Role of the efflux proteins in multidrug resistant Haemophilus influenzae

在这项研究中，我们试图确定acrAB外排系统在多重耐药流感嗜血杆菌中的作用。我们获得了acrAB类基因缺失突变体，以研究外排蛋白在抗H.流感。14元和15元大环内酯类药物对这些突变体的MIC比对亲本菌株的敏感性高4至16倍。另一方面，16元大环内酯类对这些突变体的MIC比对亲本菌株的敏感性高32至64倍。一种与H.流感尚未得到确切的鉴定。因此，我们利用计算机对H.流感病毒，并最终发现HI 1462蛋白。然后将卡那霉素抗性盒插入到HI 1462基因中，得到HI 1462的破坏突变株。大环内酯类和氨基糖苷类抗生素对H.流感病毒的MIC与HI 0894-和HI 0895-缺失突变体的MIC完全相似。我们制备了AcrAB和HI 1462蛋白的抗体，以检测其在临床分离的H.流感。我们的研究表明AcrAB-HI 1462系统在H.流感ATCC以及野生型菌株。在野生型菌株中表达该外排系统仅产生MIC的小幅增加。然而，这并不意味着这种多药外排系统永远不会对生物体的耐药表型做出重大贡献。

In this study, we tried to determine the role of this acrAB efflux system in the multidrug resistant Haemophilus influenzae. We obtained the acrAB-like gene disruption mutants to study the function of efflux proteins in the resistance of H. influenzae. The MICs of 14- and 15-membered macrolides against these mutants are 4 to 16-fold more susceptible than against parent strain. On the other hand, the MICs of 16-membered macrolides against these mutants are 32 to 64-fold more susceptible than against parent strain. An outer membrane protein associated with the AcrAB system in H. influenzae has not yet been firmly identified. Therefore, we checked the outer membrane protein by computer analysis of whole genome of H. influenzae, and finally found HI1462 protein. And then we got HI1462 disrupted mutant by inserting the kanamycin resistance cartridge into HI1462 gene. The MICs of macrolide and aminoglycoside antibiotics against HI1462 disrupted mutant of H. influenzae are completely similar to MICs of both HI0894- and HI0895-deletion mutants. We made the antibody against AcrAB and HI1462 proteins to examine the expression in clinical isolates of H. influenzae. Our study showed that AcrAB-HI1462 system is normally expressed in H. influenzae ATCC and also wild-type strains. The expression of this efflux system in the wild-type strains produced only a small increase in the MIC. This does not mean, however, that this multidrug efflux system can never make a major contribution to the resistance phenotypes of the organism.