铜绿假单胞菌主要RND外排泵表达与β-内酰胺类抗生素耐药性的相关性研究

Expressions of RND efflux pumps and β-lactams antibiotics resistance in Pseudomonas aeruginosa

目的探讨铜绿假单胞菌4种主要RND外排泵的表达水平与β-内酰胺类抗生素耐药性间关系。方法采用药敏实验检测临床菌株β-内酰胺类抗生素耐药性;构建转录融合报告基因mexA-lacZ、mexC-lacZ、mexE-lacZ和mexX-lacZ,通过测定β-半乳糖苷酶活力,分析和比较4种RND外排泵表达水平的差异,及其表达水平与菌株抗生素耐药性的相关性。结果共检测151株临床菌株,对羧苄西林、替卡西林、氨曲南和头孢他啶的耐药性分别为19.87%、9.93%、2.65%和26.49%。选择耐2种及以上抗生素的菌株23株和对4种抗生素全部敏感的菌株19株,测定β-半乳糖苷酶活力。耐药菌株的mexA、mexC和mexX基因的表达水平与敏感菌株之间的差异有统计学意义(P均<0.05)。多元线性回归分析发现,mexA、mexC和mexX基因的表达水平分别与羧苄西林、替卡西林和氨曲南的抑菌圈直径存在高度或中度负相关性;贝塔权重数据显示mexA基因表达水平是影响羧苄西林(-0.595)、替卡西林(-0.483)和氨曲南(-0.553)3种抗菌素耐药性的主要因素。结论外排泵MexAB-OprM、MexCD-OprJ和MexXY-OprM的表达水平与β-内酰胺类抗生素耐药性存在显著相关性,MexAB-OprM对临床菌株β-内酰胺类抗生素耐药性具有主要影响。

Objective To investigate the relationship between expression of 4 major RND efflux pumps and β-1actams antibiot- ics resistance in Pseudomonas aeruginosa from clinical isolates. Methods β-1actam antibiotic resistances of clinical isolates were de- tected by susceptibility test. Transcription fusion reporter genes mexA-lacZ, mexC-lacZ, mexE-lacZ and mexX-lacZ were constructed and the expressions of 4 RND efflux pumps were measured in clinical strains using β-galactosidase assay. Statistical analyses were performed to analyze differences of the expressions of the 4 major RND efflux pumps and their correlations with antibiotics resistance. Results The resistance rates of carbenicillin, ticarcillin, aztreonam, and ceftazidime were 19.87%, 9.93%, 2.65%, and 26.49% in 151 clinical isolates, respectively. Among them, 23 isolates resistant to at least two kinds of antibiotics and 19 susceptible isolates sensi- tive to 4 kinds of antibiotics were selected and their ]3-galactosidase activities were measured. The expression of drug resistant isolates mexA （P〈0.001）, mexC （P=-0.043）, and mexE （P=0.002） were found significantly different from those of susceptible isolates. Multiple linear regression analysis showed the high or moderate negative correlations between the expression ofmexA, mexC and mexE and the diameters of inhibition circles of carbenicillin, ticarcillin, and aztreonam. Beta coefficients showed that the expression of gene mexA played the key role responsible for drug resistance to carbenicillin （-0.595）, tiearcillin （-0.483）, and aztreonam （-0.553）. Conclusions The expression levels of MexAB-OprM, MexCD-OprJ, and MexXY-OprM are significantly correlated with the β-1actams antibiotics resistance and MexAB-OprM is the main cause to the resistance.