Figure 4
Δ kbvR immunization induces protection against K. pneumoniae intraperitoneal challenge. Two doses of 105 CFU ΔkbvR strain immunized mice (n = 21) or PBS (n = 19) inoculated normal mice were intraperitoneally infected with 104 (n = 15) or 105 (n = 25) CFU log-phase wild-type strain 2 weeks after the second immunization. A, B Peritoneal lavage fluids of immunized (n = 5) or normal mice (n = 5) were collected, stained, and observed with a microscope at 12 h after being infected with 105 CFU WT. Arrows indicate the bacteria. C, D Number of bacteria in peritoneal washes, liver, spleen, lung, and blood of immunized or normal mice were determined at 12 h after infection with 105 CFU WT. E Survival curves of immunized or normal mice challenged with 104 or 105 CFU WT (n = 7 for each PBS group and n = 8 for each ΔkbvR immunized group) (P < 0.0001).