大肠埃希菌耐喹诺酮类抗菌药的相关耐药基因检测及耐药机制分析

目的 探讨大肠埃希菌耐喹诺酮类抗菌药的相关耐药基因检测及耐药机制.方法 选取我院尿液等排泄物和分泌物标本中分离出的150株大肠埃希菌株,应用纸片扩散法进行药敏试验,采用PCR技术检测qnr以及aac(6')-Ib-cr质粒基因的表达,并对PCR产物进行DNA测序分析.结果 150株大肠埃希菌对喹诺酮类抗菌药物的耐药率均超过50％,20株菌检出阳性基因qnrB,qnrS以及aac(6')-Ib-cr的阳性率分别为12.20％、9.76％、13.41％,共有8株菌同时携带超过2种质粒基因,其对喹诺酮类药物均耐药,同时合并有其他类型抗菌药物的耐药情况,12株菌检出单个质粒基因,其中4株对喹诺酮类敏感.结论 大肠埃希菌的耐药情况十分严重,存在qnrB、qnrS、aac(6')-1b-cr流行,并存在两种及多种耐药基因共存于同一细菌中的现象,质粒介导的喹诺酮耐药基因数量与耐药种类数量呈正相关.     

多重耐药菌中质粒介导喹诺酮耐药基因的检测和分析

目的分析广州医学院第一附属医院临床分离的60株多重耐药大肠埃希菌和肺炎克雷伯菌质粒介导的喹诺酮耐药基因存在状况。方法采用VITEK-2全自动细菌鉴定仪检测大肠埃希菌和肺炎克雷伯菌对抗生素的药物敏感性,选择多重耐药的大肠埃希菌和肺炎克雷伯菌作为研究对象,用多重PCR法进行质粒介导的喹诺酮耐药基因的检测和分析。结果检测出耐药基因qnrA型2株,qnrB型耐药基因15株,aac（6’）-Ib基因9株,其中aac（6’）-Ib—cr型耐药基因5株。其中有1株肺炎克雷伯菌检测到同时含有qnrA和aac（6’）-Ib—cr基因;还有3株肺炎克雷伯菌检测到同时含有qnrB和aac（6’）-Ib—cr基因。未检测到qnrC、qnrD、qnrS、qepA型的耐药基因。结论临床分离的多重耐药大肠埃希菌和肺炎克雷伯菌含有多种质粒介导的喹诺酮耐药基因,应引起临床的重视。     

市售整鸡中环丙沙星耐药大肠埃希氏菌的分布及耐药机制研究

目的 本研究旨在阐明市售整鸡中环丙沙星耐药大肠埃希氏菌的分布和耐药机制特点.方法 对广东省3个不同地区市售整鸡中的环丙沙星耐药大肠埃希氏菌进行分离和鉴定,并对分离株进行种系分群、药敏试验和喹诺酮耐药机制研究.结果与结论 从58份市售整鸡中分离出41株环丙沙星耐药大肠埃希氏菌,其中27株属于A群.分离株耐药谱主要有两种:AMP-CAZ-CIP-CTX-Cl-SXT-TET和AMP-CAZ-CIP-CTX-Cl-GEN-SXT-TET.喹诺酮耐药机制研究显示,拓扑异构酶编码基因gyrA和parC均有点突变出现,其中,26株分离株携带质粒介导的喹诺酮耐药基因,包括oqxAB、qnrS、aac(6')-Ib-cr,而qnrA、qnrB、qnrC、qnrD和qepA基因则均未检出.耐药菌株在市售整鸡中的广泛分布和复杂的喹诺酮耐药机制,应引起相关部门的重视.     

志贺菌临床株耐药性分析及对氟喹诺酮类抗生素耐药机制的研究

目的:了解本地区志贺菌抗生素耐药情况,探讨志贺菌对氟喹诺酮类药物的耐药机制和耐药基因的突变及流行情况。方法:K-B纸片扩散法测定2009—2010年天津地区临床分离的119株志贺菌的药敏情况,对氟喹诺酮耐药志贺菌的gyrA、parC基因及质粒介导的喹诺酮耐药(PMQR)基因qnrA、qnrB、qnrS、aac(6′)-ib-cr、qepA进行扩增、测序,将PMQR阳性菌株与大肠埃希菌J53ARZ进行质粒接合试验,比较接合前后受体菌对抗菌药物的敏感性变化。结果:119株志贺菌对萘啶酸敏感率最低(1.72%),其次为氨苄西林(2.52%)及复方磺胺甲口恶唑(3.36%)。福氏志贺菌与宋内氏志贺菌对氟喹诺酮耐药性差别较大,5株志贺菌对环丙沙星等氟喹诺酮耐药,均为福氏志贺菌,其中2株对左氧氟沙星耐药。4株同时存在gyrA83、87位点及parC80位点突变,1株缺乏gyrA87位点突变。PMQR基因阳性菌3株,包括1株qnrS及2株aac(6′)-ib-cr阳性菌,接合菌对多种抗生素的敏感性降低。结论:本地区志贺菌临床株对多种抗生素的多重耐药率较高,对氟喹诺酮耐药率低于5%。喹诺酮耐药机制既有染色体介导靶位酶突变,也存在质粒介导喹诺酮耐药。     

质粒介导的喹诺酮耐药基因在中国大陆尿液分离的大肠埃希菌中的广泛分布

目的分析中国大陆20家三甲医院尿来源大肠埃希菌的耐药特点并调查质粒介导的喹诺酮类耐药基因的分布情况和流行特点。方法收集卫生部全国耐药监测网2007年1月至2008年3月非重复298株尿液分离大肠埃希菌;琼脂稀释法测定其对20种抗菌药物的敏感性,多聚酶链反应和DNA测序分析qn-rA,qnrB,qnrS,aac(6’)-ib和qepA基因的流行性;接合实验分析质粒的转移性;Eric-PCR分析喹诺酮基因阳性菌株之间的遗传相关性;卡方检验用于分析耐药基因与氟喹诺酮耐药之间的相关性。结果 298株大肠埃希菌对20种抗菌药物耐药现象严重,其中对环丙沙星和左氧氟沙星有很高的耐药性,耐药率高达78.5%和74.2%。经基因比对分析,62株(20.8%)细菌携带aac(6’)-Ib基因;45株(15.1%)细菌携带喹诺酮耐药基因,1株(0.3%)检测出qnrA基因,3株(11.4%)检出qnrB基因,5株(1.7%)检出qnrS基因,25株(8.4%)确定为aac(6’)-Ib-cr基因,12株(4.7%)检出qepA基因;此外,有3株细菌分别发现aac(6’)-Ib-cr和qepA1基因aac(6’)-Ib-cr和qnrB1基因,qepA和qnrS1基因共存。45株喹诺酮基因阳性菌株之间具有很大的遗传差异,并且其中有16株细菌携带的基因具有可转移性。aac(6’)-Ib的流行性与细菌的环丙沙星和左氧氟沙星不敏感性相关(P<0.05);喹诺酮耐药基因的流行性与细菌的氟喹诺酮不敏感性相关(P<0.05)。结论尿液分离的大肠埃希菌耐药严重,质粒介导的喹诺酮耐药基因主要以aac(6’)-ib-cr为主,qepA1次之,这些潜在播散的喹诺酮耐药基因对于临床尿路感染的治疗有很大的挑战。     

天津地区大肠埃希菌临床株质粒介导的喹诺酮类耐药机制的研究

目的 了解天津地区临床分离的大肠埃希菌中qnr,aac(6')-Ib-cr及gepA基因的流行情况,分析阳性菌株感染的微生物学及临床特征.方法 从天津某三甲医院收集环丙沙星耐药(CPLX,MIC 4gg/mL)的大肠埃希菌共75株,采用PCR法检测gnrA,gnrB,gnrS,aac(6')-Ib及gepA基因,对aac(6'),-Ib基因阳性菌株用Fok I酶切确认aac(6')-Ib-cr基因,接合试验验证qnr的转移性.所有阳性菌株用PCR法检测p-内酰胺酶基因,并收集阳性菌株感染患者临床资料进行分析.结果 75株环丙沙星耐药的大肠埃希菌中共有18株(24%)携带qnr基因和(或)aac(6)-Ib-cr基因,其中gnrB,gnrS和aac(6')-Ib-cr检出率分别为5.3%,4%和21.3%,未检出gnrA和gepA o 5株qnr阳性菌株均接合传递成功.18株gnr1aac(6')-1b-cr阳性的大肠埃希菌中均检测出R-内酸胺酶基因.阳性菌株对喹诺酮类和头孢菌素类药物高度耐药且主要来源于泌尿系感染,感染患者均为中老年人.结论 天津地区临床存在qnr和aac(6')-Ib-cr阳性菌株的流行,这是首次在天津发现qnr介导的喹诺酮类耐药.     

婴幼儿腹泻沙门菌分型与耐药机制分析

目的对我国武汉地区0~3岁临床婴幼儿腹泻沙门菌进行了分离、鉴定、耐药性和分子分型分析。方法超广谱头孢菌素和氟喹诺酮类抗生素是临床上用于治疗侵袭性沙门菌感染的重要抗生素,对这些抗生素的耐药性传播已引起了广泛的重视,本研究从3746例儿科临床门诊病人粪便样本中共检出221(5.9%)株沙门菌,分别属于29个血清型,抗生素的耐药谱在不同血清型间存在明显差异。环丙沙星耐药株多为鼠伤寒沙门菌,且均对4种以上非喹诺酮类抗生素耐药,22株环丙沙星耐药鼠伤寒沙门菌中19株位于同一个脉冲场群中。在18株沙门菌中检出质粒介导的喹诺酮耐药机制aac-(6’)-Ib-cr,其中4株菌中还携带qnr基因。在7株菌中检出质粒介导的超广谱-内酰胺酶类CTX-M-14编码基因,其中2株菌对环丙沙星的敏感性下降。结果与结论氟喹诺酮类抗生素不适于在当地用于侵袭性鼠伤寒沙门菌感染治疗,同时应对头孢曲松耐药-氟喹诺酮敏感性下降的菌株进行积极的主动监测。     

质粒介导的克雷伯菌耐喹诺酮类药物机制研究

目的了解华南地区qnr基因介导的克雷伯菌耐喹诺酮类药物的情况并研究其耐药机制。方法收集临床分离的克雷伯菌株共200株，其中产酸克雷伯菌6株。PCR方法筛查基因，琼脂稀释法测MIC，质粒结合试验，聚合酶链反应（PCR）通用引物扩增各组基因及测序。结果200株细菌中筛查到带qnr基因的菌株共2株（其中产酸克雷伯菌1株），均对环丙沙星敏感。进一步确证实验中证实2菌株都含qnr基因。2菌株经结合实验后在选择平板上都有菌生长，而且对环丙沙星的MIC值均有30倍以上的的提高。2株菌均有gyrA Ser83→Tyr突变，产酸克雷伯菌株有parC Ser80→Ile突变。2株菌质粒PCR扩增的qnr产物测序结果与NCBI中qnr基因比对吻合率达100％。结论华南地区已有质粒介导的耐喹诺酮类菌株存在，它们能够跨种属转移，值得临床医生重视。     

痰标本中质粒介导喹诺酮耐药基因qnr在肺炎克雷伯菌中的分布特征及耐药分析

目的:了解从痰标本中分离出的肺炎克雷伯菌对16种抗菌药物的耐药性,以及研究由质粒介导的喹诺酮类耐药基因qnr在肺炎克雷伯菌中的存在情况。方法:用PCR及直接测序的方法对135株肺炎克雷伯菌进行qnr基因检测,并用K-B纸片法检测其对16种抗菌药物的体外抗菌活性。另外,用琼脂平皿二倍稀释法检测阳性菌株对左氧氟沙星的MIC值。结果:135株肺炎克雷伯菌中,9株(6.6%)检出qnr基因。阳性菌株均对亚胺培南敏感且对多种抗生素耐药,其中2株qnr阳性菌株对左氧氟沙星敏感。结论:肺炎克雷伯菌中存在质粒介导喹诺酮类耐药基因qnr基因,qnr阳性菌株呈现多重耐药。临床工作中,应加强对耐药基因的监测,降低细菌耐药的发生。     

南通地区伤寒沙门菌质粒介导的耐药性转移的初步研究

目的 通过对南通地区伤寒沙门菌的耐药性分析,并对其携带的质粒进行PCR检测、分类其上的耐药基因,从而阐明定位于质粒上的整合子介导的耐药性传播的分子机制.方法 收集2009-2011年间南通地区的食源性伤寒沙门菌67株,采用K-B纸片扩散法进行药敏试验确定其耐药谱;筛选出多重耐药性菌株,提取质粒;选择携带质粒的耐药性菌株,以大肠埃希菌为受体进行接合试验.结果 南通地区沙门菌74.6％的沙门菌株(50/67)对抗生素产生耐药性,其中31.3％(50/67)对超过一种抗生素有耐药性,发展成为多重耐药性沙门菌.南通地区分离的株沙门菌仅少量携带质粒,且携带的质粒数量较少15％(10/67),质粒大小分布于DNA Marker的0.6～4Kb间,且1.4Kb大小的质粒出现频率较高(7/10).结论 本地区不同来源的沙门菌检出比率较高,且对氨苄西林和哌拉西林等药物呈现较高的耐药性.本地区分离的株沙门菌携带质粒较少,且大小(＜2Kb或＞2Kb)出现频率有差异.但两者于耐药性传播都有关联.     

Affective and Anxiety Disorders and Alcohol and Drug Dependence:

Depression and anxiety frequently coexist in patients with substance use disorders. This clinically-oriented article examiens the relationship between these conditions and emphasizes data showing that substances of abuse can cause signs and symptoms of both depression and anxiety. These substance-related syndromes appear to have a different course and prognosis than uncomplicated, independent anxiety and major depressive disorders, and clinicians should consider the role of alcohol and other drugs in all patients presenting with these complaints. The authors will also outline an approach for diagnosing and managing patients with the combination of a substance use and depressive or anxiety disorder.     

Synthesis and anti-nociceptive and anti-inflammatory effects of gaultherin and its analogs

The synthesis of gaultherin (1) and its analogs was carried out to provide 11 glycosides under phase-transfer catalytic conditions. The activities of all synthesized compounds were evaluated by nitric oxide production inhibitory assay in vitro. Methyl 2-O-(4-O-β-d-galactopyranosyl)-β-d-glucopyranosylbenzoate (5f) showed significantly anti-nociceptive and anti-inflammatory effects by the evaluation in vivo. Structure–activity relationships within these compounds were discussed.     

Modelling and simulation of variability and uncertainty in toxicokinetics and pharmacokinetics

Two important methodological issues within the framework of the variability and uncertainty analysis of toxicokinetic and pharmacokinetic systems are discussed: (i) modelling and simulation of the existing physiologic variability in a population; and (ii) modelling and simulation of variability and uncertainty when there is insufficient or not well defined (e.g. small sample, semiquantitative, qualitative and vague) information available. Physiologically based pharmacokinetic models are especially suited for separating and characterising the physiologic variability from the overall variability and uncertainty in the system. Monte Carlo sampling should draw from multivariate distributions, which reflect all levels of existing dependencies in the intact organism. The population characteristics should be taken into account. A fuzzy simulation approach is proposed to model variability and uncertainty when there is semiquantitative, qualitative and vague information about the model parameters and their statistical distributions cannot be defined reliably.     

成骨细胞的功能与损伤和骨质疏松的防治

骨质疏松是一种全身性骨骼疾病,导致骨折风险增加。成人的骨量通过破骨细胞的骨吸收和成骨细胞的骨形成作用来维持动态平衡,治疗骨质疏松症的理想策略是抑制破骨细胞的骨吸收和/或增强成骨细胞的骨形成功能。目前针对保护成骨细胞及增强其功能的骨质疏松疗法相对较少。因此,本文针对成骨细胞相关功能蛋白、各种细胞损伤机制（内质网应激、氧化应激、机械过载、微小RNA和长链非编码RNA的影响等）及骨质疏松的治疗与预防作一综述,以期为针对增强成骨细胞功能的骨质疏松治疗策略提供新思路。     

益生菌与肿瘤防治

益生菌广泛存在于自然界中,通过维持宿主体内菌群平衡、影响肠屏障功能和调节免疫应答等作用,提高宿主健康水平,被公认为"肠道健康卫士".一些益生菌可以增强机体的免疫功能,抑制致癌物质,影响肿瘤细胞的基因表达,对肿瘤具有拮抗作用.大量研究表明,益生菌在未来的肿瘤防治中有很好的应用和发展前景.     

Self-stimulation and amphetamine: Tolerance to d and l isomers and cross tolerance to cocaine and methylphenidate

The effects of the d and l isomers of amphetamine on self-stimulation responding were tested following acute and chronic administration. Tolerance and post-drug depression of responding occurred in tests with both isomers, indicating no role for p-hydroxynorephedrine (PHN) which is one of the metabolites of d-amphetamine. In the second experiment, d-amphetamine, methylphenidate and cocaine all produced quantitatively and qualitatively similar effects on self-stimulation responding following acute administration. Following chronic administration of d-amphetamine, animals showed tolerance to all three drugs, indicating cross-tolerance among them. These data are consistent with an hypothesis that tolerance and post-drug depression following chronic amphetamine treatment are the result of decreases in postsynaptic receptor sensitivity, which would lead to a decreased effectiveness of all three drugs, regardless of their pre-synaptic mechanisms.     

Acamprosate and naltrexone treatment effects on ethanol and sucrose seeking and intake in ethanol-dependent and nondependent rats

Rationale  Two pharmacotherapies are approved for treating alcohol craving (acamprosate and naltrexone), but both have shown mixed findings in animals and humans. Objectives  The present experiments utilized a “reinforcer blocking” approach (i.e., rats were able to consume ethanol during treatment) to better understand the efficacy of these treatments for ethanol seeking and drinking using ethanol-dependent and nondependent rats. Materials and methods  In “nondependent” experiments, drugs (acamprosate 50, 100, and 200 mg/kg; naltrexone 0.1, 0.3, and 1.0 mg/kg) were administered over 3-week periods prior to operant sessions with a low response requirement to gain access to reinforcers for 20 min. For “dependent” experiments, rats were made dependent in vapor/inhalation chambers. Results  Acamprosate and naltrexone had similar effects on intake in nondependent and dependent rats; neither drug was selective for ethanol over sucrose drinking. In nondependent animals, naltrexone was more efficacious at more doses than acamprosate, and acamprosate’s effects were limited to a dose that also had adverse effects on body weight. Both pharmacotherapies showed more selectivity when examining reinforcer seeking. In nondependent rats, acamprosate and naltrexone had response-attenuating effects in ethanol, but not sucrose, groups. In dependent animals, acamprosate had selective effects limited to a decrease in sucrose seeking. Naltrexone, however, selectively decreased ethanol-seeking in nondependent rats. Conclusions  The naltrexone-induced decreases in seeking suggested a change in incentive motivation which was selective for ethanol in nondependent rats. The “nondependent” paradigm may model early stages of “problem drinking” in humans, and the findings suggest that naltrexone could be a good intervention for this level of alcohol abuse and relapse prevention.     

Antiinfective and encrustation-inhibiting materials--myth and facts

Catheters, urethral and ureteral stents and other urological implants are frequently affected by encrustration and infection due to their permanent contact with urine. Indwelling urinary catheters provide a haven for microorganisms and thus require extensive monitoring. Several surface modification techniques have been proposed to improve the performance of devices including the immobilization of biomolecules, the incorporation of hydrophilic grafts to reduce protein adsorption, the creation of hydrophobic surfaces, the creation of microdomains to regulate cellular and protein adhesion, new polymers and antimicrobial coatings. Physico-chemical explanation to elucidate the mechanism of such encrustation or infection inhibiting materials is still not available. Our series of experiments showed a marked decrease of silver-activity in biological fluids which corresponds with the controversial clinical results obtained with silver coated urinary catheters. Rifampicin/minocycline coated catheters had very low activity against Gram-negative rods, enterococci and Candida spp., the main causing organisms of urinary catheter infection. Surface engineered materials and antimicrobial drug delivery systems will be the next generation of sophisticated urinary catheters and stents, if both efficacy as well as efficiency has been proved clinically.     

Alprazolam and lorazepam single and multiple-dose effects on psychomotor skills and sleep

Summary The effects of alprazolam 0.5 mg and lorazepam 2 mg on cognitive and psychomotor skills were assessed in twelve normal volunteer subjects in a randomised, double-blind, crossover design. Single and multiple dose effects were monitored using a battery of tests comprising critical flicker fusion threshold (CFFT), choice reaction time (CRT), simulated car tracking, and subjective ratings of perceived sedation (LARS) and of sleep behaviour (LSEQ). Compared with placebo baseline scores, treatment with lorazepam 2 mg (both single and multiple doses) resulted in a widespread impairment of CRT, tracking accuracy, and CFFT. Single doses of alprazolam 0.5 mg reduced CFFT with respect to the placebo baseline. Single and multiple dose treatment with both drugs resulted in subjective reports of sedation, a reduction of sleep onset latency, and improved sleep quality. Only lorazepam 2 mg significantly disrupted the integrity of behaviour on waking from sleep. These results suggest important pharmacodynamic differences between the two drugs in the doses used.