摘要
目的:探讨铜绿假单胞菌(Pseudomonas aeruginosa,Pa)的耐药机制及其耐药性与外排泵表达水平关系。方法:PCR法对30株铜绿假单胞菌进行MexB基因检测;采用实时荧光定量PCR的方法检测MexAB-OprM的mRNA相对表达水平;对多重耐药铜绿假单胞菌采用琼脂对倍稀释法进行外排泵抑制剂的抑制试验,观察抗菌药物的MIC变化。结果:联合外排泵抑制剂后,庆大霉素(GEN)和环丙沙星(CIP)MIC值与之前相比大部分有2个折点的变化,有4株MPa的MIC值有4个折点以上的变化,但总体耐药率差异无统计学意义(P>0.05);30株多重耐药Pa株中,均存在外排泵Mex-AB-OprM的高表达,多重耐药菌组外排泵表达量达敏感组的36.5倍。当外排泵抑制剂CCCP浓度为7.5μg/ml时,庆大霉素(GEN)、环丙沙星(CIP)、四环素(TET)MIC值不变或增加的菌株(≥1MIC组)与MIC值减小的菌株(≤1/2MIC组)的外排泵相对表达量之间有着显著性的差异(P<0.05),而头孢噻肟(CTX)MIC值不变或增加的菌株(≥1MIC组)与MIC值减小的菌株(≤1/2MIC组)的外排泵相对表达量之间无显著性的差异(P>0.05)。结论:外排泵MexAB-OprM在多重耐药铜绿假单胞菌临床分离株中起着十分重要的作用,MexAB-OprM的高表达与多重耐药Pa菌庆大霉素、环丙沙星的耐药性有着密切关系,可能起着基础性耐药作用,但其对头孢噻肟的耐药性影响较小。其高表达还与庆大霉素、环丙沙星、四环素的耐药有着直接的量的关系,具体机制有待进一步的研究。
Objective：To study the effect of efflux pump inhibitors（CCCP） on several antibiotic in multidrug resistant Pseudomonas aeruginosa（P.aeruginosa） clinical isolates and investigate the association between the resistance to antibiotic or mechanism and expression levels of efflux pump of P.aeruginosa.Methods：MexB gene of 30 strains were detected by PCR;The mRNA expression levels of efflux pump gene（MexB） were quantified by real time fluorescent quantitative PCR;MICs of antibiotic combined with efflux pump inhibitors（CCCP） against multiple resistant strains were determined by agar dilution method,and changes of MICs were observed.Results：Combined with efflux pump inhibitors（CCCP）,the MICs of gentamicin（GEN）and ciprofloxacin（CIP） was downregulated for 2-fold in most isolates,even significantly for 4-fold or more in four isolates.But the resistant rate didn′t prove any significant difference（P0.05）.Overexpression of efflux pump（MexAB-OprM） gene were present in all of the 30 isolates,and the group of Multidrug Resistance isolates were about 36.5 times more than the group of the sensitive isolates.When the concentration of CCCP were 7.5 μg/ml,with regard to Gentamicin（GEN）,ciprofloxacin（CIP）,tetracycline（TET）,there is significant differences between the MICs of strains of the same or increased（≥1MIC group） and the MICs of strains decreased（≤1/2MIC group） on the relative expression of efflux pump（P0.05）.However,in regard to cefotaxime（CTX）,there is no significant differences between the MICs of strains of the same or increased（≥1MIC group） and the MICs of strain decreases（≤1/2MIC group） on the relative expression of efflux pump（P0.05）.Conclusion：Efflux pump MexAB-OprM plays an important role in the clinical isolates of multi-drug resistant Pseudomonas aeruginosa.There was a strong relationship between overexpression of efflux pump（MexAB-OprM） gene and the resistance of Mpa to Gentamicin and ciprofloxacin,maybe a basic or intrinsic mechanism.But a little influence to cefotaxime.And there is also a direct amount relationship between the relative expression of efflux pump of MexAB-OprM and the resistant to Gentamicin.ciprofloxacin and tetracycline,Details need to be explored in the future.
出处
《中国卫生检验杂志》
CAS
2010年第4期830-833,共4页
Chinese Journal of Health Laboratory Technology
