Depletion of multidrug-resistant uropathogenic Escherichia coli BC1 by ebselen and silver ion

Ebselen, an organo-selenium compound with well-characterized toxicology and pharmacology, recently exhibited potent antibacterial activity against glutathione (GSH)-negative bacteria by disrupting redox homeostasis. In this paper, we show that ebselen and silver ion in combination exert strong bactericidal activity against multidrug-resistant (MDR) uropathogenic Escherichia coli (UPEC) BC1, a model MDR GSH-positive bacterium. The mechanisms were found to involve consumption of total intracellular GSH and inhibition of thioredoxin reductase activity, which was highly related to reactive oxygen species up-regulation. Furthermore, the therapeutic efficacy of ebselen and silver ion against UPEC-induced cystitis was assessed in a mouse model. Treatment with ebselen and silver ion significantly reduced bacterial loads, down-regulated the expression levels of tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) on-site and decreased white/red blood cell counts in mild cystitis model mice, which demonstrated the anti-inflammatory property of these agents. In addition, ebselen and silver ion also exhibited significantly high protective ability (100%) against acute cystitis infections. These results together may lay the foundation for further analysis and development of ebselen and silver ion as antibacterial agents for treatment of MDR UPEC infections.