细菌生物被膜对抗生素耐药机制的研究进展*

细菌生物被膜引发的感染已成为医院感染的主要原因之一,具有耐药性和难治性的特点,引起了基础和临床研究的极大关注。但是细菌生物被膜对抗生素的耐药机制目前还不十分明确,对近年来生物被膜怎样和为什么会对抗生素如此耐药形成了几种可能机制进行综述。     

细菌生物被膜的耐药机制及控制策略

在特定的条件下,细菌可以形成生物被膜,包被有生物被膜的细菌称为被膜菌.被膜菌无论其形态结构、生理生化特性、致病性还是对环境因子的敏感性等都与浮游细菌有显著的不同,尤其对抗生素和宿主免疫系统具有很强的抵抗力,从而导致严重的临床问题,引起许多慢性和难治性感染疾病的反复发作.细菌生物被膜粘附在各种医疗器械及导管上极难清除,以至引发大量的医源性感染.近年来,随着人们对细菌致病机制认识的逐步深入,控制细菌生物被膜的方法已有较大发展.本文拟探讨被膜菌的耐药机制并着重综述细菌生物被膜控制方法的最新研究进展.     

细菌群体感应与细菌生物被膜形成之间的关系

由于滥用抗生素,人类致病菌的耐药日益成为全球性的公共卫生难题。据统计,细菌感染80%以上与细菌生物被膜有关。近年来,有关细菌群体感应和细菌生物被膜的形成乃至机理已有报道,但就群体感应与细菌生物被膜的关系却报道较少,而揭示二者之间的关系可能会为解决致病菌耐药问题提供一个全新的思路。本文立足群体感应和细菌生物被膜的形成机制,结合本课题组的阶段性研究内容,拟阐明细菌群体感应与生物被膜形成的关系。     

植物提取物及其活性成分抑制细菌生物被膜的研究进展北大核心CSCD

大量研究报道生物被膜细菌对抗生素的耐药性是浮游菌的10–1 000倍,据报道细菌生物被膜是80%以上细菌感染的罪魁祸首,对医疗保健领域构成了严峻的挑战。植物提取物及其活性成分对细菌生物被膜有明显的抑制作用,包括减少生物被膜量、生物被膜活菌数以及清除已经成熟的生物被膜等。该文对这些有效的植物提取物及其活性成分进行了总结,并分析了其抗细菌生物被膜的作用机制。旨在为防治细菌生物被膜感染的植物类药物的开发提供参考。     

细菌信号小分子耐药机制的相关研究进展

细菌耐药性问题已逐渐成为社会广泛关注的问题。然而,可运用于临床的新型抗生素却十分匮乏。这主要是因为细菌的耐药机制极其复杂,我们对细菌耐药机制的理解不够全面和深入。近几年,多种生物小分子被发现能够使细菌获得广谱的耐药性,并被证明是广泛存在于细菌中的一种耐药机制,这是对目前细菌耐药理论和模型的一个非常重要的补充,更有助于在抗生素的研发过程中寻找新的作用靶标。我们通过总结分析一氧化氮、硫化氢及吲哚这3种信号小分子与细菌耐药的相关研究进展,探讨信号小分子使细菌获得耐药性的相关机制。     

葡萄球菌生物被膜的基因调控机制研究进展

摘要:细菌的耐药性问题是目前医学临床面临的严峻问题,其中细菌生物被膜的形成是引起细菌持续性感染的主要致病机制之一。细菌生物被膜的形成过程十分复杂,受多种因子和多基因的共同调控,且不同的因子和基因在生物被膜形成的不同阶段所起的作用不同。本文重点对引起院内感染的主要致病菌葡萄球菌的生物被膜形成的基因调控机制,以及药物抑制葡萄球菌生物被膜的研究现状进行综述,旨在为解决医学临床中存在的细菌感染,研制抗生物被膜药物和疫苗等提供参考。     

细菌生物被膜（bacterial biofilm）的研究进展

细菌生物被膜由物体表面集聚生长的细菌群落和细胞外基质构成 ,植入性医用器械表面较多见 ,其结构包括主体生物被膜层、连接层、条件层和基质层。细菌之间的信号传导影响着生物被膜的异化形成。生物被膜相关感染治疗较难 ,易慢性化及反复发作。抗生素或其他化学杀菌剂及金银包裹导管等医用材料表面是常用的预防方法。已形成的生物被膜可用物理方法或某些抗生素清除 ,而生物学控制是另一可能途径。     

抗菌肽17BIPHE2对金黄色葡萄球菌生物被膜的抑制作用

【目的】研究抗菌肽17BIPHE2单独使用及联合抗生素对金黄色葡萄球菌(Staphylococcus aureus)生物被膜的抑制作用。【方法】采用刚果红平板测试法和结晶紫染色评估受试菌形成生物被膜的能力;微量肉汤稀释法和琼脂平板测试法测定金黄色葡萄球菌最小抑菌浓度(MIC)和最小杀菌浓度(MBC);利用抑制金黄色葡萄球菌黏附实验和生物被膜形成抑制实验观察17BIPHE2单独使用及联合抗生素对生物被膜黏附阶段和形成阶段的影响;通过扫描电子显微镜(SEM)观察17BIPHE2单独使用及联合抗生素对成熟生物被膜的清除作用。【结果】17BIPHE2的MIC为8μmol/L,1/2×MIC就可以有效抑制浮游菌的生长。单独使用17BIPHE2在细菌黏附阶段抑制率为40%,在生物被膜形成阶段抑制率达到35%。17BIPHE2联合抗生素使用较单独使用抗生素其抑制率均有所下降。生物被膜成熟阶段17BIPHE2于1/4×MIC浓度即可促进生物被膜崩解,1×MIC生物被膜崩解同时细菌黏附量有所下降,联合万古霉素促进生物被膜崩解同时细菌胞质大量外泄。【结论】抗菌肽17BIPHE2具有良好的抑制金黄色葡萄球菌生物被膜作用,联合抗生素其抗生物被膜作用进一步提高。这将为治疗由金黄色葡萄球菌生物被膜引起的相关感染提供了一个新思路。     

c-di-AMP调控细菌生物被膜的形成

细菌生物被膜是细菌持续性致病的重要机制。研究细菌生物被膜的形成和发展可为顽固性细菌感染防治提供新的思路与策略。环二腺苷酸c-di-AMP(Cyclic diadenosine monophosphate)是继c-di-GMP之后在细菌中新发现的一种核苷酸第二信使分子。研究发现,c-di-AMP参与调节细菌多种生理功能,包括细菌生长代谢、生物被膜形成、细胞壁的合成以及细菌毒力因子等。本文综述了c-di-AMP参与调控细菌生物被膜形成的不同方式及其分子机制。鉴于c-di-AMP在调控细菌生物被膜中的重要性,其可作为抗细菌生物被膜感染新药研发的潜在靶点。     

引发医院感染表皮葡萄球菌生物被膜的检测

为了解引发医院感染的表皮葡萄球菌中ica操纵元的存在与生物被膜的产生的关系及其对抗生素敏感性的影响,收集了引发医院感染的表葡萄球菌106株,采用定量和定性法检测生物被膜的产生,PCR法检测ica操纵元基因的存在以及测量细菌对红霉素（ERY）、氨苄青霉素（AMP）、头孢西丁（FOX）、头孢曲松（CRO）、替考拉宁（TEC）、环丙沙星（CIP）、四环素（TCY）、复方新诺明（SXT）、万古霉素（VAN）的最小抑菌浓度（MIC）;106株表皮葡萄球菌分离株中,有33株检测出icaABC（31．1％）;ica^＋菌中产膜菌的检出率高于ica^＋菌（P=0．001）;葡萄糖和NaCl可提高产膜菌的检出率;ica^＋浮游菌对红霉素,头孢西丁和头孢曲松的耐药率高于ica^＋浮游菌株,但对氨苄青霉素,环丙沙星,四环素和复方新诺明的耐药率与ica^＋菌相似;ica位点基因的存在与引发表葡菌医院感染密切相关,但生物被膜内菌耐药机制还需进一步研究。     

The evolution of resistance against good and bad infections

Opportunities for genetic exchange are abundant between bacteria and foreign genetic elements (FGEs) such as conjugative plasmids, transposable elements and bacteriophages. The genetic novelty that may arise from these forms of genetic exchange is potentially beneficial to bacterial hosts, but there are also potential costs, which may be considerable in the case of phage infection. Some bacterial resistance mechanisms target both beneficial and deleterious forms of genetic exchange. Using a general epidemiological model, we explored under which conditions such resistance mechanisms may evolve. We considered a population of hosts that may be infected by FGEs that either confer a benefit or are deleterious to host fitness, and we analysed the epidemiological and evolutionary outcomes of resistance evolving under different cost/benefit scenarios. We show that the degree of co‐infection between these two types of infection is particularly important in determining the evolutionarily stable level of host resistance. We explore these results using the example of CRISPR‐Cas, a form of bacterial immunity that targets a variety of FGEs, and we show the potential role of bacteriophage infection in selecting for resistance mechanisms that in turn limit the acquisition of plasmid‐borne antibiotic resistance. Finally, beyond microbes, we discuss how endosymbiotic associations may have shaped the evolution of host immune responses to pathogens.     

Use of live Saccharomyces cerevisiae cells as a biological response modifier in experimental infections

Abstract A short-term oral administration of live Saccharomyces cerevisiae cells, strain Sillix Hansen DSM 1883, resulted in enhanced resistance of mice toward infections with K. pneumoniae, S. pneumoniae and S. pyogenes A produced by intranasal inoculation. Yeast pre-treatment also increased the efficacy of antibiotic therapy in bacterial infections and of antiviral drugs in viral infections. Yeast treatment of animals stimulated phagocytosis, activated the complement system and induced interferon which are likely to represent the main mechanisms of action whereby pretreatment of mice with live S. cerevisiae cells increases resistance to infection. It is concluded that preventive administration of live Saccharomyces cerevisiae cells should be used for increasing resistance to bacterial infections, in particular of the respiratory tract, or to viral infections, as well as an adjunct to antibiotic and antiviral drug therapy.     

Use of live Saccharomyces cerevisiae cells as a biological response modifier in experimental infections

A short-term oral administration of live Saccharomyces cerevisiae cells, strain Sillix Hansen DSM 1883, resulted in enhanced resistance of mice toward infections with K. pneumoniae. S. pneumoniae and S. pyogenes A produced by intranasal inoculation. Yeast pre-treatment also increased the efficacy of antibiotic therapy in bacterial infections and of antiviral drugs in viral infections. Yeast treatment of animals stimulated phagocytosis, activated the complement system and induced interferon which are likely to represent the main mechanisms of action whereby pretreatment of mice with live S. cerevisiae cells increases resistance to infection. It is concluded that preventive administration of live Saccharomyces cerevisiae cells should be used for increasing resistance to bacterial infections, in particular of the respiratory tract, or to viral infections, as well as an adjunct to antibiotic and antiviral drug therapy.     

Meta分析在细菌耐药性研究中的应用与展望

随着抗生素的大量不规范使用,细菌耐药性不断增强,导致耐药及多重耐药细菌的出现,严重威胁着人类健康。运用统计学方法对耐药性相关研究进行汇总与多元分析,有助于更好地了解全球细菌耐药性的流行与分布,明晰细菌耐药性形成规律与机制的共性问题。Meta分析是一种将多个同类型研究进行综合分析的统计学方法,已广泛应用于细菌耐药性的研究。本文简要描述了Meta分析的起源及基本流程,并采用文献计量的方法对2000-2020年关于Meta分析在细菌耐药性研究中的应用进行系统综述;进一步总结并阐述了Meta分析在细菌耐药性领域应用的成功案例和结论,而且对Meta分析方法在细菌耐药性领域中的进一步研究进行了展望,以期推动该方法在细菌耐药性研究中的应用,为耐药性问题的系统阐释和有效控制提供可靠的工具。     

Antibiotic resistance and persistence—Implications for human health and treatment perspectives

Antimicrobial resistance (AMR) and persistence are associated with an elevated risk of treatment failure and relapsing infections. They are thus important drivers of increased morbidity and mortality rates resulting in growing healthcare costs. Antibiotic resistance is readily identifiable with standard microbiological assays, and the threat imposed by antibiotic resistance has been well recognized. Measures aiming to reduce resistance development and spreading of resistant bacteria are being enforced. However, the phenomenon of bacteria surviving antibiotic exposure despite being fully susceptible, so‐called antibiotic persistence, is still largely underestimated. In contrast to antibiotic resistance, antibiotic persistence is difficult to measure and therefore often missed, potentially leading to treatment failures. In this review, we focus on bacterial mechanisms allowing evasion of antibiotic killing and discuss their implications on human health. We describe the relationship between antibiotic persistence and bacterial heterogeneity and discuss recent studies that link bacterial persistence and tolerance with the evolution of antibiotic resistance. Finally, we review persister detection methods, novel strategies aiming at eradicating bacterial persisters and the latest advances in the development of new antibiotics.     

幽门螺杆菌抗生素耐药机制研究进展

幽门螺杆菌(Helicobacter pylori,H.pylori)感染可引起消化性溃疡、胃粘膜相关淋巴组织淋巴瘤和胃癌。随着抗生素耐药性的问题越来越严重,耐药机制的研究也不断深入。分子检测方法,尤其是核酸检测技术,可高效、快速、准确地检测幽门螺杆菌抗生素耐药基因及突变,对幽门螺杆菌感染的临床治疗发挥重要的指导作用,同时也可对幽门螺杆菌抗生素耐药性进行大规模及时有效监控。本文讨论了关于幽门螺杆菌抗生素耐药机制并着重总结了相关耐药基因及突变。     

A global view of antibiotic resistance

Antibiotic resistance is one of the few examples of evolution that can be addressed experimentally. The present review analyses this resistance, focusing on the networks that regulate its acquisition and its effect on bacterial physiology. It is widely accepted that antibiotics and antibiotic resistance genes play fundamental ecological roles – as weapons and shields, respectively – in shaping the structures of microbial communities. Although this Darwinian view of the role of antibiotics is still valid, recent work indicates that antibiotics and resistance mechanisms may play other ecological roles and strongly influence bacterial physiology. The expression of antibiotic resistance determinants must therefore be tightly regulated and their activity forms part of global metabolic networks. In addition, certain bacterial modes of life can trigger transient phenotypic antibiotic resistance under some circumstances. Understanding resistance thus requires the analysis of the regulatory networks controlling bacterial evolvability, the physiological webs affected and the metabolic rewiring it incurs.     

Genetics of Antimicrobial Resistance

Antimicrobial resistant strains of bacteria are an increasing threat to animal and human health. Resistance mechanisms to circumvent the toxic action of antimicrobials have been identified and described for all known antimicrobials currently available for clinical use in human and veterinary medicine. Acquired bacterial antibiotic resistance can result from the mutation of normal cellular genes, the acquisition of foreign resistance genes, or a combination of these two mechanisms. The most common resistance mechanisms employed by bacteria include enzymatic degradation or alteration of the antimicrobial, mutation in the antimicrobial target site, decreased cell wall permeability to antimicrobials, and active efflux of the antimicrobial across the cell membrane. The spread of mobile genetic elements such as plasmids, transposons, and integrons has greatly contributed to the rapid dissemination of antimicrobial resistance among several bacterial genera of human and veterinary importance. Antimicrobial resistance genes have been shown to accumulate on mobile elements, leading to a situation where multidrug resistance phenotypes can be transferred to a susceptible recipient via a single genetic event. The increasing prevalence of antimicrobial resistant bacterial pathogens has severe implications for the future treatment and prevention of infectious diseases in both animals and humans. The versatility with which bacteria adapt to their environment and exchange DNA between different genera highlights the need to implement effective antimicrobial stewardship and infection control programs in both human and veterinary medicine.     

Genetics of antimicrobial resistance

Antimicrobial resistant strains of bacteria are an increasing threat to animal and human health. Resistance mechanisms to circumvent the toxic action of antimicrobials have been identified and described for all known antimicrobials currently available for clinical use in human and veterinary medicine. Acquired bacterial antibiotic resistance can result from the mutation of normal cellular genes, the acquisition of foreign resistance genes, or a combination of these two mechanisms. The most common resistance mechanisms employed by bacteria include enzymatic degradation or alteration of the antimicrobial, mutation in the antimicrobial target site, decreased cell wall permeability to antimicrobials, and active efflux of the antimicrobial across the cell membrane. The spread of mobile genetic elements such as plasmids, transposons, and integrons has greatly contributed to the rapid dissemination of antimicrobial resistance among several bacterial genera of human and veterinary importance. Antimicrobial resistance genes have been shown to accumulate on mobile elements, leading to a situation where multidrug resistance phenotypes can be transferred to a susceptible recipient via a single genetic event. The increasing prevalence of antimicrobial resistant bacterial pathogens has severe implications for the future treatment and prevention of infectious diseases in both animals and humans. The versatility with which bacteria adapt to their environment and exchange DNA between different genera highlights the need to implement effective antimicrobial stewardship and infection control programs in both human and veterinary medicine.     

A Window of Opportunity to Control the Bacterial Pathogen Pseudomonas aeruginosa Combining Antibiotics and Phages

The evolution of antibiotic resistance in bacteria is a global concern and the use of bacteriophages alone or in combined therapies is attracting increasing attention as an alternative. Evolutionary theory predicts that the probability of bacterial resistance to both phages and antibiotics will be lower than to either separately, due for example to fitness costs or to trade-offs between phage resistance mechanisms and bacterial growth. In this study, we assess the population impacts of either individual or combined treatments of a bacteriophage and streptomycin on the nosocomial pathogen Pseudomonas aeruginosa. We show that combining phage and antibiotics substantially increases bacterial control compared to either separately, and that there is a specific time delay in antibiotic introduction independent of antibiotic dose, that minimizes both bacterial density and resistance to either antibiotics or phage. These results have implications for optimal combined therapeutic approaches.