MRSA表面标志物PBP2a的检出与苯唑西林MIC的相关性分析

目的研究MRSA表面标志物PBP2a与苯唑西林MIC的相关性。方法收集62株金黄色葡萄球菌临床分离株,通过乳胶凝集试验和全自动细菌分析仪分别检测青霉素结合蛋白2a(PBP2a)和苯唑西林MIC值。结果62株金葡中32株PBP2a检测阳性,30株PBP2a检测阴性。苯唑西林MIC≥4μg/ml31株,苯唑西林MIC≤2μg/ml31株。在苯唑西林MIC≥4μg/ml的31株MRSA中30株PBP2a检测均为阳性。结论金黄色葡萄球菌耐苯唑西林的耐药水平与PBA2a的检出有较好的相关性。     

耐甲氧西林金黄色葡萄球菌的苯唑西林、头孢西丁最低抑菌浓度与青霉素结合蛋白2a的相关性

为分析金黄色葡萄球菌(S·aureus,SA)的青霉素结合蛋白2a(PBP2a)的产生与头孢西丁、苯唑西林最低抑菌浓度(MIC)相关性,收集102株临床分离株,采用MIC法分别检测SA对头孢西丁、苯唑西林的耐药性,并与耐甲氧西林SA(MRSA)胶乳凝集法对比分析。结果表明,头孢西丁MIC≥32μg/ml71例(69·6%),其中乳胶凝集试验阳性70例(98·6%);苯唑西林MIC≥4μg/ml80例(78·4%),乳胶凝集试验阳性70例(87·5%)。头孢西丁阳性的PBP2a检出率明显高于苯唑西林(98·6%比87·5%,P<0·05)。结论:头孢西丁MIC≥32μg/ml或产生PBP2a的SA均能正确地表达为MRSA;苯唑西林MIC≥4μg/ml解释标准对SA评价MRSA正确性较低。     

黄芩素对耐甲氧西林金黄色葡萄球菌的体外抗菌活性研究

目的:了解黄芩素对耐甲氧西林金黄色葡萄球菌(MRSA)的体外抗菌活性。方法:用美国临床实验室标准化委员会(CLSI/NCCLS)介绍的方法,检测黄芩素和万古霉素对117株临床分离的MRSA的体外抗菌活性。结果:黄芩素对MRSA的MIC_(50)、MIC_(90)和MBC分别为32.0、96.0和168.0μg/mL。结论:黄芩素为一种对MRSA敏感的抗菌药物,可用于临床治疗由MRSA感染引起的多种疾病。     

耐甲氧西林金黄色葡萄球菌检测方法的比较

目的 对耐甲氧西林金黄色葡萄球菌(MRSA)的检测方法进行比较.方法 分别用mecA基因PCR扩增法、PBP2a胶乳凝集试验法、头孢西丁纸片扩散法和苯唑西林纸片扩散法对临床分离的135株金黄色葡萄球菌进行榆测.结果 mecA基因PCR扩增法显示阳性79株,阴性56株;PBP2a胶乳凝集试验法的敏感性和特异性分别为96.2%和100.0%;头孢西丁纸片扩散法的敏感性和特异性分别为94.9%和96.4%;苯唑西林纸片扩散法的敏感性和特异性分别为94.9%和62.5%.结论 PBP2a胶乳凝集试验法和头抱西丁纸片扩散法与mecA基因PCR扩增法的检测结果高度一致;苯唑西林纸片扩散法特异性低,不再适用于MRSA的检测.     

黄芩和黄柏对耐甲氧西林金葡萄球菌的疗效对比观察

目的了解黄芩和黄柏对耐甲氧西林金黄色葡萄球菌(MRSA)的体外抗菌活性。方法用琼脂扩散法和琼脂稀释法,检测黄芩和黄柏对100株MRSA的体外抗菌活性。结果黄芩对MRSA的MIC50、MIC90分别为0.84、6.7mg。黄柏对MRSA的MIC50、MIC90分别1.48、11.8mg。结论与黄柏相比较,黄芩更适合作为MRSA敏感的抗菌药物用于临床治疗。     

绿茶及其提取物抗耐甲氧西林金黄色葡萄球菌作用研究

目的 研究绿茶及提取物对耐甲氧西林金黄色葡萄球菌(MRSA)的抗菌作用并分析其主要抗菌成分.方法 采用琼脂稀释法测定各种茶叶的水浸出物及茶叶的主要成分对MRSA的MIC.纸片扩散法观察绿茶浸出物和茶叶主要成份与抗生素合用对MRSA的协同抗菌情况.结果 ①绿茶浸出物对MRSA的MIC范围为0.125-0.5%,青茶浸出物为0.125-0.5%,白茶浸出物为0.0625-0.25%,红茶浸出物为0.5%,黑茶浸出物为0.25-0.5%.②茶多酚对MRSA的MIC范围为128-256μg/mL,茶色素为256-512μg/mL,茶多糖为512-1024μg/mL,茶皂素和咖啡因则均大于1024μg/mL.③青霉素、苯唑西林、氨苄西林、头孢他啶、头孢替唑、米诺环素、四环素与绿茶浸出物合用的抑菌圈明显大于单用抗生素的抑菌圈,红霉素和氯霉素单用/合用的抑菌圈相同,环丙沙星加入绿茶浸出物后抑菌圈反而减小.④茶多糖、茶皂素、茶色素、咖啡因与苯唑西林单用/合用的抑菌圈均相同,茶多酚与苯唑西林合用的抑菌圈明显大于单用苯唑西林的抑菌圈,表儿茶素没食子酸酯(ECg)/表没食子儿茶素没食子酸酯(EGCg)与苯唑西林合用的抑菌圈明显大于各自单用的抑菌圈.结论 各种茶叶对MRSA均有一定的抗菌作用,其中绿茶和白茶的抗菌作用最强.绿茶抗MRSA的主要成分为茶多酚,并且茶多酚对β-内酰胺类抗生素和四环素抗MRSA有增效作用,但对其它类抗生素呈无关或拮抗作用.茶多酚中的2个单体ECg和EGCg能增强苯唑西林的抗MRSA作用.     

黄芩苷协调大黄素 薄荷醇对胃癌SGC-7901细胞增殖抑制作用的研究

目的探讨黄芩苷协同大黄素、薄荷醇对人胃癌SGC-7901细胞增殖的抑制作用。方法采用四甲基偶氮唑盐(MTT)法测定黄芩苷、大黄素、薄荷醇及其联合用药在处理SGC-7901细胞24 h后的生长抑制率。结果不同浓度(20、40、80、160、320μmol/L)的黄芩苷均可显著抑制胃癌细胞SGC-7901增殖,在浓度为320μmol/L时抑制率最高。黄芩苷、大黄素、薄荷醇对SGC-7901细胞的半数抑制浓度(IC_(50))分别为179.30、148.38、323.23μmol/L。结论黄芩苷对胃癌细胞增殖有显著的抑制作用。黄芩苷与大黄素联合用药后对胃癌细胞增值抑制率大于黄芩苷和薄荷醇联合用药作用后的抑制率。     

黄芩苷、黄芩素抑制铜绿假单胞菌生物膜形成的研究

目的:研究黄芩苷、黄芩素对铜绿假单胞菌生物膜形成的影响。方法:选用铜绿假单胞菌X140为研究对象,用32μg·mL-1的黄芩苷、2μg·mL-1的黄芩素干预X140生物膜的培养。以阿奇霉素为对照,采用倍比稀释法对生物膜内活菌菌落计数。扫描电子显微镜(SEM)观察不同培养条件下生物膜的变化。结果:32μg·mL-1的黄芩苷、2μg·mL-1的黄芩素可以显著抑制铜绿假单胞菌的黏附性和抑制生物膜的形成(P<0.01)。结论:黄芩苷、黄芩素可抑制细菌生物膜的形成,影响铜绿假单胞菌的黏附性。     

黄芩素与黄芩苷的体外抗骨肉瘤作用的比较

目的 探讨黄芩素与黄芩苷对骨肉瘤细胞系U2OS和U2OS/MTX300生长抑制和诱导凋亡的作用,并比较两者间的差别.方法 应用MTT比色法,测定黄芩素与黄芩苷对u2OS和U2OS/MTX300细胞株增殖的影响,检测其抑制骨肉瘤细胞的时间、剂量效应;应用形态学观察,测定黄芩素对U2OS和U2OS/MTX300细胞的凋亡作...     

黄芩素的药理学研究进展

黄芩素(黄芩苷元,BaicaleinBAI)是从唇形科植物黄芩的干燥根中提取的有效成份之一,具有多种药理作用,如:抗菌、抗病毒、抗炎、抗变态反应、抗氧化、清除氧自由基、抗癌、抗肿瘤、抗凝、抗血栓形成和保护肝脏、心脑血管、神经元等作用。目前临床主要用于抗炎和抗菌。现概述国内外对黄芩素的药理作用及可能的作用机制的研究进展,为黄芩素的开发和更广泛地应用于临床提供依据。1抗菌、抗病毒黄芩抗菌范围较广,体外试验证明,其煎剂对多种革兰氏阳性菌、革兰氏阴性菌及螺旋体等均有抑制作用。BAI对尖孢镰刀菌和白色念珠菌有抑制作用,最小抑制…     

Modulation of beta-lactam resistance in Staphylococcus aureus by catechins and gallates

Aqueous extracts of Japanese green tea (Camellia sinensis) are able to reverse beta-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA). We have attributed the capacity to reverse oxacillin resistance in the homogeneous PBP2a producer BB568 and in EMRSA-16 to (-)-epicatechin gallate (ECG) and (-)-catechin gallate (CG). Minimum inhibitory concentration (MIC) values for oxacillin were reduced from 256 and 512 to 1-4 mg/l, respectively, in the presence of these polyphenols. In addition, (-)-epigallocatechin gallate (EGCG) had a moderate capacity to modulate oxacillin activity against S. aureus BB568, but none against EMRSA-16. ECG, CG and EGCG increased the sensitivity of EMRSA-15 to oxacillin. The gallate moiety was essential for the oxacillin-modulating activity of ECG, as both (-)-epicatechin and (-)-epicatechin-3-cyclohexylcarboxylate were unable to reverse resistance to oxacillin. Gallic acid and three alkyl gallates (methyl gallate, propyl gallate, and octyl gallate) did not modulate beta-lactam resistance in MRSA. Octyl gallate exhibited direct antibacterial activity against S. aureus BB568 (16 mg/l). Modulation of beta-lactam resistance by ECG significantly enhanced the activities of flucloxacillin and the carbapenem antibiotics imipenem and meropenem against 40 MRSA isolates, with MIC(90) values for the antibiotics reduced to the susceptibility breakpoint or below. Consequently, EGCG, CG and, particularly, ECG warrant further investigation as agents to combat beta-lactam resistance in S. aureus.     

Methicillin-resistant Staphylococcus aureus in the hospitals of central Greece.

A total of 250 consecutive Staphylococcus aureus clinical isolates were collected during the period 1999-2000 from the five major hospitals of the district of Thessaly (Central Greece). Thirty seven (14.8%) of the isolates were mecA-positive (MRSA) in a PCR-based assay; all exhibited resistance to oxacillin (agar dilution MICs > or =4 mg/L) and were also resistant to multiple antibiotics. Most of the MRSA isolates had been collected in the intensive care units and the surgical wards of the participating hospitals in a sporadic fashion. The MRSA incidence found here was significantly lower than reported in previous studies from Greece. Molecular typing by PFGE showed that the MRSA isolates were distributed between three pulsotypes. Evaluation of various conventional methods for assessing methicillin resistance showed that oxacillin agar dilution and immunological detection of PBP2a with the Slidex MRSA Detection kit were the most reliable in this setting. Misclassifications of isolates exhibiting low-level resistance (oxacillin MIC 2-4 mg/L) occurred with the salt agar screen, the oxacillin disk diffusion and the ATB Staph System methods.     

Artesunate in combination with oxacillin protect sepsis model mice challenged with lethal live methicillin-resistant Staphylococcus aureus (MRSA) via its inhibition on proinflammatory cytokines release and enhancement on antibacterial activity of oxacillin

Sepsis induced by methicillin-resistant Staphylococcus aureus (MRSA) has worse outcome because of multiresistance to a large group of antibiotics, which may lead to death from septic shock. In the present study, we firstly found that artesunate in combination with oxacillin was capable of protecting mice challenged with live MRSA WHO-2 (WHO-2) and the protection was related to the reduced TNF-α and IL-6 levels and decreased bacterial load. Based on above results, artesunate was further investigated from two aspects in vitro, anti-inflammation effect and antibacterial enhancement effect on antibiotics. Artesunate not only inhibited TNF-α and IL-6 release but also inhibited mRNA and protein expressions of TLR2 and Nod2, two important receptors, in murine peritoneal macrophages stimulated with heat-killed WHO-2, further demonstrating anti-inflammatory effect of artesunate was related to the inhibition of TLR2- and Nod2-mediated proinflammatory cytokines. Significantly, artesunate enhanced antibacterial activity of oxacillin and ampicillin not levofloxacin against WHO-2 and a clinical MRSA strain; the fractional inhibitory concentration indexes were lower than 0.5. Further, artesunate possessed moderate affinity for penicillin-binding protein 2a (PBP2a) and reduced the mecA mRNA expression up-regulated by oxacillin, suggesting that artesunate's enhancement on antibacterial activity of β-lactams was related to the inhibition of PBP2a and down-regulation of mecA mRNA expression. In conclusion, our results demonstrated that artesunate in combination with oxacillin protected mice challenged with lethal live MRSA via its inhibition on proinflammatory cytokines release and enhancement on antibacterial activity of oxacillin. Artesunate could be further investigated as a candidate drug for MRSA sepsis.     

Polyoxotungstates reduce the beta-lactam resistance of methicillin-resistant Staphylococcus aureus

Bacterial strains isolated from clinical specimens have become more and more resistant to many anti-microbials. This is because we have consumed large amounts of strong antimicrobials over long periods of time and thus bacterial cells are able to survive by altering the target(s) of antimicrobial agents. A good example of this phenomenon is methicillin-resistant Staphylococcus aureus (MRSA). One of the cell wall-synthesizing enzymes (known as PBP2') of this pathogen has low affinity to beta-lactams, and therefore the bacterial cells continue to grow even under high concentrations of the agents. However, this drug resistance does not seem to be total. They seem to have some weak spots and several substances are known to sensitize strains of MRSA to beta-lactams. This review discusses the ability of polyoxotungstates (POTs) to sensitize MRSA to beta-lactams by reducing the expression of PBP2'. It is also possible that the sensitization is a type of stress response of MRSA to POTs. This idea may provide a hint for the development of a new antimicrobial agent.     

新建医院金黄色葡萄球菌感染分布与耐药性分析

目的:探讨金黄色葡萄球菌感染分布及耐药特征,指导临床合理用药。方法:应用西门子公司MicroScan-40SI全自动细菌鉴定/药敏分析系统、K-B法药敏试验(美国BD)、β-内酰胺酶测试(OXOID),并以"WHONET5.3"软件对数据进行分析处理。结果:三年共检出病原菌2901株,金黄色葡萄球菌277株占(9.5%),其中产β-内酰胺酶86株,占31.0%,MRSA占SA感染标本总数的32.6%,MRSA耐药率介于2.4%-91.0%。本室三年来未检出耐万古霉素、替考拉宁、奎奴普丁/达福普汀、利奈唑胺菌株;耐药率低的抗生素有利福平、哌拉西林/他唑巴坦、阿莫西林/克拉维酸、复方磺胺甲口恶唑、头孢唑啉;耐药率高的有青霉素、氨苄西林、苯唑西林、红霉素等。结论:本组对新建民营医院三年金黄色葡萄球菌感染菌株的分布与耐药性进行统计分析,产β-内酰胺酶菌株比例较其他报告53.3%为低,头孢唑啉药物敏感性较稳定,但对其它β一内酰胺类抗菌药物耐药性高,并对β一内酰胺酶抑制剂耐药性出现逐年上升趋势,应引起关注。     

355株金黄色葡萄球菌药敏试验结果分析

目的：探讨金黄色葡萄球菌（S-aureus）对抗菌药物的敏感性,为临床应用抗生素提供科学依据。方法：按《全国临床检验操作规程》对S—aureus进行培养分离鉴定,采用纸片扩散法进行药敏试验,参照美国国家临床实验室标准化委员会标准（NCCLS）读取结果。结果：8年来从各类临床标本中分离出355株S—aureus,其中耐甲氧西林金黄色葡萄球菌（MRSA）为140株。金黄色葡萄球菌对万古霉素、利福平、头孢哌酮、丁胺卡那霉素、头孢唑啉、庆大霉素、环丙沙星、氟哌酸、氨苄西林、青霉素G、苯唑西林的敏感率分别为100．0％、97．8％、76．1％、76．1％、69．9％、60．3％、60．1％、54．7％、3．9％、2．1％、0．9％。结论：MRSA感染呈上升趋势,青霉素类已不能成为治疗S—aureus感染的一线药物,万古霉素、利福平可作为治疗S—aureus感染的首选药物。     

Thioridazine reduces resistance of methicillin-resistant staphylococcus aureus by inhibiting a reserpine-sensitive efflux pump

Previous studies suggested that the phenothiazine chlorpromazine (CPZ) could reverse or reduce the antibiotic resistance of bacteria. In some areas of the world, the majority of Staphylococcus aureus isolates are now resistant to methicillin, prompting this study to see whether such resistance can be altered by phenothiazine thioridazine (TZ), an agent with equal antibacterial activity, which is free of the severe side-effects associated with chronic administration of CPZ. The results indicated that, whereas methicillin-sensitive strains of Staphylococcus aureus (MSSA) were not rendered more susceptible to oxacillin, resistance to oxacillin by highly-resistant strains (MRSA) could be significantly reduced by sub-inhibitory concentrations of TZ. Reserpine, an inhibitor of efflux pumps, was also shown to reduce the resistance of MRSA strains to oxacillin in a concentration-dependent manner. The phenothiazines have been shown, by others, to inhibit the efflux pumps of bacteria and the mechanism by which MRSA are rendered more susceptible to oxacillin in the presence of TZ is believed to be due to a similar efflux pump.     

大蒜素、川穹嗪与万古霉素联用抗MRSA的作用研究

目的探讨中成药大蒜素、川穹嗪分别与万古霉素联合应用对耐甲氧西林金黄色葡萄球菌(MRSA)的体外抑制作用。方法临床分离5株MRSA,采用K-B法测定细菌对苯唑西林、头孢唑林、头孢曲松、红霉素、妥布霉素和万古霉素的敏感性;采用微量稀释法分别测定大蒜素、川穹嗪和万古霉素对MRSA的最低抑菌浓度MIC,采用棋盘稀释法测定大蒜素、川穹嗪分别与万古霉素联用时对MRSA的MIC,计算联合指数FICI。结果 5株MRSA均为多耐药菌株,仅对万古霉素敏感。大蒜素、川穹嗪对MRSA的MIC与对甲氧西林敏感的金黄色葡萄球菌(MSSA)即标准株ATCC29213的MIC比较无统计学差异。大蒜素与万古霉素在体外联合应用时,万古霉素的MIC为(0.60±0.22)μg/mL,与单用万古霉素时的MIC(2.40±0.89)μg/mL比较有统计学差异(P=0.004);川穹嗪与万古霉素在体外联合应用时,万古霉素的MIC为(0.40±0.37)μg/mL,与单用万古霉素时的MIC=(2.40±0.89)μg/mL比较有统计学差异(P=0.002)。万古霉素加大蒜素的平均FICI为0.32±0.13,呈协同作用,万古霉素加川穹嗪的平均FICI为0.65±0.09,呈相加作用。结论大蒜素、川穹嗪对MRSA有一定抑制作用。大蒜素、川穹嗪与万古霉素联合使用时具有协同或相加作用,大蒜素、川穹嗪可能成为万古霉素的增敏剂用于治疗MRSA引起的感染。