This study was designed to evaluate the synergistic effect of phage (P22) and antibiotic on the inhibition of Salmonella Typhimurium exposed to ceftriaxone (CEF) and ciprofloxacin (CIP). The effect of phage and antibiotic treatments was evaluated by plaque size, disk diffusion, antibiotic susceptibility and phage multiplication assays. The sequential treatment effect of phage and antibiotic was carried out in different treatment order and time for 12 h at 37°C. P22 plaque sizes were increased by 28 and 71%, respectively, in the presence of CEF and CIP. The clear zone sizes in disk diffusion assay were significantly increased to >37 mm in the presence of CEF and CIP compared to the control (28–31 mm). Pre-treatment with P22 enhanced the antimicrobial effect of CIP, showing >2 log reduction after a 12 h incubation. Phage P22 combined with antibiotics (CEF and CIP) effectively inhibited the growth of S. Typhimurium depending on the treatment order and time. These results provide useful information for understanding the synergistic effect of phage and antibiotic treatment which can be an effective option to control antibiotic resistant pathogens.

中文翻译：

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亚致死浓度的头孢曲松和环丙沙星对噬菌体对鼠伤寒沙门氏菌的抑制作用评估

本研究旨在评估噬菌体（P22）和抗生素对沙门氏菌抑制的协同作用。鼠伤寒暴露于头孢曲松（CEF）和环丙沙星（CIP）。通过噬斑大小，盘扩散，抗生素敏感性和噬菌体增殖测定法评估噬菌体和抗生素治疗的效果。噬菌体和抗生素的顺序治疗效果在37℃下以不同的处理顺序和时间进行了12小时。在存在CEF和CIP的情况下，P22斑块的大小分别增加了28％和71％。与对照组（28-31 mm）相比，在CEF和CIP的情况下，椎间盘扩散测定法中的透明区大小显着增加至> 37 mm。用P22预处理可增强CIP的抗菌作用，在孵育12小时后显示> 2 log减少。噬菌体P22与抗生素（CEF和CIP）联合有效抑制S的生长。鼠伤寒取决于治疗顺序和时间。这些结果为理解噬菌体和抗生素治疗的协同效应提供了有用的信息，这可能是控制抗生素耐药病原体的有效选择。