Orally administered beta-lactamase enzymes represent a novel strategy to prevent colonization by Clostridium difficile.

Objectives: Antibiotics that are excreted into the intestinal tract and that disrupt the indigenous microbiota may promote infection by Clostridium difficile. We previously demonstrated that oral administration of a proteolysis-resistant, recombinant class A beta-lactamase inactivates ampicillin or piperacillin excreted into the small intestine during parenteral treatment. We hypothesized that oral administration of this beta-lactamase in conjunction with parenteral ampicillin or piperacillin would preserve the colonic microbiota, thus preventing the overgrowth of and toxin production by C. difficile in mice.

Methods: Subcutaneous ampicillin, subcutaneous piperacillin or either of these plus oral beta-lactamase or either of these plus tazobactam-inactivated oral beta-lactamase were administered to mice 24 and 12 h prior to harvest of caecal contents. Contents were inoculated with one of four strains of C. difficile, and growth and toxin production were assessed after 24 h of incubation under anaerobic conditions. To assess changes in stool microbiota, denaturing gradient gel electrophoresis (DGGE) of PCR-amplified ribosomal RNA genes was performed.

Results: Mice treated with ampicillin, piperacillin or either of these plus tazobactam-inactivated oral beta-lactamase developed high-density colonization with C. difficile, whereas those treated with ampicillin or piperacillin plus the beta-lactamase did not. DGGE demonstrated that antibiotic treatment resulted in significant alteration of the indigenous stool microbiota, whereas antibiotic plus beta-lactamase treatment did not.

Conclusions: Administration of oral recombinant beta-lactamase preserved the colonic microbiota of mice during parenteral beta-lactam antibiotic treatment and prevented the overgrowth of and toxin production by C. difficile in caecal contents. Oral beta-lactamase therapy may represent a novel approach towards preventing C. difficile infections in healthcare settings.