemic heart. Occurring as early as 50 min after the onset of ischemia, a high apoptotic index was present adjacent to the ligature placed around the coronary artery. This observation provides the opportunity to selectively examine factors leading to apoptosis in the ischemic heart under controlled experimental conditions.