细菌持留与抗生素表型耐药机制

持留菌是细菌群体中一小部分具有表型耐药的细菌。自1944年被发现后,近几十年来因其在慢性持续性感染和生物膜感染中的重要作用而得到越来越多的重视。已有的研究结果表明,细菌持留的机理复杂,涉及的相关信号通路有毒素-抗毒素系统、细胞能量代谢及蛋白核酸合成等生理状态的降低、DNA保护修复系统、蛋白酶系统、反式翻译、外排泵系统等。虽然不同细菌的持留机理有一定的相似性和保守性,但不同细菌的持留机制也存在差异,如毒素-抗毒素系统在大肠埃希菌(Escherichia coli)中的过度激活可导致持留菌增加,但在金黄色葡萄球菌(Staphylococcus aureus)中却并无相同作用。本文从持留菌的研究历史出发,综述了当前对革兰氏阴性菌和阳性菌的持留机制方面的研究进展,同时探讨了在持留菌相关感染疾病方面的治疗策略,以期为更好地解决持留菌带来的问题,缩短治疗时间提供新的思路。     

金黄色葡萄球菌sdhCAB操纵子影响持留菌形成机制的研究

持留菌是细菌群体中的一小部分细菌,可耐受致死浓度抗生素的处理,是引起慢性感染的重要原因。金黄色葡萄球菌(Staphylococcus aureus,S. aureus)作为常见致病菌,有重要临床意义。分别敲除sdhA和sdhB后,金黄色葡萄球菌持留菌形成水平下降,但sdhCAB操纵子对持留菌形成的作用及机制尚不明确。本研究敲除sdh操纵子,通过酸压力、氧化压力、热压力及抗生素压力实验检测敲除株的持留菌水平,转录组测序检测敲除株的代谢通路变化,高通量微生物细胞表型检测评估敲除株的代谢水平变化。结果显示,敲除sdhCAB或sdhAB后,金黄色葡萄球菌对酸压力、氧化压力的耐受能力均下降;而在抗生素压力、热压力条件下,分别仅sdhCAB敲除株、sdhAB敲除株耐受能力下降。转录组测序发现,sdhCAB敲除后三羧酸循环、甲烷代谢通路及聚合酶Ⅳ等基因表达上调,耐药相关基因、氨基酸代谢基因、糖类代谢基因、卟啉代谢基因及一些转运体基因等表达下调,提示这些通路的基因参与sdhCAB影响持留菌形成的过程。此外,高通量微生物细胞表型检测发现,敲除sdhCAB可降低金黄色葡萄球菌对琥珀酸、柠檬酸、糖原、L-天冬氨酸等64种碳源的代谢。结果提示,sdhCAB操纵子对金黄色葡萄球菌持留菌形成水平有重要影响。本研究初步阐明了sdhCAB操纵子影响持留菌形成的可能机制,为研究和治疗金黄色葡萄球菌慢性感染提供了新的思路。     

耐甲氧西林金黄色葡萄球菌的耐药及其检测方法

耐甲氧西林金黄色葡萄球菌（MRSA）是引起医院感染的多重耐药菌,其有效的治疗药物为万古霉素。近年已发现对万古霉素耐受的金黄色葡萄球菌,金黄色葡萄球菌一旦对万古霉素耐药,临床将面临无药可供选择的局面。由于其所造成治疗上的困难,对其耐药机制的深入研究和该菌准确、及时的检出对于寻找新的治疗靶位和防止其播散有着极其重要的意义。本文就mecA耐药决定子、调节基因、染色体上的辅助基因对耐甲氧西林金黄色葡萄球菌耐药表达的影响及其表型和基因检测方法作一综述。     

鲍曼不动杆菌AmpC酶的检测

<正>鲍曼不动杆菌是医院感染重要条件致病菌。近年来,鲍曼不动杆菌感染日益增多,仅次于金黄色葡萄球菌和大肠埃希菌,并且呈现多重耐药现象,已引起临床医生和微生物工作者的高度关注,而其体内产生的AmpC酶是导致鲍曼不动杆菌耐药的重要原因之一。     

金黄色葡萄球菌耐药基因及新型抗菌药物的研究进展

金黄色葡萄球菌(Staphylococcus aureus,S.aureus),简称金葡菌,是一种临床常见致病菌,可引起皮肤化脓性感染、肺炎、心包炎、败血症及脓毒血症等多种疾病。目前临床上金黄色葡萄球菌的多重耐药情况已十分严峻,特别是耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)的出现,已成为临床抗感染治疗的棘手难题,严重危害人类健康。本文主要介绍金黄色葡萄球菌基因水平的耐药性、新型抗菌药物的研发及临床治疗金黄色葡萄球菌感染三方面的进展,为金黄色葡萄球菌的耐药性研究及耐药菌株的临床有效治疗提供科学依据。     

金黄色葡萄球菌溶血素的研究进展

金黄色葡萄球菌简称金葡菌,是一类革兰阳性需氧或兼性厌氧菌,可导致化脓性感染、肺炎、伪膜性肠炎、心包炎等局部感染,以及败血症、脓毒血症等全身感染。金黄色葡萄球菌的致病力强弱主要取决其产生的毒素和侵袭性酶,其中溶血素已经成为该细菌的一个重要致病因子。本文对金黄色葡萄球菌溶血素的分子特征、作用机制、免疫预防及临床应用方面的研究进展进行综述。     

耐药机制指导下的抗金葡菌药物开发现状

金黄色葡萄球菌是全球院内感染的首要病原菌,临床分离的金葡菌80%以上为耐甲氧西林(MRSA)菌株,因其耐药性,尤其是多重耐药性的快速增长,抗MRSA感染日益成为抗感染治疗的难点和热点。近年来,人们在充分认识金葡菌耐药机制的基础上,积极开发新型抗MRSA药物,取得了长足发展。对MRSA的耐药机制及该机制指导下抗金葡菌药物开发现状作一综述。     

医院感染病原菌及耐药性监测报告

从３９０４ 例住院病人标本中分离出医院内感染病原菌７８１ 株,结合临床常用的１４ 种抗菌药物药敏试验结果进行整理分析。结果,革兰阳性球菌所占比例呈上升趋势,革兰阴性杆菌呈下降趋势。引起医院感染的主要病原菌为真菌、大肠埃希菌、克雷伯菌、肠球菌、金黄色葡萄球菌。２ 年间金黄色葡萄球菌对青霉素的耐药率已＞ ９３ ％ ,对第三代喹诺酮类的耐药率下降了１６．６６ ％ ～４０．８３ ％ 。肠球菌对万古霉素的耐药率上升了２７．５９ ％ 。克雷伯菌、沙雷菌、大肠埃希菌对头孢菌素类、第三代喹诺酮类的耐药率呈上升趋势。金黄色葡萄球菌、表皮葡萄球菌、肠杆菌属、铜绿假单胞菌对阿米卡星的耐药率呈下降趋势。     

耐万古霉素的金黄色葡萄球菌

目前认为万古霉素中度耐药的金黄色葡萄球菌菌株一般从苯唑西林耐药的金黄色葡萄球菌转变而来。万古霉素中度耐药的金黄色葡萄球菌感染患者往往长期使用万古霉素或有慢性疾病。目前还没有系统检测万古霉素中度耐药的金黄色葡萄球菌的试验。如果用万古霉素治疗苯唑西林耐药的金黄色葡萄球菌感染失败,临床医生应警觉是否为万古霉素中度耐药的金黄色葡萄球菌感染。     

儿科住院患儿下呼吸道感染的病原菌分布及耐药性分析

目的:分析我院儿科患儿医院下呼吸道感染的病原菌分布情况和耐药性情况,为临床合理使用抗菌药物提供依据。方法:本文以我院儿科近年来(2015年8月至2016年8月期间)临床收治的下呼吸道感染患儿566例为研究对象,针对患儿的病原菌分布情况和耐药性情况进行了调查研究。结果:本次研究的566例患儿共检出病原菌126株,病原菌检出率为22.26%。其中肺炎克雷伯菌、大肠埃希氏菌、金黄色葡萄球菌和表皮葡萄球菌,构成比分别为23.80%、17.56%、10.32%和7.14%;肺炎克雷伯菌对氨苄西林、头抱曲松、复方新诺明、氨曲南的耐药率分别为76.67%、73.33%、36.67%和26.67%;大肠埃希氏菌对氨苄西林、复方新诺明、头抱曲松、哌拉西林、头孢吡肟、头孢他啶的耐药率分别为72.73%、72.73%、68.18%、45.46%、27.27%、22.72%;金黄色葡萄球菌对氨苄西林、红霉素、阿奇霉素、克林霉素、复方新诺明、庆大霉素的耐药率分别为100.00%、84.6%、84.6%、69.23%、53.85%和38.46%。结论:儿科医院呼吸道感染的病原菌以肺炎克雷伯菌、大肠埃希氏菌和金黄色葡萄球菌为主,且多重耐药菌感染增多,临床抗菌药选择的应根据药敏试验结果进行针对性的选择用药以提高临床治疗的有效性及合理性,减少耐药菌株产生。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.