光动力抗微生物化学疗法对解脲脲原体体外活性的影响

解脲脲原体是一种重要的病原微生物,近年来其耐药形势十分严峻,因此寻找一种全新的有效替代治疗方案尤为重要。本研究旨在探索光动力抗微生物化学疗法对解脲脲原体体外活性的影响。选取解脲脲原体两种生物群（Parvo生物群及T960生物群）代表菌株,包括标准株及临床株,与系列稀释的2.5~0.039 062 5 mmol/L光敏剂甲苯胺蓝孵育20 min或60 min,再以（633±10）nm红光照射,设置48、102、204和408 mJ/cm²共4组能量密度,48 h后判读结果。观察不同解脲脲原体与甲苯胺蓝孵育时间、甲苯胺蓝浓度、光照能量密度对光动力抗微生物化学疗法灭活解脲脲原体效果的影响,并观察两种生物群对光动力抗微生物化学疗法敏感性的差异。结果显示,光动力抗微生物化学疗法在体外对解脲脲原体有明显灭活作用。在光照能量密度及解脲脲原体与甲苯胺蓝孵育时间固定的前提下,这种灭活作用随甲苯胺蓝浓度的增加而增强;单一633 nm红光光源在408 J/cm²及以下的能量密度对解脲脲原体的活性无明显影响。在甲苯胺蓝浓度及解脲脲原体与甲苯胺蓝孵育时间固定的条件下,光动力抗微生物化学疗法对解脲脲原体的灭活作用随光照能量密度（48~408 mJ/cm²）的增加而增强;随甲苯胺蓝孵育时间（30~60 min）延长,光动力抗微生物化学疗法对解脲脲原体的灭活作用有增强的趋势。结果提示,解脲脲原体两种生物群对光动力抗微生物化学疗法的敏感性相似。本研究证实,光动力抗微生物化学疗法在体外能有效灭活解脲脲原体,有望成为解脲脲原体感染的有效替代治疗方法。     

光动力疗法在治疗消化道肿瘤中的应用与研究进展

光动力疗法是目前临床上出现的一种新型治疗肿瘤的方法,利用光敏剂吸收可见-近红外光并在组织氧的参与下发生光化学反应,产生活性氧物质进而诱导肿瘤细胞凋亡或坏死。光动力疗法对肿瘤侵袭性低,具有较高的选择性和良好的患者依从性,因此被广泛用于各种消化道恶性肿瘤的姑息性治疗和挽救性治疗。本文对近年来国内外应用光动力疗法治疗消化道肿瘤的文献进行综述,对所报道的疾病类型、治疗病例数、光敏剂和光源、疗效和安全性等信息进行分类整理,并对所面临的挑战和近期的研究进展进行了汇总,以期全面和客观地了解光动力疗法在治疗消化道肿瘤中的应用和研究进展,探讨目前的新应用及存在的问题和可能的发展方向。     

纳米金提高光敏剂单态氧产率的研究

光动力疗法是效果很好的癌症微创治疗方法,主要依靠光敏性药物(也称为光敏剂)进行癌细胞杀伤。在光动力治疗中,光敏剂单态氧产率是影响光动力效果的关键因素。利用纳米金的光学特性来提高光敏剂的单态氧产率为研制新型光敏剂来改进光动力治疗方法提供了一种新的途径。利用绿光LED灯、红光LED灯、氙灯和635 nm连续激光四种光源对混合有光敏剂原卟啉Ⅸ和纳米金的溶液进行光照。用单态氧检测试剂测定了光照后的单态氧产率。     

细胞器靶向光敏剂的研究进展

光动力治疗是一种利用特定波长的激光激发光敏剂产生活性氧物种(ROS),进而对肿瘤细胞进行杀伤的治疗模式。然而,ROS的半衰期很短,且只能作用在产生部位附近,这明显限制了光动力治疗的疗效。细胞器是细胞能正常工作和运转不可缺失的部分。因此,将光敏剂有效地靶向递送至细胞器是一种提高光动力治疗效果的有效策略。本文将介绍有机靶向光敏剂的设计原理、靶向策略、目前面临的挑战和未来的发展方向。     

耐碳青霉烯类肠杆菌科细菌耐药基因传播机制研究现状

耐碳青霉烯类肠杆菌科细菌(Carbapenem-resistant enterobacteriaceae,CRE)在临床中的分离率越来越高,在抗菌药物的选择性压力下,碳青霉烯酶耐药基因可位于不同的移动元件,在不同种属和同种属细菌之间播散,给临床抗感染治疗带来了极大的困难。对碳青霉烯酶耐药基因可移动元件进行了简要综述,旨在阐明CRE耐药基因传播机制,为CRE感染的预防、治疗及感染的控制提供了参考依据。     

光动力治疗与抗肿瘤免疫

光动力治疗是通过特定波长的光激发光敏剂产生活性氧反应物实现对微生物和肿瘤细胞的杀伤。由于光动力治疗的疗效确切,副作用小,并易于与其他治疗方式联用,因而已成为临床肿瘤治疗的新手段。近年来,抗肿瘤免疫的基础研究和临床应用获得了重大进展。研究表明,光动力治疗与抗肿瘤免疫治疗的联合应用具有显著的协同抗肿瘤效应。本文综述了光动力治疗研究进展及其在抗肿瘤免疫治疗的应用,讨论了其面临的障碍及发展前景。     

脑膜败血黄杆菌医院感染的分布及耐药性分析

目的了解温州医学院附属第一医院脑膜败血黄杆菌医院感染的分布及耐药趋势,为临床治疗提供参考。方法收集该院2003年1月至2006年3月脑膜败血黄杆菌医院感染共47例,采用全自动微生物鉴定仪进行细菌鉴定及药敏试验。结果脑膜败血黄杆菌对多种抗菌药物耐药,对头孢哌酮／舒巴坦、环丙沙星、哌拉西林／他唑巴坦、左氧氟沙星的耐药率较低,分别为0％、8．7％、10．8％、10．9％。结论脑膜败血黄杆菌是一种高度耐药的细菌,治疗上应根据药敏选用抗菌药物。     

细菌耐药专刊序言

抗生素是人类对抗病原微生物感染的重要"武器"。然而,抗生素的大规模使用导致细菌耐药性不断增强并广泛传播。细菌耐药不仅是医学问题,同时也是社会和经济问题,涉及公共卫生、环境污染、食品安全等诸多领域。本专刊从临床耐药与流行病学、动物及环境耐药、细菌耐药机制、抗菌药物研发和耐药防控策略等角度对细菌耐药性问题进行了较系统的综述和探讨,为全面认识细菌耐药现状、深入开展耐药机制研究并制定综合防控策略等提供参考。     

基于细菌裂解酶的功能性生物材料及其应用

抗生素的广泛使用引起了耐药细菌的大量出现和传播,严重危害公共健康。细菌裂解酶作为一类天然存在的细菌细胞壁水解酶,对普通细菌及其耐药菌株具有高效、高特异性(选择性)的抗菌性能,被视为抗生素的一种潜在替代品。将细菌裂解酶的底物识别特异性或者选择性杀菌特性与某些材料结合,通过酶固定化的方法,可形成具有特定功能的生物材料,以选择性地识别或杀灭特定细菌。本文中,笔者综述基于细菌裂解酶的功能性生物材料的开发及其在食品、医药卫生等行业中的应用。     

阴沟肠杆菌感染的临床分布及耐药性变迁

目的:分析阴沟肠杆菌感染的临床分布及耐药性变迁,为临床合理用药提供指导。方法:采用临床微生物指南中的常规方法对医院各类标本进行分离培养,对医院近3年阴沟肠杆菌感染的临床分布及耐药性变迁情况进行总结分析。结果:2009年12月~2011年12月,从临床标本中共分离出165株阴沟肠杆菌,菌株的主要来源为痰液、尿液和其他分泌物,分别占50.3%、32.7%和27%;临床药物敏感试验结果显示,阴沟肠杆菌对头孢菌素类、青霉素类、氯霉素和氨基糖苷类的抗菌药物呈现较高的耐药率,对亚胺培南、头孢吡肟比较敏感,而头孢西丁、氨苄西林及头孢唑林对阴沟肠杆菌无效。结论:阴沟肠杆菌主要导致呼吸道和尿路感染,是一种对多种抗菌素耐药的高耐药性细菌,临床医生应结合临床药敏结果合理地选用抗菌药物,以减少耐药菌株的产生和蔓延。     

Photodynamic antimicrobial therapy

Photodynamic antimicrobial therapy (PACT) involves the utilisation of photosensitizers activated by exposure to visible light in order to eradicate microbes (this method has already been applied in photodynamic therapy of tumours). Photodynamic effect of the particular photosensitive substance (PS) is attributed to its ability to penetrate susceptible microorganisms, to absorb the light of certain wavelength, and to generate reactive cytotoxic oxygen products. The target microorganisms for photoinactivation are bacteria, fungi, viruses and protozoa. Photodynamic antimicrobial therapy is proposed as a potentially topical, non-invasive approach suitable for treatment of locally occurring infection. The fact that bacteria are becoming increasingly resistant to antibiotics and antiseptics has lead to an increased interest in the development of new alternative eradication methods, such as PACT. Research and development of photosensitive substances are aimed at finding effective antimicrobial substances, which would have a broad-spectrum potency.     

Development of Photodynamic Antimicrobial Chemotherapy (PACT) for Clostridium difficile

Background

Clostridium difficile is the leading cause of antibiotic-associated diarrhoea and pseudo membranous colitis in the developed world. The aim of this study was to explore whether Photodynamic Antimicrobial Chemotherapy (PACT) could be used as a novel approach to treating C. difficile infections.

Methods

PACT utilises the ability of light-activated photosensitisers (PS) to produce reactive oxygen species (ROS) such as free radical species and singlet oxygen, which are lethal to cells. We screened thirteen PS against C. difficile planktonic cells, biofilm and germinating spores in vitro, and cytotoxicity of effective compounds was tested on the colorectal adenocarcinoma cell-line HT-29.

Results

Three PS were able to kill 99.9% of bacteria in both aerobic and anaerobic conditions, both in the planktonic state and in a biofilm, after exposure to red laser light (0.2 J/cm²) without harming model colon cells. The applicability of PACT to eradicate C. difficile germinative spores indirectly was also shown, by first inducing germination with the bile salt taurocholate, followed by PACT.

Conclusion

This innovative and simple approach offers the prospect of a new antimicrobial therapy using light to treat C. difficile infection of the colon.     

The photodynamic effect of methylene blue and toluidine blue on <Emphasis Type="Italic">Candida albicans</Emphasis> is dependent on medium conditions

Due to the increased number of immunocompromised patients, the infections associated with the pathogen of the genus Candida and other fungi have increased dramatically. Photodynamic antimicrobial chemotherapy (PACT) has been presented as a potential antimicrobial therapy, in a process that combines light and a photosensitizing drug, which promotes a phototoxic response by the treated cells. In this work, we studied the effects of the different medium conditions during PACT, using either methylene blue (MB) or toluidine blue (TB) on Candida albicans. The inhibition of the growth produced by PACT was decreased for different pH values (6.0, 7.0, and 8.0) in a buffered medium. The phototoxic effects were observed only in the presence of saline (not buffered medium). PACT was modulated by calcium in a different manner using either MB or TB. Also when using MB both verapamil or sodium azide were able to decrease the phototoxic effects on the C. albicans. These results show that PACT is presented as a new and promising antifungal therapy, however, new studies are necessary to understand the mechanism by which this event occurs.     

Antifungal photodynamic therapy

In photodynamic antimicrobial chemotherapy (PACT), a combination of a sensitising drug and visible light causes selective destruction of microbial cells. The ability of light-drug combinations to kill microorganisms has been known for over 100 years. However, it is only recently with the beginning of the search for alternative treatments for antibiotic-resistant pathogens that the phenomenon has been investigated in detail. Numerous studies have shown PACT to be highly effective in the in vitro destruction of viruses and protozoa, as well as Gram-positive and Gram-negative bacteria and fungi. Results of experimental investigations have demonstrated conclusively that both dermatomycetes and yeasts can be effectively killed by photodynamic action employing phenothiazinium, porphyrin and phthalocyanine photosensitisers. Importantly, considerable selectivity for fungi over human cells has been demonstrated, no reports of fungal resistance exist and the treatment is not associated with genotoxic or mutagenic effects to fungi or human cells. In spite of the success of cell culture investigations, only a very small number of in vivo animal and human trials have been published. The present paper reviews the studies published to date on antifungal applications of PACT and aims to raise awareness of this area of research, which has the potential to make a significant impact in future treatment of fungal infections.     

Bactericidal effects of hematoporphyrin monomethyl ether-mediated photosensitization against pathogenic communities from supragingival plaque

Photodynamic antimicrobial chemotherapy (PACT) is proposed as a potential candidate to inactivate pathogens in localized infections due to the rapid evolution of bacterial resistance. The treatment modality utilizes nontoxic agents called photosensitizers and harmless visible light to generate reactive oxygen species which result in microbial cells’ killing. Hematoporphyrin monomethyl ether (HMME) as a novel and affordable photosensitizer has been used in treating various clinical diseases for years, but few applications in infection. In this report, we studied the bactericidal effects of the HMME-mediated photodynamic reaction on the pathogenic microbes in supragingival plaque which can lead to many oral infectious diseases such as caries, gingivitis, and so on. Our findings demonstrated that HMME promoted an effective action in bacterial reduction with the application of laser energy. Moreover, the antimicrobial activities were dramatically enhanced as the HMME concentration and exposure time were increased, but reached a plateau when matched the appropriate agent concentration and illumination. It was found that the survival fraction of microorganisms is exponentially dependent on the product of HMME concentration and irradiation time. These promising results suggest the HMME may be an excellently cost-effective photosensitizing agent for mediating PACT in the treatment of supragingival plaque-related diseases. An optimized HMME concentration and irradiation time has been found to achieve the best results under our experimental conditions. The high HMME concentration matching short curative time, or vice versa, can achieve the similar therapeutic effect, which may provide more flexible treatment plans according to specific conditions.     

综述人工合成型抗菌肽及其药学应用研究进展

天然抗菌肽（antimicrobial peptides, AMPs）是一类小分子阳离子多肽,具备多种杀菌机制,呈现出高效、广谱的杀菌特性,在抑制耐药性细菌、制备新型抗菌素等方面具有重要的研究价值。以天然抗菌肽为蓝本,设计和开发的人工合成型抗菌肽可以有效克服天然抗菌肽对蛋白酶敏感、细胞毒性较大、生产成本高等缺陷,作为抗感染的潜在药物具有更广阔的应用前景。综述了目前主要的抗菌肽人工改造技术,包括化学修饰法、蛋白质工程技术、计算机分子模拟技术和从头设计最小化抗菌肽方法的研究进展,并对人工合成抗菌肽作为抗菌药物的应用现状进行了简介。     

The Impact of Different Antibiotic Regimens on the Emergence of Antimicrobial-Resistant Bacteria

Backgroud

The emergence and ongoing spread of antimicrobial-resistant bacteria is a major public health threat. Infections caused by antimicrobial-resistant bacteria are associated with substantially higher rates of morbidity and mortality compared to infections caused by antimicrobial-susceptible bacteria. The emergence and spread of these bacteria is complex and requires incorporating numerous interrelated factors which clinical studies cannot adequately address.

Methods/Principal Findings

A model is created which incorporates several key factors contributing to the emergence and spread of resistant bacteria including the effects of the immune system, acquisition of resistance genes and antimicrobial exposure. The model identifies key strategies which would limit the emergence of antimicrobial-resistant bacterial strains. Specifically, the simulations show that early initiation of antimicrobial therapy and combination therapy with two antibiotics prevents the emergence of resistant bacteria, whereas shorter courses of therapy and sequential administration of antibiotics promote the emergence of resistant strains.

Conclusions/Significance

The principal findings suggest that (i) shorter lengths of antibiotic therapy and early interruption of antibiotic therapy provide an advantage for the resistant strains, (ii) combination therapy with two antibiotics prevents the emergence of resistance strains in contrast to sequential antibiotic therapy, and (iii) early initiation of antibiotics is among the most important factors preventing the emergence of resistant strains. These findings provide new insights into strategies aimed at optimizing the administration of antimicrobials for the treatment of infections and the prevention of the emergence of antimicrobial resistance.     

Investigation of in vitro antimicrobial activity of honey.

Apitherapy or therapy with bee products as honey is an old tradition. In this study, the antimicrobial activity of 84 honey samples were investigated against 8 bacteria potential pathogens and 2 fungi. Honey samples were obtained from 10 different floral sources. The findings indicate that honey samples with thyme, thyme + acorn, pine + carob, pine + carob + anis and pine + chestnut are more effective than the other honey of floral sources. The results of the survey show that most of honey samples at 50% (w/v) can completely inhibit the growth of all of the tested bacteria. The fungi were less sensitive than the bacteria to the antimicrobial activity of honey. The sensitivity of microorganisms to sugar solutions with similar sugar contents as some honey samples which have high antimicrobial activity were also assayed. This sugar solutions inhibited a narrow range of bacteria and did not inhibit any of the fungi tested. In conclusion, these results encourage further studies to investigate possible benefits of the use of honey among therapies in the treatment of bacterial infections.     

抗菌肽在宿主防御中作用

抗菌肽广泛地存在于自然界中,其中许多抗菌肽具有直接抗微生物活性,能作用于G-、 G+细菌、真菌、寄生虫甚至是包膜病毒,并且在宿主先天免疫和适应性反应中有重要的调节作用。近来,越来越多的证据表明抗菌肽是有效的免疫辅助因子,能够与其他的众多免疫效应子协同作用,从而起始适应性免疫,促进伤口愈合,抑制前炎症反应以及诱导和调节细胞因子和趋化因子的产生。另外,随着抗菌肽作用机理逐渐被揭开,将这些内源性肽及其衍生物制成抗感染治疗药剂将会有广阔的应用前景。