Antibacterial activity of ibezapolstat against antimicrobial-resistant clinical strains of Clostridioides difficile.

Antimicrobial resistance is emerging in clinical strains of Clostridioides difficile. Ibezapolstat (IBZ) is a DNA polymerase IIIC inhibitor that has completed phase II clinical trials. IBZ has potent in vitro activity against wild-type, susceptible strains but its effect on C. difficile strains with reduced susceptibility to metronidazole (MTZ), vancomycin (VAN), or fidaxomicin (FDX) has not been tested. The primary objective of this study was to test the antibacterial properties of IBZ against multidrug-resistant C. difficile strains. The in vitro activity, bactericidal, and time-kill activity of IBZ versus comparators were evaluated against 100 clinical strains of which 59 had reduced susceptibility to other C. difficile antibiotics. Morphologic changes against a multidrug resistance strain were visualized by light and scanning electron microscopy. The overall IBZ MIC50/90 values (µg/mL) for evaluated C. difficile strains were 4/8, compared with 2/4 for VAN, 0.5/1 for FDX, and 0.25/4 for MTZ. IBZ MIC50/90 values did not differ based on non-susceptibility to antibiotic class or number of classes to which strains were non-susceptible. IBZ bactericidal activity was similar to the minimum inhibitory concentration (MIC) and maintained in wild-type and non-susceptible strains. Time-kill assays against two laboratory wild-type and two clinical non-susceptible strains demonstrated sustained IBZ activity despite reduced killing by comparator antibiotics for IBZ and VAN non-susceptible strains. Microscopy visualized increased cell lengthening and cellular damage in multidrug-resistant strains exposed to IBZ sub-MIC concentrations. This study demonstrated the potent antibacterial activity of IBZ against a large collection of C. difficile strains including multidrug-resistant strains. This study highlights the therapeutic potential of IBZ against multidrug-resistant strains of C. difficile.

Multi-country surveillance of Clostridioides difficile demonstrates high prevalence of spores in non-healthcare environmental settings.

BACKGROUND: C. difficile spores are frequently isolated from hospital and non-healthcare settings but a worldwide analysis has not been done. The study objectives were to assess C. difficile spore contamination in the hospital and non-healthcare environments across a variety of countries. METHODS: Field studies assessed hospital vs. non-healthcare C. difficile spore contamination in hospitals, non-healthcare buildings, outdoor environments, and shoes. Swabs were cultured anaerobically for C. difficile and typed using PCR-fluorescent ribotyping. C. difficile contamination by swabbing area and geographic locations were compared. FINDINGS: A total of 7,857 unique samples were collected primarily from the USA (89%) in addition to 9 other countries. The global prevalence of C difficile from environmental samples was 25.3% and did not differ between countries. In USA based studies, C. difficile contamination rates were similar for healthcare buildings (23.2%), non-healthcare buildings (23.4%), and outdoor spaces (24.7%). Floor samples had significantly higher (p < 0.001) C. difficile contamination rate (46.5%) followed by non-floor samples (21.1%), and bathrooms (15.3%). In a comparison of USA to other country samples, C. difficile contamination rates were similar for USA samples (21.5%) compared to rest of world samples (22.3%; p = 0.61). The most common ribotypes included F014-020 (15.7%), F106 (12.6%), F010 (8.9%), F027 (8.8%), and F002 (8.1%) and did not differ significantly between USA and non-USA samples. Finally, 546 of 1,218 (44.8%) shoe soles swabbed from the USA were contaminated with C. difficile spores. INTERPRETATION: This large surveillance study of several countries demonstrated high prevalence of toxigenic C. difficile in non-healthcare environments with high contamination rates from floors and shoe soles.

Efficacy, Safety, Pharmacokinetics, and Microbiome Changes of Ibezapolstat in Adults with Clostridioides difficile Infection: A Phase 2a Multicenter Clinical Trial.

BACKGROUND: This study was the first human validation of the gram-positive bacterial DNA polymerase IIIC target in patients with Clostridioides difficile infection. The primary objectives were to assess clinical cure rates and adverse events (AEs). Secondary objectives were to evaluate plasma/fecal pharmacokinetics, microbiologic eradication, microbiome and bile acid effects, and sustained clinical cure (SCC) with ibezapolstat. METHODS: This single-arm, open-label, phase 2a study enrolled adults with C. difficile infection at 4 US centers. Patients received ibezapolstat 450 mg orally every 12 hours for 10 days and followed for an additional 28 days to assess study objectives. RESULTS: Ten patients with a mean (standard deviation [SD]) age of 49 [15] years were enrolled. Seven AEs were reported classified as mild-moderate. Plasma levels of ibezapolstat ranged from 233 to 578 ng/mL while mean (SD) fecal levels were 416 (494) µg/g stool by treatment day 3 and >1000 µg/g stool by days 8-10. A rapid increase in alpha diversity in the fecal microbiome was noted after starting ibezapolstat therapy, which was maintained after completion of therapy. A proportional decrease in Bacteroidetes phylum was observed (mean change [SD], -10.0% [4.8%]; P = .04) with a concomitantly increased proportion of Firmicutes phylum (+14.7% [5.4%]; P = .009). Compared with baseline, total primary bile acids decreased by a mean (SD) of 40.1 (9.6) ng/mg stool during therapy (P < .001) and 40.5 (14.1) ng/mg stool after completion of therapy (P = .007). Rates of both initial clinical cure and SCC at 28 days were 100% (10 of 10 patients). CONCLUSIONS: In this phase 2a study, 10 of 10 patients achieved SCC, demonstrated favorable pharmacokinetics, minimal AEs, and beneficial microbiome and bile acids results. These results support continued clinical development.