Title: Study on in vitro antibacterial activity of the combined therapy of imipenem with polymyxin B against Pseudomonas aeruginosa with different phenotypes
Abstract: Objective To investigate the in vitro antibacterial activity of the combined therapy of imipenem with polymyxin B against Pseudomonas aeruginosa with different phenotypes.Methods A total of 133 clinically isolated Pseudomonas aeruginosa were collected from Renji Hospital(West Department) and Ruijin Hospital,and the phenotypes were determined by disc diffusion(K-B) method.The minimum inhibitory concentrations(MIC) of imipenem,polymyxin B and imipenem with polymyxin B against Pseudomonas aeruginosa were calculated by agar dilution method,and the fractional inhibitory concentrations(FIC) were calculated.The combined effect was analyzed.There were 2 ratios,1∶ 0.5 and 1∶ 1 with imipenem to polymyxin B.Results The drug sensitivities of those 2 therapies turned out to be inconsistent when conducting Kappa test.The synergistic rate of 1∶ 1 with imipenem to polymyxin B was 51.13%,which was much higher than 1∶ 0.5 with imipenem to polymyxin(19.55%).Fisher′s exact test demonstrated that 1∶ 1 with imipenem to polymyxin B maintained high synergistic rate between different phenotypes,and there was no statistically significant difference.However,the difference was significant regarding to 1∶ 0.5 with imipenem to polymyxin B.Conclusions Comparing with monotherapy,the combined therapy of imipenem with polymyxin B significantly increases the sensitivity of Pseudomonas aeruginosa in vitro.The combined therapy applying 1∶ 1 with imipenem to polymyxin B with a higher synergistic rate than that applying 1∶ 0.5 with imipenem to polymyxin B and a good stability may be a good choice for the antibiotics resistant Pseudomonas aeruginosa with different phenotypes.
Publication Year: 2013
Publication Date: 2013-01-01
Language: en
Type: article
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