Study On Correlation Between Degree Of Resistance And The Active Efflux Transporters In Acinetobacter Baumannii

Objective To understand the Acinetobacter baumannii strains present situation and levels of the drug resistance in Changsha,to provide the basis for the reasonable clinical application of the antibiotics;To investigate the function and gene expression of active effiux transporters in Acinetobacter baumannii,and initial exploration of the mechanisms of transcription regulation of the active efflux transporters.Methods At first,the susceptibilities of 64 strains clinical Acinetobacter baumannii to 8 kinds of antibiotic agents were tested by disc diffusion method,then these strains were divided into three groups based on the susceptibilities:group A(resistant to 1～2 antibiotics), group B(resistant to 3～5 antibiotic)and group C(resistant to 6～8 antibiotics);The effiux of Rhodamine 6G in these 64 strains of clinical Acinetobacter baumannii was tested and the strains with high increased efflux of Rhodamine 6G were identified;Reverse transcriptase polymerase chain reaction(RT—PCR)was used to measure the mRNA expression levels of active effiux gene adeABC;To explore the mechanisms of overexpression of adeABC,the fragments in adeRS were amplified by PCR and directly sequenced.Results Among the 64 strains,4 were resistant to 1～2 antibiotics (group A),33 strains were resistant to 3～5 antibiotics(group B)and 27 isolates were resistant to 6～8 antibiotics(group C);The efflux of Rhodamine 6G was significantly increased in some multiple resistant strains,and the level of adeABC were also significantly increased;The mutants Val₂₂₈→Ile,Ile₂₄₃→Val in AdeR were discovered in these strains.Conclusionsâ‘ The antibiotic resistance is very popular in Acinetobacter baumannii;â‘¡The multiple resistance of Acinetobacter baumannii is related to the active efflux ability.;â‘¢The elevated expression level of active efflux pump gene may be respond to the increased activity of active efflux in Acinetobacter baumannii;â‘£The substitutions Val₂₂₈→Ile,Ile₂₄₃→Val in AdeR maybe responsible for the overexpression of adeABC.