Fletcher Megan, McCormack Alex, Parcell Benjamin J, Coote Peter J
Biomedical Sciences Research Complex, School of Biology, University of St Andrews, The North Haugh, St Andrews, Fife KY16 9ST, UK.
NHS Tayside, Medical Microbiology, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
Antibiotics (Basel). 2023 Jul 26;12(8):1236. doi: 10.3390/antibiotics12081236.
The aim of this work was to (i) evaluate the efficacy of a combination treatment of pentamidine with ciprofloxacin against larvae infected with an MDR strain of and (ii) determine if pentamidine acts as an efflux-pump inhibitor. Resistant clinical isolates, mutant strains overexpressing one of three RND efflux pumps (MexAB-OprM, MexCD-OprJ, and MexEF-OprN), and a strain with the same three pumps deleted were used. MIC assays confirmed that the clinical isolates and the mutants overexpressing efflux pumps were resistant to ciprofloxacin and pentamidine. The deletion of the three efflux pumps induced sensitivity to both compounds. Exposure to pentamidine and ciprofloxacin in combination resulted in the synergistic inhibition of all resistant strains in vitro, but no synergy was observed versus the efflux-pump deletion strain. The treatment of infected larvae with the combination of pentamidine and ciprofloxacin resulted in enhanced efficacy compared with the monotherapies and significantly reduced the number of proliferating bacteria. Our measurement of efflux activity from cells revealed that pentamidine had a specific inhibitory effect on the MexCD-OprJ and MexEF-OprN efflux pumps. However, the efflux activity and membrane permeability assays revealed that pentamidine also disrupted the membrane of all cells. In conclusion, pentamidine does possess some efflux-pump inhibitory activity, in addition to a more general disruptive effect on membrane integrity that accounts for its ability to potentiate ciprofloxacin activity. Notably, the enhanced efficacy of combination therapy with pentamidine and ciprofloxacin versus MDR strains in vivo merits further investigation into its potential to treat infections via this pathogen in patients.
（i）评估喷他脒与环丙沙星联合治疗对感染多重耐药菌株的幼虫的疗效，以及（ii）确定喷他脒是否作为外排泵抑制剂。使用了耐药临床分离株、过表达三种RND外排泵之一（MexAB - OprM、MexCD - OprJ和MexEF - OprN）的突变菌株，以及缺失相同三种泵的菌株。MIC测定证实临床分离株和过表达外排泵的突变株对环丙沙星和喷他脒耐药。三种外排泵的缺失诱导了对这两种化合物的敏感性。联合暴露于喷他脒和环丙沙星导致体外对所有耐药菌株的协同抑制，但与外排泵缺失菌株相比未观察到协同作用。与单一疗法相比，用喷他脒和环丙沙星联合治疗感染的幼虫提高了疗效，并显著减少了增殖细菌的数量。我们对细胞外排活性的测量表明，喷他脒对MexCD - OprJ和MexEF - OprN外排泵有特异性抑制作用。然而，外排活性和膜通透性测定表明，喷他脒也破坏了所有细胞的膜。总之，喷他脒除了对膜完整性有更普遍的破坏作用外，确实具有一些外排泵抑制活性，这解释了其增强环丙沙星活性的能力。值得注意的是，喷他脒和环丙沙星联合治疗对体内多重耐药菌株的疗效增强，值得进一步研究其在治疗患者中该病原体感染的潜力。
