26
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      In vitro antibacterial activity of combinations of fosfomycin, minocycline and polymyxin B on pan-drug-resistant Acinetobacter baumannii

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          The aim of this study was to determine the effects of combinations of fosfomycin, minocycline and polymyxin B in the treatment of pan-drug-resistant Acinetobacter baumannii (PDR-Ab). The in vitro antibacterial activities of the drugs were evaluated by determination of the minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index (FICI). A total of 25 strains of PDR-Ab were selected using the VITEK32 microbial analysis instrument and the Kirby-Bauer (K-B) method. A broth microdilution method was used to determine the MIC for each of the three drugs, and the checkerboard method was simultaneously used to determine the MICs for combinations of the drugs. FICI values were also calculated. While fosfomycin alone was ineffective for the treatment of PDR-Ab, its MIC value was significantly reduced when used in combination with minocycline or polymyxin B. The combined use of minocycline and polymyxin B also significantly reduced the MIC value of each drug. The FICI values revealed that the drugs had synergistic or additive effects when used in combination. The determination of the MIC and FICI values for the combinations of drugs demonstrated that there is synergistic or additive effect upon the combined use of fosfomycin with minocycline or polymyxin B. The combined use of minocycline and polymyxin B also results in a significant reduction in the MIC values of the two drugs. These experimental results may provide a basis for the future clinical treatment of Acinetobacter baumannii.

          Related collections

          Most cited references 9

          • Record: found
          • Abstract: found
          • Article: not found

          Synergy testing by Etest, microdilution checkerboard, and time-kill methods for pan-drug-resistant Acinetobacter baumannii.

          Pan-drug-resistant (PDR) Acinetobacter baumannii is an important nosocomial pathogen that poses therapeutic challenges. Tigecycline alone or in combination with agents such as colestimethate, imipenem, and/or amikacin is being used clinically to treat PDR A. baumannii infections. The purpose of this study was to compare in vitro susceptibility testing by epsilometric (Etest) methods and the checkerboard (CB) method with testing by time-kill analysis. PDR A. baumannii clinical strains representing eight unique pulsed-field gel electrophoresis clones selected from a total of 32 isolates were tested in vitro with tigecycline, colestimethate, imipenem, and amikacin in single- and two-drug combinations by using two different methods of Etest (with a fixed ratio method [method 1] and with the incorporation of the active drug in medium [method 2]) and by using CB. The three-drug combination of imipenem, tigecycline, and amikacin was also tested by CB. These results were compared to time-kill results. Synergy was consistently detected with the imipenem plus colestimethate and tigecycline plus imipenem combinations. The Etest method with active drug incorporated into the agar allowed us to detect synergy even in the presence of the active drug and was more comparable to CB and time-kill tests. Synergy was detected with the three-drug combination of imipenem, tigecycline, and amikacin by both CB and time-kill methods among several tested clones. These findings indicate the utility of synergy testing to predict activity of specific antibiotic combinations against PDR A. baumannii.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: found
            Is Open Access

            Activities of colistin- and minocycline-based combinations against extensive drug resistant Acinetobacter baumannii isolates from intensive care unit patients

            Background Extensive drug resistance of Acinetobacter baumannii is a serious problem in the clinical setting. It is therefore important to find active antibiotic combinations that could be effective in the treatment of infections caused by this problematic 'superbug'. In this study, we analyzed the in vitro activities of three colistin-based combinations and a minocycline-based combination against clinically isolated extensive drug resistant Acinetobacter baumannii (XDR-AB) strains. Methods Fourteen XDR-AB clinical isolates were collected. The clonotypes were determined by polymerase chain reaction-based fingerprinting. Susceptibility testing was carried out according to the standards of the Clinical and Laboratory Standards Institute. Activities of drug combinations were investigated against four selected strains and analyzed by mean survival time over 12 hours (MST12 h) in a time-kill study. Results The time-kill studies indicated that the minimum inhibitory concentration (MIC) of colistin (0.5 or 0.25 μg/mL) completely killed all strains at 2 to 4 hours, but 0.5×MIC colistin showed no bactericidal activity. Meropenem (8 μg/mL), minocycline (1 μg/mL) or rifampicin (0.06 μg/mL) did not show bactericidal activity. However, combinations of colistin at 0.5×MIC (0.25 or 0.125 μg/mL) with each of the above were synergistic and shown bactericidal activities against all test isolates. A combination of meropenem (16 μg/mL) with minocycline (0.5×MIC, 4 or 2 μg/mL) was synergitic to all test isolates, but neither showed bactericidal activity alone. The MST12 h values of drug combinations (either colistin- or minocycline-based combinations) were significantly shorter than those of the single drugs (p < 0.01). Conclusions This study indicates that combinations of colistin/meropenem, colistin/rifampicin, colistin/minocycline and minocycline/meropenem are synergistic in vitro against XDR-AB strains.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              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.
                Bookmark

                Author and article information

                Journal
                Exp Ther Med
                Exp Ther Med
                ETM
                Experimental and Therapeutic Medicine
                D.A. Spandidos
                1792-0981
                1792-1015
                June 2013
                02 April 2013
                02 April 2013
                : 5
                : 6
                : 1737-1739
                Affiliations
                [1 ]Departments of Infectious Diseases, Shandong 250012, P.R. China
                [2 ]Laboratory Medicine, Qilu Hospital, Shandong University, Jinan, Shandong 250012, P.R. China
                Author notes
                Correspondence to: Professor Lixian Ma, Department of Infectious Diseases, Qilu Hospital, Shandong University, 107 Wenhua West Road, Jinan, Shandong 250012, P.R. China, E-mail: malx123456@ 123456163.com
                Article
                etm-05-06-1737
                10.3892/etm.2013.1039
                3702694
                23837064
                Copyright © 2013, Spandidos Publications

                This is an open-access article licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. The article may be redistributed, reproduced, and reused for non-commercial purposes, provided the original source is properly cited.

                Categories
                Articles

                Comments

                Comment on this article