大黄及单体对金黄色葡萄球菌的体外抑菌作用及作用机制研究

目的研究大黄及单体对金黄色葡萄球菌的体外抑菌作用及作用机制。方法采用高效液相色谱仪分析不同溶剂萃取大黄及8种单体,采用抑菌试验检测大黄对3株金黄色葡萄球菌及8种单体对标准菌株的抑菌作用。采用微量倍比稀释法测定大黄对80株金黄色葡萄球菌及8种大黄单体对标准菌株的最小抑菌浓度(MIC)。采用全自动鉴定药敏仪对80株金黄色葡萄球菌进行鉴定和药敏试验,并测定标准菌株的生长曲线。采用酶标仪检测DNA、RNA等大分子物质的外渗水平。结果选择乙醇作为溶剂对大黄进行萃取,在8种单体中,大黄酚、大黄素等5种大黄单体提取率最高,其中大黄素对标准菌株抑菌效果最明显,平均抑菌圈直径为20 mm, MIC为0.025 mg/mL。大黄对耐甲氧西林金黄色葡萄球菌的抑菌作用较明显,抑菌圈直径为19 mm。大黄对80株金黄色葡萄球菌的MIC范围为16～128 mg/mL。40株耐甲氧西林金黄色葡萄球菌抗菌药物中青霉素、苯唑西林、阿莫西林/克拉维酸的耐药率均为100.0%,40株甲氧西林敏感金黄色葡萄球菌抗菌药物中青霉素的耐药率(90.0%)最高。大黄对标准菌株金黄色葡萄球菌有抑菌作用,能够破坏金黄色葡萄球菌的细胞膜,导致菌体中DNA、RNA等大分子物质外渗。结论大黄及抑菌单体对金黄色葡萄球菌具有较好的抑菌作用,作用机制是通过破坏金黄色葡萄球菌的细胞膜,导致菌体中DNA、RNA等大分子物质外渗,发挥抗菌作用。     

中药黄檗对金黄色葡萄球菌体外抑菌效果的初步研究

目的研究中药黄檗对金黄色葡萄球菌的体外抑菌效果。方法采用琼脂稀释法、常量肉汤稀释法和微量肉汤稀释法检测黄檗水煎剂对20株金黄色葡萄球菌的最低抑菌浓度(MIC)。结果琼脂稀释法抑制90%菌株生长的MIC(MIC90)为12.5 mg/m L,常量肉汤稀释法MIC90为25 mg/m L,微量肉汤稀释法MIC90为25 mg/m L。结论中药黄檗对金黄色葡萄球菌在体外有较好的抑菌效果。     

白藜芦醇对金黄色葡萄球菌标准株 抑菌作用及超微结构的影响

目的 研究白藜芦醇(resveratrol,RES)对金黄色葡萄球菌标准株ATCC 25923(简称金葡菌标准株)抑菌作用。方法 采用微量肉汤稀释法,检测金葡菌标准株最低抑菌浓度(minimal inhibitory concentrations,MIC); 通过透射和扫描电子显微镜观察白藜芦醇对金葡菌标准株超微形态的影响。结果 白藜芦醇对金葡菌标准株的MIC为0.256 mg/ml。白藜芦醇对金葡菌标准株作用后,与对照组相比,电镜下可见金葡菌标准株菌体细胞形态变形严重,菌体大小不一,菌体边界粗糙不圆润,细胞壁缺损并有破裂,边缘疏松不光滑,菌体内结构松散,核膜断裂,局部呈现空泡化特征,菌体细胞形态超微结构有明显破坏和抑制作用。结论白藜芦醇对金葡菌标准株有明显抑制和破坏作用,抑制机制可能和破坏细胞膜通透性有关。     

耐甲氧西林金黄色葡萄球菌对3种消毒剂的抗力观察

目的研究耐甲氧西林金黄色葡萄球菌对临床常用化学消毒剂抗力,为实际消毒提供参考。方法采用肉汤稀释法测定3种常用消毒剂对8株临床分离耐甲氧西林金黄色葡萄球菌最小抑菌浓度和最小杀菌浓度,同时与金黄色葡萄球菌标准株作平行比较。结果三氯异氰尿酸对8株临床分离的耐甲氧西林金黄色葡萄球菌的最小抑菌浓度范围为有效氯250～1000mg/L,最小杀菌浓度范围为500～2000mg/L;对金黄色葡萄球菌标准株的MIC为500mg/L,MBC为1000mg/L。碘伏对8株临床分离的耐甲氧西林金黄色葡萄球菌和标准株的MIC和MBC分别为25mg/L和50mg/L。戊二醛对8株临床分离的耐甲氧西林金黄色葡萄球菌和标准株MIC和MBC分别为31mg/L和62mg/L。结论临床分离的耐甲氧西林金黄色葡萄球菌对三氯异氰尿酸的抗力与标准株比较有所不同,但碘伏和戊二醛对耐甲氧西林金黄色葡萄球菌抗力与标准株一致。     

复方三黄液对60株骨科分离金黄色葡萄球菌体外抑菌效果研究

目的：了解复方三黄液对金黄色葡萄球菌的体外抑菌效果,为临床应用提供实验室依据。方法采用肉汤稀释法,以复方三黄液为抑菌药,观察其对骨科感染分离出的60株金黄色葡萄球菌的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。结果42株 MSSA 中32株 MIC 为7．8μg/mL,10株 MIC 为15．6μg/mL;18株 MRSA 中14株 MIC 为7．8μg/mL,4株 MIC为15．6μg/mL。MRSA 组均值为9．6μg/mL,MSSA 均值为9．5μg/mL。结论复方三黄液对金黄色葡萄球菌体外抑菌效果明显,并能避免耐药菌的产生。     

大蒜素对MRSA和白念珠菌后效应的研究

目的 测定大蒜素对耐甲氧西林金黄色葡萄球菌(MRSA)和白念珠菌(C.alb)的最低抑菌浓度(MIC)、抗菌药后效应(PAE)和抗菌后亚抑菌浓度效应(PASME).方法 取临床分离的MRSA和C.alb各1株,以肉汤稀释法测定大蒜素MIC;以菌落计数法测定菌落形成单位(CFU),根据CFU做生长曲线,计算PAE和PAS...     

芦荟苷对金黄色葡萄球菌生长抑制作用及对溶血毒素表达的影响

目的研究芦荟苷体外对金黄色葡萄球菌生长抑制作用以及对溶血素表达的影响。方法采用肉汤倍比稀释法检测芦荟苷水溶物对金黄色葡萄球菌最低抑菌浓度(MIC);琼脂打孔法观察芦荟苷对金黄色葡萄球菌的抑菌圈大小;试管法检测芦荟苷作用下金黄色葡萄球菌凝固酶的产生变化;检测芦荟苷作用下金黄色葡萄球菌溶血素活性变化;采用实时荧光定量PCR检测芦荟苷水溶物作用于金黄色葡萄球菌后对hla和agr A基因表达的影响。结果芦荟苷水溶物可抑制金黄色葡萄球菌生长并呈现浓度依赖性,作用于ATCC 25923和临床菌株SA1.5后的抑菌圈直径和MIC分别为21.5 mm、12.5 mg/m L和17mm、15 mg/m L;与对照组凝固酶效价32比较,1/2MIC组、MIC和2MIC组芦荟苷作用ATCC 25923后的凝固酶效价分别降为16、4和2;与对照组相比,1/2MIC组、MIC组及2MIC组芦荟苷水溶物降低ATCC 25923溶血活性,溶血率分别为(77.4±3.41)%、(42.2±2.4)%和(38.7±2.4)%;1/2MIC组、MIC组和2MIC组芦荟苷作用ATCC 25923后hla表达量分别为0.020 3(0.019 6,0.028 8)、0.011 6(0.010 6,0.013 1)和0.033 7(0.020 2,0.042 9),3组间差异有统计学意义(H=16.807,P0.05);agr A表达量分别为0.074 6(0.066 2,0.098 2)、0.020 8(0.012 2,0.032 6)和0.021 3(0.010 2,0.029 6),3组间差异有统计学意义(H=16.320,P0.05)。结论芦荟苷可抑制金黄色葡萄球菌生长,并对α-溶血素表达有抑制作用。     

MRSA对6种消毒剂耐药性及相关抗性基因的比较研究

目的观察医院分离的2株耐甲氧西林金黄色葡萄球菌(MRSA)和金黄色葡萄球菌标准株(ATCC 6538)对6种消毒剂的抗性与耐药基因变化。方法选择最小抑菌浓度(MIC)试验、悬液定量杀菌试验和耐消毒剂基因PCR检测。结果 MIC检测,医院分离的2株MRSA,对6种消毒剂的MIC,明显高于标准菌株。只有醋酸氯己定对MRSA-1的MIC值与标准菌株相同。PCR检测,2株MRSA均未携带耐消毒剂基因qacA/B。定量杀菌实验,苯扎氯铵、过氧乙酸、双癸基二甲基氯化铵对MRSA-1菌株的杀灭对数值低于标准菌株;苯扎氯铵、过氧乙酸、有效氯对MRSA-2菌株的杀灭对数值低于标准株。结论医院分离的2株MRSA对消毒剂的抗性普遍高于标准菌株,PCR检测未发现qacA/B基因。     

头孢西丁诱导试验证实一株苯唑西林敏感的耐甲氧西林金黄色葡萄球菌

目的研究不同浓度的头孢西丁对1株苯唑西林敏感的耐甲氧西林金黄色葡萄球菌(MRSA)体外抗菌活性的影响和青霉素结合蛋白(PBP)2a的诱导作用。方法利用不同浓度的头孢西丁诱导1株苯唑西林敏感的MRSA,测定诱导前后苯唑西林的药敏直径、最低抑菌浓度(MIC)和出现PBP2a阳性时的菌液浓度。结果在低浓度头孢西丁诱导前后苯唑西林的药敏直径和MIC变化不大,高浓度则出现较大变化,在诱导前后出现PBP2a凝集试验阳性的菌液浓度有明显变化。结论头孢西丁可诱导金黄色葡萄球菌产生PBP2a。     

头孢噻肟与阿奇霉素对金黄色葡萄球菌的联合药敏研究

目的 研究头孢噻肟(CTX)与阿奇霉素(AZI)联合用药对临床分离的金黄色葡萄球菌的体外抗菌效应.方法 采用棋盘法设计,用微量肉汤稀释法测定不同浓度组合的抗菌药物对32株临床分离的金黄色葡萄球菌的最低抑菌浓度(MIC),并计算抑菌指数(FIC)以判断联合效应.结果 CTX与AZI联用后金黄色葡萄球菌MIC明显下降,抗菌作用显著增加.对金黄色葡萄球菌主要为相加和协同作用,协同作用为12.50%,相加作用为68.75%,无关作用为18.75%,无拮抗作用.结论 CTX与AZI联用对临床分离的金黄色葡萄球菌的体外抗菌效应增强,联合应用是合理的.     

白藜芦醇抑菌作用及抑菌机制研究进展

白藜芦醇（resveratrol，RES）是一种抵制真菌侵袭时植物产生的具有多种生物学活性、对多种微生物有抑制作用的抗毒素物质。近几年研究表明 RES对各种微生物具有明显的抑制作用，该文对 RES干扰细胞壁蛋白质合成、细胞膜损伤和通过 RsbA介导的抑菌因子形成的抑菌机制进行了综述分析。     

Antibacterial non-glycosidase activity of invertebrate destabilase-lysozyme and of its helical amphipathic peptides

BACKGROUND: Since bactericidal properties of some lysozymes are independent of their glycosidase activity, we have investigated this phenomenon for destabilase-lysozyme (DL) from medicinal leech (Hirudo medicinalis). METHODS: Glycosidase activity was determined on Micrococcus luteus, non-enzymatic antibacterial activity of heat-treated DL and of synthetic peptides alpha1, alpha2 and alpha3 (fragments of its primary structure) on M. luteus, Escherichia coli, Bacillus brevis and Streptomyces chrysomallus. RESULTS: Glycosidase activity disappeared after the heating of native DL at 100 degrees C for 40 min. Antibacterial activity of heat-treated DL for M. luteus MDMSU128 and MDMSU140 expressed as minimal inhibitory concentration was 9.8.10(-8) and 12.10(-8) M, respectively, and to E. coli MDMSU52 11.10(-8) M. Antibacterial activity of synthetic peptide alpha1 for M. luteus MDMSU128 and for E. coli MDMSU52 was 8.3.10(-5) and 4.9.10(-5) M, respectively. CONCLUSION: DL is the first invertebrate lysozyme with combined enzymatic and non-enzymatic antibacterial action.     

Protective mechanisms of resveratrol against methotrexate‐induced renal damage may involve BCRP/ABCG2

Resveratrol (RES) is a well‐known polyphenol antioxidant. We have previously shown that testicular protective effect of RES against the anticancer drug methotrexate (MTX)‐induced toxicity involves transporter‐mediated mechanisms. Here, we investigated the effect of RES on MTX‐induced nephrotoxicity. Rats were administered RES (10 mg/kg/day) for 8 days, with or without a single MTX dose (20 mg/kg i.p.) at day 4 of the experiment. MTX induced nephrotoxicity, as evidenced by a significant increase in serum blood urea nitrogen and creatinine compared to the control, as well as distortion of kidney microscopic structure. MTX also significantly increased renal nitric oxide level along with inducible nitric oxide synthase, fas ligand, and caspase 3 expressions. Administering RES prior to MTX significantly improved kidney function and microscopic picture and also significantly decreased nitrosative and apoptotic markers compared to MTX alone. RES, but not MTX, caused a significant increase in expression of breast cancer resistance protein (BCRP), an apical efflux renal transporter that participates in urinary elimination of both MTX and RES. Interestingly, concomitant MTX and RES caused further upregulation of renal BCRP compared to RES alone. Using Human BCRP ATPase assay, both RES and MTX exhibited a dose‐dependent increase in ATPase activity, with Km values of 0.52 ± 0.03 and 30.9 ± 4.2 μm , respectively. Furthermore, combined RES and MTX caused ATPase activity which was significantly less than maximum ATPase activity attained by the positive control, sulfasalazine (12.5 μm ). In conclusion, RES exerted nephroprotection against MTX‐induced toxicity through antinitrosative and anti‐apoptotic effects, as well as via upregulation of renal BCRP.     

STUDIES ON THE MECHANISM OF ACTION OF RILEY VIRUS : I. ACTION OF SUBSTANCES AFFECTING THE RETICULOENDOTHELIAL SYSTEM ON PLASMA ENZYME LEVELS IN MICE

Plasma LDH levels were determined in normal and Riley virus-infected mice following treatment with various drugs known to alter the activity of the RES. The rise in plasma LDH level after Riley virus infection was considerably enhanced by previous treatment with thorotrast (to produce blockade of the RES), and decreased by previous treatment with stilboestrol (to stimulate the RES). A dose of 2000 r whole-body x-irradiation, lethal within 3 to 4 days, did not alter the phagocytic activity of the RES, and was without effect on plasma LDH activity in normal mice, or on the rise in plasma LDH level following infection with Riley virus. Blockade of the RES with cholesterol oleate, thorotrast, or zymosan, resulted in a 2- to 3-fold rise in plasma LDH level within a few hours. The level returned to normal by 1 to 3 days. Stimulation of the RES with stilboestrol resulted in a decrease in plasma LDH level by 1 to 2 days in both normal and infected mice, with a return to normal by about a week. Blockade of the RES in uninfected mice with thorotrast or cholesterol oleate, besides increasing the plasma LDH level caused a rise in plasma phosphoglucose isomerase level, but no significant alterations in plasma aldolase or alanine transaminase levels, studied up to 10 days. Riley virus causes a similar pattern of enzyme elevation. It is suggested that the increased levels of certain plasma enzymes in Riley virus-infected mice may be due to competitive inhibition by virus particles of plasma enzyme clearance by the RES.     

Some physiopathological parameters of natural resistance to infection in murine salmonellosis

Susceptible (BSVS) and resistant (BRVR) mice were experimentally infected with Salmonella typhimurium. The double strain inoculation technique was used in which both avirulent and virulent representatives of S. typhimurium were admitted into the hosts. The BSVS mice succumbed without exception while the BRVR mice survived to 52 per cent. No deaths occurred during the experimental period in non-infected control mice. Parallel to the survivorship test, and concurrent with it, the activity of the reticulo-endothelial system (RES) was measured at frequent intervals in identically infected BSVS and BRVR mice and in their non-infected controls. For this measurement the carbon clearance method was used. No pre-infection difference of activity of the RES could be discerned in susceptible BSVS mice vs. resistant BRVR. Following infection, increases in the RES activity were detected in about the same magnitude in both mouse stocks. However, a difference was found in the time of onset. The susceptible animals showed an early and short increase in the activity of the RES, followed by a drop to control levels at the time of death. The resistant group exhibited a considerably delayed, but significant increase in RES activity, which returned to control levels approximately 4 weeks after infection. The absolute white blood count did not undergo significant change in either of the two infected groups, but the susceptible animals showed a relative increase of their neutrophils at the expense of their lymphocytes. Extensive anatomical changes were observed in both mouse strains, mainly confined to liver and spleen. These consisted of stasis, swelling of Kupffer cells, necrotic foci, histiocytic-monocytic nodules, widespread thrombosis of branches of the portal and splenic veins, and extensive areas of necrosis. These changes appeared earlier in susceptible than in resistant animals. The implications of these findings are discussed.     

MECHANISMS OF ENDOTOXIN TOLERANCE : II. RELATIONSHIP BETWEEN ENDOTOXIN TOLERANCE AND RETICULOENDOTHELIAL SYSTEM PHAGOCYTIC ACTIVITY IN MAN

Healthy male volunteers were rendered tolerant to the pyrogenic and toxic activities of bacterial endotoxin by daily intravenous injections. Five subjects were given 0.5 µg Salmonella typhosa endotoxin for 7 days; four subjects were given Pseudomonas endotoxin, increasing over a period of 30 days from 25 to 250 µg. Reticuloendothelial system (RES) phagocytic activity was assessed by serial measurements of the clearance of I¹³¹-labeled aggregated human serum albumin. In no subject was an increase in RES phagocytic activity detectable. Such negative findings could not be attributed to decreased RES blood flow.—Additional studies on the pyrogenic responses of man to various schedules of endotoxin administration revealed: (a) Hyperreactivity of some subjects to a second injection of endotoxin administered 24 hours after the initial dose; (b) prevention of such hyperreactivity by plasma from donors tolerant to a heterologous endotoxin, but not from normal donors; (c) reduced reactivity to a second injection of endotoxin given 7 days after the initial dose; (d) reversal of induced tolerance by administration of half the dose of endotoxin followed 2 hours later by the second half; (e) reversal of induced tolerance 24 hours after administration of a heterologous endotoxin; (f) enhanced dermal reactivity to endotoxin induced inflammation during tolerance. The observations are consistent with the hypothesis that tolerance to the pyrogenic activity of endotoxin in man is not based upon generalized enhancement of RES phagocytic activity or exhaustion of host reactivity but rather involves the participation of specific antibody which assists the RES in the clearance and inactivation of the endotoxin molecule.     

Uptake of liposomes and sheep red blood cells by the liver and spleen of rats with normal or decreased function of the reticuloendothelial system

The distribution of negatively charged liposomes in rats with normal or depressed function of the liver RES was examined. RES activity was determined by the uptake of the sheep red blood cells (SRBC). Whereas pretreatment with colloidal carbon or dextran sulphate drastically diminishes the SRBC uptake by the liver, the liposome uptake is decreased by 12-15% only. In the spleen, such pretreatment boosts the SRBC uptake five- to sixfold, whereas liposome uptake was decreased by about 50%. This indicates that phagocytosis by the RES is only of several liposome-cell interactions. Consequently, the suppression of the RES function is of no practical use when attempting to suppress the preferential liposome uptake by the liver and spleen.     

Metabolism and disposition of resveratrol in rats: extent of absorption,glucuronidation, and enterohepatic recirculation evidenced by a linked-rat model

Pharmacokinetics of trans-resveratrol in its aglycone (RES(AGL)) and glucuronide (RES(GLU)) forms were studied following intravenous (15 mg/kg i.v.) and oral (50 mg/kg p.o.) administration of trans-resveratrol in a solution of beta-cyclodextrin to intact rats. In addition, the enterohepatic recirculation of RES(AGL) and RES(GLU) was assessed in a linked-rat model. Multiple plasma and urine samples were collected and concentrations of RES(AGL) and RES(GLU) were determined using an electrospray ionization-liquid chromatography/tandem mass spectrometry method. After i.v. administration, plasma concentrations of RES(AGL) declined with a rapid elimination half-life (T(1/2), 0.13 h), followed by sudden increases in plasma concentrations 4 to 8 h after drug administration. These plasma concentrations resulted in a significant prolongation of the terminal elimination half-life of RES(AGL) (T(1/2TER), 1.31 h). RES(AGL) and RES(GLU) also displayed sudden increases in plasma concentrations 4 to 8 h after oral administration, with T(1/2TER) of 1.48 and 1.58 h, respectively. RES(AGL) bioavailability was 38% and its exposure was approximately 46-fold lower than that of RES(GLU) (AUC(inf), 7.1 versus 324.7 micromol.h/l). Enterohepatic recirculation was confirmed in the linked-rat model since significant plasma concentrations of RES(AGL) and RES(GLU) were observed in bile-recipient rats at 4 to 8 h. The percentages of the exposures of RES(AGL) and RES(GLU) that were due to enterohepatic recirculation were 24.7 and 24.0%, respectively. The fraction of drug excreted in the urine over a period of 12 h was negligible. These results confirm that RES(AGL) is bioavailable and undergoes extensive first-pass glucuronidation, and that enterohepatic recirculation contributes significantly to the exposure of RES(AGL) and RES(GLU) in rats.     

The relationship between the vascular manifestations of shock produced by endotoxin,trauma, and hemorrhage. II. The possible role of the reticulo-endothelial system in resistance to each type of shock

In studies designed to establish the interrelationship between bacterial endotoxins and the vascular sequelae of hemorrhagic and traumatic shock, the effect of factors known to influence the phagocytic behavior of the reticulo-endothelial system (RES) were investigated. Measures which induced a so called "blockade" of the RES were uniformly associated with an exacerbation of the vascular effects of the endotoxin of E. coli. Such pretreatment also counteracted the cross-tolerance induced by endotoxins against the lethal effects of hemorrhage or drum trauma. The vascular reactions characteristic of irreversible hemorrhagic shock could be simulated by a combination of pretreatment with carbon or proferrin and the infusion of small doses of E. coli endotoxin. An increase in the phagocytic activity of the RES, induced by repeated injections of certain colloids, was associated with an enhanced tolerance of shock. Measurement of carbon clearance values indicated that although an augmented phagocytic capacity was present in rats with induced tolerance to bacterial endotoxins, the development of resistance to trauma was not associated with a comparable change in the phagocytic function of the RES.