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1.
Four laboratory methods including, E-test MIC, Oxacillin screen agar, manitol salt agar plus oxacillin and CHROMagar MRSA were compared for detection of methicilin resistant Staphylococcus aureus (MRSA). CHROMagar MRSA had a high sensitivity and specificity comparing to conventional E-test method. Sensitivity and specificity by manitol salt agar was 95 and 100%, respectively, while oxacillin screening agar method had 100% sensitivity and 95% specificity.  相似文献   

2.
Infections caused by drug-resistant pathogens are on the rise. The ongoing spread of methicillin-resistant Staphylococcus aureus (MRSA) strains exemplifies the urgent need for new antibiotics. The marine natural product, marinopyrrole A, was previously shown to have potent antibiotic activity against Gram-positive pathogens, including MRSA. However, its minimum inhibitory concentration (MIC) against MRSA was increased by >500 fold in the presence of 20% human serum, thus greatly limiting therapeutic potential. Here we report our discovery of a novel derivative of marinopyrrole A, designated 1a, featuring a 2-4 fold improved MIC against MRSA and significantly less susceptibility to serum inhibition. Importantly, compound 1a displayed rapid and concentration-dependent killing of MRSA. Compared to the natural product counterpart, compound 1a provides an important natural product based scaffold for further Structure Activity Relationship (SAR) and optimization.  相似文献   

3.
There is an urgent need for new antibiotics to treat hospital- and community-associated methicillin-resistant Staphylococcus aureus (MRSA) infections. Previous work has indicated that both terrestrial and marine-derived members of the napyradiomycin class possess potential anti-staphylococcal activities. These compounds are unique meroterpenoids with unusual levels of halogenation. In this paper we report the evaluation of two previously described napyradiomycin derivatives, A80915A (1) and A80915B (2) produced by the marine-derived actinomycete, Streptomyces sp. strain CNQ-525, for their specific activities against contemporary and clinically relevant MRSA. Reported are studies of the in vitro kinetics of these chemical scaffolds in time-kill MRSA assays. Both napyradiomycin derivatives demonstrate potent and rapid bactericidal activity against contemporary MRSA strains. These data may help guide future development and design of analogs of the napyradiomycins that could potentially serve as useful anti-MRSA therapeutics.  相似文献   

4.
Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a major problem, causing severe and intractable infections worldwide. MRSA is resistant to all beta-lactam antibiotics, and alternative treatments are limited. A very limited number of new antibiotics have been discovered over the last half-century, novel agents for the treatment of MRSA infections are urgently needed. Marinopyrrole A was reported to show antibiotic activity against MRSA in 2008. After we reported the first total synthesis of (±)-marinopyrrole A, we designed and synthesized a series of marinopyrrole derivatives. Our structure activity relationship (SAR) studies of these novel derivatives against a panel of Gram-positive pathogens in antibacterial assays have revealed that a para-trifluoromethyl analog (33) of marinopyrrole A is ≥63-, 8-, and 4-fold more potent than vancomycin against methicillin-resistant Staphylococcus epidermidis (MRSE), methicillin-susceptible Staphylococcus aureus (MSSA) and MRSA, respectively. The results provide valuable information in the search for new-generation antibiotics.  相似文献   

5.
The marine natural product, marinopyrrole A (1), was previously shown to have significant antibiotic activity against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Although compound (1) exhibits a significant reduction in MRSA activity in the presence of human serum, we have identified key modifications that partially restore activity. We previously reported our discovery of a chloro-derivative of marinopyrrole A (1a) featuring a 2–4 fold improved minimum inhibitory concentration (MIC) against MRSA, significantly less susceptibility to serum inhibition and rapid and concentration-dependent killing of MRSA. Here, we report a novel fluoro-derivative of marinopyrrole A (1e) showing an improved profile of potency, less susceptibility to serum inhibition, as well as rapid and concentration-dependent killing of MRSA.  相似文献   

6.
2-(2′,4′-Dibromophenoxy)-4,6-dibromophenol isolated from the marine sponge Dysidea granulosa (Bergquist) collected off the coast of Lakshadweep islands, Indian Ocean, exhibited potent and broad spectrum in-vitro antibacterial activity, especially against methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), vancomycin resistant Enterococci (VRE), vancomycin sensitive Enterococci (VSE) and Bacillus spp. Minimal inhibitory concentration (MIC) was evaluated against 57 clinical and standard strains of Gram positive and Gram negative bacteria. The observed MIC range was 0.117–2.5 μg/mL against all the Gram positive bacteria and 0.5–2 μg/mL against Gram negative bacteria. The in-vitro antibacterial activity observed was better than that of the standard antibiotic linezolid, a marketed anti-MRSA drug. The results establish 2-(2′,4′-dibromophenoxy)-4,6-dibromophenol, as a potential lead molecule for anti-MRSA and anti-VRE drug development.  相似文献   

7.
金线莲乙醇提取物对金黄色葡萄球菌抑菌性能研究   总被引：1，自引：0，他引：1  
用乙醇作为溶剂,提取出金线莲中的有效抑菌物质,采用二倍稀释法确定金线莲乙醇提取物对金黄色葡萄球菌的最小抑菌浓度(Minimal inhibition concentration,MIC)为5.000 mg/m L;并经介质pH、热处理和紫外线处理提取物,发现其抑菌圈直径在pH9.0和30℃下最大;分析金线莲乙醇提取物对供试菌蛋白质和还原糖的利用能力,表明金线莲乙醇提取物通过减弱蛋白质和还原糖的代谢来抑制细菌的生长繁殖。  相似文献   

8.
Recent genomic studies have demonstrated that fungi can possess gene clusters encoding for the production of previously unobserved secondary metabolites. Activation of these attenuated or silenced genes to obtain either improved titers of known compounds or new ones altogether has been a subject of considerable interest. In our efforts to discover new chemotypes that are effective against infectious diseases, including malaria and methicillin-resistant Staphylococcus aureus (MRSA), we have isolated a strain of marine fungus, Leucostoma persoonii, that produces bioactive cytosporones. Epigenetic modifiers employed to activate secondary metabolite genes resulted in enhanced production of known cytosporones B (1, 360%), C (2, 580%) and E (3, 890%), as well as the production of the previously undescribed cytosporone R (4). Cytosporone E was the most bioactive, displaying an IC(90) of 13 μM toward Plasmodium falciparum, with A549 cytotoxicity IC(90) of 437 μM, representing a 90% inhibition therapeutic index (TI(90) = IC(90) A459/IC(90)P. falciparum) of 33. In addition, cytosporone E was active against MRSA with a minimal inhibitory concentration (MIC) of 72 μM and inhibition of MRSA biofilm at roughly half that value (minimum biofilm eradication counts, MBEC90, was found to be 39 μM).  相似文献   

9.
The aim of this study is to identify the antibiotic sensitivity pattern of pathogens involved in the process of surgical site infection, in surgical wards. Changes made in the pattern of antibiotic use will result in different microorganism susceptibility patterns, which needs correct determination for precise empiric antibiotic therapy. One thousand patients (62% men and 38% women, 18- 74-years-old, with mean age 43 +/- 8)) who underwent surgical treatment, in Alzahra University Hospital, Isfahan University of Medicine, Isfahan, Iran, were studied from 2005 to 2006. Surgical wound infections, based on the reported criteria, were aspirated for culturing within 1 plus gram staining of prepared smears. Minimum Inhibitory Concentrations (MICs) were determined for samples and all derived data were compared by SPSS 13 and WHO net 5 software. The prevalence of SSI was 13.3% with 150 positive cultures, totally. Of 150 bacteria, isolated from surgical site infections Staphylococcus aureus had most frequency (43%). Resistance of isolated organisms was 41.7% in amikacin, 65 and 78.6% in ceftazidime, 85.7% in ceftriaxone, 61.5% in ciprofloxacin, 78.8% in gentamicine, 6.4% in imipenem, 13% in meropenem and 70.6% in trimethoprim/sulfamethoxazole, respectively. 78.9% of Staphylococcus aureus isolates were MRSA and vancomycine was the most effective antibiotic without any resistance. Among 10 isolates of coagulase negative Staphylococcus, no vancomycine resistance was seen, but in contrast all cases were resistant to oxacillin. The most common gram negative organism was Klebsiella (18 isolates) in which 100 and 80% were sensitive to imipenem and meropenem, respectively. Seventeen cases were E. coli, in which the most sensitivity was to meropenem (80%) and imipenem (77.8%). Thirteen cases of Pseudomonas were detected, in which 16.7% were resistant to imipenem and 8.3% to meropenem. Our results demonstrated that the total antibiotic resistance is increasing among SSIs, with an up sloping pattern, which will contact with a constant empiric antibiotic therapy. So, precise up to date antibiogram tantalize us toward balancing the rate of total antibiotic resistance to SSIs.  相似文献   

10.
During a global research expedition, more than five hundred marine bacterial strains capable of inhibiting the growth of pathogenic bacteria were collected. The purpose of the present study was to determine if these marine bacteria are also a source of compounds that interfere with the agr quorum sensing system that controls virulence gene expression in Staphylococcus aureus. Using a gene reporter fusion bioassay, we recorded agr interference as enhanced expression of spa, encoding Protein A, concomitantly with reduced expression of hla, encoding α-hemolysin, and rnaIII encoding RNAIII, the effector molecule of agr. A marine Photobacterium produced compounds interfering with agr in S. aureus strain 8325-4, and bioassay-guided fractionation of crude extracts led to the isolation of two novel cyclodepsipeptides, designated solonamide A and B. Northern blot analysis confirmed the agr interfering activity of pure solonamides in both S. aureus strain 8325-4 and the highly virulent, community-acquired strain USA300 (CA-MRSA). To our knowledge, this is the first report of inhibitors of the agr system by a marine bacterium.  相似文献   

11.
袁媛  庞玉新  元超 《热带作物学报》2018,39(6):1195-1199
本研究采用硅胶柱层析、ODS反相柱层析、sephadex LH-20分子筛等技术进行分离纯化艾纳香乙酸乙酯部位,共获得7个化合物。采用波谱学技术进行结构鉴定,7个化合物分别为：3,3’,5,7-四羟基-4’-甲氧基-二氢黄酮（1）,7-甲氧基紫衫叶素(padmatin)（2）,木犀草素-7-甲醚（3）,咖啡酸（4）,北美圣草素（5）,槲皮素（6）和木犀草素（7）。采用96孔板倍比稀释法,对单体化合物抗细菌活性进行评价,结果显示化合物2和3具有较好的抑制金黄色葡萄球菌活性,MIC值均为64 μg/mL。化合物2和4均为首次从该植物中分离,化合物2 和3可作为艾纳香抗菌活性先导化合物,为相关新药研发提供依据。  相似文献   

12.
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13.
Drug-resistant Staphylococcus aureus is a continuing public health concern, both in the hospital and community settings. Antibacterial compounds that possess novel structural scaffolds and are effective against multiple S. aureus strains, including current drug-resistant ones, are needed. Previously, we have described the chrysophaentins, a family of bisdiarylbutene macrocycles from the chrysophyte alga Chrysophaeum taylori that inhibit the growth of S. aureus and methicillin-resistant S. aureus (MRSA). In this study we have analyzed the geographic variability of chrysophaentin production in C. taylori located at different sites on the island of St. John, U.S. Virgin Islands, and identified two new linear chrysophaentin analogs, E2 and E3. In addition, we have expanded the structure activity relationship through synthesis of fragments comprising conserved portions of the chrysophaentins, and determined the antimicrobial activity of natural chrysophaentins and their synthetic analogs against five diverse S. aureus strains. We find that the chrysophaentins show similar activity against all S. aureus strains, regardless of their drug sensitivity profiles. The synthetic chrysophaentin fragments indeed mimic the natural compounds in their spectrum of antibacterial activity, and therefore represent logical starting points for future medicinal chemistry studies of the natural products and their analogs.  相似文献   

14.
Desotamides A, a cyclohexapeptide produced by the deep-sea-derived Streptomyces scopuliridis SCSIO ZJ46, displays notable antibacterial activities against strains of Streptococcus pnuemoniae, Staphylococcus aureus, and methicillin-resistant Staphylococcus epidermidis (MRSE). In this study, to further explore its antibacterial potential and reveal the antibacterial structure-activity relationship of desotamides, 13 cyclopeptides including 10 new synthetic desotamide A analogues and wollamides B/B1/B2 were synthesized and evaluated for their antibacterial activities against a panel of Gram-positive and -negative pathogens. The bioactivity data reveal that residues at position II and VI greatly impact antibacterial activity. The most potent antibacterial analogues are desotamide A4 (13) and A6 (15) where l-allo-Ile at position II was substituted with l-Ile and Gly at position VI was simultaneously replaced by d-Lys or d-Arg; desotamides A4 (13) and A6 (15) showed a 2–4-fold increase of antibacterial activities against a series of Gram-positive pathogens including the prevalent clinical drug-resistant pathogen methicillin-resistant Staphylococcus aureus (MRSA) with MIC values of 8–32 μg/mL compared to the original desotamide A. The enhanced antibacterial activity, broad antibacterial spectrum of desotamides A4 and A6 highlighted their potential as new antibiotic leads for further development.  相似文献   

15.
Four new sesquiterpene hydroquinones, xishaeleganins A–D (6–9), along with eleven known related ones (12 and 14–23) were isolated from the Xisha marine sponge Dactylospongia elegans (family Thorectida). Their structures were determined by extensive spectroscopic analysis, ECD calculations, and by comparison with the spectral data reported in the literature. Compounds 7, 15, 20, and 21 showed significant antibacterial activity against Staphylococcus aureus, with minimum inhibitory concentration values of 1.5, 2.9, 5.6, and 5.6 µg/mL, which are comparable with those obtained for the positive control vancomycin (MIC: 1.0 µg/mL).  相似文献   

16.
茶多酚与绿原酸生物活性的比较研究   总被引：8，自引：4，他引：4  
为了研究茶叶与金银花中主要药效成分茶多酚和绿原酸生物活性的差异,应用过氧化值测定法、分光光度法、最小抑菌浓度(MIC)测定法分别比较茶多酚和绿原酸的抗氧化性、自由基清除能力、体外抑菌活性;结果表明在6周的观测期内,浓度为100βµg/g和200βµg/g的茶多酚可将猪油的POV抑制在10βmeq/kg范围内,且抗氧化能力随浓度增加而增强,这与81％绿原酸有相似结果;20％绿原酸、81％绿原酸、95％茶多酚对DPPH和·OH的半数抑制浓度(IC50)分别为327、1β432、65、135、52βmg/L和1β908βmg/L;95％茶多酚对大肠杆菌和金黄色葡萄球菌的MIC分别为500βμg/g和250βμg/g,81％绿原酸和20％绿原酸相应值分别为500βμg/g、500βμg/g和500βμg/g、1β000βμg/g;研究结论为茶多酚（95%）在抗氧化性、清除DPPH能力及对金黄色葡萄球菌的抑菌效果方面都要强于绿原酸（81%）,在清除·OH能力上要弱于绿原酸,在食品、药品行业中茶多酚有望比绿原酸发挥更大的作用。  相似文献   

17.
Three myxobacterial strains, designated SWB004, SWB005 and SWB006, were obtained from beach sand samples from the Pacific Ocean and the North Sea. The strains were cultivated in salt water containing media and subjected to studies to determine their taxonomic status, the presence of genes for the biosynthesis of polyketides and antibiotic production. 16S rDNA sequence analysis revealed the type strain Enhygromyxa salina SHK-1(T) as their closest homolog, displaying between 98% (SWB005) and 99% (SWB004 and SWB006) sequence similarity. All isolates were rod-shaped cells showing gliding motility and fruiting body formation as is known for myxobacteria. They required NaCl for growth, with an optimum concentration of around 2% [w/v]. The G + C-content of genomic DNA ranged from 63.0 to 67.3 mol%. Further, the strains were analyzed for their potential to produce polyketide-type structures. PCR amplified ketosynthase-like gene fragments from all three isolates enhances the assumption that these bacteria produce polyketides. SWB005 was shown to produce metabolites with prominent antibacterial activity, including activity towards methicillin resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE).  相似文献   

18.
This study was conducted to determine the prevalence of bacteria recovered from bloodstream samples by Bactec 9240 at our hospital wards and to evaluate their antibacterial susceptibility patterns. During January 2001 through December 2004, 9407 referred blood samples in Bactec bottles from admitted patients at three main wards, neonates, pediatrics and adults at Nemazee Hospital, affiliated to Shiraz University of Medical Sciences in Shiraz were processed. Positive cultures were purified and identified according to standard methods. Sensitivity of bacteria to different antibiotics was determined by Kirby-Bauer disk diffusion method. Staphylococcus aureus 132(25%), Escherichia coli 64(12.1%) and Pseudomonas aeruginosa 52(9.8%) were the most pathogenic bacteria which were recovered from the blood samples. Pathogenic microorganisms were isolated from blood samples of 305 (57.8%) at pediatrics, from 181 (34.2%) at adults and from 42 (8%) at neonates wards. The highest antibiotics activities against gram positive isolates observed for vancomycin (98.4%), chloramphenicol (86.4%) and ciprofloxacin (77.4%), while in gram negative bacteria imipenem (96.1%), ciprofloxacin (83%) and amikacin (77.9%), were effective antibiotics. Frequency of isolated bacteria at pediatrics compared to adults and neonates wards were approximately two and seven folds high, respectively which indicates special attention should be paid to pediatrics patients both in prevention and treatment aspects. Vancomycin and imipenim are the effective antibiotics and could cover majority of gram positive and negative bacteria. Therefore, combined administrations of these antibiotics seems mandatory for empirical therapy.  相似文献   

19.
The objectives of the present study were to investigate phytochemical screening and to assay cytotoxicity and antibacterial activities of ethanolic extracts of leaves of two medicinal plants, Aglaonema hookerianum Schott (Family: Araceae) and Lannea grandis Engl. (Family: Anacardiaceae) available in Bangladesh. The brine shrimp lethality bioassay showed that the ethanolic extracts of Aglaonema hookerianum and Lannea grandis possessed cytotoxic activities with LC50 5.25 (microg mL(-1)) and 5.75 (microg mL(-1)) and LC90 10.47 (microg mL(-1)) and 9.55 (microg mL(-1)), respectively. Two extracts obtained from leaves were examined for their antibacterial activities against some gram positive bacteria such as Bacillus subtilis, Bacillus megaterium and Staphylococcus aureus, also gram negative strains of Pseudomonas aeruginosa, Escherichia coli, Shigella dysenteriae, Salmonella typhi, Salmonella paratyphi and Vibrio cholerae. Agar disc diffusion method was applied to observe the antibacterial efficacy of the extracts. Results indicated that both plant extracts (500 microg disc(-1)) displayed antibacterial activity against all of the tested microorganisms. These results were also compared with the zones of inhibition produced by commercially available standard antibiotic, Amoxicillin at concentration of 10 microg disc(-1). Observed antibacterial properties of the ethanolic extract of Aglaonema hookerianum Schott and Lannea grandis Engl. showed that both plants might be useful sources for the development of new potent antibacterial agents.  相似文献   

20.
Four new polycyclic antibiotics, citreamicin θ A (1), citreamicin θ B (2), citreaglycon A (3), and dehydrocitreaglycon A (4), were isolated from marine-derived Streptomyces caelestis. The structures of these compounds were elucidated by 1D and 2D NMR spectra. All four compounds displayed antibacterial activity against Staphylococcus haemolyticus, Staphylococcus aureus, and Bacillus subtillis. Citreamicin θ A (1), citreamicin θ B (2) and citreaglycon A (3) also exhibited low MIC values of 0.25, 0.25, and 8.0 μg/mL, respectively, against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300.  相似文献   

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