Figure 6

Killing effects of phage treatment. (A) Killing effects of phage treatment and capsule depolymerase treatment on the Klebsiella strains. The K9534 and its capsule deletion mutant strains were incubated with the K5-4 phage (multiplicity of infection, 1000) and 10 μg K5 depolymerase. The survival bacterial counts after 30 minutes compared with initial counts were represented by the survival ratio from 3 independent experiments (mean ± standard deviation [SD]). **P < 0.01 by Student’s t test (compared to enzyme-treated group). (B) The Klebsiella reference K8, K30 and K69 strains were incubated with the K5-4 phage, K5-2 phage (multiplicity of infection, 1000) and 10 μg CPS depolymerase, respectively. The survival bacterial counts after 30 minutes compared with initial counts were represented by the survival ratio from 3 independent experiments (mean ± standard deviation [SD]). ^* P < 0.05 by Student’s t test (compared to enzyme-treated group). (C) Treatment efficacy of the phage K5-4 in mice. Groups of ten infected mice received either no phage or a single dose of the K5-4 phage administered intraperitoneally 4 h after the K. pneumoniae NTUH-K9534 infection. Treatment with the K5-4 phage (P < 0.0001; log–rank test) significantly increased the survival of mice infected with the NTUH-K9534.