抗菌药物联用对耐甲氧西林金黄色葡萄球菌体外抗菌活性研究

目的了解万古霉素与头孢哌酮/舒巴坦、亚胺培南、左氧氟沙星联用对MRSA的体外抗菌活性,指导临床合理用药。方法常规方法培养分离细菌,用VITEK微生物自动分析仪或API系统鉴定到种。MRSA鉴定应用乳胶凝集试剂盒,药敏试验采用肉汤倍比稀释法和琼脂平板稀释法。结果万古霉素对40株MRSA的MIC90为4mg/L,而与头孢哌酮/舒巴坦、亚胺培南、左氧氟沙星联用MIC90降为0.25～1mg/L。结论万古霉素与上述三种药物联用以协同作用为主,抗菌活性提高4倍以上。临床上治疗由MRSA引起的重症感染应根据药敏试验结果采用万古霉素与亚胺培南或头孢哌酮/舒巴坦或其它抗菌药物联合应用。     

In vitro combination effect of pazufloxacin with various antibiotics against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus

The in vitro combination effects of pazufloxacin (PZFX) with various antibiotics were investigated by the checkerboard dilution method using piperacillin (PIPC), tazobactam/piperacillin (TAZ/PIPC), ceftazidime (CAZ), cefozoprane (CZOP), imipenem/cilastatin (IPM/CS), meropenem (MEPM), panipenem/betamipron (PAPM/BP), amikacin (AMK) and isepamicin (ISP) for clinical isolates of 27 Pseudomonas aeruginosa strains, vancomycin (VCM), teicoplanin (TEIC) and arbekacin (ABK) for clinical isolates of methicillin-resistant 26 Staphylococcus aureus (MRSA) strains, respectively. The following results were obtained. 1. For 27 P. aeruginosa strains, the synergistic effects were observed with the combination of PZFX and CAZ or MEPM (11.1%: 3 strains), and PZFX and CZOP or PAPM/BP (3.7%: 1 strain), respectively. The additive and synergistic effects of PZFX were observed with the combination in all beta-lactams tested in the strains more than 50%. No antagonistic effect was observed. The additive effects were also observed with the combination of PZFX and AMK or ISP in the strains more than 50% of the test strains and no antagonistic effect was observed. 2. For 26 MRSA strains, no antagonistic effect was observed with the combination of all antibiotics tested. The indifference was observed with the combination of PZFX and VCM or ABK in the strains more than 60%, and the additive effects were observed with the combination of TEIC in the strains more than 80%. In conclusion, no antagonistic effect was observed in PZFX with the combination of beta-lactams and anti-MRSA agents, suggesting that the combination therapy of PZFX with these antibiotics would be possible to use for the infections caused by P. aeruginosa and MRSA.     

Synthesis and effect of silver nanoparticles on the antibacterial activity of different antibiotics against Staphylococcus aureus and Escherichia coli

Silver nanoparticles (Ag-NPs) have been known to have inhibitory and bactericidal effects. Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major health problem. The combination effects of Ag-NPs with the antibacterial activity of antibiotics have not been studied. Here, we report on the synthesis of metallic nanoparticles of silver using a reduction of aqueous Ag(+) ion with the culture supernatants of Klebsiella pneumoniae. Also in this article these nanoparticles are evaluated for their part in increasing the antimicrobial activities of various antibiotics against Staphylococcus aureus and Escherichia coli. The antibacterial activities of penicillin G, amoxicillin, erythromycin, clindamycin, and vancomycin were increased in the presence of Ag-NPs against both test strains. The highest enhancing effects were observed for vancomycin, amoxicillin, and penicillin G against S. aureus.     

Antibacterial activity of hydroxychalcone against methicillin-resistant Staphylococcus aureus

Anti-candidal hydroxychalcone, 2,4,2′-trihydroxy-5′-methylchalcone (THMC), was investigated for its antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). THMC showed the minimum inhibitory concentrations of 25.0–50.0 μg/ml against tested 20 strains, at which the effect was based on a bacteriostatic action. THMC of 25.0 μg/ml completely inhibited the incorporation of radio-labelled thymidine and uridine into MRSA cells. In combination with antibiotics, the fractional inhibitory concentration indices were 0.47 for gentamicin and 0.79 for vancomycin, indicating that THMC acts synergistically with these agents. THMC would be a potent therapeutic agent for MRSA infections.     

香叶醇体外抗MRSA活性研究

目的 通过体外抑菌实验,评价香叶醇单独使用以及与3种β-内酰胺类抗生素(阿莫西林、头孢氨苄及头孢吡肟)联合使用对耐甲氧西林金黄色葡萄球菌(methicillin resistant Staphylococcus aureus, MRSA)的抑制效果。方法 采用微量稀释法测定香叶醇与3种β-内酰胺类抗生素的最低抑菌浓度(minimum inhibitory concentration, MIC)及最低杀菌浓度(minimum bactericidal concentration, MBC);微量棋盘法测定香叶醇与3种β-内酰胺类抗生素的分级抑菌浓度指数(fractional inhibitory concentration, FIC)。结果与结论 香叶醇具有明显的体外抗MRSA活性,MIC和MBC分别为0.34~0.69mg/mL和0.69~10.76mg/mL。联合药敏试验发现香叶醇与3种β-内酰胺类抗生素联合使用FIC指数集中分布在≤0.5和0.5~1;能够增强β-内酰胺类抗生素的活性,降低其用量,使其MIC50和MIC90降低为单独用药的1/8~1/4和1/4~1/2。     

Activity of combinations of ceftazidime, imipenem and pefloxacin against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa

The chequerboard technique was used to look for synergistic combinations of ceftazidime, imipenem and pefloxacin. The synergistic combinations were used in vivo in mice experimentally infected with Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa. In vitro ceftazidime/imipenem, ceftazidime/pefloxacin and pefloxacin/imipenem combinations showed synergistic effects against Staphylococcus aureus and S. typhimurium and additive effects against P. aeruginosa. Only the ceftazidime/pefloxacin combination was synergistic against E. coli while the ceftazidime/imipenem and pefloxacin/imipenem combinations resulted in additive effects. In vivo, combination of ceftazidime/imipenem against E. coli infection and the pefloxacin/imipenem combination against S. typhimurium infection were protective.     

国产米诺环素对耐甲氧西林金葡球菌的体外抗菌活性观察

用琼脂稀释法进行国产米诺环素对１０４株耐甲氧西林金葡球菌（ＭＲＳＡ）和１２０株甲氧西林敏感金葡球菌（ＭＳＳＡ）的抗菌活性研究，并与日本产米诺环素等进行了抗菌作用比较。结果表明国产米诺环素对ＭＲＳＡ和ＭＳＳＡ的抑菌效果，与日本产米诺环素基本一致。对ＭＲＳＡ的ＭＩＣ５０和ＭＩＣ９０前者分别为２和８ｍｇ／Ｌ，而后者分别为２和４ｍｇ／Ｌ。两者对ＭＳＳＡ的ＭＩＣ５０和ＭＩＣ９０均为０．５和４ｍｇ／Ｌ。国产米诺环素与其它６种抗生素比较，除去甲万古霉素外，其对ＭＲＳＡ和ＭＳＳＡ的抗菌效果，均优于头孢唑林等抗生素     

Basis for nebulized antibiotics: droplet characterization and in vitro antimicrobial activity versus Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.

The aims of this study were to (1) quantify the particle size characteristics of several antibiotics considered suitable for aerosol therapy after aerosolization with the PARI IS/2 nebulizer (Pari GmbH, Sarnberg, Germany) and (2) determine the degree to which in vitro antimicrobial activity of these antibiotics is maintained after nebulization. The aerosolized drugs were tobramycin sulfate, streptomycin, and imipenem, with saline solution as the control. Mean mass aerodynamic diameter of the nebulized drugs was 3.25 microns for tobramycin, 2.26 microns for imipenem, and 2.38 microns for streptomycin. In vitro tests showed that tobramycin and imipenem were unaltered in their bacteriostatic activity against strains of Escherichia coli (American Type Culture Collection [ATCC] 25922) and Staphylococcus aureus (ATCC 29213) as well as against Pseudomonas aeruginosa (ATCC 27853) with minimal inhibitory concentration (MIC) values less than 0.3 microgram/mL. Nebulized streptomycin showed significantly higher MIC values against P. aeruginosa (ATCC 27853). These results suggest that tobramycin and imipenem may be prescribed as an aerosol generated by jet nebulization (PARI IS/2) to treat S. aureus, E. coli, and P. aeruginosa infections without any risk of altering the drugs minimum bacteriostatic activity by the nebulization process. Aerosolization of streptomycin with this nebulizer may not be as effective against P. aeruginosa because it seems to alter the bacteriostatic activity.     

绿茶对耐甲氧西林金黄色葡萄球菌的抗菌作用及机制研究进展

泛耐药的出现,使得耐甲氧西林金黄色葡萄球菌(MRSA)感染的治疗成为临床棘手的问题。绿茶提取物对MRSA有一定的抗菌作用。本文就绿茶对MRSA感染的临床试验、与抗生素的协同抗MRSA作用、有效成分的分离分析及作用机制作一综述。     

Synergistic effect of rosmarinic acid with antibiotics against Staphylococcus aureus and MRSA

OBJECTIVE To evaluate the synergistic effect of rosmarinic acid(RA)with antibiotics against Staphylococcus aureus(S.aureus)and MRSA and to identify the possible mechanism of action responsible for synergism if any.METHODS The antibacterial activity of Rosmarinic acid was studied for its zone of inhibition by agar well diffusion and MIC determination by liquid broth dilution technique against MRSA and VRSA.The synergistic effect of RA with antibiotics like amoxicillin,ofloxacin and vancomycin was evaluated by Broth checker board method and further confirmed with time kill kinetic studies.Microbial Surface Components Recognizing Adhesive Matrix Molecules(MSCRAMMs)were isolated by protein precipitation technique and its expression was studied by SDS PAGE.Further RA was evaluated for its beta lactamase inhibition property.RESULTS Rosmarinic acid exhibited antibacterial activity against S.aureus and MRSAby showing a MIC value of 0.8mg·mL-1 against S.aureus and 10mg·mL-1 against MRSA.Rosmarinic acid at 1/4X MIC value reduced the MIC of vancomycin,amoxicillin and ofloxacin by 1/4 times against S.aureus.But against MRSA,vancomycin was found to be synergistic.All the synergistic combinations have shown FIC value of 0.5.In order to measure the kinetics of the anti-bacterial activity,the bacterial growth rate with RA,antibiotics and synergistic combinations against S.aureus and MRSA was studied.It is observed that the synergistic combinations showed better time kill kinetics as compared to RA and antibiotics.Further RA could able to destruct the cell surface proteins MSCRAMMs which was studied by SDS PAGE.RA was also found to showβlactamase inhibiting property.CONCLUSION It is concluded that RA possess antibacterial activity but at a very higher concentration(in mg/mL)against S.aureus and MRSA.However it shows synergism with antibiotics and could able to reduce the MIC of antibiotics.Thus RA could be developed as an adjuvant for antibiotics against S.aureus and MRSA caused infections.Further studies are needed to identify the mechanism for its synergism with antibiotics.     

Synergistic effect of tetrandrine and ethidium bromide against methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) along with other resistant bacteria have become a significant social and clinical problem. Therefore, there is an urgent need to develop bioactive compounds from natural products as alternatives to the very few antibiotics that remain effective. Recently, the efflux mechanism has been identified as the main contributor to antibiotic resistance in bacteria. This study therefore aimed to evaluate tetrandrine (TET), an efflux pump inhibitor (EPI), as a potential antibiotic against MRSA. We investigated the antimicrobial activity of TET against 17 MRSA strains, of which 3 selected strains were studied in further detail using a time-kill assay. When these bacterial strains (1 × 10(6) colony-forming units (cfu)/ml) were incubated with TET in a time-kill assay, log-scale bactericidal activity was observed, which lasted for 24 hr. In addition, TET exhibits a synergistic effect when combined with the multi-drug resistance (MDR)-efflux pump substrate ethidium bromide (EtBr). Structure-function studies of the antibiotic activity of TET in combination with EtBr may lead to the discovery of more effective efflux pump inhibitors.     

Resistance against antimicrobial peptides is independent of Escherichia coli AcrAB, Pseudomonas aeruginosa MexAB and Staphylococcus aureus NorA efflux pumps

The role of clinically important multidrug resistance (MDR) efflux pumps in bacterial resistance to various human antimicrobial peptides (AMPs), including cathelicidin LL-37, the alpha-defensins human neutrophil peptides (HNPs)-1-3 and HD-5 and the beta-defensins hBD-2 and -3, was investigated. AMP susceptibility testing was performed by killing assays and standard minimal inhibitory concentration assays. AMP susceptibility was determined in Escherichia coli and Pseudomonas aeruginosa strains overexpressing resistance-nodulation-cell division (RND)-type pumps AcrAB and MexAB, respectively, and in their pump-deficient parental strains. Furthermore, the impact of a member of the major facilitator (MF) efflux pump family was investigated in Staphylococcus aureus overexpressing NorA and in wild-type strains. The E. coli AcrAB and P. aeruginosa MexAB RND-type efflux pumps as well as the S. aureus NorA MF efflux pump were unable to confer resistance to AMPs. These findings do not support a critical role of MDR efflux pumps in the tested pathogens as a strategy to increase virulence by circumventing the antimicrobial action of innate defence AMPs.     

Neocitreamicins I and II, novel antibiotics with activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci

Two novel antibiotics, neocitreamicins I and II, were isolated from a fermentation broth of a Nocardia strain. This producing strain was obtained using an in situ diffusion chamber that facilitates the cultivation of soil microorganisms. The structures of neocitreamicins I and II were elucidated using UV, MS, and NMR data, and found to be related to the polycyclic xanthone antibiotics of the citreamicin class. The neocitreamicins showed in vitro activity against Gram-positive bacteria including strains of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis.     

Synergistic effect of emodin in combination with ampicillin or oxacillin against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial contributor to morbidity and mortality. In search of a natural products capable of inhibiting this multidrug resistant bacteria, we have investigated the antimicrobial activity of emodin (EM) isolated from Rheum palmatum L. (Polygonaceae) against 17 different strains of the bacterium. New antimicrobial activity was found using the paper disc diffusion method, agar dilution as well as checkerboard method. Against the 17 strains, the disc diffusion test was in the range of 18–30?mm, and the minimum inhibitory concentrations (MICs) of EM were in the range of 1.5–25 μg/mL. From those results we performed the checkerboard test to determine the synergism of EM in combination with ampicillin (AM) or oxacillin (OX) against all strains. The combined activity of EM and two antimicrobial agents (AM, OX) against all strains resulted in a fractional inhibitory concentrations index (FICI) ranging from 0.37–0.5 and from 0.37–0.75, respectively. The effect of EM with AM and OX was found to be synergistic or partially synergistic. We found that EM reduced the MICs of AM and OX. EM and in combination with AM or OX could lead to the development of new combination antibiotics against MRSA infection.     

Synergistic effect of emodin in combination with ampicillin or oxacillin against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial contributor to morbidity and mortality. In search of a natural products capable of inhibiting this multidrug resistant bacteria, we have investigated the antimicrobial activity of emodin (EM) isolated from Rheum palmatum L. (Polygonaceae) against 17 different strains of the bacterium. New antimicrobial activity was found using the paper disc diffusion method, agar dilution as well as checkerboard method. Against the 17 strains, the disc diffusion test was in the range of 18-30?mm, and the minimum inhibitory concentrations (MICs) of EM were in the range of 1.5-25 μg/mL. From those results we performed the checkerboard test to determine the synergism of EM in combination with ampicillin (AM) or oxacillin (OX) against all strains. The combined activity of EM and two antimicrobial agents (AM, OX) against all strains resulted in a fractional inhibitory concentrations index (FICI) ranging from 0.37-0.5 and from 0.37-0.75, respectively. The effect of EM with AM and OX was found to be synergistic or partially synergistic. We found that EM reduced the MICs of AM and OX. EM and in combination with AM or OX could lead to the development of new combination antibiotics against MRSA infection.     

替考拉宁在耐甲氧西林金黄色葡萄球菌所致感染性心内膜炎的应用评价

目的：评价替考拉宁在耐甲氧西林金黄色葡萄球菌（MRSA）所致感染性心内膜炎的应用。方法：通过比较2014-2015年国内外相关指南、共识及《抗菌药物临床应用指导原则（2015年版）》对MRSA所致感染性心内膜炎的推荐方案,提出有争议的问题：替考拉宁是否适用于治疗MRSA所致感染性心内膜炎？通过查询国内外文献,从循证医学证据、替考拉宁在心脏赘生物的分布、给药方案、治疗药物浓度监测等4个方面进行评价。结果：替考拉宁治疗MRSA所致感染性心内膜炎的循证医学证据还很少,有限的证据表明,替考拉宁常规剂量治疗感染性心内膜炎时,出现更高的失败率。定量放射自显影术显示,替考拉宁只分布在心脏赘生物的外围。替考拉宁用于治疗严重感染时,需要优化给药方案,并进行血药浓度监测。目前替考拉宁的治疗药物浓度监测还未广泛开展,不利于替考拉宁用于严重感染的治疗。结论：不推荐替考拉宁用于治疗MRSA所致的感染性心内膜炎。     

Novel pogostone analogous XW-12-loading nanoparticles display enhanced systematic activity against methicillin-resistant Staphylococcus aureus

Pogostone analogous XW-12 displays an inhibitory effect on Staphylococcus aureus. However, the insolubility of the compound has restricted its further applications. This work aims to improve the water-solubility of XW-12, we used previously synthesised pogostone derivatives XW-12, forming nanoparticles with PLGA-PEG by a single-emulsion solvent-evaporation technique. Characterisations of XW-12 nanoparticles were performed. The in vitro and in vivo experiments confirmed its antimicrobial efficacy and toxicity. The results revealed that the XW-12 NPs had a particle size of approximately 200.0?nm, a slower and sustained release. An antibacterial experiment showed that XW-12 NPs had a lower minimal inhibitory concentration value of 1?μg/mL. In the mouse systemic infection model of MRSA, XW-12 NPs indicated high antibacterial activity. In addition, in vivo, toxicity studies declared that XW-12 NPs had a low cytotoxicity. Therefore, this study suggested that XW-12 NPs may be a great potential antibacterial agent in the treatment of clinical MRSA infection.     

Synergistic activity of isepamicin and beta-lactam antibiotics against Pseudomonas aeruginosa in vitro and in vivo

Synergistic activities of isepamicin (ISP) and a beta-lactam antibiotic such as piperacillin (PIPC) or cefotaxime (CTX) against Pseudomonas aeruginosa were demonstrated in vitro and in vivo. In vitro synergistic activity was observed when ISP was used together PIPC or CTX. The synergy observed in vitro was reproduced in vivo against experimental mouse infections, and a ISP-PIPC or a ISP-CTX combination showed significantly greater protective effects than individual antibiotics by themselves.     

Synergistic activity of astromicin and beta-lactam antibiotics against Pseudomonas aeruginosa in vitro and in vivo

Synergistic activity of astromicin and an antipseudomonal beta-lactam antibiotic such as piperacillin, cefsulodin or carbenicillin against Pseudomonas aeruginosa was demonstrated in vitro and in vivo. Synergy in vitro was observed more often when astromicin was combined with piperacillin or cefsulodin than when it was combined with carbenicillin. The combination of astromicin with piperacillin showed a bactericidal activity against Pseudomonas aeruginosa at a bacteriostatic concentration of each antibiotic alone. The synergy observed in vitro was reproduced against experimental mouse infections, and the astromicin-piperacillin or cefsulodin combination produced significantly greater protective effects than the single use of individual antibiotics.     

Estimation of antibacterial activity of various antibiotics against Pseudomonas aeruginosa by score method]

Antibacterial activity of various antibiotics against Pseudomonas aeruginosa isolated from each hospitals depends on the variety or amount of antibiotics used in each hospital. The antibiotic, which is effective to P. aeruginosa in a certain hospital is not always effective to that in other hospital. The excellent antibiotics in antibacterial activity have low MIC and hard to progress in resistance, and such antibiotics may be effective against P. aeruginosa isolated from any hospitals. Therefore we thought that the antibiotic, which was progress to resistance, would show a great difference in MIC among hospitals, and we investigated MIC and difference of MIC of various antibiotics against P. aeruginosa isolated from six hospitals. Furthermore, we converted the data of MICs and difference of MIC among six hospitals into the score, and tried to estimate antibacterial activity of various antibiotics by using those scores. From the results of analysis in this report, we think the antibiotics actually surpass in antibacterial activity may be imipenem, cefozopran, cefsulodin and amikacin. New analytical method proposed in this report will become one of potential methods to estimate antibacterial activity of antibiotics against bacteria isolated from inpatient with bacterial infections.