The antibacterial activity of alamethicins and zervamicins

Consistent results were obtained in biological assays of alamethicins on agar gels only when the antibiotics were allowed to diffuse under strictly defined conditions of temperature and time before inoculation. In liquid culture obligatory anaerobic rumen bacteria were sensitive to these antibiotics and in certain cases their ability to produce volatile fatty acids was reduced. Among the bacteria examined there was a 1000-fold difference in their sensitivity. Modifications of the structure of the peptaibol, e.g. substitution of an alanine residue for a 2-methylalanine residue resulted in ca two-fold changes in activity.     

Comparison of Macromolecular Oxidation by Reactive Oxygen Species in Three Bacterial Genera Exposed to Different Antibiotics

Proteins and lipids maybe important targets of oxidation and this may alter their functions. We evaluated whether ceftazidima (CAZ), piperacillin (PIP), chloramphenicol (CMP), and ciprofloxacin (CIP) could oxidize the macromolecules in the three bacterial genera Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. There was an increase in lipid peroxidation observed in these three species. However, this was lower in the Gram negative bacteria than in S. aureus. A reduction of the carbonyl residue in S. aureus with ciprofloxacin was observed whereas in Gram negative bacteria the antibiotics increased the carbonyl residue with respect to the control. Although the strains suffered a rise in advanced oxidation protein products (AOPP) in the presence of ciprofloxacin, the S. aureus strain had a smaller increase of AOPP than the other strains. The results described in this article provide data about the susceptibility of the three bacterial genera to the oxidative stress induced by the antibiotics studied.     

2005年至2009年舟山地区血培养病原菌分布及耐药性分析

目的了解舟山地区近5年住院与门诊患者血培养病原菌分布及常见病原菌对抗菌药物的耐药情况,为指导临床诊断及合理用药提供可靠依据。方法对收集的2005年1月至2009年12月10086份血标本采用BACTEC 9120全自动血培养仪进行检测,794株阳性菌株由ATB Expression半自动微生物分析仪进行菌株鉴定及药敏试验。结果 10 086份血培养标本共分离出病原菌794株,总阳性率为7.9%,其中革兰阳性菌424株,占总分离率的53.4%,以表皮葡萄球菌为主,革兰阴性菌328株,占总分离率的41.31%,以大肠埃希菌为主。药敏结果显示表皮葡萄球菌对青霉素耐药最高,未发现对万古霉素、替考拉宁的耐药株,对呋喃妥因耐药率较低,对庆大霉素和左旋氧氟沙星的耐药率逐年明显上升(χ2=11.41,P<0.05;χ2=13.07,P<0.05)。大肠埃希菌未发现亚胺培南和美罗培南的耐药株,对环丙沙星的耐药率逐年明显上升(χ2=12.00,P<0.05)。结论该地血培养病原菌以表皮葡萄球菌和大肠埃希菌为主,药敏结果提示多药耐药,对部分抗生素的耐药率逐年上升应加以重视。     

重症监护病房非发酵菌分布及耐药分析

目的分析医院重症监护病房非发酵菌感染的耐药情况,以指导临床合理使用抗菌药物。方法回顾性分析2008年至2009年医院自重症监护病房分离的非发酵菌,对其检出率及药敏结果进行统计分析。结果共检出4 273株非发酵菌,检出率为38%,分离率居前4位的依次是铜绿假单胞菌(44.09%)、鲍氏不动杆菌(27.64%)、嗜麦芽寡养单胞菌(10.58%)和洋葱伯克霍尔德菌(5.99%);4种常见的非发酵菌对常用抗菌药物耐药性均较高,头孢哌酮/舒巴坦等含酶抑制剂的复合型抗菌药物对非发酵菌有较高的敏感性。结论医院重症监护病房非发酵菌检出率高且耐药性强,应加强临床细菌学的检测,按照药敏试验结果合理用药。     

Mono- and binuclear Zn2+-beta-lactamase. Role of the conserved cysteine in the catalytic mechanism

When expressed by pathogenic bacteria, Zn2+-beta-lactamases induce resistance to most beta-lactam antibiotics. A possible strategy to fight these bacteria would be a combined therapy with non-toxic inhibitors of Zn2+-beta-lactamases together with standard antibiotics. For this purpose, it is important to verify that the inhibitor is effective under all clinical conditions. We have investigated the correlation between the number of zinc ions bound to the Zn2+-beta-lactamase from Bacillus cereus and hydrolysis of benzylpenicillin and nitrocefin for the wild type and a mutant where cysteine 168 is replaced by alanine. It is shown that both the mono-Zn2+ (mononuclear) and di-Zn2+ (binuclear) Zn2+-beta-lactamases are catalytically active but with different kinetic properties. The mono-Zn2+-beta-lactamase requires the conserved cysteine residue for hydrolysis of the beta-lactam ring in contrast to the binuclear enzyme where the cysteine residue is not essential. Substrate affinity is not significantly affected by the mutation for the mononuclear enzyme but is decreased for the binuclear enzyme. These results were derived from kinetic studies on two wild types and the mutant enzyme with benzylpenicillin and nitrocefin as substrates. Thus, targeting drug design to modify this residue might represent an efficient strategy, the more so if it also interferes with the formation of the binuclear enzyme.     

放线菌来源的糖肽类抗生素的药学机制研究进展

糖肽类抗生素具有较好的抑制革兰氏阳性细菌生长的活性,临床上广泛用于治疗革兰氏阳性细菌导致的严重感染性疾病,也被认为是对抗这类顽固性病原菌的最后一道防线。随着耐药菌的不断涌现,糖肽类抗生素的应用越来越受到限制。本文针对糖肽类抗生素的结构特征与药效关系、生物学活性和病原菌对于它们的耐药机制,以及糖肽类抗生素的生物合成机制及其结构的合成生物学改造等方面进行了概述。最后,对糖肽类抗生素在应用中面临的问题进行了展望。     

革兰氏阴性杆菌对14种抗生素的MIC范围及耐药性分析

利用全自动微生物分析仪VITEKAMS 3 2鉴定G-杆菌及进行药敏试验。分离率依高至低依次是大肠埃希菌 (E .coli) (esccol) 3 1 .1 %、肺炎克雷伯菌 (Klebsiellapneumoniae) (klepne) 1 8.6%、铜绿假单胞菌 (Pseudomonasaeruginosa) (pneaer) 1 4 .5%、醋酸钙不动杆菌 (Acinetobactercalcoacetieus) (acicba) 1 2 .9%、阴沟肠杆菌 (Enterobactercloacae) (entclo) 1 0 .3 %、普通和奇异变形杆菌 (Proteusvulgaris和Proteusmirabilis) (pro .pp) 9.3 %、费劳地枸橼酸杆菌 (Citrobacterfreundii) (citfre) 3 .4 %。esccol和klepne对头孢一、二代 ,青霉素类耐药率达 4 1 %～ 1 0 0 % ,MIC90 3 2～ 2 56mg/L ,显示了较高耐药性。pneaer对亚胺硫霉素 (IMP)的耐药率达3 6% ,MIC90 1 6mg/L ,对氧哌嗪青霉素耐药率较低( 1 2 % )。82 % pneaer显示六重或以上耐药。entclo、citfre、pro .pp中尚未发现 1株entclo对IMP耐药 ,但后 2种细菌对IMP的耐药率分别是 1 7% ,1 8% ;不动杆菌对所测抗生素广谱耐药 ,IMP较有效 (耐药率 8% )。肠杆菌科细菌已出现对IMP耐药菌株。铜绿假单胞菌对IMP的耐药率达 3 6%。     

2002年至2007年太原地区儿童细菌性腹泻病原菌分布及耐药分析

目的了解太原地区近6年儿童细菌性腹泻病原菌分布及耐药情况。方法对临床诊断细菌性腹泻病,便培养已分离到病原菌1080例作回顾性分析,分析其病原菌的分布及耐药情况。结果埃希菌属486株（45％）,居于首位,前5位的病原菌依次为埃希菌属、肠球菌属、酵母样真菌、志贺菌属、假单胞菌属。各年均以大肠埃希菌为主要检出菌,志贺菌逐年减少。年龄分布中,婴儿的构成比最高（44．4％）。埃希菌属、志贺菌属、假单胞菌属、沙门菌属、气单胞菌属此5种杆菌对13种抗生素的平均耐药率依次为舒普深、痢特灵、头孢他啶、庆大霉素、环丙沙星、头孢哌酮、头孢曲松、丁胺卡那、头孢噻肟、诺氟沙星、头孢呋辛、哌拉西林、头孢唑啉。从埃希菌属近6年的耐药性变迁资料可以看出,对13种抗生素的耐药率均有不同程度上升。结论传统的致病菌志贺菌属、沙门菌属较少,而肠球菌属、假单胞菌属、枸橼酸杆菌属、克雷伯杆菌属、肠杆菌属、酵母样真菌等条件致病菌肠炎占有相当比例。各种致病菌的耐药性增加,第三代头孢除头孢他啶的耐药率较低外,其余都较高。提示应严格掌握抗生素用药指证,合理选用抗生素。     

临床常用抗生素对G-致病菌的效价分析

目的:调查我院常用抗生素的种类及其对,临床常见的G~-致病菌的效价情况,为合理选用抗生素提供临床资料。方法:从2246个样本中分离到646株G~-致病茵,用全自动微生物分析仪-VITEK 32进行菌种鉴定及20种抗生素的药敏实验。结果:646株G~-致病菌经鉴定属于14大类,其中铜绿假单胞菌160株,占24.77%;大肠埃希氏菌135株,占20.90%;鲍曼不动杆菌90株,占13.93%;克雷伯菌属116株,占17.96%;其它9种G~-致病菌所占的比例均小于7%。头孢类抗生素是目前最为常用的。在检测的20种抗生素对检测的14种G~-致病菌的效价最高的前三位分别是:亚胺培南(IMP)82.66%、美洛西林(MEZ)81.15%、环丙沙星(CIP)61.06%;效价最差的三位分别是:头孢呋辛(CFO)23.76%、头孢噻吩(CEP)26.74%、替卡西林(TIC)31.58%。结论:经典的抗生素对G~-致病菌的效价不容乐观,且非科学的联合用药可能会降低药效。     

呼吸道感染常见致病菌耐药趋势分析

目的：调查我院临床常见的G-致病菌在院内呼吸道感染病人的分布,并检测常用抗生素的种类对致病菌的效价情况,为呼吸道感染病人合理选用抗生素提供依据。方法：对来源于院内呼吸道感染病人的样本300个进行分离培养,用microscan au-toscan4（美国德灵半自动细菌分析仪）菌种鉴定及抗生素的药敏实验,回顾性分析肺部感染患者的痰细菌培养及药物敏感性测定结果。结果：从样本中分离获得825株主要致病菌,其中G＋致病菌389株,占47.2%,G-致病菌380株,占46.1%,真菌46株,占6.7%。G＋致病菌对检测10种抗生素的药敏性主要表现为传统的抗生素的疗效普遍偏低;而G-致病菌对检测的抗生素10种的药敏性情况表现出多元化态势。结论：院内呼吸道感染常见致病菌以革兰阴性菌为主,耐药性高,临床实践应重视病原学的监测,了解细菌的种类分布和耐药趋势,合理使用抗生素。     

<Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis> antibiotic resistance identified by atomic force microscopy

In the last decade the detection of the resistance of bacteria to antibiotics treatment, developed by different kind of bacteria, is becoming a huge problem. We hereby present a different approach to the current problem of detection of bacteria resistance to antibiotics. Our aims were to use the atomic force microscopy (AFM) to investigate bacteria morphological changes in response to antibiotics treatment and explore the possibility of reducing the time required to obtain information on their resistance. In particular, we studied Klebsiella pneumoniae bacteria provided by the Lavagna Hospital ASL4 Liguria (Italy), where there are cases linked with antibiotics resistance of the Klebsiella pneumoniae. By comparing AFM images of bacteria strains treated with different antibiotics is possible to identify unambiguously the Klebsiella pneumoniae strains resistant to antibiotics. In fact, the analysis of the AFM images of the antibiotic-sensitive bacteria shows clearly the presence of morphological alterations in the cell wall. While in the case of the antibiotic-resistant bacteria morphological alterations are not present. This approach is based on an easy and potentially rapid AFM analysis.     

对安贞医院革兰阴性杆菌的耐药趋势调查

目的分析安贞医院感染菌中,居前5位的革兰阴性杆菌的耐药趋势,为临床合理使用抗生素提供必要依据。方法对2000～2002年该院分离的医院感染菌株中,居前5位的革兰阴性杆菌的耐药性,进行回顾性分析。结果革兰阴性杆菌中前5位细菌,对3代头孢菌素的耐药性增高。大多数细菌对亚胺培南和美洛培南敏感。阿米卡星的耐药性有所下降。大肠埃希菌对喹诺酮类抗生素耐药率在85％以上。结论不规范使用抗生素,使细菌的耐药性越来越高,交替使用抗生素可能是降低细菌对抗生素耐药性的有效方法。医院应宏观控制使用抗生素。     

采伐剩余物不同处理方式对杉木幼林土壤有机氮组分的影响

采伐剩余物不同处理方式会改变输入土壤的有机质数量和质量,直接或间接影响土壤的养分组成与含量。氮作为重要的土壤养分之一,其有机氮组分对采伐剩余物不同处理方式的响应仍不明确。本研究在福建省三明市格氏栲自然保护区内,对50多年生的杉木成熟林皆伐后的采伐剩余物分别进行清除、保留、火烧处理,并种植杉木5年时,采用H₂SO₄水解法对不同土层(0～10、10～20 cm)土壤有机氮组分及其影响因素进行研究。结果表明: 保留处理显著提高了土壤有机氮及活性组分的含量。0～10 cm土层中,保留处理土壤有机氮含量(3.36 g·kg^-1)分别是清除处理、火烧处理的1.5和1.3倍,活性氮Ⅰ、Ⅱ含量也以保留处理最高;10～20 cm土层中,保留处理土壤有机氮和活性氮Ⅱ含量(2.20、0.73 g·kg^-1)也显著高于清除和火烧处理,而且保留处理的活性氮指数Ⅱ(33.9%)显著高于火烧处理(26.1%)。两个土层均以保留处理的总碳、可溶性有机碳、可溶性有机氮含量,以及微生物生物量碳、氮最高。与清除处理相比,保留处理显著提高0～10 cm土层细菌(革兰氏阳性菌、阴性菌)含量;10～20 cm土层中,保留处理的真菌含量最高,放线菌含量最低。相关分析表明,土壤有机氮及活性组分与土壤总碳、可溶性有机碳、可溶性有机氮、微生物生物量及土壤细菌(革兰氏阳性菌、阴性菌)、真菌呈显著正相关,与放线菌呈显著负相关。保留处理有利于提高土壤有机氮及活性氮组分含量,改善土壤生化性质,对土壤微生物群落组成具有积极的影响,是维持土壤肥力和提高森林生产力的有效经营管理措施。     

Detection of broad-spectrum aminoglycoside antibiotics through fluorescence-labeling aminoglycoside acetyltransferase(6')-Ii

Aminoglycosides are among the most commonly used antibiotics. The intensive use of aminoglycoside antibiotics has led to the problem of food contamination and the development of antibiotic-resistant bacteria. In the present study, we developed an effective method for easy sensitive detection of broad-spectrum aminoglycoside antibiotics. Aminoglycoside 6′-N-acetyltransferase family catalyzes the transfer of an acetyl group from acetyl coenzyme A (acetyl-CoA) to the 6′ amino group of the aminoglycoside, which is one of the most widespread determinants of aminoglycoside resistance. Because acetyl-CoA is naturally present only in living organisms, it is expected that the enzyme can bind with aminoglycoside antibiotics without catalysis in vitro. The enzyme was mutated for the introduction of a cysteine residue to flexible loops close to the binding site, which was then labeled with thio-labeling reagent fluorescein-5-maleimide. The labeled enzymes were characterized with kinetic and binding studies of various known aminoglycoside antibiotics. The binding of the labeled enzyme with aminoglycoside antibiotics causes a conformational change of the enzyme, which subsequently changes the hydrophobicity and hydrophilicity environment of fluorescent labeling reagent resulting in emission of fluorescence. This study provides a sensitive detection method for residual aminoglycoside antibiotics and strategies to screen and discover new effective aminoglycoside antibiotics.     

Regulation and biosynthesis of carbapenem antibiotics in bacteria

Carbapenem antibiotics are members of the beta-lactam family of antibiotics, the most important class of antibiotics currently in clinical use. They are active against many important Gram-positive and Gram-negative pathogens. One important feature of carbapenem antibiotics is their resistance to several beta-lactamases. Thienamycin, isolated from Streptomyces cattleya, was the first carbapenem described. Other well-studied carbapenems were isolated from the Gram-negative bacteria Erwinia carotovora subsp. carotovora, Serratia sp. strain ATCC39006 and Photorhabdus luminescens strain TT01. Here, we review the genetics and biochemistry of carbapenem production in these bacteria. Research into carbapenems could uncover a new repertoire of bioactive molecules and biosynthetic enzymes, and exploiting these novel enzymes could lead to development of new classes of antibiotics with useful chemotherapeutic activities.     

Factors Which Influence Synergism by Neomycin and Oxytetracycline

Six strains of enteropathogenic gram-negative bacteria were tested for susceptibility to neomycin or oxytetracycline alone and combined in fixed ratios. The minimal inhibitory concentration for the combination was less than one-half of that expected if the antibiotic activities were simply additive. Neomycin alone was more effective against bacteria multiplying in the presence of abundant oxygen, whereas oxytetracycline alone was more effective against bacteria multiplying in relatively anaerobic environments; when combined, the antibiotics complemented each other by their opposing optima for activity. Oxygen concentration, pH, and neomycin activity are related, and the depression of acid production by oxytetracycline is believed to be partially responsible for the synergistic activity of this pair of antibiotics.     

大环内酯类9 位羰基结构修饰衍生物的研究进展

大环内酯类抗生素自上市以来一直用于治疗呼吸系统等疾病，但随着该类药物的广泛应用，耐药菌日益增多。为此，研究者们一 直致力于半合成大环内酯类抗生素的研究，希望开发出对耐药菌有效、抗菌谱广的半合成衍生物。综述近年来对大环内酯9 位羰基结构 修饰的研究进展，并着重介绍一些活性较好的化合物。     

医院感染重要革兰氏阴性菌的耐药谱分析

应用Ｋ－Ｂ氏纸片扩散法测定了５年间本院分离的４种２４５１株革兰氏阴性菌大肠埃希氏菌、沙雷氏菌、铜绿假单胞菌、醋酸钙不动杆菌对临床常用１１～１４种抗生素的敏感性,４种菌对受试抗菌素均有不同程度的耐药性,且对多种抗菌素的耐药率有逐年增加的趋势,表明细菌耐药性在医院内感染中有着越来越重要的作用。     

颅内感染患者细菌分布及耐药性分析

目的分析神经外科颅内感染感染患者细菌的分布及其耐药性,指导合理应用抗生素及感染管理。方法回顾分析2009年至2010年神经外科颅内感染患者的细菌分离株及耐药性。结果细菌共92株,革兰阳性球菌40株,革兰阴性杆菌52株;排前6位的病原菌分别是鲍曼不动杆菌(15.22%)、表皮葡萄球菌(13.04%)、金黄色葡萄球菌(10.87%)、铜绿假单胞菌(10.87%)、肺炎克雷伯菌(8.7%)和粘质沙雷菌(8.7%)。结论神经外科颅内感染中革兰阴性菌与阳性菌比例相当,多重耐药性比例高;依据细菌及耐药性监测结果指导抗生素的合理应用,是治疗颅内感染的重要手段。     

Diffusion of beta-lactam antibiotics through oligomeric or monomeric porin channels of some gram-negative bacteria

The penetration of anionic beta-lactam antibiotics through porins was evaluated as a mechanism of drug resistance. The major proteins with porin activity were purified from the outer membranes of six bacteria. Three of the six porins were oligomeric porins. The molecular weights of their monomers were 37 kDa from Photobacterium damsela, 42 kDa from Serratia liquefaciens, and 36 kDa from E. coli B. The other three porins were heat-modifiable monomeric porins with molecular weights of 43 kDa from Porphyromonas asaccharolytica and Acinetobacter baumannii, and 37 kDa from Escherichia coli K12.Comparison of the six porin proteins revealed that, independent of their aggregation state, their amino acid content is similar but not identical. All have double the amount of negatively charged amino acids compared with positively charged amino acids. They have a similar polarity and polarity index. Two of the six tested bacteria do not produce beta-lactamase. These two bacteria were sensitive to the different beta-lactams tested. The other four bacteria were resistant to all or to several beta-lactams.A modified liposome swelling method was used for determining the rate of penetration of charged beta-lactam antibiotics. Zwitterionic beta-lactams were found to penetrate into liposomes at a rate that more or less fits their molecular weight, whether the porins are monomeric or oligomeric. The penetration rates of negatively charged beta-lactams are different for oligomeric and monomeric porins. Negatively charged beta-lactams penetrate through oligomeric porins better than estimated by their molecular weight, whereas monomeric porins are less penetrable to negatively charged beta-lactams than estimated by their molecular weight. The contribution of all types of porins to the susceptibility of bacteria to beta-lactam antibiotics (zwitterionic or negatively charged) is apparently doubtful. The porins may decrease or increase bacterial penetration rates to beta-lactams, and only the existence of a potential beta-lactamase that can destroy the penetrating drug will cause resistance.