Fig. 2: Both T6SS loci of K. pneumoniae are important for gut colonization.
A Fecal shedding of K. pneumoniae infected mice. Mice were orally infected with 106 CFU of either the WT(n = 10), T6−/+ (locus 1 deletion) (n = 12), T6+/− (locus 2 deletion) (n = 11), or T6−/− (double deletion) (n = 11). Two-tailed Mann-Whitney U test was used to compare the WT to each mutant on a given day for statistical analysis. p-values from left to right: 0.0002, 0.0001, <0.0001, 0.0074, 0.0019, 0.0001, 0.0018, 0.008, <0.0001, <0.0001, 0.0148, <0.0001. B Colonization of lungs and spleens from K. pneumoniae infected mice. Mice were infected intranasally with 104 CFU of either WT or T6−/− and tissues were collected at 24 or 72 h post-infection (WT 24 h: n = 10, T6−/− 24 h: n = 10, WT 72 h: n = 9, T6−/− 72 h: n = 10). A two-tailed Mann-Whitney U test was performed between the WT and the T6−/− at each time point and no significant differences were identified. C Fecal shedding from in vivo competition studies. Mice were orally infected with a 1:1 mixture of WT and T6−/+ (n = 9), T6+/− (n = 9), or T6−/− (n = 7). Each point represents the log10 competitive index value from an individual mouse on the indicated day, the bars indicate the median competitive index (CI), and the dotted line indicates a CI of 1. The CI was determined as described in Methods. One sample Wilcoxon signed-rank tests were performed for each group against a theoretical value of 0. p-values from left to right: 0.0195, 0.0117, 0.0156, 0.0039, 0.0039, 0.0156, 0.0039, 0.0039, 0.0156, 0.0039, 0.0039, 0.0156, 0.0078, 0.0039, 0.0156. D K. pneumoniae fecal burden from antibiotic-treated mice inoculated with either the WT (n = 4) or the T6−/− strain (n = 5). Mice were given 0.25 g/L ampicillin in their drinking water beginning 24 h prior to inoculation and for the duration of the experiment. The red dashed line indicates the super-shedder threshold (≥108 CFU [SS Threshold]). A two-tailed Mann-Whitney U test was performed between the WT and the T6−/− at each time point and no significant differences were identified. For graphs (A and D), *, p < 0.05; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001. In graphs (A, B, and D) each symbol represents tissue from a single mouse, the bars indicate median bacterial burden, and the dotted line indicates the L.O.D.
