Tapering Courses of Oral Vancomycin Induce Persistent Disruption of the Microbiota That Provide Colonization Resistance to Clostridium difficile and Vancomycin-Resistant Enterococci in Mice

Abstract

Vancomycin taper regimens are commonly used for the treatment of recurrent Clostridium difficile infections. One rationale for tapering and pulsing of the dose at the end of therapy is to reduce the selective pressure of vancomycin on the indigenous intestinal microbiota. Here, we used a mouse model to test the hypothesis that the indigenous microbiota that provide colonization resistance against C. difficile and vancomycin-resistant enterococci (VRE) is repopulated during tapering courses of vancomycin. Mice were treated orally with vancomycin daily for 10 days, vancomycin in a tapering dose for 42 days, fidaxomicin for 10 days, or saline. To assess colonization resistance, subsets of mice were challenged with 10⁴ CFU of C. difficile or VRE at multiple time points during and after completion of treatment. The impact of the treatments on the microbiome was measured by cultures, real-time PCR for selected anaerobic bacteria, and deep sequencing. Vancomycin taper-treated mice developed alterations of the microbiota and disruption of colonization resistance that was persistent 18 days after treatment. In contrast, mice treated with a 10-day course of vancomycin exhibited recovery of the microbiota and of colonization resistance by 15 days after treatment, and fidaxomicin-treated mice maintained intact colonization resistance. These findings demonstrate that alteration of the indigenous microbiota responsible for colonization resistance to C. difficile and VRE persist during and after completion of tapering courses of vancomycin.

Keywords: colonization resistance; oral vancomycin.

FIG 1

Concentrations of vancomycin in stool of mice treated with a 10-day course of vancomycin, followed by the tapered and pulsed vancomycin regimen. Mean concentrations of vancomycin (n = 5 mice) are shown at each time point. The bars show the vancomycin dose in mg per day. Error bars show the standard errors.

FIG 2

Effect of antibiotic treatment on in vivo colonization resistance to Clostridium difficile (A) and vancomycin-resistant enterococci (VRE) (B). Mice received oral antibiotic treatment or sterile water (control) for the durations shown, and subgroups (five per group) were challenged by gastric gavage with 10,000 CFU of C. difficile spores or VRE on days 13, 25, 45, and 60 after the initial antibiotic dose. Treatment days indicate days after the start of antibiotic treatment. Error bars show standard error. *, inoculation of C. difficile spores or VRE.

FIG 3

Effect of antibiotic treatment on the concentrations of facultative Gram-negative bacilli in stool by culture. Mice received oral vancomycin for 10 days, vancomycin taper and pulsed regimen for 42 days, fidaxomicin for 10 days, or sterile water (control). Results for five mice from each treatment group are shown at each time point. Error bars show the standard errors. *, P < 0.05.

FIG 4

Effect of antibiotic treatment on the concentrations of Bacteroides spp. (A) and Prevotella spp. (B) in the stool specimens of mice as determined by real-time PCR. Results for five mice from each treatment group are shown at each time point. Error bars represent the standard errors. *, P < 0.05.

FIG 5

Comparison of stool microbiota of mice (n = 3 per group at each time point) by 16S deep-sequencing analysis before, during, and after treatment with oral vancomycin for 10 days, vancomycin taper and pulsed regimen for 42 days, fidaxomicin for 10 days, or sterile water (control). The relative abundances of the major bacterial phyla are shown at each time point.