Figure 4. Antibiotic administration at the time of catheterization prevents infection for 6 hours.

Trimethoprim/sulfamethoxazole (TMP-SMZ), carbenicillin, or PBS was administered intraperitoneally to naive female mice concurrent with catheter implantation. Cohorts of animals were then infected with approximately 1 × 10⁴ CFU of (A and B) UPEC or (C and D) E. faecalis at the same time (A and C) or at the indicated time point after catheterization (B and D), CFU per bladder and catheter were assessed 24 hours following infection. Each dot represents 1 mouse, and the experiment was performed 3 times (n = 7 mice per experimental group) and pooled. Black dots represent animals that were colonized exclusively by the organism inoculated into the bladder. Red dots represent animals that were negative for UPEC, but positive for an unknown bacterial species. Blue dots indicate animals that were colonized by (A and B) UPEC and another bacterial species or by (C and D) E. faecalis and another bacterial species. In both cases, the blue dot reflects the value of UPEC or E. faecalis CFU only. The presence of the catheter was verified at the time of sacrifice, and mice without a catheter were excluded from the analysis. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 for comparison of PBS-treated groups to antibiotic-treated groups, Kruskal-Wallis test with Dunn’s post-test to correct for multiple comparisons.