铜绿假单胞茵主动外排系统与耐药性关系的研究

铜绿假单胞菌是一种重要的院内感染条件致病菌,常感染癌症患者、烧伤患者等机体免疫力低下的患者,它对多种不同理化性质的药物高度耐药,其主动外排系统在耐药性中起主要作用.主要研究了铜绿假单胞菌主动外排泵的类型、组成及对抗生素耐药性的影响.     

铜绿假单胞菌中新型的β内酰胺酶介导的羧苄青霉素抗性

为了探究铜绿假单胞菌抗羧苄青霉素的机制,通过基因敲除以及克拉维酸钾和羧苄青霉素协同实验对羧苄青霉素抗性菌株进行研究。在对羧苄青霉素具有抗性的转座突变体基础上敲除amp C后,其对羧苄青霉素抗性没有变化;8株羧苄青霉素抗性转座突变体菌株克拉维酸钾协同实验呈阳性。基因组中预测为β内酰胺酶的PA5514基因的敲除突变菌株及过表达菌株对氨苄青霉素以及羧苄青霉素的敏感性也没有变化。结果说明amp C及PA5514表达升高并不是羧苄青霉素抗性转座突变体抗性产生的原因,基因组中存在新的受克拉维酸钾抑制的β内酰胺酶可能是铜绿假单胞菌抗羧苄青霉素的一种新机制。同时,克拉维酸钾与羧苄青霉素联合使用能够提高羧苄青霉素对铜绿假单胞菌抗性菌株的治疗效果。     

铜绿假单胞菌医院感染流行病学分子研究及基因分型

目的建立随机扩增多态性DNA（RAPD）基因分型方法检测铜绿假单胞菌（PA）,调查铜绿假单胞菌医院感染流行病学的情况,为控制院内感染提供直接可靠的参考依据。方法对2008—2009年分离的180株铜绿假单胞菌进行统计分析其临床分布;通过抗生素敏感性试验进行抗菌谱分型;再采用PAPD基因分型方法进行分析。结果标本主要来自ICU、烧伤科、呼吸内科等。从痰液标本中分离的铜绿假单胞菌占58．9％,其次伤口分泌物标本占18．9％、中段尿16．7％,其它类型标本占5．5％。抗菌谱分型分为5型。180株铜绿假单胞菌用RAPD分型共得178株,分型率98．9％（178／180）,分为9种类型：Ⅰ～Ⅸ。结论RAPD分型技术对铜绿假单胞菌临床分离株分型率较高;同一抗菌谱型的基因型可能不同,同一基因型的抗菌谱也可能不同。     

铜绿假单胞菌多重耐药性分子机制的研究

铜绿假单胞菌是重要的医院感染条件致病菌.由于各种抗生素的广泛使用,细菌耐药问题日趋严重,导致了铜绿假单胞菌产生了很强的耐药性而且多重耐药,铜绿假单胞菌通过多种途径产生耐药.而从分子水平对其耐药性机制进行研究具有重要意义.     

豌豆根瘤菌RND外排转运基因tpaA的功能研究

Rhizobium. leguminosarum 3841 tpa A基因编码RND家族内膜外排转运蛋白,RND外排泵的过量表达是革兰阴性菌细菌抗生素耐药性形成的重要原因之一.采用基因同源重组构建豌豆根瘤菌tpa A基因突变株RLtpa A,并研究了该基因突变对根瘤菌生长、抗生素耐药性以及共生固氮的影响.结果表明,tpa A基因突变会使根瘤菌在AMS基本培养基生长延迟,但不影响其在TY天然培养基中的正常生长. tpa A基因突变可能抑制了根瘤菌中的RND家族外排泵的过量表达,从而使其抗生素耐药性降低.接种了tpa A基因突变株的豌豆植株能形成红色有效根瘤,但其接种根瘤固氮酶活性降低.实时荧光定量RT-PCR分析表明tpa A基因在根瘤类菌体中的表达显著上调.     

铜绿假单胞菌的耐药现状及外膜孔蛋白分析

目的:总结分析我院2007年-2009年铜绿假单胞菌对常用抗生素的耐药状况,以指导临床合理选用抗生素,同时探讨外膜孔蛋白缺失介导的铜绿假单胞菌对亚胺培南的耐药机制.方法:采用PCR方法检测外膜孔蛋白OprD的编码基因,利用Whonet 5.4 软件对药敏资料进行统计分析.结果:3年中铜绿假单胞菌每年的分离数量分别为13...     

铜绿假单胞菌耐药机理

铜绿假单胞菌是耐药性十分突出的一类院内感染条件致病革兰氏阴性细菌．本文从生物被膜、细胞密度依赖式毒力因子、外排系统、基因盒一整合子系统及铜绿假单胞菌噬菌体几方面对其耐药性机理进行了概述，并提出了未来对微生物耐药性研究和应用的一些策略。     

标本中铜绿假单胞菌的临床分布及耐药情况

目的分析我院铜绿假单胞菌临床分布及耐药情况,为临床合理选用抗生素提供依据。方法采用K-B纸片扩散法对临床分离的铜绿假单胞菌进行抗生素敏感性测定,对检测结果进行对比统计分析。结果分离出的27株铜绿假单胞菌主要来源于痰,临床主要分布于脑外科与呼吸内科,对铜绿假单胞菌保持抗菌活性较强同时耐药率〈30%的抗生素有亚胺培南（IPM）,阿米卡星（AMK）,头孢他啶（CAZ）,左氧氟沙星等,但复方新诺明（SXT）耐药率为92.6%,头孢噻肟耐药率为60.6%,原来被认为抗铜绿假单胞菌较为有效的头孢呱酮耐药率也升至60.0%。结论铜绿假单胞菌对常用抗生素耐药率高,建议根据药敏结果,采用有效药物单一或联合疗法,以控制细菌耐药性的增长。     

标本中铜绿假单胞菌的临床分布及耐药情况

目的分析我院铜绿假单胞菌临床分布及耐药情况,为临床合理选用抗生素提供依据。方法采用K-B纸片扩散法对临床分离的铜绿假单胞菌进行抗生素敏感性测定,对检测结果进行对比统计分析。结果分离出的27株铜绿假单胞菌主要来源于痰,临床主要分布于脑外科与呼吸内科,对铜绿假单胞菌保持抗菌活性较强同时耐药率<30%的抗生素有亚胺培南(IPM),阿米卡星(AMK),头孢他啶(CAZ),左氧氟沙星等,但复方新诺明(SXT)耐药率为92.6%,头孢噻肟耐药率为60.6%,原来被认为抗铜绿假单胞菌较为有效的头孢呱酮耐药率也升至60.0%。结论铜绿假单胞菌对常用抗生素耐药率高,建议根据药敏结果,采用有效药物单一或联合疗法,以控制细菌耐药性的增长。     

540株铜绿假单胞菌12年耐药情况分析

目的：分析导致临床感染的540株铜绿假单胞菌的临床特点及耐药情况,为临床预防感染及合理用药提供依据。方法：回顾性分析12年来540株铜绿假单胞菌的耐药情况。结果：住院患者铜绿假单胞菌检出率明显高于门诊患者,且以重症病房（ICU）尤为显著;下呼吸道感染是主要的临床感染来源;中老年人及慢性病患者,重症患者为易被侵袭人群;铜绿假单胞菌对多数抗生素有较高的耐药性及多重耐药性,且耐药性有逐年上升的趋势。结论：铜绿假单胞菌是临床常见条件致病菌,耐药性严重。治疗中应根据分离株耐药特点选择合理用药方案,避免多重耐药铜绿假单胞菌的出现。     

Complete genome sequence of Pseudomonas aeruginosa PAO1, an opportunistic pathogen

Pseudomonas aeruginosa is a ubiquitous environmental bacterium that is one of the top three causes of opportunistic human infections. A major factor in its prominence as a pathogen is its intrinsic resistance to antibiotics and disinfectants. Here we report the complete sequence of P. aeruginosa strain PAO1. At 6.3 million base pairs, this is the largest bacterial genome sequenced, and the sequence provides insights into the basis of the versatility and intrinsic drug resistance of P. aeruginosa. Consistent with its larger genome size and environmental adaptability, P. aeruginosa contains the highest proportion of regulatory genes observed for a bacterial genome and a large number of genes involved in the catabolism, transport and efflux of organic compounds as well as four potential chemotaxis systems. We propose that the size and complexity of the P. aeruginosa genome reflect an evolutionary adaptation permitting it to thrive in diverse environments and resist the effects of a variety of antimicrobial substances.     

A genetic basis for Pseudomonas aeruginosa biofilm antibiotic resistance

Biofilms are surface-attached microbial communities with characteristic architecture and phenotypic and biochemical properties distinct from their free-swimming, planktonic counterparts. One of the best-known of these biofilm-specific properties is the development of antibiotic resistance that can be up to 1,000-fold greater than planktonic cells. We report a genetic determinant of this high-level resistance in the Gram-negative opportunistic pathogen, Pseudomonas aeruginosa. We have identified a mutant of P. aeruginosa that, while still capable of forming biofilms with the characteristic P. aeruginosa architecture, does not develop high-level biofilm-specific resistance to three different classes of antibiotics. The locus identified in our screen, ndvB, is required for the synthesis of periplasmic glucans. Our discovery that these periplasmic glucans interact physically with tobramycin suggests that these glucose polymers may prevent antibiotics from reaching their sites of action by sequestering these antimicrobial agents in the periplasm. Our results indicate that biofilms themselves are not simply a diffusion barrier to these antibiotics, but rather that bacteria within these microbial communities employ distinct mechanisms to resist the action of antimicrobial agents.     

大肠杆菌耐药机制中激活外排泵和减少摄入量的研究进展

概述了大肠杆菌中激活外排泵和减少摄入量这两个重要的耐药机制和克服它们的新策略,主要包括近年来在理解外排泵系统的物理结构、功能和调控子中的进步和有利于开发以外排泵为靶位的药物研究进展。     

Gene expression in Pseudomonas aeruginosa biofilms.

Bacteria often adopt a sessile biofilm lifestyle that is resistant to antimicrobial treatment. Opportunistic pathogenic bacteria like Pseudomonas aeruginosa can develop persistent infections. To gain insights into the differences between free-living P. aeruginosa cells and those in biofilms, and into the mechanisms underlying the resistance of biofilms to antibiotics, we used DNA microarrays. Here we show that, despite the striking differences in lifestyles, only about 1% of genes showed differential expression in the two growth modes; about 0.5% of genes were activated and about 0.5% were repressed in biofilms. Some of the regulated genes are known to affect antibiotic sensitivity of free-living P. aeruginosa. Exposure of biofilms to high levels of the antibiotic tobramycin caused differential expression of 20 genes. We propose that this response is critical for the development of biofilm resistance to tobramycin. Our results show that gene expression in biofilm cells is similar to that in free-living cells but there are a small number of significant differences. Our identification of biofilm-regulated genes points to mechanisms of biofilm resistance to antibiotics.     

烧伤病房感染患者铜绿假单胞菌的分离及耐药性分析

目的 了解烧伤病房感染患者铜绿假单胞菌耐药谱的变化,为防治烧伤病区患者感染铜绿假单胞菌提供合理用药依据.方法 常规方法收集同一时间烧伤病房9名感染患者的患部浓汁和血液标本,分离鉴定出9株铜绿假单胞菌,K-B法进行药敏试验及统计学分析.结果 9株铜绿假单胞菌对氨苄西林、哌拉西林、亚胺培南/西司他丁、头孢他啶、氨曲南、阿米卡星、复方磺胺等11种抗菌药物耐药率均为100%.结论 烧伤病房感染患者铜绿假单胞菌耐药现象严重,应注意铜绿假单胞菌耐药性的监测.     

铜绿假单孢菌yfa操纵子中α2-M基因与抵抗力的关系

目的研究铜绿假单孢菌yfa-α2M基因与其抵抗力的关系。方法通过基因敲除的方法,得到铜绿假单孢菌的突变株PAO1Δyfa-α2M。在不同的底物存在的条件下,比较突变株和野生型菌株的生长曲线。结果突变株PAO1Δyfa-α2M对Polymixin的抗性明显降低。结论基因yfa-α2M可能与铜绿假单胞菌的抗性有关。