Figure 7. Recovery of in vivo colonization resistance over time in piperacillin/tazobactam treated animals.

Mice (3–6 per group at each time point) were challenged with 10⁴ colony-forming units of toxigenic Clostridium difficile spores (A) or vancomycin-resistant Enterococci (VRE) (B) by orogastric gavage either before treatment or 1, 5, or 12 days following treatment with 3 days of daily subcutaneous piperacillin/tazobactam. Concentrations of the pathogens in feces were measured by quantitative cultures 2 days (black bars) and 4 days (white bars) following pathogen challenge. Error bars represent standard error.