Abstract：This study aims to evaluate the efficacy of phage therapy against Serratia marcescens infections in mice and to provide the basis of phage therapy applied in bacterial infections. Double－agar overlay plaque method was employed to screen lytic phages from sewage, using Serratia marcescens isolates as hosts. Serratia marcescens strains at minimal lethal dose (MLD) were injected intraperitoneally (i.p.) into BALB/c mice and an i．p. of phage was followed. The survival rate of animals and protective dose of phage were examined at different time points (0, 20, 40, 60 and 180 min) after the bacterial challenge. Pharmacokinetics of phages injected alone or with bacteria was analyzed respectively. The results showed that a lytic phage, designated φSM9－3Y, was isolated and characterized from sewage. Electron microscope revealed that phage φSM9－3Y was in Siphoviridae family, Caudovirales order. After injection of Serratia marcescens isolates, immediate phage therapy at dose of 108 PFU/ml reached a protection rate of 100%. The protection rate was around 60% with a phage therapy (1010 PFU/ml) delivered 60 min after the infection. Pharmacokinetics analysis showed that phage titer in blood was maintained at level of 1010 PFU/ml within 6 h when phages were injected i．p. together with bacteria. These data indicate that phages can save animals from pathogenic Serratia marcescens infection and suggest that phage therapy may be potentially used for the control of bacterial infections.
徐花1，李毅2，逯茵茵1，周佳琦1，韩放1，李诗恒1，孙延波1 . 噬菌体对黏质沙雷菌感染BALB/c小鼠的保护作用[J]. 微生物与感染, 2015, 10(2): 103-107.
XU Hua1, LI Yi2, LU Yin-yin1, ZHOU Jia-qi1, HANG Fang1, LI Shi-hen1, SUN Yan-bo1. Experimental phage therapy against Serratia marcescens infection in BALB/c mice. JOURNAL OF MICROBES AND INFECTIONS, 2015, 10(2): 103-107.