Abstract
Objective:Enterococci have been isolated frequently worldwide and have difficulties in the treatment. Combination antibiotherapies have a distinct advantage over monotherapies in terms of their synergistic effect. In the study, it was aimed to investigate in vitro activity of vancomycin combined with fosfomycin against VRE strains.Methods:A total of 30 VRE strains were included in the study. Bacterial identifications of the strains were undertaken using conventional routine methods. The resistance to agents tested was investigated by using the broth microdilution method. Glucose-6-phosphate (25 mcg/mL) for fosfomycin were used in all experiments. The activity of antibiotics in combination was assessed using a broth microcheckerboard. The fractional inhibitory concentration index (FICI) was interpreted as follows: synergism, FICI ≤0.5. Additionally, two strains in 30 VRE were studied to determine the time-kill curves to verify the synergistic results. For each strain, antibiotics were studied alone and in combination at the minimum inhibitory concentration (1xMIC) values.Results:Susceptibility rate to fosfomycin was found at 26.6 % (8/30). The MIC50, MIC90 and MIC interval values of antimicrobials were 512, 512, and 512 - 1024 mcg/mL for vancomycin, and 128, 160, and 64 - 224 mcg/mL for fosfomycin, respectively. The rate of synergism was found as 100 % by both checkerboard and time-kill methods.Conclusion:The result shows that the combination of vancomycin with fosfomycin could be an alternative in the treatment of infections caused by VRE.
Highlights
Enterococci cause serious infections in society, and in hospitalised patients.[1]
Vancomycin-resistant enterococci associated infections have been increasing in recent years despite the coming into use of the new antimicrobials in the treatment of infections caused by the pathogen bacteria with multiple antibiotic resistance
In accordance with the obtained minimum inhibitory concentration (MIC) values with broth microdilution, all VRE strains were found resistant to vancomycin, and 8 strains (26.6%) were found sensitive to fosfomycin because the fosfomycin MIC values were found as MIC ≤ 64 mcg/mL
Summary
Enterococci cause serious infections in society, and in hospitalised patients.[1] In addition, entorocci. 1. Gulseren Aktas Ph.D. Department of Medical Microbiology, Faculty of Medicine, Istanbul University, Istanbul-Turkey. Correspondence: July 12, 2019 October 31, 2019 November 3, 2019 are the problematic bacteria due to their natural resistance to some of the frequently used antibiotics and due to antibiotic resistance as a consequence of genetic material inheritance or mutations.[2,3]. Vancomycin-resistant enterococci associated infections have been increasing in recent years despite the coming into use of the new antimicrobials in the treatment of infections caused by the pathogen bacteria with multiple antibiotic resistance. The number of antimicrobial agents to be used in treatment is limited.
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