多重耐药因子A在临床菌株中的检测与分析

Detection and analysis of the multi-drug resistant regulator A in the clinical isolates

目的调查大肠埃希菌临床菌株中多重耐药因子A(MarA)的表达情况,并分析其与第3、4代头孢菌素耐药的关系。方法随机抽取2003至2009年间大肠埃希菌49株,采用实时定量逆转录聚合酶链反应(RT-PCR)检测外膜孔通道蛋白F(OmpF)的反义RNA-F因子(MicF)、主动外排系统AB(AcrAB)和MarA的相对表达量,纸片扩散法检测抗菌药物的敏感性。结果 49株大肠埃希菌中,7株(14.29%)AcrAB转录水平上调;13株(26.53%)膜孔蛋白MicF转录水平上调;11株(22.45%)MarA转录水平上调;3种耐药因素同时升高的有2株。49株大肠埃希菌对头孢噻肟、头孢他啶和头孢吡肟的耐药率依次为79.59%、75.51%和51.02%,其中AcrAB表达升高组对此3种抗菌药物的耐药率依次为100.00%、100.00%和57.14%,MicF表达升高组为80.00%、86.67%和53.33%,MarA表达升高组为75.00%、100.00%和58.33%,3种耐药因素同时存在时耐药率则均为100.00%。结论 MarA在大肠埃希菌临床菌种中起到一定的调控AcrAB和膜孔蛋白MicF的作用,当MarA同时调控二者高表达时可引起耐药率大幅升高。

Objective To detect the expression of muhi-drug resistant regulator A （MarA） in Escherichia coli, and to analyze the relationship of MarA with the resistance to 3rd and 4th generation cephalosporin. Methods A total of 49 isolates of Escherichia coli between 2003 and 2009 were collected randomly. Real-time quantitation reverse transcription polymerase chain reaction （RT-PCR） was used to detect the expression levels of anti-putative outer membrane porin F protein （OmpF） antisense RNA-F （MicF）,efflux pump AB （AcrAB） and MarA. The antibiotic sensitivity was also analyzed by disk diffusion method. Results Among the 49 isolates of Escherichia coli,7 of 49 isolates （14.29%） had high AcrAB transcription level, 13 of 49 isolates （26.53 % ） had MicF transcription level, 11 of 49 isolates （ 22.45% ） had high MarA transcription level, and 2 isolates had the 3 resistant factors simultaneously with increasing level. The resistance rates to cefotaxime, ceftazidime and cefepime were 79. 59%, 75. 51% and 51. 02%. The increasing expression level of AerAB group showed that the resistance rates to these 3 antibiotics were 100.00% , 100.00% and 57.14% ,respectively. The increasing expression level of MieF group showed that the resistance rates to these 3 antibiotics were 80.00% ,86.67% and 53.33% , respectively. The increasing expression level of MarA group showed that the resistance rates to these 3 antibiotics were 75.00% , 100.00% and 58.33% , respectively. The resistance rate increased to 100.00% ,when all the 3 resistant factors existed simultaneously. Conclusions MarA plays an important role in regulating the expressions of AcrAB and MicF. The increasing expression levels of AcrAB and MicF regulated by MarA will lead to high resistance rate to antibiotics.