BACKGROUND An increasing rate of antibiotic resistance among Gram-negative bacterial pathogens has created an urgent need to discover novel therapeutic agents to combat infectious diseases. Use of bacteriocins as therapeutic agents has immense potential due to their high potency and mode of action different from that of conventional antibiotics. RESULTS In this study, a novel bacteriocin E20c of molecular weight 6.5 kDa was purified and characterized from the probiotic strain of Enterococcus hirae. E20c had bactericidal activities against several multidrug resistant (MDR) Gram-negative bacterial pathogens. Flow cytometry and scanning electron microscopy studies showed that it killed the Salmonella enterica cells by forming ion-permeable channels in the cell membrane leading to enhanced cell membrane permeability. Further, checkerboard titrations showed that E20c had synergistic interaction with antibiotics such as ampicillin, penicillin, ceftriaxone, and ciprofloxacin against a ciprofloxacin- and penicillin-resistant strain of S. enterica. CONCLUSION Thus, this study shows the broad spectrum antimicrobial activity of novel enterocin E20c against various MDR pathogens. Further, it highlights the importance of bacteriocins in lowering the minimum inhibitory concentrations of conventional antibiotics when used in combination.

中文翻译：

---

从平肠肠球菌20c中纯化的新型肠球菌E20c与ß-内酰胺和环丙沙星协同抗肠沙门氏菌。

背景技术革兰氏阴性细菌病原体中抗生素抗性的增加率已经迫切需要发现新的治疗剂来抵抗传染病。细菌素作为治疗剂的应用具有巨大的潜力，因为它们的功效和作用方式与常规抗生素不同。结果在本研究中，从平肠肠球菌的益生菌菌株中纯化并鉴定了分子量为6.5 kDa的新型细菌素E20c。E20c具有针对多种耐多药（MDR）革兰氏阴性细菌病原体的杀菌活性。流式细胞仪和扫描电子显微镜研究表明，它通过在细胞膜上形成离子渗透通道杀死了沙门氏菌，从而增强了细胞膜的渗透性。进一步，棋盘滴定显示，E20c与抗环丙沙星和青霉素的肠炎链球菌菌株具有协同作用，例如氨苄青霉素，青霉素，头孢曲松和环丙沙星。结论因此，本研究显示了新型肠球菌E20c对多种MDR病原体的广谱抗菌活性。此外，它突出了结合使用细菌素在降低常规抗生素的最低抑菌浓度中的重要性。