黄芩水提物对耐甲氧西林的金黄色葡萄球菌体外抑菌作用及成分研究

目的 探讨黄芩水提物治疗耐甲氧西林金黄色葡萄球菌(MRSA)的实验室抑菌作用及有效成分.方法 采用微量半固体琼脂稀释法检测黄芩水提物对119株MRSA的MIC值,同时采用高效液相色谱检测黄芩水提物中黄芩苷含量,制备相同含量的黄芩苷碱溶液并经高效液相色谱验证其黄芩苷含量.比较黄芩水提物及黄芩苷碱溶液对28株MRSA的黄芩苷MIC值差异.结果 黄芩水提物对119例MRSA的MIC90值为7.81 mg/ml,MIC50值为1.95 mg/ml;比较黄芩苷含量相同的黄芩水提物及黄芩苷碱溶液对28株MRSA的黄芩苷MIC值差异,黄芩水提物优于黄芩苷,具有统计学意义(P<0.05).结论 黄芩水提物对MRSA菌有抑菌作用,黄芩苷不是黄芩水提物抑制MRSA的主要有效成分.     

耐甲氧西林金黄色葡萄球菌耐药性观察

随着介入治疗手段的广泛应用,以及免疫抑制剂,超广谱、广谱药物的大量使用等诸多因素,使金黄色葡萄球菌成为医院感染的主要病原菌之一,临床上尤其以耐甲氧西林的金黄色葡萄球菌（MRSA）为多见。MRSA除对甲氧西林耐药外,还对其他抗生素呈多重耐药,所以感染后治疗不仅难度大,而且病死率高,准确分离MRSA合理选用抗生素及控制其感染是一系列急需解决的问题,其中首要任务是对MRSA的严密监测,为此我们从临床各类标本中分离出金黄色葡萄球菌（SA）进行实验研究。1材料与方法1．1菌株来源60株SA全部来自山西医大二院1998年8月初一…     

耐甲氧西林金黄色葡萄球菌对消毒剂抗性的观察

目的了解临床分离的耐甲氧西林金黄色葡萄球菌对消毒剂的抗力水平,以指导医院消毒。方法采用悬液定量杀菌试验方法进行检测,同时与金黄色葡萄球菌标准株作平行比较。结果20株MRSA对戊二醛、碘伏、乙醇等三种常用消毒剂的抗性率分别为15%、15%、5%,对上述三种消毒剂中一种以上具有抗性的抗性率为25%,多重抗性率为10%。结论MRSA存在抗消毒剂菌株,提示在医院消毒工作中要合理使用消毒剂,防止MRSA感染的传播和流行。     

耐甲氧西林金黄色葡萄球菌性肺炎40例临床观察

目的:探讨耐甲氧西林金黄色葡萄球菌性肺炎的临床特点及治疗方法.方法:回顾性分析耐甲氧西林金黄色葡萄球菌性肺炎患者40例的临床资料.结果:治愈33例(82.5%).死亡7例(17.5%),其中2例死于大咯血,2例死于感染性休克,3例死于多脏嚣功能衰竭.结论:早期,足量选用糖肽类抗生素,加强免疫及营养支持治疗,可明显提高耐甲氧西林金黄色葡萄球菌性肺炎患者的生存率.     

耐甲氧西林金黄色葡萄球菌的实验研究

目的 探讨耐甲氧西林金黄色葡萄球菌抗生素药敏试验的情况.方法 药敏试验采用纸片扩散法.结果63株金黄色葡萄球菌中,耐甲氧西林金黄色葡萄球菌(MRSA)有33株,占52.4%,并呈多重耐药,对青霉素、红霉素、庆大霉素、氯林可霉素和四环素均100%耐药,对利福平、左旋沙星表现为较高耐药率;甲氧西林敏感金黄色葡萄球菌(MSSA),对青霉素、红霉素和庆大霉素的耐药率均在80%以上.MRSA和MSSA对万古霉素和替考拉宁耐药率为0.结论 耐甲氧西林金黄色葡萄球菌对抗生素表现为多重耐药,临床应注意合理使用抗生素.     

耐甲氧西林金黄色葡萄球菌对消毒剂抗性研究进展

<正>目前耐甲氧西林金黄色葡萄球菌(MRSA)已成为医院内感染的重要病原菌,临床分离率逐年攀升,多重耐药菌已经引起医务工作者的高度重视。医疗机构为控制各种细菌感染、切断传播途径,采用各种消毒与灭菌手段,其中包括使用了大量化学消毒剂。     

耐甲氧西林金黄色葡萄球菌感染研究进展

<正>耐甲氧西林金黄色葡萄球菌(MRSA)是造成住院患者医院感染发生及高病死率的主要病原体之一[1-2],由于MRSA具有致病性强、传播途径广的特点,加上抗菌药物的长期使用和滥用,MRSA的耐药范围日益扩大,耐药程度日益严重,给临床治疗带来巨大的困难,也有人将其称为"超级细菌"。MRSA感染同乙型肝炎、艾滋病(AIDS)成为世界三大感染性疾病。     

耐甲氧西林金黄色葡萄球菌院内感染研究进展

院内感染一直是困扰医院的一大难题,尤其是在耐甲氧西林金黄色葡萄球菌(methicillin resistant staphylococcus aureus,MRSA)出现之后,院内感染问题就显得相当棘手。这主要是由于MRSA感染的发病率和致死率都较高,而且传染性强,最易     

耐甲氧西林金黄色葡萄球菌临床耐药性分析

目的 为预防和控制医院感染的发生,对耐甲氧西林金黄色葡萄球菌的临床分布和耐药性进行分析.方法 使用ATB细菌鉴定分析仪进行细菌鉴定,用纸片扩散法鉴定耐甲氧西林金黄色葡萄球菌,药敏试验用K-B法.结果 在各临床科室中,由耐甲氧西林金黄色葡萄球菌引起的医院感染,ICU的比例最高,下呼吸道是最常见的感染部位,52株耐甲氧西林金黄色葡萄球菌对多种抗菌药物耐药,没有发现耐万古霉素菌株.结论 由耐甲氧西林金黄色葡萄球菌引起的医院感染以ICU病人最多见,以下呼吸道感染为主,耐甲氧西林金黄色葡萄球菌除对万古霉素敏感外对多种抗菌药物耐药.因此,临床医生要合理使用抗菌药物.     

耐甲氧西林金黄色葡萄球菌对万古霉素敏感性的研究

目的探讨耐甲氧西林金黄色葡萄球菌(MRSA)对万古霉素的敏感性。方法取2007—2014年医院分离的MRSA102株,采用琼脂稀释法检测万古霉素对MRSA的最低抑菌浓度(MIC),采用PCR方法进行SCCmec分型及相关基因检测。结果 2007—2014年万古霉素对MRSA的MIC_(90)分别为1、1、2、2、2、2、2、2 mg/L,MIC_(50)分别为1、1、1、2、1、1、1、1 mg/L。SCCmecⅡ型的MIC_(50)和MIC_(90)都为2 mg/L,SCCmecⅢ型的MIC_(50)和MIC_(90)分别为1 mg/L和2 mg/L,SCCmec V型和Ⅳ型的MIC_(50)和MIC_(90)都为1 mg/L。结论 2007—2014年万古霉素对MRSA的最低抑菌浓度无显著变化,SCCmecⅡ型和Ⅲ型MRSA对万古霉素的敏感性低于SCCmec V型和Ⅳ型菌株。     

耐甲氧西林金黄色葡萄球菌的SPA基因分型研究与耐药性分析

目的 探讨鄂尔多斯地区耐甲氧西林金黄色葡萄球菌(MRSA)分离株杀白细胞毒素(PVL)基因分布特点及药物敏感性。方法 收集2012年6月～2014年12月临床分离的SCCmecⅡ型和Ⅲ型MRSA菌株66株,应用聚合酶链反应对菌株进行PVL基因型检测,用琼脂稀释法测定PVL阳性菌株对常用抗菌药物的敏感性。结果 66例MRSA有6例PVL阳性,阳性率9.09%,其中Ⅱ型4株,Ⅲ型2株; 6株PVL阳性菌均对万古霉素、替考拉宁、利奈唑胺和对多种非β内酞胺类抗菌药敏感,对β内酞胺类、大环内酯类和克林霉素高度耐药。结论 在鄂尔多斯地区MRSA菌株中PVL阳性菌株较低,4株为CA-MRSA,2株为HA-MRSA,若以PVL阳性作为区分MRSA类型的标志有待进一步研究。     

红霉素体外诱导金黄色葡萄球菌耐药分析

目的 体外诱导金黄色葡萄球菌标准株ATCC25923对红霉素耐药,分析其耐药后菌株生长及对其它药物敏感性变化。方法 用红霉素浓度2倍递增的方法对金黄色葡萄球菌ATCC25923进行体外诱导,比较诱导前后金黄色葡萄球菌的生长表型以及对其它抗菌药物的耐药性变化。结果 诱导后ATCC25923红霉素MIC由0.032 5 mg/L增加到>256 mg/L,诱导耐药后金黄色葡萄球菌出现生长缓慢,溶血性减弱等变异,对其它非诱导抗菌药物耐药性未发生变化。结论经红霉素体外诱导后金黄色葡萄球菌可以获得稳定耐药性,但同时也产生了表型及部分生化特性变化,与其它非诱导抗菌药物无交叉耐药。     

Methicillin Potentiates the Effect of Gentamicin on Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) strains show an unusual type of resistance at 37 degrees C; only a small subpopulation of cells is resistant to the beta-lactam antibiotics. Incubation in the presence of methicillin (MET), however, results in the emergence of a homogenous population highly resistant to MET. The purpose of the present study was to determine whether MET, despite its lack of killing effect on MRSA, would promote the bactericidal effect of gentamicin (GM), as demonstrated for MET-susceptible strains of S. aureus. Eleven epidemiologically distinct strains of MRSA were incubated with MET at various concentrations, in the presence or absence of sub-bactericidal concentrations (1/5 or 1/10 of the minimal bactericidal concentration) of GM, and tested for the synergistic action of both antibiotics by three different methods. Population analysis of the 11 strains in the presence of high concentrations of MET showed that the addition of GM at 1/5 or 1/10 of its minimal bactericidal concentration resulted in marked killing of the 11 strains. Time-kill curves obtained with 32 mug of MET per ml and GM at 1/5 or 1/10 of its minimal bactericidal concentration confirmed this synergistic killing at 24 h. These results were further documented by the checkerboard method on two strains. We conclude that the synergism between MET and GM, previously demonstrated for MET-susceptible S. aureus, holds true for MRSA as well and that it can be demonstrated at sub-bactericidal concentrations of GM.     

白藜芦醇对葡萄球菌标准株抑菌作用研究

目的 探讨白藜芦醇(resveratrol,简称RES)对金黄色葡萄球菌抑菌作用。方法 以金黄色葡萄球菌标准株ATCC 25923(金葡菌标准株)作为研究主体检测RES对其的最低抑菌浓度(MIC),绘制不同浓度RES作用下金黄色葡萄球菌的生长曲线。结果 RES对金黄色葡萄球菌标准株MIC为0.256 mg/ml; 在RES浓度为1/4 MIC和1/2 MIC时,生长明显受抑,生长曲线不典型,对数生长期比正常对照组减缓; RES浓度为1MIC和2MIC时金黄色葡萄球菌完全受抑制,生长曲线完全失去正常生长状态,趋于平缓。结论 RES对金黄色葡萄球菌标准株抑制作用明显。     

Observed Antagonistic Effect of Linezolid on Daptomycin or Vancomycin Activity against Biofilm-Forming Methicillin-Resistant Staphylococcus aureus in an In Vitro Pharmacodynamic Model

Pharmacodynamic activity in antibiotic combinations of daptomycin, vancomycin, and linezolid was investigated in a 48-h in vitro pharmacodynamic model. Using human-simulated free drug concentrations, activity against clinical biofilm-forming methicillin-resistant Staphylococcus aureus isolates was evaluated. Linezolid antagonized vancomycin activity at 24 and 48 h. Linezolid antagonized daptomycin at 24 and 48 h depending on dose and strain. Adding daptomycin increased vancomycin activity at 48 h (P < 0.03). These results may be strain dependent and require further clinical investigation.     

Pharmacokinetic-Pharmacodynamic Modeling of the In Vitro Activities of Oxazolidinone Antimicrobial Agents against Methicillin-Resistant Staphylococcus aureus

Linezolid is the first FDA-approved oxazolidinone with activity against clinically important gram-positive pathogens, including methicillin (meticillin)-resistant Staphylococcus aureus (MRSA). RWJ-416457 is a new oxazolidinone with an antimicrobial spectrum similar to that of linezolid. The goal of the present study was to develop a general pharmacokinetic (PK)-pharmacodynamic (PD) model that allows the characterization and comparison of the in vitro activities of oxazolidinones, determined in time-kill curve experiments, against MRSA. The in vitro activities of RWJ-416457 and the first-in-class representative, linezolid, against MRSA OC2878 were determined in static and dynamic time-kill curve experiments over a wide range of concentrations: 0.125 to 8 μg/ml (MIC, 0.5 μg/ml) and 0.25 to 16 μg/ml (MIC, 1 μg/ml), respectively. After correction for drug degradation during the time-kill curve experiments, a two-subpopulation model was simultaneously fitted to all data in the NONMEM VI program. The robustness of the model and the precision of the parameter estimates were evaluated by internal model validation by nonparametric bootstrap analysis. A two-subpopulation model, consisting of a self-replicating, oxazolidinone-susceptible and a persistent, oxazolidinone-insusceptible pool of bacteria was appropriate for the characterization of the time-kill curve data. The PK-PD model identified was capable of accounting for saturation in growth, delays in the onsets of growth and drug-induced killing, as well as naturally occurring bacterial death. The simultaneous fit of the proposed indirect-response, maximum-effect model to the data resulted in concentrations that produced a half-maximum killing effect that were significantly (P < 0.05) lower for RWJ-416457 (0.41 μg/ml) than for linezolid (1.39 μg/ml). In combination with the appropriate PK data, the susceptibility-based two-subpopulation model identified may provide valuable guidance for the selection of oxazolidinone doses or dose regimens for use in clinical studies.Gram-positive pathogens are major causes of a wide range of infections, including skin and skin structure infections and life-threatening infections such as bacteremia, endocarditis, and pneumonia (18, 24). The treatment of these infections has become increasingly challenging due to the rapid development of resistance to the first-choice antibiotics. In many cases, only a few agents, such as vancomycin, retain activity against these multiresistant strains, despite its increased utilization. However, with the appearance of vancomycin-resistant strains, for example, vancomycin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, the once powerful antibiotic arsenal is becoming increasingly ineffective (3, 12). Therefore, it is critically important to develop new potent antibiotics or antibiotic classes that may successfully treat these infections.In 2000, the FDA approved the use of linezolid, the first representative of a novel class of antibiotics, the oxazolidinones. At the time of approval, linezolid was one of the few agents that showed activity against vancomycin-resistant strains (2, 5). However, resistance to linezolid was reported as early as 2002 (10, 32). In addition, toxic side effects such as reversible thrombocytopenia, neutropenia, and, rarely, neuropathy have occurred during prolonged use (4, 13, 16, 28). Due to these limitations, there is a definite opportunity to develop new oxazolidinones with optimized exposure-response relationships. RWJ-416457 is a new investigational oxazolidinone that is being developed as both an oral and an intravenous formulation for the treatment of infections caused by clinically important gram-positive bacteria. RWJ-416457 has a MIC that is frequently two- to fourfold lower than that of linezolid against multidrug-resistant gram-positive pathogenic bacteria, including methicillin (meticillin)-resistant S. aureus (MRSA), vancomycin-intermediate susceptible S. aureus, vancomycin-resistant S. aureus, vancomycin-resistant enterococci, and penicillin-resistant streptococci (8, 17). Although the MIC is routinely determined in clinical settings and has contributed much to the understanding of antibiotic dosing, it does not provide any information on the time course of bacterial growth or antibiotic-induced killing (21, 27). More detailed information can be obtained from the evaluation of growth and kill profiles over time (time-kill curves). A major strength of the time-kill curve approach is its capability of simulating the effect of changing concentrations on the antimicrobial outcome. Changing concentration time-kill curves can, subsequently, be used to evaluate the efficacies of antibiotics with different half-lives (t_1/2s). Once these experiments have been performed, a mathematical model can be simultaneously fitted to the data and the respective pharmacodynamic (PD) parameters can be calculated. These PD parameters can then be linked to in vivo pharmacokinetic (PK) information for prediction of the clinical outcome.The aims of this study were (i) to establish a general mathematical model that is appropriate for characterizing the in vitro PDs of oxazolidinones determined in static as well as dynamic time-kill curve experiments and (ii) to apply this model in order to compare the in vitro potencies of the investigational oxazolidinone RWJ-416457 and the first-in-class representative linezolid.     

Temperature Effect on the Susceptibility of Methicillin-Resistant Staphylococcus aureus to Four Different Cephalosporins

Forty isolates of methicillin-resistant Staphylococcus aureus were tested for in vitro susceptibility to cephalothin, cefamandole, cefotaxime, and moxalactam, using the disk diffusion and microbroth dilution methods at incubation temperatures of 30 and 35°C. Resistance to all four antibiotics was more clearly evident at an incubation temperature of 30°C.