Molecular basis of azithromycin-resistant Pseudomonas aeruginosa biofilms
Molecular basis of azithromycin-resistant Pseudomonas aeruginosa biofilms
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DOI：
10.1128/aac.49.9.3858-3867.2005
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发表时间：
2005-09-01
影响因子：
4.9
通讯作者：
Iglewski, BH
中科院分区：
文献类型：
--
作者：
Gillis, RJ;White, KG;Iglewski, BH
铜绿假单胞菌生物被膜对抗生素治疗极为不利。阿奇霉素（AZM）治疗囊性纤维化患者已显示出希望。我们使用DNA微阵列来鉴定暴露于2 μ g/ml AZM的铜绿假单胞菌生物膜中差异表达的转录物。我们报告说，转录的多限制-增殖-细胞分裂（RND）外排泵，已知参与抗生素耐药性，和转录参与III型分泌上调的耐药生物膜中的存在下开发的AZM。有趣的是，MexAB-OprM和MexCD-OprJ外排泵，而不是III型分泌，似乎是在AZM存在下生物膜形成的组成部分，如在mexAB-oprM和mexCD-oprJ两者中缺失的突变体在AZM存在下不能形成生物膜的事实所证明的。III型分泌缺失的突变体在药物存在下仍然能够形成生物膜。此外，单个mexAB-oprM-和mexCD-opJ-无效突变体能够在药物存在下形成生物膜，表明在生物膜发育期间，任一泵都可以赋予对AZM的抗性。与无张力生长的细胞相反，无论AZM的存在与否，都检测不到mexC表达，生物膜从它们形成的一开始就表现出mexC表达的诱导，但仅在AZM存在下。mexA，这是组成型表达的细胞中，均匀地表达在生物膜中，无论AZM的存在。这些数据表明MexCD-OprJ泵作为AZM抗性的生物膜特异性机制。
Pseudomonas aeruginosa biofilms are extremely recalcitrant to antibiotic treatment. Treatment of cystic fibrosis patients with azithromycin (AZM) has shown promise. We used DNA microarrays to identify differentially expressed transcripts in developing P. aeruginosa biofilms exposed to 2 mu g/ml AZM. We report that transcripts for multiple restriction-nodulation-cell division (RND) efflux pumps, known to be involved in planktonic antibiotic resistance, and transcripts involved in type III secretion were upregulated in the resistant biofilms that developed in the presence of AZM. Interestingly, the MexAB-OprM and MexCD-OprJ efflux pumps, but not type III secretion, appear to be integral to biofilm formation in the presence of AZM, as evidenced by the fact that a mutant deleted in both mexAB-oprM and mexCD-oprJ was unable to form a biofilm in the presence of AZM. A mutant deleted in type III secretion was still able to form biofilms in the presence of drug. Furthermore, single mexAB-oprM- and mexCD-opJ-null mutants were able to form a biofilm in the presence of drug, indicating that either of the pumps can confer resistance to AZM during biofilm development. In contrast to planktonically grown cells, where no mexC expression was detectable regardless of the presence of AZM, biofilms exhibited induction of mexC expression from the outset of their formation, but only in the presence of AZM. mexA, which is constitutively expressed in planktonic cells, was uniformly expressed in biofilms regardless of the presence of AZM. These data indicate that the MexCD-OprJ pump acts as a biofilm-specific mechanism for AZM resistance.