Identification of a novel antibacterial compound 1-((2,4-dichlorophenethyl)amino)-3-phenoxypropan-2-ol active against persisters of Pseudomonas aeruginosa [PublishAheadOfPrint]

Antibiotics typically fail to completely eradicate a bacterial population, leaving a small fraction of transiently antibiotic-tolerant persister cells intact. Persisters are therefore seen as a major cause of treatment failure and greatly contribute to the recalcitrant nature of chronic infections. The current report is focused on Pseudomonas aeruginosa, a Gram-negative pathogen belonging to the notorious ESKAPE group and, due to an increasing resistance against most conventional antibiotics, posing a serious threat to human health. Greatly contributing to the difficult treatment of P. aeruginosa infections is the presence of persister cells and elimination of these cells would therefore significantly improve patient outcome. In this study, a small-molecule library was screened for compounds that, in combination with the fluoroquinolone antibiotic ofloxacin, reduced the number of P. aeruginosa persisters as compared to treatment with the antibiotic alone. Based on early structure-activity relationship, 1-((2,4-dichlorophenethyl)amino)-3-phenoxypropan-2-ol (SPI009) was selected for further characterization. Combination of SPI009 with mechanistically distinct classes of antibiotics reduced the number of persisters up to 10⁶-fold in both lab strains and clinical isolates of P. aeruginosa. Further characterization of the compound revealed a direct and efficient killing of persister cells. SPI009 caused no erythrocyte damage and demonstrated minor cytotoxicity. In conclusion, we identified a novel anti-persister compound active against P. aeruginosa with promising applications for the design of novel, case-specific combination therapies in the fight against chronic infections.

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