两种纸片检测耐甲氧西林葡萄球菌结果比较

目的以苯唑西林琼脂筛选法为标准,比较苯唑西林和头孢西丁2种药敏纸片检测耐甲氧西林葡萄球菌(MRS)结果的准确性和一致性。方法分别用苯唑西林琼脂筛选法,头孢西丁和苯唑西林纸片扩散法检测临床分离的595株葡萄球菌。以琼脂筛选法为标准,计算2种纸片法的敏感性和特异性,比较二者的检测准确率差异是否存在统计学意义。结果金黄色葡萄球菌中,MRSA的检出率为55.97%,两药敏纸片的敏感性和特异性均在97%以上;二者在筛选MRSA的准确率上差异无统计学意义(P>0.05)。凝固酶阴性葡萄球菌中,MRSCN的检出率为69.68%,两纸片的敏感性均为100.00%,特异性分别为92.86%(头孢西丁)和77.38%(苯唑西林)。二者在检测MRSCN的准确率上差异存在统计学意义(P(0.05)。结论常规工作中,头孢西丁可准确检测所有的MRS,但苯唑西林只能用于检测MRSA,不能检测MRSCN。     

头孢西丁纸片扩散法检测耐甲氧西林溶血葡萄球菌

目的以PCR方法检测溶血葡萄球菌mecA基因为标准,评价头孢西丁纸片扩散法、苯唑西林纸片扩散法和VITEKGPS109卡微量肉汤稀释法检测耐甲氧西林溶血葡萄球菌（methicillin resistant Staphylococcus haemolyticus,MRSH）的敏感度和特异性。方法用PCR扩增临床分离的114株溶血葡萄球菌．检测特异性的mecA基因片段;头孢西丁纸片扩散法、苯唑西林纸片扩散法和VITEK GPS109卡微量肉汤稀释法检测溶血葡萄球菌中耐甲氧西林的溶血葡萄球菌。结果114株溶血葡萄球菌经PCR法检测,MRSH有97株,占85．1％;头孢西丁纸片扩散法、苯唑西林纸片扩散法和VITEKGPS 109卡微量肉汤稀释法检测MRSH分别有92、65、93株．与mecA基因法结果比较,头孢西丁纸片扩散法、苯唑西林纸片扩散法和VITEK GPS109卡微量肉汤稀释法敏感性分别为94．8％（92／97）、67．0％（65／97）、93．8％（91／97）;特异性分别为i00％（17／17）、100％（17／17）、88．2％（15／17）。矿检验,头孢西丁纸片扩散法和mecA基因法差异无显著性。结论头孢西丁纸片扩散法检测MRSH具有很高敏感度和特异性,是筛选和确认MRSH的一种可靠方法。     

耐甲氧西林葡萄球菌检测方法的研究

耐甲氧西林葡萄球菌（ＭＲＳ）的检测大致分为３个方面,药敏试验、ｍｅｅＡ基因和青霉素结合蛋白２ａ（ＰＢＰ２ａ）检测,药敏试验易受实验体系中多种因素影响,自动化检测仅属定性筛选试验,Ｅ－Ｔｅｓｔ法操作简便,准确性好,因价格昂贵,临床应用受限。ｍｅｅＡ基因检测耗时短,特异性、敏感性高,但ｍｅｅＡ基因阳性的菌株,其表型不一定就 耐药株,琼脂筛选法仍是检测的金标准。ＰＢＰ２ａ含量分析在一定程度上解决了表型与     

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。     

耐甲氧西林金黄色葡萄球菌的检测和分型方法研究进展

耐甲氧西林金黄色葡萄球菌 (Methcillin - resistantStaphylococcus aureus,MRSA )引起的院内感染 (nosocomialinfection)已经成为全世界一个越来越严重的问题。要想尽快获得 MRSA的相关信息从而采取适当的控制感染的措施 ,就必须依靠快速、可靠的检测和分型方法。由于 MRSA对甲氧西林耐药性的不断变化 ,故虽然目前存在检测和分型方法很多 ,但仍很难提供一种最优方法。在这里 ,我们对多种方法进行了比较 ,以便大家能从中选出既准确又省时且适合自己实验室使用的检测的分型方法。1　检测方法1.1　完整结构水平1.1.1琼脂平皿 2倍稀释法…     

mecA基因PCR扩增法检测耐甲氧西林金黄色葡萄球菌

目的 应用mecA基因PCR扩增法检测耐甲氧西林金黄色葡萄球菌（methicillin resistant staphylococcus aureus,MRSA）。方法 临床分离的70株金黄色葡萄球菌,应用mecA基因PCR扩增法鉴定MRSA,并与苯唑西林纸片扩散法进行比较。结果 70株金黄色葡萄球菌用PCR扩增法和纸片扩散法有6株鉴定有差异,4株。mecA基因阳性而纸片扩散法鉴定为敏感,1株mecA基因阳性纸片扩散法鉴定为临界耐药,1株mecA基因阴性却表现为苯唑西林耐药,2种方法符合率为91．43％。结论 mecA基因PCR扩增法可以准确、快速判定MRSA,特别是对隐匿型或低水平耐药菌株的检出有重要的价值。     

儿童耐甲氧西林金黄色葡萄球菌的分布特征及临床分析

目的通过分析住院患儿分离出的耐甲氧西林金黄色葡萄球菌(MRSA)菌株的分布情况及临床特点,了解MRSA感染的危险因素,为预防、控制MRSA的传播提供参考。方法分析临床分离出的445株MRSA,对其季节分布、年龄特点、科室分布及标本类型等进行分析。结果 MRSA的检出率为30.44%(445/1462),其中男287例(检出率64.49%),女158例(检出率35.51%),男性高于女性。从季节分布看:6月份最多,12月份最少;从科室分布看,呼吸科最多,其次为骨科、新生儿科、心内科感染MRSA患儿居多;从标本类型来看,痰液中MRSA检出率最高。结论患儿由于自身因素,年龄小、体内产生抗体的器官尚未发育完善,全身抵抗力差,较易感染。因此,医院应加强侵入性操作的无菌管理,避免不必要的侵入性操作,实行对导管插管等相关医院感染危险因素的预防与控制,缩短住院时间,及时隔离MRSA感染者,并做好监测。     

耐甲氧西林葡萄球菌的分布及耐药性分析

目的：了解我院临床分离的耐甲氧西林葡萄球菌（MRS）的分布及耐药性。方法：用Kirby-Bauer法对我院临床分离的394株MRS进行药敏试验并对其标本来源和病区分布进行分析。结果：471株葡萄球菌中MRS394株,占83.7%。各类标本中,检出MRS最多的是血液（40.36%),检出MRS最多的科室是ICU（23.35%）。MRS除对万古霉素和替考拉宁耐药率为0外,对其余8种抗生素的耐药率高达27.7%-84.7%。结论：本地区MRS的检出率高,血液标本和ICU病房检出MRS最多,MRS耐药形势严峻,值得高度重视。     

耐甲氧西林葡萄球菌感染的调查与分析

目的调查住院患者耐甲氧西林葡萄球菌(methicillin-resistant staphylococci,MRS)的感染情况,以便采取有效的防治措施。方法收集临床分离菌株,用mecA基因PCR扩增法鉴定MRS,并结合临床资料对本院MRS感染进行回顾性调查研究。结果住院患者标本中共收集到68株葡萄球菌,其中MRS 38株(阳性率为55.9%)。MRS感染主要多发于年龄>60岁,男性,合并多种疾病患者,科室分布以呼吸内科、泌尿外科及ICU病房为主。药敏结果显示MRS对万古霉素、利奈唑烷及喹努普汀的敏感率为100%,对替考拉宁敏感率为94.7%,对利福平的敏感率为57.9%,其余抗菌药物敏感率均<30%。结论及时了解本院患者MRS感染分布及耐药情况,有助于我们采取相应的监测及防治措施。     

耐甲氧西林葡萄球菌和肠球菌blaTEM及tetM基因检测

目的了解临床分离的耐甲氧西林葡萄球菌(MRS)和肠球菌中blaTEM及tetM基因存在状况。方法分离50株耐甲氧西林金黄色葡萄球菌(MRSA),7株耐甲氧西林表皮葡萄球菌(MRSE)、5株耐甲氧西林溶血葡萄球菌(MRSH)、15株粪肠球菌和9株屎肠球菌,采用PCR技术检测耐药基因。结果MRSA、MRSE、MRSH、粪肠球菌和屎肠球菌中blaTEM基因阳性率分别为40.0%、57.1%、60.0%、6.7%和88.9%,tetM基因阳性率分别为100%、0%、0%、66.7%、0%。结论blaTEM基因阳性率在MRS中较高,在屎肠球菌中则很高;携带tetM基因是MRSA和粪肠球菌对四环素耐药的主要原因。     

300 株鲍曼不动杆菌琼脂稀释法与纸片扩散法药敏检测结果比较

目的:比较琼脂稀释法和纸片扩散法对鲍曼不动杆菌的药敏试验结果。方法:随机挑选的300株鲍曼不动杆菌,检测其标本及科室的分布情况,并采用琼脂稀释法和纸片扩散法检测鲍曼不动杆菌对环丙沙星(CIP)、庆大霉素(CN)、阿米卡星(AK)、头孢他啶(CAZ)、头孢吡肟(FEP)、左氧氟沙星(LEV)、氨苄西林-舒巴坦(SAM)、妥布霉素(TOB)、美洛培南(MEN)、米诺环素(MH)、头孢哌酮-舒巴坦(SCF)11种抗菌药物的敏感性,比较两种检测结果的差异。结果:300株鲍曼不动杆菌主要分布在痰液标本中,共214株,占71.3%,主要来源于ICU 101株(33.7%)及脑外科59株(19.7%)。药敏检测结果显示,两种检测方法所得的SCF和MH的敏感性差异具有统计学意义(P0.05),其他9种抗菌药物的药敏检测结果差异没有统计学意义(P0.05)。结论:琼脂稀释法和纸片扩散法对鲍曼不动杆菌药敏试验结果并不完全一致,临床用药时尤其要注意SCF和MH这两种药物药敏结果的可靠性。     

热脉冲技术3种方法组合在测量树干液流中的应用

利用树干液流方法获取树木蒸腾特征对理解树木水分生理、森林生态和森林系统水分交换具有重要意义.利用广泛应用于土壤热参数和土壤蒸发测量的
三针热脉冲探头,基于热比率法(HRM)、最大温度法(T_Max)和单针热脉冲法(SHPP)同时实现了旱柳液流密度的测定,并与热扩散探针(TDP)测量结果进行对比分析.结果表明： 三针热脉冲探头安装约5周后进入稳定测量阶段,3种方法初期测量结果比稳定测量阶段高135%~220%,HRM、T_Max和SHPP法与TDP测量结果具有显著的线性相关性,R2分别为0.93、0.73和0.91,SHPP与HRM法测定结果的R²达到0.94.HRM在低速和逆向液流时测量具有较高的精度;SHPP探头配置简单、测量精度高,但无法甄别液流方向,是测定液流非常有前途的方法;T_Max测量液流误差较大,无法测量<5 cm³·cm^-2·h^-1的液流,不建议单独用于液流测量,但其能够准确测定树干热扩散系数,并可用于其他方法液流计算.建议根据试验目的,选取不同方法或者几种方法组合进行树干液流测量.     

Different chain length specificity among three polyphosphate quantification methods

Polyphosphate is ubiquitous among living organisms and has a variety of biochemical functions. Arbuscular mycorrhizal fungi have been known to accumulate polyphosphate as a key compound for their function. However, an enzymatic assay using polyphosphate kinase (PPK) reverse reaction, in which polyphosphate is converted to adenosine triphosphate (ATP) and quantified by luciferase assay, failed to detect accumulation of polyphosphate in some mycorrhizal root. When yeast exopolyphosphatase (PPX) was applied to these samples, a much higher polyphosphate level was detected than when the PPK assay was applied. Detailed analysis of substrate chain length specificity of these methods using polyphosphate chain length standards revealed that the PPX method was the most appropriate to detect short-chain polyphosphate. The average chain length of the shortest polyphosphate fraction that could be quantified with more than 50% efficiency was 3 for the PPX method and 38 for the PPK method. It was also suggested that the ratio of the PPK value to the PPX value may be useful as a simple and relative index to compare polyphosphate chain length distribution in different samples.     

Capillary electrophoresis coupled with end‐column electrochemiluminescence for the determination of ephedrine in human urine,and a study of its interactions with three proteins

A tris(2,2‐bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺)‐based electrochemiluminescence (ECL) detection coupled with capillary electrophoresis (CE) method has been established for the sensitive determination of ephedrine for the first time. Under the optimized conditions [ECL detection at 1.15 V, 25 mmol/L phosphate buffer solution (PBS), pH 8.0, as running buffer, separation voltage 12.5 kV, 5 mmol/L Ru(bpy)₃²⁺ with 60 mmol/L PBS, pH 8.5, in the detection cell] linear correlation (r = 0.9987) between ECL intensity and ephedrine concentration was obtained in the range 6.0 × 10^–8–6.0 × 10^–6 g/mL. The detection limit was 4.5 × 10^–9 g/mL (S:N = 3). The developed method was successfully applied to the analysis of ephedrine in human urine and the investigation of its interactions with three proteins, including bovine serum albumin (BSA), cytochrome C (Cyt‐C) and myoglobin (Mb). The number of binding sites and the binding constants between ephedrine and BSA, Cyt‐C and Mb were 8.52, 12.60, 10.66 and 1.55 × 10⁴ mol/L, 6.58 × 10³ mol/L and 1.59 × 10⁴ mol/L, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

Auxiliary Method for Clonal Identification of Staphylococcus aureus by Protein Band Pattern of Released Proteins on SDS-Polyacrylamide Gel

A supportive method for clonal identification of Staphylococcus aureus strains was devised. Culture supernatant obtained by cellophane surface culture was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) without performing any concentration procedure prior to electrophoresis. The combined use of cellophane surface culture and SDS-PAGE was convenient for determining whether the strains belonged to the same clone or not when conducted in conjunction with other tests for bacteriological characterization.     

Comparison of the Virulence of Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus

The virulence of methicillin-resistant Staphylococcus aureus (MRSA) was compared with that of methicillin-sensitive S. aureus (MSSA), using 13 MRSA and 7 MSSA strains isolated from clinical specimens. The infectivity and lethality of the two groups were examined as to the inoculum required to infect 50% of guinea pigs (ID₅₀) and to kill 50% of mice (LD₅₀), respectively. The mean ID₅₀ [log₁₀ colony forming units (CFU)] for MRSA strains was 7.1 ± 0.60 standard deviation, which was 1.5 higher than that for MSSA strains (P < 0.001). The mean LD₅₀ (log₁₀ CFU) for MRSA strains was 9.0 ± 0.42, being 1.1 higher than that for MSSA strains (P = 0.001). Pretreatment of mice with cyclophosphamide decreased the mean LD₅₀ for MRSA strains more than that for MSSA strains, resulting in the difference in the mean LD₅₀ being insignificant (P = 0.502). These results indicate that MRSA is less virulent than MSSA in normal hosts, but that they are equally virulent in immunocompromised hosts. The growth of MRSA strains was much slower than that of MSSA strains in the lag phase, although their growth rates were almost the same in the exponential growth phase, suggesting that the difference in virulence between them may be at least partly due to such a difference in growth.     

Evaluation of methods for total selenium determination in yeast

The selenium determination in biological materials by the classical fluorometric method (FM) is time-consuming and also hazardous, as it requires the destruction of the organic matrix samples with hot HNO₃/HClO₄ mixtures prior to analysis. Accordingly, commercial analytical laboratories are increasingly using faster instrumental methods; for sample digestion, avoid using HClO₄. Because of these procedural changes, the results obtained by commercial laboratories may be unreliable, especially for samples containing Se in organic forms. One such “difficult” substrate is Se yeast, which contains most of its Se as selenomethionine. To establish which methods for Se analysis and sample digestion are applicable, samples of Se yeast and of selenomethionine standards were sent to laboratories employing either flame atomic absorption spectrometry (FAAS), inductively coupled plasma-mass spectrometry (ICP-MS), or hydride generation atomic absorption spectrometry (HGAAS). The result were compared with those obtained by FM and non-destructive instrumental neutron activation analysis (INAA). ICP-MS, after microwave digestion of sample with HNO₃/H₂O₂, produced results within 5% of the expected values, as did those obtained by FM and INAA. With FAAS, acceptable results were obtained after digestion with HNO₃/HCl. With HGAAS, sample digestion with HNO₃/H₂O₂ produced values that were systematically elevated by about 10% and exhibited standard deviations of ≥10%. Thus, current methods of sample digestion are applicable for Se yeast analysis by ICP-MS and FAAS, but not by HGAAS.     

Ab initio prediction of optical rotation: comparison of density functional theory and Hartree-Fock methods for three 2,7,8-trioxabicyclo[3.2.1]octanes

We report ab initio calculations of the frequency-dependent electric dipole-magnetic dipole polarizabilities, beta(nu), at the sodium D line frequency and, thence, of the specific rotations, [alpha](D), of 2,7,8-trioxabicyclo[3.2.1]octane, 1, and its 1-methyl derivative, 2, using the Density Functional Theory (DFT) and Hartree-Fock/Self-Consistent Field (HF/SCF) methodologies. Gauge-invariant (including) atomic orbitals (GIAOs) are used to ensure origin-independent [alpha](D) values. Using large basis sets which include diffuse functions DFT [alpha](D) values are in good agreement with experimental values (175.8 degrees and 139.2 degrees for (1S,5R)-1 and -2, respectively); errors are in the range 25-35 degrees. HF/SCF [alpha](D) values, in contrast, are much less accurate; errors are in the range 75-95 degrees. The use of small basis sets which do not include diffuse functions substantially lowers the accuracy of predicted [alpha](D) values, as does the use of the static limit approximation: beta(nu) approximately beta(o). The use of magnetic-field-independent atomic orbitals, FIAOs, instead of GIAOs, leads to origin-dependent, and therefore nonphysical, [alpha](D) values. We also report DFT calculations of [alpha](D) for the 1-phenyl derivative of 1, 3. DFT calculations find two stable conformations, differing in the orientation of the phenyl group, of very similar energy, and separated by low barriers. Values of [alpha](D) predicted using two different algorithms for averaging over phenyl group orientations are in good agreement with experiment. In principle, the absolute configuration (AC) of a chiral molecule can be assigned by comparison of the optical rotation predicted ab initio to the experimental value. Our results demonstrate the critical importance of the choice of ab initio methodology in obtaining reliable optical rotations and, hence, ACs, and show that, at the present time, DFT constitutes the method of choice.     

A newly developed assay for the quantitative determination of antimicrobial (anticyanobacterial) activity of both hydrophilic and lipophilic test compounds without any restriction

This paper reports about a newly developed assay which enables the user to quantify and compare the antimicrobial (anticyanobacterial) activity of both hydrophilic and lipophilic test compounds without any restriction. The assay is characterised by the application of a test compound solution on a porous matrix (silica gel) in well-defined concentrations per unit area, and by the coating of this matrix by a concentrated suspension of the tested living cyanobacterium (using a spraying or a dipping technique). The organism was only applied after the complete evaporation of the solvent used for preparation of the test compound solution to avert potential influences of this solvent on micro-organisms' viability. Toxic concentrations of a test compound caused a clearly contoured regional damage in the blue-green coloured uniform layer of the cyanobacterial test organism. The resulting regional decolourisation was readily identifiable within a species-dependent short time (e.g. for the species Arthrospira laxissima after 24h). This newly developed assay is applied for a patent in Germany.