Correlation between biofilm formation and efflux pump gene AdeABC expression in carbapenem resistant Acinetobacter baumannii
Objective To study the formation of biofilm in Acinetobacter baumannii and the effect of the relative expression level of the efflux pump gene AdeABC on the resistance mechanism of carbapenem antibiotics in both planktonic and biofilm states.Methods The strains were divided into the carbapenem-resistant Acinetobacter baumannii(CRAB)group and the carbapenem-sensitive Acinetobacter baumannii(CSAB)group by drug sensitivity testing,and the biofilm formation ability of the two groups was detected using the crystal violet staining method.The MIC and MBIC values of two groups of imipenem using the micro broth dilution method were measured,and the MBIC/MIC ratio was calculated to further compare and analyze the drug resistance of biofilm bacteria compared to planktonic bacteria.Simultaneously,RNA from both planktonic and biofilm states of the CRAB group was extracted,and the relative expression level of the efflux pump gene AdeABC through RT-qPCR was detected.Results The positive rate of biofilm in 35 specimens was 91.43％,of which the positive detection rate of biofilm in the CRAB group was 92％.The negative,weakly positive,positive,and strongly positive biofilms accounted for 8％,48％,36％,and 8％,respectively.The MBIC/MIC ratio showed that after the formation of biofilm,the resistance of Acinetobacter baumannii increased to varying degrees,with the CSAB group showing the most significant increase in resistance compared to strains with a 2-fold increase;The increase in CRAB group was highest among strains with a 4-fold increase.At the same time,the RT-qPCR results of the CRAB group showed that the relative expression levels of the efflux pump genes adeA and adeB were significantly increased compared to the planktonic state of the biofilm(P＜0.01),while the relative expression levels of the efflux pump gene adeC were not significantly different(P＞0.05).Conclusion The carbapenem resistance of Acinetobacter baumannii was closely related to biofilm,and the biofilm state of Acinetobacter baumannii could promote the expression of the efflux pump gene AdeABC compared to the floating state,thereby enhancing the resistance of carbapenem antibiotics.
万方数据
维普
