Oral Administration of β-Lactamase Preserves Colonization Resistance of Piperacillin-Treated Mice

We hypothesized that orally administered, recombinant class A β-lactamase would inactivate the portion of parenteral piperacillin excreted into the intestinal tract, preserving colonization resistance of mice against nosocomial pathogens. Subcutaneous piperacillin or piperacillin plus oral β-lactamase were administered 24 and 12 h before orogastric inoculation of piperacillin-resistant pathogens. Oral administration of β-lactamase reduced piperacillin-associated alteration of the indigenous microflora and prevented overgrowth of pathogens