In vitro analysis of the antibacterial activity of Micafungin against Pseudomonas aeruginosa / 中华检验医学杂志

ABSTRACT

Objectives Selecting and constructing the biofilm -model of Pseudomonas aeruginosa in vitro.Observing the antibacterial activity of using Micafungin alone , or combined with Meropenem against Pseudomonas aeruginosa ( plankton-grown and biofilm-grown ) . Methods Ten clinical isolates of Pseudomonas aeruginosa were collected in July 2012, constructing the biofilm-model by microwell plate from Xiangya Hospital, Central South University.The ability of biofilm-formation of these strains was estimated by crystal violet colorimetric method, and optical microscope was used to observe the shape of the biofilm .MICs of Micafungin and Meropenem against plankton -grown and biofilm-grown Pseudomonas aeruginosa were tested by broth microdilution method, and the changes of MICs were compared.Using broth microdilution method, and connecting with the crystal violet colorimetric method , to observe the antibacterial effect of using Micafungin alone, or combined with antibiotics in the inhibition of the biofilm formation and destruction of mature biofilm of Pseudomonas aeruginosa.SPSS18.0 and t-test were used in comparing the differences between both treatment group and control group.P <0.05 showed the difference was statistically significant . Results Ten strains of Pseudomonas aeruginosa were successful in forming biofilms.Comparing with their planktonic counterparts, biofilms became more resistant to Meropenem , with the MIC raised 4-128 times. However, MIC of Micafungin could not be measured.Micafungin can inhibit the formation of biofilm in 9 experimental strains (PA1-PA9), where the minimum effective concentration of Micafungin were 156.25, 625, 10 000, 2 500, 1 250, 2 500, 1 250, 625 and 10 000 mg/L respectively.The absorbance values of the minimum effective concentration group and its positive growth control group were 0.342 ±0.020 vs 0.491 ±0.027, 0.512 ±0.018 vs 0.627 ±0.043, 0.862 ±0.021 vs 1.155 ±0.027, 0.731 ±0.028 vs 0.863 ± 0.017, 0.311 ±0.003 vs 0.447 ±0.021, 0.435 ±0.021 vs 0.597 ±0.011, 0.520 ±0.012 vs 0.605 ± 0.027, 0.611 ±0.059 vs 0.734 ±0.017, 0.223 ±0.011 vs 0.343 ±0.037 respectively, where the P values were 0.02, 0.03, 0.00, 0.01, 0.01, 0.00, 0.03, 0.01 and 0.03 respectively.The differences are statistically significant.Micafungin can damage the mature biofilm of 7 strains (PA1, PA2, PA4 -PA8), where the minimum effective concentration of Micafungin were 2 500, 2 500, 5 000, 2 500, 5 000, 2 500, 5 000 mg/L respectively.The absorbance values of the minimum effective concentration group and its positive growth control group were 1.459 ±0.014 vs 1.534 ±0.020, 1.279 ±0.020 vs 1.431 ±0.007, 1.365 ±0.024 vs 1.467 ±0.065, 1.322 ±0.028 vs 1.530 ±0.090, 0.920 ±0.004 vs 1.047 ±0.013, 1.860 ±0.005 vs 1.953 ±0.055, 1.407 ±0.005 vs 1.553 ±0.045 respectively, where the P values were 0.01, 0.01, 0.02, 0.01, 0.00, 0.03, 0.02.The difference is statistically significant.Micafungin combined with Meropenem applied in multiple drug resistant strains , which can inhibit the formation of biofilm better.Conclusions Micafungin can inhibit the formation Pseudomonas aeruginosa biofilm and damage the mature biofilms.Micafungin combined with Meropenem can act on multiple drug resistant strain , which may get a higher inhibition rate of the biofilm.