Oral Beta-Lactamase Protects the Canine Gut Microbiome from Oral Amoxicillin-Mediated Damage

Abstract

Antibiotics damage the gut microbiome, which can result in overgrowth of pathogenic microorganisms and emergence of antibiotic resistance. Inactivation of antibiotics in the small intestine represents a novel strategy to protect the colonic microbiota. SYN-004 (ribaxamase) is a beta-lactamase formulated for oral delivery intended to degrade intravenously administered beta-lactam antibiotics in the gastrointestinal (GI) tract. The enteric coating of ribaxamase protects the enzyme from stomach acid and mediates pH-dependent release in the upper small intestine, the site of antibiotic biliary excretion. Clinical benefit was established in animal and human studies in which ribaxamase was shown to degrade ceftriaxone in the GI tract, thereby preserving the gut microbiome, significantly reducing Clostridioides difficile disease, and attenuating antibiotic resistance. To expand ribaxamase utility to oral beta-lactams, delayed release formulations of ribaxamase, SYN-007, were engineered to allow enzyme release in the lower small intestine, distal to the site of oral antibiotic absorption. Based on in vitro dissolution profiles, three SYN-007 formulations were selected for evaluation in a canine model of antibiotic-mediated gut dysbiosis. Dogs received amoxicillin (40 mg/kg, PO, TID) +/- SYN-007 (10 mg, PO, TID) for five days. Serum amoxicillin levels were measured after the first and last antibiotic doses and gut microbiomes were evaluated using whole genome shotgun sequence metagenomics analyses of fecal DNA prior to and after antibiotic treatment. Serum amoxicillin levels did not significantly differ +/- SYN-007 after the first dose for all SYN-007 formulations, while only one SYN-007 formulation did not significantly reduce systemic antibiotic concentrations after the last dose. Gut microbiomes of animals receiving amoxicillin alone displayed significant loss of diversity and emergence of antibiotic resistance genes. In contrast, for animals receiving amoxicillin + SYN-007, microbiome diversities were not altered significantly and the presence of antibiotic resistance genes was reduced. These data demonstrate that SYN-007 diminishes amoxicillin-mediated microbiome disruption and mitigates emergence and propagation of antibiotic resistance genes without interfering with antibiotic systemic absorption. Thus, SYN-007 has the potential to protect the gut microbiome by inactivation of beta-lactam antibiotics when administered by both oral and parenteral routes and to reduce emergence of antibiotic-resistant pathogens.

SYN-007, an Orally Administered Beta-Lactamase Enzyme, Protects the Gut Microbiome from Oral Amoxicillin/Clavulanate without Adversely Affecting Antibiotic Systemic Absorption in Dogs

“…However, the majority of beta-lactams are delivered orally, not systemically [14], and the ribaxamase formulation is not appropriate for co-administration with oral beta-lactams [15]. Amoxicillin, and other oral beta-lactams, are absorbed from the proximal small intestine [16], the site of ribaxamase release [8].…”

“…Amoxicillin, and other oral beta-lactams, are absorbed from the proximal small intestine [16], the site of ribaxamase release [8]. Indeed, administration of ribaxamase with oral amoxicillin in dogs resulted in no detectable antibiotic in the blood, indicating that ribaxamase degraded the antibiotic within the GI tract prior to its systemic absorption [15]. A novel formulation of ribaxamase was developed for use with oral beta-lactams [15].…”

“…Indeed, administration of ribaxamase with oral amoxicillin in dogs resulted in no detectable antibiotic in the blood, indicating that ribaxamase degraded the antibiotic within the GI tract prior to its systemic absorption [15]. A novel formulation of ribaxamase was developed for use with oral beta-lactams [15]. This delayed release formulation of ribaxamase, SYN-007, targets enzyme release to the lower small intestine distal to the site of oral beta-lactam absorption [15] (Figure 1).…”

“…A novel formulation of ribaxamase was developed for use with oral beta-lactams [15]. This delayed release formulation of ribaxamase, SYN-007, targets enzyme release to the lower small intestine distal to the site of oral beta-lactam absorption [15] (Figure 1). SYN-007 employs a dual coating approach using enteric-coated ribaxamase pellets [8] packaged into enteric-coated capsules [15].…”

“…This delayed release formulation of ribaxamase, SYN-007, targets enzyme release to the lower small intestine distal to the site of oral beta-lactam absorption [15] (Figure 1). SYN-007 employs a dual coating approach using enteric-coated ribaxamase pellets [8] packaged into enteric-coated capsules [15]. The enteric coating of the capsule dissolves at pH > 7.0, the pH of the ileum in the lower small intestine [17].…”