FIG 1.

K. pneumoniae colonizes the gut of immunocompetent mice without the need for antibiotic pretreatment. (A) Weight loss of mice infected with different doses of Kp52145 over 12 days. 4 to 6 mice were included in each group, except in the group infected with 3 × 10⁸ CFU, in which three mice died within 5 days postinfection. (B and C) CFU per gr of small (B) and large intestine (C) of the mice infected in panel A at 12 days postinfection. (D) The relative distribution of K. pneumoniae across the intestine sections was determined as 100% of the combined bacterial loads of the small and large intestine sections. (E and F) Bacterial loads in the small (E) and large (F) intestines of mice infected with Kp43816, SGH10, and NJST258-1. In each group, 9 to 10 mice were infected. (G) Relative distribution of K. pneumoniae strains across the intestine sections. (H) Bacterial loads in the spleen of infected mice with different K. pneumoniae strains at 12 days postinfection. Dashed lines indicate the plating detection limit. In all panels, each value is presented as the mean ± SD. **, P ≤ 0.01; ****, P ≤ 0.0001; ns, P > 0.05 for the indicated comparisons, which were determined using a one way-ANOVA with the Bonferroni correction for testing multiple comparisons.