Objective To evaluate bacteriophage therapy for gut-derived sepsis caused by Acinetobacter baumannii in mice.Methods Lyric phages of Acinetobacter baumannii were isolated from environment by using double-layer agar method.A murine model of gut-derived sepsis was established by oral administration of ampicillin-resistant Acinetobacter baumannii and injection of ampicillin and cyclophosphamide into peritoneal cavities of mice.Bacteriophage therapy were given 1 d before infection (group 1),2 d(group 2) and 6 d(group 3) after infection.The survival of the mice was observed,mice without bacteriophage therapy were as control.Independent-sample t test was performed to compare inflammatory cytokines levels in peripheral blood and liver,number of bacteria in liver and spleen between mice with and without bacteriophage therapy.Results The minimal lethal dose of Acinetobacter baumannii for mice with gut-derived sepsis was 1 × 107 CFU/mL.The survival of the mice in group 2 (4/6 survived),which were treated with bacteriophage 2 d after inoculation of Acinetobacter baumannii,was higher than those of group 1 (2/6 survived),group 3 (3/6 survived) and the control group (phage-untreated,0/6 survived).Interleukin (IL)-1 β,tumor necrosis factor (TNF)-α and IL-6 in peripheral blood in mice with bacteriophage therapy were (105 ±6) ng/L,(105 ± 11) ng/L and (104 ± 12)ng/L,which were lower than those in control group (t =5.04,9.05 and 9.33,P ＜ 0.01) ; IL-1 β and TNF-α in liver of mice with bacteriophage therapy were (104 ± 9) ng/L and (104 ± 11) ng/L,which were lower than those in the controls (t =13.70 and 12.80,P ＜0.01),but IL-6 levels were not of statistical difference between therapy and control groups (t =1.06,P ＞ 0.05).Number of bacteria in liver and spleen in mice with bacteriophage therapy were (2.9 ± 1.3) × 103CFU/g and (8.3 ±7.6) × 102 CFU/g,which were also lower than those in control group (t =9.16 and 8.96,P ＜ 0.01).Conclusions Bacteriophage therapy can be effective against gut-derived sepsis caused by Acinetobacter baumannii.