129. Antimicrobial Resistance Genes Were Reduced Following Administration of Investigational Microbiota-Based Live Biotherapeutic RBX2660 to Individuals with Recurrent Clostridioides difficile Infection

Background

Intestinal colonization by antimicrobial resistant (AMR) pathogens is a known health and infection risk, and is common among individuals with recurrent Clostridioides difficile infections (rCDI). Accordingly, therapeutic approaches that decolonize the gut of AMR pathogens could be valuable to patients to reduce risk of associated illnesses. Herein, we assessed gut colonization with AMR bacteria before and after treatment with RBX2660—a microbiota-based investigational live biotherapeutic—in the PUNCH CD3 Phase 3 trial for reducing CDI recurrence.

Methods

rCDI participants enrolled in PUNCH CD3 received a blinded single dose of RBX2660 or placebo within 24 to 72 hours after completing antibiotic treatment for the most recent rCDI episode. Clinical response was the absence of CDI recurrence at eight weeks after treatment, and participants were asked to submit stool samples prior to RBX2660 or placebo treatment (baseline) and 1, 4 and 8 weeks, 3 and 6 months after study treatment. Samples were extracted and sequenced using a shallow shotgun method. The presence and number of AMR genes was determined for 175 participant samples and 116 RBX2660 samples using 90% K-mer sequence coverage based on the MEGARes database. AMR gene count data were collapsed into count columns to adjust for sparseness in the matrices and were analyzed using a Generalized Linear Mixed Model.

Results

Clinically, RBX2660 demonstrated superior efficacy versus placebo (70.4% and 58.1%, respectively), and the total AMR genes per participant decreased significantly from before to after treatment in RBX2660-treated responders (p< .05, Figure 1) and remained low to at least 6 months. Among genes that decreased in RBX2660 responders were clinically important extended-spectrum beta-lactamase (bla_TEM, bla_SHV, bla_CTX-M), vancomycin resistance (vanA, vanB), and fluoroquinolone resistance genes (gyrA, parC).

Total AMR genes per PUNCH CD3 participant among RBX2660-treated responders at the indicated time points and in the RBX2660 investigational product. The red lines indicate timepoint group medians.

Conclusion

In the PUNCH CD3 Phase 3 trial of RBX2660 for rCDI, AMR gene content decreased after RBX2660 treatment and remained low to at least 6 months, consistent with prior RBX2660 trials. This underscores the potential of microbiota-based biotherapeutics for decolonizing AMR bacteria from gut microbiota and thereby reducing AMR infection risks.

Disclosures

Heidi Hau, PhD, Rebiotix Inc. (Employee) Dana M. Walsh, PhD, Rebiotix (Employee) Ken Blount, PhD, Rebiotix Inc., a Ferring Company (Employee)

670. VRE Clearance in Patients with Recurrent Clostridium difficile Infection Following Treatment with Microbiota-Based Drug RBX2660

Background

Vancomycin-resistant Enterococcus (VRE) infection is frequently associated with immunocompromised and critically ill patients. VRE carriers are at increased risk for infection due to VRE colonization and they pose a risk as a transmission source. VRE infection and Clostridium difficile infection (CDI) share common risk factors, including disruption of the intestinal microbiome. Thus, therapeutic approaches that decolonize VRE would be valuable. Herein, we report on stool VRE clearance in a cohort analysis from a Phase 2 open-label study of RBX2660, standardized microbiota-based drug, for recurrent CDI.

Methods

This prospective, multicenter, open-label Phase 2 study enrolled subjects with recurrent CDI. Participants received up to 2 doses of RBX2660 delivered via enema with doses 7 days apart. Patients were requested to voluntarily submit stool samples at baseline and at 7, 30 and 60 days, 6, 12, and 24 months after the last administration of RBX2660. Stool samples were tested for VRE using bile esculin azide agar with 6 µg/mL vancomycin and gram staining. Vancomycin resistance was confirmed via blood agar and etest.

Results

Stool samples were available for 143 patients. Twenty-one patients were VRE-positive at the first test (baseline or 7 day). Of the 19 VRE-positive patients that provided additional samples at later timepoints, 18 (94.7%) converted to negative as of the last available follow-up (30 or 60 days and 6, 12, or 24 months). The remaining patient remained positive at all follow-ups.

Conclusion

This cohort analysis of VRE-positive patients within an rCDI population provides additional support that microbiota-based formulations, such as RBX2660, may have additional benefit beyond reducing the recurrence of CDI. Additional study is needed to confirm the role of microbiome restoration on VRE clearance.

Disclosures

All authors: No reported disclosures

Guidelines To Validate Control of Cross-Contamination during Washing of Fresh-Cut Leafy Vegetables

The U.S. Food and Drug Administration requires food processors to implement and validate processes that will result in significantly minimizing or preventing the occurrence of hazards that are reasonably foreseeable in food production. During production of fresh-cut leafy vegetables, microbial contamination that may be present on the product can spread throughout the production batch when the product is washed, thus increasing the risk of illnesses. The use of antimicrobials in the wash water is a critical step in preventing such water-mediated cross-contamination; however, many factors can affect antimicrobial efficacy in the production of fresh-cut leafy vegetables, and the procedures for validating this key preventive control have not been articulated. Producers may consider three options for validating antimicrobial washing as a preventive control for cross-contamination. Option 1 involves the use of a surrogate for the microbial hazard and the demonstration that cross-contamination is prevented by the antimicrobial wash. Option 2 involves the use of antimicrobial sensors and the demonstration that a critical antimicrobial level is maintained during worst-case operating conditions. Option 3 validates the placement of the sensors in the processing equipment with the demonstration that a critical antimicrobial level is maintained at all locations, regardless of operating conditions. These validation options developed for fresh-cut leafy vegetables may serve as examples for validating processes that prevent cross-contamination during washing of other fresh produce commodities.

A mini-review on novel intraperiodontal pocket drug delivery materials for the treatment of periodontal diseases

Periodontal disease is defined as chronic inflammatory condition characterized by the destruction of the periodontal tissues causing loss of connective tissue attachment, loss of alveolar bone, and the formation of pathological pockets around the diseased teeth. The use of systemic antibiotics has been advocated for its treatment, but concerns emerged with respect to adverse drug reactions and its contribution to bacterial resistance. Thus local drug delivery devices have been developed that aim to deliver a high concentration of antimicrobial drugs directly to the affected site, while minimizing drug's systemic exposure. A burst release of antimicrobial agent from carrier, resulting in a short and inadequate exposure of bacteria residing in periodontal pocket to the agent, remains the main challenge of current local delivery systems for the treatment of periodontal disease. This review aims to investigate and compare different local antimicrobial delivery systems with regard to the treatment of periodontal disease.

Selective inhibitory effects of the anticoagulant activated protein C on the responses of human mononuclear phagocytes to LPS, IFN-gamma, or phorbol ester

Recent studies have shown that infusion of the anticoagulant protein, activated protein C (APC), can ameliorate many of the systemic effects of endotoxemia in experimental animals, although the mechanisms in this action are unknown. We investigated the effects of APC on the responses of blood monocytes, alveolar macrophages, and cells of the monocyte line, THP-1, to stimulation in vitro by LPS, IFN-gamma, or PMA. Mononuclear phagocyte (MO) activation was associated with rapid production of TNF-alpha, down-regulation of the glycophosphatidylinositol-linked protein CD14 (the key MO receptor for complexes of LPS and LPS-binding protein responsible for intracellular signaling), and down-regulation of the related LPS-binding proteins CD11b and CD18. Addition of APC, but not the zymogen, PC, or active site-blocked APC, inhibited selected MO responses involving the CD14-dependent LPS-induced pathway of MO activation, or activation induced by IFN-gamma or PMA. Thus, APC inhibited the production of TNF-alpha and prevented down-regulation of membrane CD11b, CD14, and CD18, but had no effect on up-regulation of MHC class II, ICAM-1, or IL-2R, down-regulation of MO expression of another glycophosphatidylinositol-linked protein, CD59, or production of reactive oxygen intermediates. These data show that APC inhibits host cytokine production but maintains MO responses associated with adhesion, phagocytosis, and killing of Gram-negative bacteria, such that use of APC may be a logical and potent adjunctive therapy in select inflammatory diseases involving MO activation and damaging host cytokine overproduction.

Selective inhibitory effects of the anticoagulant activated protein C on the responses of human mononuclear phagocytes to LPS, IFN-gamma, or phorbol ester

Recent studies have shown that infusion of the anticoagulant protein, activated protein C (APC), can ameliorate many of the systemic effects of endotoxemia in experimental animals, although the mechanisms in this action are unknown. We investigated the effects of APC on the responses of blood monocytes, alveolar macrophages, and cells of the monocyte line, THP-1, to stimulation in vitro by LPS, IFN-gamma, or PMA. Mononuclear phagocyte (MO) activation was associated with rapid production of TNF-alpha, down-regulation of the glycophosphatidylinositol-linked protein CD14 (the key MO receptor for complexes of LPS and LPS-binding protein responsible for intracellular signaling), and down-regulation of the related LPS-binding proteins CD11b and CD18. Addition of APC, but not the zymogen, PC, or active site-blocked APC, inhibited selected MO responses involving the CD14-dependent LPS-induced pathway of MO activation, or activation induced by IFN-gamma or PMA. Thus, APC inhibited the production of TNF-alpha and prevented down-regulation of membrane CD11b, CD14, and CD18, but had no effect on up-regulation of MHC class II, ICAM-1, or IL-2R, down-regulation of MO expression of another glycophosphatidylinositol-linked protein, CD59, or production of reactive oxygen intermediates. These data show that APC inhibits host cytokine production but maintains MO responses associated with adhesion, phagocytosis, and killing of Gram-negative bacteria, such that use of APC may be a logical and potent adjunctive therapy in select inflammatory diseases involving MO activation and damaging host cytokine overproduction.

P-selectin and platelet-activating factor mediate initial endotoxin-induced neutropenia

Polymorphonuclear neutrophil (PMN) accumulation within damaged tissues, a hallmark of acute inflammation, is dependent upon initial adhesion to endothelial cells. In vitro studies suggest that P-selectin and platelet activating factor (PAF) are key molecules in this process by promoting the initial adhesion of PMN to endothelial cells. We report in vivo studies in which intravenous administration of lipopolysaccharide (LPS) to anesthetized rats caused a very rapid onset (< 5 min) of neutropenia, in association with induction of surface expression of P-selectin on microvascular endothelial cells in kidney, liver and lung; analogous induction of P-selectin expression by cultured endothelial cells was observed in response to LPS stimulation in vitro. In addition, treatment with an antibody (Ab) to P-selectin (or use of a PAF antagonist) blocked development of neutropenia in vivo for at least 15 min post-LPS injection, and Ab treatment was shown to block PMN accumulation in tissues. These studies document roles for P-selectin and PAF in the early adhesion of PMN to endothelial cells in vivo.

In vitro action of combined salbutamol and theophylline on anaphylactic contractions, mediator release and cyclic 3',5'-adenosine monophosphate in lung parenchyma

The mechanisms involved in the anti-asthmatic action of combined bronchodilator therapy was studied by determining the effects of combined salbutamol and theophylline on anaphylactic contractions, histamine release, prostaglandin (PG)F2 ALha release, cyclic 3',5'-adenosine monophosphate (c-AMP) and smooth muscle tone in guinea-pig peripheral airways in vitro. Combined, salbutamol (3 X 10(=8) M) and theophylline (3 X 10(-4) M) markedly inhibited anaphylactic contractions (85.8%) in lung strips. The inhibition of anaphylactic contractions was significantly greater than inhibition of histamine and PGF2 alpha-induced contractions. Histamine release was reduced by 66.1% but PGF2 alpha was not significantly altered. Increased c-AMP was observed with combined salbutamol (3 X 10(-8) M) and theophylline (3 X 10(-4) M) in the absence of antigen. The combined effect of salbutamol and theophylline was always greater than the sum of their individual effects. The results demonstrate that in peripheral airways theophylline potentiates the action of salbutamol both directly via smooth muscle relaxation and indirectly via inhibition in mediator release.