Validation of a Health-Related Quality of Life Questionnaire in Patients With Recurrent Clostridioides difficile Infection in ECOSPOR III, a Phase 3 Randomized Trial

BACKGROUND

Debilitating symptoms of recurrent Clostridioides difficile infection (rCDI) often lead to long-term effects on health-related quality-of-life (HRQOL). In ECOSPOR III, SER-109, an investigational oral microbiome therapeutic, was superior to placebo in reducing rCDI. We investigated the validity, reliability, and responsiveness of a 32-item, CDI-specific questionnaire-the Clostridium difficile Quality of Life Survey (Cdiff32)-across mental, physical, and social domains in patients with rCDI.

METHODS

In this post hoc analysis of a phase 3 clinical trial, 182 outpatients with rCDI completed Cdiff32 and EQ-5D at baseline and at 1 and 8 weeks. Cdiff32 was evaluated for item performance, internal reliability, and convergent validity. To assess known-groups validity, Cdiff32 scores were compared by disease recurrence status at week 1; internal responsiveness was evaluated in the nonrecurrent disease group by 8 weeks by means of paired t test.

RESULTS

All 182 patients (mean age [standard deviation], 65.5 [16.5] years; 59.9% female) completed baseline Cdiff32. Confirmatory factor analysis identified 3 domains (physical, mental, and social relationships) with good item fit. High internal reliability was demonstrated (Cronbach α = 0.94 with all subscales >0.80). Convergent validity was evidenced by significant correlations between Cdiff32 subscales and EQ-5D (r = 0.29-0.37; P < .001). Cdiff32 differentiated patients by disease recurrence status at week 1 (effect sizes, 0.38-0.42; P < .05 overall), with significant improvement from baseline through week 8 in patients with nonrecurrent disease at week 1 (effect sizes, 0.75-1.02; P < .001 overall).

CONCLUSIONS

Cdiff32 is a valid, reliable, and responsive disease-specific HRQOL questionnaire that is fit for purpose for interventional treatment trials. The significant improvement in patients with nonrecurrent disease by 8 weeks demonstrates the negative impact of rCDI on HRQOL.

Nonmammalian models to study Clostridioides difficile infection; a systematic review

Clostridioide difficile is the leading cause of diarrhea disease worldwide and is a CDC-designated urgent threat level pathogen. Mammalian models are commonly utilized as gold standard to study the pathogenesis of C. difficile infection (CDI); however, alternatives are needed due to cost, higher throughput ability, and mammalian animal ethics. Nonmammalian models such as great wax worm, nematode, fruit fly, and zebrafish have been used as CDI models. This review provides a comprehensive summary of nonmammalian models used to study CDI. Multiple studies were identified using these models to study C. difficile infection, pathogenicity, colonization, host immunity, and therapy. Translational outcomes and strength and weakness of each nonmammalian model are discussed.

Omadacycline and Clostridioides difficile: A Systematic Review of Preclinical and Clinical Evidence

OBJECTIVE

The objective of this systematic review is to summarize in vitro, preclinical, and human data related to omadacycline and Clostridioides difficile infection (CDI).

DATA SOURCES

PubMed and Google Scholar were searched for "omadacycline" AND ("Clostridium difficile" OR "C difficile" OR "Clostridioides difficile") for any studies published before February 15, 2022. The US Food and Drug Administration (FDA) Adverse Events Reporting System (AERS) was searched for omadacycline (for reports including "C. difficile" or "CDI" or "gastrointestinal infection"). The publications list publicly available at Paratek Pharmaceuticals, Inc. Web site was reviewed.

STUDY SELECTION AND DATA EXTRACTION

Publications presenting primary data on omadacycline and C. difficile published in English were included.

DATA SYNTHESIS

Preclinical and clinical evidence was extracted from 14 studies. No case reports in indexed literature and no reports on FDA AERS were found. Omadacycline has potent in vitro activity against many C. difficile clinical strains and diverse ribotypes. In phase 3 studies, there were no reports of CDI in patients who received omadacycline for either community-acquired bacterial pneumonia or acute bacterial skin and skin structure infection.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Omadacycline should be considered a low-risk antibiotic regarding its propensity to cause CDI.

CONCLUSIONS

Reducing the burden of CDI on patients and the health care system should be a priority. Patients with appropriate indications who are at heightened risk of CDI may be suitable candidates for omadacycline therapy. In these patients, omadacycline may be preferable to antibiotics with a high CDI risk.

Clinical characteristics, microbiology and outcomes of a cohort of patients treated with ceftolozane/tazobactam in acute care inpatient facilities, Houston, Texas, USA

Background

Ceftolozane/tazobactam is a β-lactam/β-lactamase inhibitor combination with activity against a variety of Gram-negative bacteria, including MDR Pseudomonas aeruginosa. This agent is approved for hospital-acquired and ventilator-associated bacterial pneumonia. However, most real-world outcome data come from small observational cohorts. Thus, we sought to evaluate the utilization of ceftolozane/tazobactam at multiple tertiary hospitals in Houston, TX, USA.

Methods

We conducted a multicentre retrospective study of patients receiving at least 48 h of ceftolozane/tazobactam therapy from January 2016 through to September 2019 at two hospital systems in Houston. Demographic, clinical and microbiological data were collected, including the infecting bacterial isolate, when available. The primary outcome was composite clinical success at hospital discharge. Secondary outcomes included in-hospital mortality and clinical disposition at 14 and 30 days post ceftolozane/tazobactam initiation. Multivariable logistic regression analysis was used to identify predictors of the primary outcome and mortality. Recovered isolates were tested for susceptibility to ceftolozane/tazobactam and underwent WGS.

Results

A total of 263 patients were enrolled, and composite clinical success was achieved in 185 patients (70.3%). Severity of illness was the most consistent predictor of clinical success. Combination therapy with ceftolozane/tazobactam and another Gram-negative-active agent was associated with reduced odds of clinical success (OR 0.32, 95% CI 0.16-0.63). Resistance to ceftolozane/tazobactam was noted in 15.4% of isolates available for WGS; mutations in ampC and ftsI were common but did not cluster with a particular ST.

Conclusions

Clinical success rate among this patient cohort treated with ceftolozane/tazobactam was similar compared with previous experiences. Ceftolozane/tazobactam remains an alternative agent for treatment of susceptible isolates of P. aeruginosa.

Fusobacteria behaving badly: Masquerading strains of strictly anaerobic Escherichiacoli misidentified due to the deletion of the hemB gene

Three strictly anaerobic strains of Escherichia coli were misidentified as Fusobacterium mortiferum, due to a deletion of the hemB gene which is involved in anaerobic respiration. An unusual antimicrobial susceptibility pattern sparked the further diagnostic strategies that eventually identified these strains as true anaerobic E. coli This phenomenon is more common than appreciated and can have an impact on clinical practice including persistent and relapsing infections.

Assessment of Quality of Life Among Patients With Recurrent Clostridioides difficile Infection Treated with Investigational Oral Microbiome Therapeutic SER-109: Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

Recurrent Clostridioides difficile infection (CDI) is a debilitating disease leading to poor health-related quality of life (HRQOL), loss of productivity, anxiety, and depression. The potential association of treatment with HRQOL has not been well evaluated.

OBJECTIVES

To explore the association of SER-109 compared with placebo on HRQOL in patients with recurrent CDI up to week 8.

DESIGN, SETTING, AND PARTICIPANTS

This study was a secondary analysis of a randomized, double-blind, placebo-controlled trial that took place at 56 sites in the US and Canada from July 2017 to April 2020 and included 182 patients randomized to SER-109 or placebo groups.

INTERVENTIONS

SER-109 or placebo (4 capsules once daily for 3 days) following antibiotics for CDI.

MAIN OUTCOMES AND MEASURES

Exploratory analysis of HRQOL using the disease specific Clostridioides difficile Quality of Life Survey (Cdiff32) assessed at baseline, week 1, and week 8.

RESULTS

In this study, 182 patients (109 [59.9%] female; mean age, 65.5 [16.5] years) were randomized to SER-109 (89 [48.9%]) or placebo (93 [51.1%]) groups and were included in the primary and exploratory analyses. Baseline Cdiff32 scores were similar between patients in the SER-109 and placebo groups (52.0 [18.3] vs 52.8 [18.7], respectively). The proportion of patients with overall improvement from baseline in the Cdiff32 total score was higher in the SER-109 arm than placebo at week 1 (49.4% vs 26.9%; P = .012) and week 8 (66.3% vs 48.4%; P = .001).Greater improvements in total and physical domain and subdomain scores were observed in patients in the SER-109 group compared with placebo as early as week 1, with continued improvements observed at week 8. Among patients in the placebo group, improvements in HRQOL were primarily observed in patients with nonrecurrent CDI while patients in the SER-109 group reported improvements in HRQOL, regardless of clinical outcome.

CONCLUSIONS AND RELEVANCE

In this secondary analysis of a phase 3 clinical trial, SER-109, an investigational microbiome therapeutic was associated with rapid and steady improvement in HRQOL compared with placebo through 8 weeks, an important patient-reported outcome.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03183128.

Risk Factors Associated with Severe Clostridioides difficile Infection in Patients with Cancer

INTRODUCTION

Antibiotic use is a risk factor for Clostridioides difficile infection (CDI). Few studies have correlated use of prior antibiotic classes with CDI, microbiome composition, and disease severity in patients with cancer. We hypothesized that previous antibiotic exposure and fecal microbiome composition at time of presentation are risk factors for severe CDI in patients with cancer.

METHODS

This non-interventional, prospective, cohort study examined 200 patients with cancer who had their first episode or first recurrence of CDI. C. difficile was identified using nucleic acid amplification testing. Univariate analysis was used to determine significant risk factors for severe CDI. Fecal microbiome composition was determined by sequencing the V3/V4 region of 16 s rDNA encoding gene. Differential abundance analyses were used to single out significant microbial features which differed across severity levels.

RESULTS

On univariate analysis, factors associated with severe CDI included the presence of toxin A/B in stools (odds ratio [OR] 2.14 [1.05-4.36] p = 0.04 and prior 90-day metronidazole use (OR 2.66 [1.09-6.50] p = 0.03). Although alpha and beta diversity was similar between disease severity groups and toxin A/B in stools, increased abundance of Bacteroides uniformis, Ruminococcaceae, and Citrobacter koseri were associated with protection from severe CDI (p < 0.05) and depletion of anaerobes was higher in patients with prior metronidazole exposure.

CONCLUSION

Use of metronidazole for non-CDI indications within 90 days prior to diagnosis and presence of toxin A/B in stools were associated with severe CDI. Findings provide valuable insights into risk factors for severe CDI in an underserved population with cancer that warrants further exploration.

Gut microbiota changes associated with Clostridioides difficile infection and its various treatment strategies

Human gut microbiota are critical to both the development of and recovery from Clostridioides difficile infection (CDI). Antibiotics are the mainstay of CDI treatment, yet inherently cause further imbalances in the gut microbiota, termed dysbiosis, complicating recovery. A variety of microbiota-based therapeutic approaches are in use or in development to limit disease- and treatment-associated dysbiosis and improve rates of sustained cure. These include the recently FDA-approved fecal microbiota, live-jslm (formerly RBX2660) and fecal microbiota spores, live-brpk (formerly SER-109), which represent a new class of live biotherapeutic products (LBPs), traditional fecal microbiota transplantation (FMT), and ultra-narrow-spectrum antibiotics. Here, we aim to review the microbiome changes associated with CDI as well as a variety of microbiota-based treatment approaches.

Heterogeneity and lyophilization comparison of stool processing for gastrointestinal bile acid measurement by LC-MS/MS

Fecal bile acid (BA) analysis is an emerging area of gut microbiome research. However, sample preparation procedures for fecal BA analysis are not standardized. Current fecal BA analysis often utilizes either original or lyophilized aliquot, and fecal BA result difference between these two processing steps remains not systematically investigated. Moreover, the distribution pattern of fecal BA in the collected stool sample also remains unclear but affects interpretation of fecal BA for downstream experiments. To address these two questions regarding effect of lyophilization on fecal BA and fecal heterogeneity, fourteen separate BAs were quantified from 60 aliquots obtained from 10 clinical fecal samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). BA concentrations in the lyophilized sample were typically 2-4 folds higher than those in the original sample, but were almost identical using a water-adjusted lyophilized BA concentration. The fecal BA compositional profile and four BA ratios were similar utilizing either the original or lyophilized samples. BA concentrations were similar among different aliquots of differing starting mass except for the relatively trace-level BA. Therefore, it is suggested that fecal BA concentrations should be presented as the original sample concentration or water-adjusted lyophilization concentration to allow comparisons between studies. A single aliquot (20-100 mg) of stool can be used to reflect the concentrations in the entire sample. These results help to standardize analyses in this emerging field.

522. Significant Improvement in Health-Related Quality of Life (HRQL) with RBX2660: Results from a Phase 3 Randomized, Placebo-Controlled Trial in Recurrent Clostridioides Difficile Infection (PUNCH CD3)

Background

Recurrence of Clostridioides difficile infection (rCDI) is common - up to 35% of patients may recur. RBX2660 is a microbiota restoration therapy to reduce rCDI. Here we report 8 weeks HRQL results using the Clostridioides difficile Health-related Quality-of-Life Questionnaire (Cdiff32), a disease-specific instrument, from PUNCH CD3 (a randomized, double-blinded, placebo-controlled RBX2660 Phase 3 trial, NCT03244644).

Methods

Cdiff32 includes three domains (physical, mental, and social) and a total score (all range from 0 to 100 [100 best possible]). Changes in Cdiff32 from baseline to week 8 were compared between RBX2660 and placebo (PBO) using unadjusted and adjusted analyses controlling for baseline score, demographic and disease characteristics. Per trial protocol, missing data were imputed via last observation carried forward (LOCF); as-observed data were also analyzed. Patients experiencing recurrence after blinded treatment received open-label RBX2660 per physician discretion; these participants were excluded unless, per LOCF, data were available from the blinded period for week 8 use.

Results

A total of 206 patients (140 RBX2660, 66 PBO) were included, with similar age (mean±SD) 61.1±16.9 yrs (RBX2660) and 57.3±16.4 yrs (PBO) and baseline Cdiff32 scores. More than half of the patients had multiple comorbidities. Cdiff32 scores improved significantly from baseline to weeks 1, 4, and 8 for both arms, with greater improvements for RBX2660 through week 8 (Figs. 1 & 2). At week 8, statistical differences were found for mental domain (unadjusted: 8.01±3.64; adjusted: 7.07, 95% confidence interval: [0.28, 13.86], both P< 0.05) and total score (adjusted: 6.11, [0.14, 12.08], P< 0.05), all favoring RBX2660. Results were similar for the as-observed analyses, with the adjusted physical domain also statistically favoring RBX2660.

Conclusion

Most patients in this study reported improved HRQL. Improvements were observed in both arms, but RBX2660-treated patients had more robust and sustained improvements with statistically significant differences in Cdiff32 scores. This study suggests that microbiome restoration therapy might positively affect HRQL; future research may link these improvements directly with microbiota changes.

Disclosures

Paul Feuerstadt, MD, FACG, AGAF, Ferring/Rebiotix Pharmaceuticals: Advisor/Consultant|Ferring/Rebiotix Pharmaceuticals: Grant/Research Support|Merck and Co: Advisor/Consultant|SERES Therapeutics: Advisor/Consultant|SERES Therapeutics: Grant/Research Support|Takeda Pharmaceuticals: Advisor/Consultant Erik R. Dubberke, MD, MSPH, Abbott: Advisor/Consultant|Ferring: Advisor/Consultant|Ferring: Grant/Research Support|Merck: Advisor/Consultant|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Seres: Advisor/Consultant|Summit: Advisor/Consultant|Synthetic Biologics: Grant/Research Support Amy Guo, PhD, Ferring Pharmaceuticals: Employee Adam Harvey, PhD, Ferring Pharmaceuticals: Employment Min Yang, MD, PhD, Analysis Group, Inc.: I am an employee of Analysis Group, Inc., which has received consulting fees from Ferring for the conduct of this study. Viviana García-Horton, PhD, Analysis Group, Inc.: Employee of Analysis Group, Inc., which received consulting fees from Ferring for the conduct of this study. Mirko Fillbrunn, PhD, Analysis Group, Inc.: I am an employee of Analysis Group, Inc., which has received consulting fees from Ferring for the conduct of this study. Glenn S. Tillotson, PhD, Ferring Pharmaceuticals: Advisor/Consultant|Paratek Pharmaceuticals: Grant/Research Support|Spero Pharmaceuticals: Advisor/Consultant|Taro Pharmaceuticals: Advisor/Consultant Lindy Bancke, PharmD, Rebiotix, a Ferring Company: Employee Kevin W. Garey, PharmD, MS, Acurx: Grant/Research Support|cidara: Advisor/Consultant|cidara: Grant/Research Support|Paratek: Grant/Research Support|Seres Health: Grant/Research Support|Summit: Grant/Research Support.

221. Assessment and Proposed Revision of Clinical Trial Clostridioides difficile Infection Clinical Response and Outcomes Definitions

Background

Clostridioides difficile infection (CDI) research is limited by a lack of standardized definitions for clinical response and disease outcomes, which impacts clinical drug development and results comparison between studies. We aimed to assess outcome definitions in CDI therapeutic trials to propose new versions that are clinically relevant, discrete and objective.

Methods

A multidisciplinary group of CDI experts met monthly to review response endpoints from published clinical trials of antibiotic therapy for CDI. Previously published phase III or IV trials were assessed for outcome definitions. Discussions were held to reach a consensus on new clinical trial endpoints for adults and children to improve the accuracy and clinical relevance of measures of treatment success.

Results

Significant heterogeneity was noted amongst the primary endpoints in phase III and IV CDI antibiotic treatment trials. Initial clinical cure (ICC), strictly defined as < 3 unformed bowel movements/24 hour, and sustained clinical cure (SCC) were primary outcome measures for recent clinical trials. The strict ICC definition incompletely measures treatment success as assessed in clinical practice and, since ICC is necessary to achieve SCC, may lead to type II error for SCC. A set of proposed alternative outcome definitions was developed using the terms initial response (IR) and sustained response (SR) (Figure 1). IR allows for investigator assessment of overall improvement in CDI response more analogous to clinical practice and will lead to more patients eligible to meet SR. Achievement of SR requires both IR and no need for retreatment of CDI by day 30 after antibiotic completion and is the more relevant endpoint for CDI therapeutic development. The use of a less restrictive IR definition will more accurately capture early responses to treatment and importantly increase the validity of SR. The shortening of follow-up period by 30 days is also anticipated to reduce costs and efforts associated with conducting trials.

Timeline of CDI outcome assessments for clinical trials

Conclusion

The set of definitions proposed here will more accurately capture clinical success and standardize the approach to outcome assessment in trials of CDI therapeutics.

Disclosures

Carolyn D. Alonso, MD, Cidara Therapeutics: Advisor/Consultant|Merck: Advisor/Consultant Oliver A. Cornely, Prof. Dr., Abbott: Honoraria|Abbvie: Advisor/Consultant|Actelion: Board Member|Al-Jazeera Pharmaceuticals: Honoraria|Allecra Therapeutics: Board Member|Amplyx: Advisor/Consultant|Amplyx: Grant/Research Support|Astellas: Honoraria|Basilea: Advisor/Consultant|Basilea: Grant/Research Support|Biocon: Advisor/Consultant|Biosys: Advisor/Consultant|BMBF: Grant/Research Support|Cidara: Advisor/Consultant|Cidara: Board Member|Cidara: Expert Testimony|Cidara: Grant/Research Support|CoRe Consulting: Stocks/Bonds|Da Volterra: Advisor/Consultant|DLR: Grant/Research Support|DZIF: Grant/Research Support|Entasis: Board Member|EU Directorate-General for Resarch and Innovation: Grant/Research Support|F2G: Grant/Research Support|German Patent and Trade Mark Office: German patent (DE 10 2021 113 007.7)|Gilead: Advisor/Consultant|Gilead: Grant/Research Support|Grupo Biotoscana/United Medical/Knight: Honoraria|Hikma: Honoraria|IQVIA: Board Member|Janssen: Board Member|Matinas: Advisor/Consultant|Matinas: Grant/Research Support|MedPace: Advisor/Consultant|MedPace: Grant/Research Support|MedScape: Honoraria|MedUpdate: Honoraria|Menarini: Advisor/Consultant|Merck/MSD: Grant/Research Support|Merck/MSD: Honoraria|Molecular Partners: Advisor/Consultant|MSG-ERC: Advisor/Consultant|Mundipharma: Grant/Research Support|Mylan: Honoraria|Noxxon: Advisor/Consultant|Octapharma: Advisor/Consultant|Octapharma: Grant/Research Support|Paratek: Board Member|Pardes: Advisor/Consultant|Pfizer: Grant/Research Support|Pfizer: Honoraria|Projektträger Jülich: Grant/Research Support|PSI: Advisor/Consultant|PSI: Board Member|Pulmocide: Board Member|Scynexis: Advisor/Consultant|Scynexis: Grant/Research Support|Seres: Advisor/Consultant|Shionogi: Board Member|Wiley (Blackwell): Editor-in-Chief, Mycoses Kevin W. Garey, PharmD, MS, Acurx Pharmaceuticals: Grant/Research Support|Paratek Pharmaceuticals: Grant/Research Support|Seres Therapeutics: Grant/Research Support|Summit Pharmaceuticals: Grant/Research Support Dale N. Gerding, MD, Destiny Pharma plc.: Advisor/Consultant Stuart Johnson, M.D., Ferring Pharmaceuticals: Membership on Ferring Publication Steering Committee|Ferring Pharmaceuticals: Employee|Summit Plc: Advisor/Consultant Stacy A. Kahn, MD, Lilly: Stocks/Bonds Ciaran P. Kelly, n/a, Artugen: Advisor/Consultant|Facile Therapeutics: Advisor/Consultant|Ferring Pharma: Advisor/Consultant|Finch: Advisor/Consultant|Finch: Advisor/Consultant|First Light Biosciences: Advisor/Consultant|First Light Biosciences: Ownership Interest|Milky Way Biosciences: Advisor/Consultant|Milky Way Biosciences: Grant/Research Support|Pfizer: Advisor/Consultant|Seres Therapeutics: Advisor/Consultant|Summit Therapeutics: Advisor/Consultant Larry K. Kociolek, MD, MSCI, Merck: Grant/Research Support Thomas J. Louie, MD, Artugen: Advisor/Consultant|Artugen: Grant/Research Support|Crestone: Advisor/Consultant|Crestone: Grant/Research Support|Finch Therapeutics: Advisor/Consultant|Finch Therapeutics: Grant/Research Support|Rebiotix: Advisor/Consultant|Rebiotix: Grant/Research Support|Seres Therapeutics: Advisor/Consultant|Seres Therapeutics: Grant/Research Support|summit plc: Advisor/Consultant|summit plc: Grant/Research Support|Vedanta Biosciences: Advisor/Consultant|Vedanta Biosciences: Grant/Research Support Maria Vehreschild, Prof. Dr., 3M: speaker fee|Astellas: Advisor/Consultant|Astellas: speaker fee|biologische heilmittel heel gmbh: Grant/Research Support|BioNtech: Grant/Research Support|EUMEDICA: Advisor/Consultant|Farmak International Holding: Advisor/Consultant|Ferring: Advisor/Consultant|Ferring: Speaker fee|Gilead Sciences: Advisor/Consultant|Immunic AG: Advisor/Consultant|MaaT: Advisor/Consultant|Merck: Advisor/Consultant|Merck: speaker fee|MSD: Advisor/Consultant|MSD: Grant/Research Support|MSD: speaker fees|Pfizer: speaker fee|Roche Molecular Systems: Grant/Research Support|Roche Molecular Systems: speaker fees|SocraRTec R&D GmbH: Advisor/Consultant|Takeda California: Grant/Research Support Professor Mark H. Wilcox, MD, FRCPath, GSK: Advisor/Consultant|GSK: Board Member|GSK: Grant/Research Support|Pfizer: Advisor/Consultant|Phico Therapeutics: Board Member|Seres: Advisor/Consultant|Seres: Board Member|Seres: Grant/Research Support|Summit: Advisor/Consultant|Summit: Grant/Research Support Erik R. Dubberke, MD, MSPH, Abbott: Advisor/Consultant|Ferring: Advisor/Consultant|Ferring: Grant/Research Support|Merck: Advisor/Consultant|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Seres: Advisor/Consultant|Summit: Advisor/Consultant|Synthetic Biologics: Grant/Research Support.

489. Bile Acid Concentrations in Healthy Volunteers Receiving Oral Omadacycline or Vancomycin

Background

Microbiome disruption associated with Clostridioides difficile infection (CDI) includes reduced metabolism of primary to secondary bile acids leading to increased likelihood of C. difficile germination and CDI recurrence. Omadacycline has potent in vitro activity against C. difficile but its effect on the microbiome is unknown. The purpose of this study was to assess changes in bile acid concentrations in healthy volunteers given omadacycline compared to vancomycin, the most common antibiotic used to treat CDI.

Methods

As part of an ongoing healthy volunteer study of adults between 18 and 40 years, subjects received a 10-day course of oral omadacycline or vancomycin. Stool samples were collected and bile acids were extracted and quantified via targeted liquid chromatography-mass spectrometry (LC-MS). For this analysis, samples collected at the end of antibiotic therapy (day 9-10) were analyzed for primary and secondary bile acids. Results were compared and visualized using R (ggplot2).

Results

Between October 2020 and December 2021, 16 healthy volunteers aged 26 ± 5 years (male: 69%; Caucasian: 31%; mean body mass index: 23.6 ± 3.8 kg/m2) were enrolled. Concentrations of primary bile acids (cholic acid and chenodeoxycholic acid) were higher in patients receiving oral vancomycin than those receiving omadacycline (Table 1). Secondary bile acids were higher in the omadacycline arm compared to vancomycin. Secondary:primary bile ratio was higher for omadacycline (0.43) than vancomycin (0.03).

Conclusion

Omadacycline preserved bile acid homeostasis in the gut to a higher extent that vancomycin, suggesting reduced microbiome dysbiosis. With potent in vitro C. difficile activity, availability as an oral and IV formulations, and favorable microbiome properties, further development of omadacycline for the treatment of CDI is warranted.

Disclosures

Kevin W. Garey, PharmD, MS, Acurx Pharmaceuticals: Grant/Research Support|Paratek Pharmaceuticals: Grant/Research Support|Seres Therapeutics: Grant/Research Support|Summit Pharmaceuticals: Grant/Research Support.

401. Rigor and Reproducibility of Clostridioides difficile susceptibility testing

Background

The growth and susceptibility testing of anaerobic bacteria presents many unique challenges. The Clinical Laboratory Standards Institute (CLSI) recommends performing minimum inhibitory concentration (MIC) testing for C. difficile through agar dilution (AD) assay, which carries logistical and time burdens compared to broth microdilution (BMD) methods. In this project we aim to assess the intra-and inter-laboratory reproducibility of MIC testing for C. difficile.

Methods

A total of 30 C. difficile isolates underwent MIC testing using AD and BMD techniques. To test intra-lab reproducibility, proficiency testing to develop a reproducible MIC testing process using 18 isolates was implemented across two multi-disciplinary labs, which was then validated in a prospective cohort of 116 isolates. MICs obtained by each method and lab were compared and essential agreement (EA) and major and minor error rates were calculated. To combat the labor and time-intensive demands of AD testing, automation with Integra Assist Plus was tested. Times for plate set up using a technician versus the Integra Assist Plus were measured twice and the average times were compared.

Results

AD and BMD yielded discordant resistant/susceptible results in 16.7% (5/30) of isolates tested. During proficiency testing, intra-lab comparison of AD MICs yielded 88.9% (16/18) EA and no disagreements occurred with more than 1 dilution difference. EA improved in the larger cohort to 93.9% (109/116), of which minor and major disagreements occurred in 17% (21/116) and 25% (29/116), respectively. A total of 10’4” minutes were saved using automation (12’44” mean) versus a technician (24’40” mean).

Conclusion

Here we present the process undertaken to ensure the rigor and reproducibility of C. difficile susceptibility testing. We developed a procedure that yields accurate results from two different labs, minimizes cost, and lowers the overall time required. Our future research will include validation with a larger sample and more academic partners.

Disclosures

Kevin W. Garey, PharmD, MS, Acurx: Grant/Research Support|cidara: Advisor/Consultant|cidara: Grant/Research Support|Paratek: Grant/Research Support|Seres Health: Grant/Research Support|Summit: Grant/Research Support.

468. Assessment of The Proportion of Hospitalized Patients (Pts) with Candidemia (C) and Invasive Candidiasis without Candidemia (IC) Who Received an Echinocandin (EC) and Were Potentially Eligible for an Earlier Hospital Discharge (HD)

Background

The primary driver of costs for C/IC pts is hospital length of stay. Studies across multiple infections demonstrate that most clinically stable pts with modest diagnostic & therapeutic requirements can be safely discharged prior to actual HD day. Few studies have assessed if there is an opportunity to accelerate time to HD in pts with C/IC. This study sought to determine the proportion of US hospitalized adult pts with C/IC who received an EC near HD & was potentially eligible for an earlier HD.

Methods

Design: Retrospective, multi-centered observational study using Premier Healthcare Database (1/2016-4/2019). Study criteria: hospitalized; age ≥ 18 years; Candida sp. on a culture consistent with C/IC; ≥3 days of an EC for C/IC; discharged alive; & received an EC near HD (-2 day to HD day). Pts were considerable potentially dischargeable if they met the following 3 criteria & maintained these 3 criteria until HD: resided on a non-ICU hospital ward, taking oral medications, & had no receipt of any diagnostic/therapeutic interventions (insertion of PICC lines were permitted). The difference in hospital days between first potentially eligible HD day & actual HD day was quantified. The proportion of pts that was potentially eligible for an earlier HD was examined overall & by Charlson Comorbidity index (CCI), C/IC, & Candida sp.

Results

During study period, 1,599 pts received an EC ≥ 3 days for C/IC & were discharged alive. Of the 1,599 pts, 1,008 (63%) were on an EC near HD. For the 1,008 pts on an EC near HD, the mean (SD) age was 59 (16) years, 52% were male, 40% had a CCI ≥4, 35% were in the ICU on index C/IC culture day, & 64% had C vs IC. C. glabrata (31%) & C. albicans (31%) were the most frequent Candida. sp. Of the 1,008 pts on an EC near HD, 14%, 21%, 29%, & 38% were potentially dischargeable 4, 3, 2, & 1 day(s), respectively, prior to the actual HD day (Figure). The proportion of pts who were potentially eligible for HD at least 2 days prior to actual HD day did not vary by CCI score, C/IC, & Candida sp.

Conclusion

Our findings suggest that a high proportion of hospitalized pts with C/IC receiving an EC near the time of HD, had modest diagnostic/therapeutic requirements prior to actual HD day & were potentially eligible for an earlier HD regardless of CCI, infection type, or Candida sp.

Disclosures

Thomas Lodise, Jr., Pharm.D., PhD, BioFire Diagnostics: Grant/Research Support|cidara: Advisor/Consultant|cidara: Honoraria|Entasis: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support|Paratek: Advisor/Consultant|Shionogi: Advisor/Consultant|Spero: Advisor/Consultant|Venatrox: Advisor/Consultant Kevin W. Garey, PharmD, MS, Acurx: Grant/Research Support|cidara: Advisor/Consultant|cidara: Grant/Research Support|Paratek: Grant/Research Support|Seres Health: Grant/Research Support|Summit: Grant/Research Support Brian H. Nathanson, Ph.D., cidara: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support.

730. A Phase 3, Randomized, Double-Blind Study to Evaluate the Efficacy and Safety of Ridinilazole Compared with Vancomycin for the Treatment of Clostridioides difficile Infection

Background

Vancomycin (VAN) therapy for C. difficile infection (CDI) is effective with &gt; 80% clinical response (CR) but is associated with 20–30% recurrence rate (rCDI). Secondary bile acids (2° BAs) inhibit C. difficile germination and help prevent rCDI. VAN depletes the gut microbiome decreasing the conversion of primary bile acids to 2° BAs. Ridinilazole (RDZ) is a highly selective anti-CDI, DNA-binding antibiotic in development for the treatment of CDI and prevention of rCDI.

Methods

A global, double-blinded, randomized Phase 3 trial assessed a 10-day treatment with RDZ 200 mg BID vs VAN 125 mg QID for CDI. The primary endpoint was sustained clinical response (SCR) defined as CR and no rCDI through 30 days post-end of treatment (EOT). Other endpoints included rCDI, microbiome diversity and composition, and microbiome-derived 2° BAs concentration. rCDI was defined as a new episode of diarrhea with confirmed positive free toxin test (FTT), requiring additional CDI therapy. All participants were monitored for treatment emergent adverse events (TEAE).

Results

Of the 759 patients (pts) enrolled, 745 were included in the mITT population (RDZ n=370, VAN n=375). RDZ achieved a numerically higher SCR rate than VAN (73.0% vs 70.7%) p=0.4672. RDZ resulted in a significant reduction in rCDI rate (8.1% vs 17.3%, p=0.0002) (Fig 1). In a pre-specified subpopulation, this was most notable in pts not receiving other antibiotics (rCDI 6.7% in RDZ vs 16.5% in VAN, p=0.0005). Microbiome alpha diversity was higher for RDZ vs VAN at EOT and EOT+30d (p&lt; 0.0001 and p≤ 0.0007 respectively, Fig 2) as were relative abundance (p&lt; 0.0001 and p=0.0203 respectively), and concentrations of 2° BAs (Fig 3). Higher microbiome diversity and concentrations of 2° BAs at EOT were associated with both lower rCDI and higher SCR rates. RDZ was well tolerated (pts with ≥ 1 TEAE: RDZ 36.4% vs VAN 35.5%, treatment discontinuation due to TEAE: RDZ 0.8% vs. VAN 2.9%).

Conclusion

RDZ was effective for sustained clinical response and safe for the treatment of patients with CDI. This was most notable in pts not receiving antibiotics. Compared to VAN, RDZ patients had faster recovery of fecal 2° BA, consistent with the preservation of microbiome diversity, resulting in a significantly lower rate of rCDI.

Disclosures

Pablo C. Okhuysen, MD, AstraZeneca: Stocks/Bonds|Beam Therapeutics: Stocks/Bonds|Biontech: Stocks/Bonds|Deinove: Grant/Research Support|Ferring: Advisor/Consultant|Glaxo Smith Kleine: Stocks/Bonds|Johnson and Johnson: Stocks/Bonds|Melinta: Grant/Research Support|Merck Sharp & Dohme Corp: Grant/Research Support|Moderna: Stocks/Bonds|Napo Pharmaceuticals: Advisor/Consultant|Napo Pharmaceuticals: Grant/Research Support|Novavax: Stocks/Bonds|Pfizer: Stocks/Bonds|Summit: Advisor/Consultant|Summit: Grant/Research Support Kevin W. Garey, PharmD, MS, Acurx: Grant/Research Support|cidara: Advisor/Consultant|cidara: Grant/Research Support|Paratek: Grant/Research Support|Seres Health: Grant/Research Support|Summit: Grant/Research Support Thomas J. Louie, MD, adiso therapeutics: Advisor/Consultant|adiso therapeutics: Grant/Research Support|crestone: Advisor/Consultant|crestone: Grant/Research Support|Finch: Advisor/Consultant|Finch: Grant/Research Support|Seres Therapeutics: Advisor/Consultant|Seres Therapeutics: Grant/Research Support|Seres Therapeutics: Honoraria|summit plc: Grant/Research Support|vedanta biosciences: Advisor/Consultant|vedanta biosciences: Grant/Research Support Jianling LI, MS, Abbott: Stocks/Bonds|Abbvie: Stocks/Bonds|ALX Oncology: Stocks/Bonds|BioNTech: Stocks/Bonds|Bluebird Bio: Stocks/Bonds|Cytokinetics: Stocks/Bonds|I-Mab: Stocks/Bonds|Johnson & Johnson: Stocks/Bonds|Moderna: Stocks/Bonds|TG Therapeutics: Stocks/Bonds Esther Duperchy, PhD, Summit Plc: Employee Jose G. Montoya, MD, Summit: Honoraria|Summit: Stocks/Bonds Lori Styles, MD, Abbvie: Stocks/Bonds|Summit Therapeutics: employee|Summit Therapeutics: Stocks/Bonds Fong Clow, Sc. D, Summit Therapeutics: Employee Danelle James, MD, Summit Therapeutics: Employee.

620. Pharmacokinetic-Pharmacodynamic Analysis of Oral Vancomycin and Gut Microbiome Changes in Healthy Volunteers: an Exploratory Study

Background

Oral vancomycin causes profound changes to the gut microbiome due to high intra-colonic vancomycin concentrations. However, pharmacokinetics of oral vancomycin causing pharmacodynamic changes have not been explored, especially during the early dosing period. The purpose of this study was to investigate fecal vancomycin concentrations in healthy individuals in relation to gut microbiome diversity changes.

Methods

Healthy subjects 18-45 years with no antibiotic use for at least 28 days were given oral vancomycin 125 mg was given every 6 hours for 10 days. Stool samples were collected at baseline and during antibiotic therapy. Vancomycin concentrations were obtained through high-performance liquid chromatography (HPLC) assay. For this early pharmacokinetics analysis, stool samples from day 0 (baseline) to day 4 were included. Shotgun metagenomics sequencing was used for microbiome analysis. Descriptive analysis was performed to identify gut-microbiome phyla changes in correlation with detectable oral vancomycin fecal concentrations.

Results

A total of 6 healthy volunteers aged 32±5 years (Male: 100%; Caucasian: 50%; mean BMI: 26.8±4.5 kg/m²) were included. In the early dosing period (day 0-4), the mean fecal vancomycin concentrations increased daily with the highest concentration of 1,586 μg/g of stool occurring on day 4. Three of 9 subjects (50%) had undetectable oral vancomycin levels one days 1 and 2 of dosing. Within 24-48 hour of detectable vancomycin levels, subject-specific changes of gut microbiome phylum-level proportions were observable. Overall, an increase in Actinobacteria and Proteobacteria phyla and decrease in Firmicute phylum was observed within 24 hours that vancomycin was detected in the feces.

Conclusion

High concentrations of vancomycin are achieved in the stool by day four of dosing for all subjects; however, low concentrations are observed early in the dosing period for some subjects. Proportional, subject specific differences in gut microbiome phyla were observed within 24 hours of detectable vancomycin levels in the feces.

Disclosures

Kevin W. Garey, PharmD, MS, Acurx Pharmaceuticals: Grant/Research Support|Paratek Pharmaceuticals: Grant/Research Support|Seres Therapeutics: Grant/Research Support|Summit Pharmaceuticals: Grant/Research Support.

521. Investigating the Gram-Positive Selective Spectrum of Ibezapolstat, a First-in-Class DNA Polymerase IIIC (Pol IIIC) Inhibitor

Background

Ibezapolstat (IBZ) is a non-absorbable antimicrobial currently in phase 2 clinical trials for the treatment of Clostridioides difficile infection (CDI). In vitro and human studies have shown potent activity of IBZ against C. difficile but selective activity against other beneficial Gram-positive gut microbiota shown to reduce the risk of recurrent CDI. As the target DNA Pol IIIC enzyme is present in most Gram-positive species, the reasons for this selectivity are unclear. The purpose of this study was to assess the selectivity of IBZ against Gram-positive gut microbiota.

Methods

Using stool samples and microbiome data from the phase 1 and 2 studies, changes in proportional abundance of gut microbiome species were analyzed over time in healthy volunteers or patients with CDI given IBZ. Using a separate collection of gut microbiota species, MIC determinations against a variety of Gram-positive gut species were assessed by broth microdilution.

Results

Baseline gut microbiota from healthy volunteers were primarily Firmicutes, Bacteroidetes, or Actinobacteria. Actinobacteria increased in abundance after starting IBZ (primarily Bifidobacteriales or Coriobacteriales) and persisted for the entire dosing period. In comparison to the phase 1 study, the phase 2a CDI study baseline microbiota had a lower proportion of Actinobacteria and Firmicutes and increased Bacteroidetes. In CDI patients, Actinobacteria increased in abundance after starting IBZ (primarily Coriobacteriales) followed within 2-3 days by decreased abundance of Bacteroidetes, and an increased abundance of Lachnospiraceae and Ruminococcaceae. Using isolated gut microbiota species, IBZ was inactive (MIC >64 µg/mL) against representative Actinobacteria (Bifidobacteriaceae and Coriobacteriaceae) and certain Firmicutes (Lachnospiraceae and Lactobacillaceae) but highly active against strains of C. difficile (MIC<2 µg/mL).

Conclusion

Microbiome changes with IBZ were dependent on underlying composition of the baseline microbiome but consistently demonstrated increased abundance of Actinobacteria after starting therapy. IBZ microbiome data coupled with in vitro MIC determinations demonstrated persistence or regrowth of healthy microbiota associated with beneficial physiologic effects.

Disclosures

Kevin W. Garey, PharmD, MS, Acurx Pharmaceuticals: Grant/Research Support|Paratek Pharmaceuticals: Grant/Research Support|Seres Therapeutics: Grant/Research Support|Summit Pharmaceuticals: Grant/Research Support.

469. Healthcare Resource Utilization (HRU) among Hospitalized Patients (Pts) with Candidemia (C) and Invasive Candidiasis without Candidemia (IC) Who Received Definitive Treatment with an Echinocandin (EC) Across United States (US) Hospitals

Background

Guidelines recommend ECs as preferred agents for C/IC. Although studies demonstrate that the ECs are safe and effective for the treatment of pts with C/IC, there are scant HRU data among hospitalized adult pts who received an EC for C/IC. This study sought to describe current EC use patterns and outcomes for C/IC across US hospitals.

Methods

A retrospective, multi-centered observational study was performed using the Premier Healthcare Database (1/2016-4/2019). Inclusion criteria: hospitalized; age ≥ 18 years, presence of Candida sp. on clinical culture consistent with C/IC; and received ≥3 days of an EC between -2 days of index culture to discharge. Pts were stratified by presence of C/IC. Baseline characteristics and treatment patterns (EC received, receipt of EC in relation to index culture, and EC duration) were assessed. Outcomes: discharge status (in-hospital death vs discharge location), hospital length of stay (LOS) post index culture, and hospital costs (overall and component costs) post index culture.

Results

1,865 pts met study criteria. The mean (SD) age was 58.9 (19), 48% were female, mean (SD) Charlson Comorbidity Index was 3.4 (2.7) and 55% resided in the ICU at index culture. The most common Candida sp. were C. albicans (37%), C. glabrata (28%), C. parapsilosis (11%), and C. tropicalis (10%). Most pts had C (66%). Baseline characteristic and treatment patterns were largely similar between C/IC pts except for Candida sp., EC received, and EC duration (Table). Mean HRU was greater in pts with IC vs C (Table and Figure). No differences in HRU were observed in pts who died vs survived. In-hospital mortality was higher in pts with C vs IC. Most pts with C/IC received additional medical care post-discharge and pts with IC vs C were more likely to be discharged to a home health agency.

Conclusion

Hospital costs associated with C/IC are substantial, with most attributable to room and board costs. In-hospital mortality was considerable for pts with C/IC and many pts with C/IC required additional medical care in a long-term care facility or with a home health agency post-discharge. New treatment options are needed to mitigate the costs and outcomes associated with daily receipt of EC for pts with C/IC.

Disclosures

Thomas Lodise, Jr., Pharm.D., PhD, BioFire Diagnostics: Grant/Research Support|cidara: Advisor/Consultant|cidara: Honoraria|Entasis: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support|Paratek: Advisor/Consultant|Shionogi: Advisor/Consultant|Spero: Advisor/Consultant|Venatrox: Advisor/Consultant Kevin W. Garey, PharmD, MS, Acurx: Grant/Research Support|cidara: Advisor/Consultant|cidara: Grant/Research Support|Paratek: Grant/Research Support|Seres Health: Grant/Research Support|Summit: Grant/Research Support Brian H. Nathanson, Ph.D., cidara: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support.

1669. A US Based National Surveillance Study for the Susceptibility and Epidemiology of Clostridioides difficile Associated Diarrheal Isolates with Special Reference to Ridinilazole: 2020-2021

Background

We have previously reported on a US based national surveillance study from 6 geographically dispersed medical centers for the susceptibility and epidemiology of C. difficile isolates. This current survey was conducted with isolates collected in 2020-21 with specific attention to the susceptibility to ridinilazole as well as nine comparators.

A summary of the susceptibilities of 300 isolates of C. difficile tested against 10 antimicrobial agents

Methods

in 2020-21 C. difficile isolates or stools from patients with C. difficile toxin positive antibiotic associated diarrhea were collected in 6 US medical centers and referred to a central lab. After confirmation of 300 isolates antibiotic susceptibilities were determined by agar dilution method (CLSI M11-A9) against 10 agents listed in Table below. Ribotyping was performed by PCR capillary gel electrophoresis on all isolates.

Results

A summary of the susceptibilities of the 300 isolates against 10 antimicrobial agents are shown in the Table. The most common ribotype was 014-020 (14.4% compared to 11.8% in 2016), followed by 106 (10%, compared to 15% in 2016), 027 (10% compared to 13.1% in 2016), 002 (8% compared to 8.5% in 2016, 078-126 (4.3% compared to 1.3% in 2016). Ridinilazole was very potent against all isolates collected in the US with an MIC 90 of 0.25 mcg/ml, including against all the hypervirulent ribotypes as well as those isolates with antibiotic resistances to other antibiotics in the test panel.

Conclusion

Ridinilazole showed excellent in-vitro activity against C. difficile isolates in the US, independent of ribotype. There has been a striking change in ribotype distribution compared to 2016, accompanied by a reduction in C. difficile resistance to moxifloxacin and imipenem.

Disclosures

Cheleste M. Thorpe, MD, Actelion: Grant/Research Support|Deinove: Advisor/Consultant|General Mills: Grant/Research Support|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Summit: Advisor/Consultant|Summit: Grant/Research Support Stuart Johnson, M.D., Ferring Pharmaceuticals: Membership on Ferring Publication Steering Committee|Ferring Pharmaceuticals: Employee|Summit Plc: Advisor/Consultant Dale N. Gerding, MD, Destiny Pharma plc.: Advisor/Consultant Karen C. Carroll, MD, Abbott Diagnostics: Advisor/Consultant|BD Diagnostics: Advisor/Consultant|BD Diagnostics: Grant/Research Support|BioRad, Inc: Grant/Research Support|Meridian Biosciences: Grant/Research Support|Roche Diagnostics: Advisor/Consultant|Scanogen, Inc: Advisor/Consultant|Scanogen, Inc: Grant/Research Support|Thermo Fisher, Inc: Advisor/Consultant Kevin W. Garey, PharmD, MS, Acurx: Grant/Research Support|cidara: Advisor/Consultant|cidara: Grant/Research Support|Paratek: Grant/Research Support|Seres Health: Grant/Research Support|Summit: Grant/Research Support Esther Duperchy, PhD, Summit Plc: Employee David R. Snydman, MD, Merck: Advisor/Consultant|Merck and Company: Grant/Research Support|Prolacta: Advisor/Consultant|Prolacta: Grant/Research Support|Seres: Advisor/Consultant|Seres Health: Grant/Research Support|Summit Plc: Grant/Research Support|Takeda: Advisor/Consultant|Takeda: Grant/Research Support|Visterra: Advisor/Consultant.

380. A molecular epidemiological exploration of reduced vancomycin susceptibility in Clostridioides difficile

Background

Use of vancomycin to treat Clostridioides difficile infection (CDI) has increased following recent IDSA/SHEA treatment guideline updates, applying a selection pressure for resistance development. We previously demonstrated acquired mutations in VanSR two-component system led to constitutive vanG expression and improved in vitro C. difficile survival in physiologic vancomycin concentrations. We aim to describe the molecular epidemiology of reduced vancomycin susceptibility in clinical isolates during a period of high vancomycin use.

Methods

A cohort study was performed including adult patients hospitalized with CDI in two health systems (14 hospitals) in the Houston Area between 2017-2021. (Stool transport) C. difficile were ribotyped by fluorescent PCR and susceptibility tested by agar dilution in accordance with CLSI standards. Reduced vancomycin susceptibility was defined by minimum inhibitory concentrations (MICs) >2 mg/L. Sanger sequencing was conducted on a subgroup of isolates to identify VanSR mutations. Analysis using Chi square was performed using IBM SPSS Statistics (v 28.0.1.0).

Results

A total of 36% (165/465) of isolates exhibited reduced vancomycin susceptibility (MIC₅₀ = 2 mg/L, MIC₉₀ = 4 mg/L, range 0.5-16 mg/L), of which 348 were ribotyped. A significantly higher proportion of ribotype (RT) 027 isolates demonstrated reduced vancomycin susceptibility (83%) compared to other common ribotypes (30%); p< 0.001). No differences based on collection year (p=0.3) or healthcare system (p=0.08) were observed. Overall, 11% (7/56) of isolates exhibiting mutations in VanS (n=1), VanR (n=5), or both (n=1). VanSR mutations were present in 47% (7/15) of those with MICs >2mg/L vs 0% (0/41) of those with MICs ≤2 mg/L (p< 0.001).

Conclusion

A high proportion of clinical C. difficile isolates exhibited elevated MICs to vancomycin, which was most common in RT027 isolates. Mutations in the vanG regulator, VanSR, correlated with elevated MICs in a subgroup of isolates. Future research is needed to expand upon molecular mechanisms and clinical implications of reduced vancomycin susceptibility.

Disclosures

Kevin W. Garey, PharmD, MS, Acurx Pharmaceuticals: Grant/Research Support|Paratek Pharmaceuticals: Grant/Research Support|Seres Therapeutics: Grant/Research Support|Summit Pharmaceuticals: Grant/Research Support.

883. Stool Toxin Concentrations Are Higher in Children with Baseline Severe Disease, Severe Outcomes, and Recurrence

Background

In adults with C. difficile infection (CDI), higher baseline stool concentrations of toxins A and B are associated with severe baseline disease, CDI-attributable severe outcomes, and recurrence. We evaluated whether stool toxin concentration predicts these presentations in children with CDI.

Methods

We performed a prospective cohort study from 2016-2019. Participants were inpatients ≤17 years old at two pediatric hospitals with diarrhea and positive C. difficile testing who received therapy. Patients were followed for 40 days after baseline stool sample for severe outcomes (intensive care unit admission, colectomy, or death, categorized as CDI primarily attributable, CDI contributed, or CDI not contributing) and recurrence (resolution followed by new diarrhea and re-initiation of therapy). Baseline stool toxin A & B concentrations were measured using ultrasensitive single molecule array assay (cutoff for positive result = 20 pg/mL). Median baseline toxin concentrations were compared between groups using Wilcoxon tests.

Results

We enrolled 206 patients [median age 8.9 years (IQR, 4.7–13.2)]. Children with severe baseline disease by IDSA-SHEA criteria (n = 39) had higher median stool toxin A+B concentration than those without severe disease (n = 131) (2,912.6 vs. 500.5 pg/mL, P=0.05). Of the cohort, 40 (19%) had a severe outcome (4 primarily attributed to CDI, 19 with contribution from CDI, and 17 unrelated to CDI). Median toxin A+B concentration was non-significantly higher in children with a primarily-attributed severe outcome versus those without severe outcome (19,473 vs. 429.1 pg/mL, P=0.317) (Figure 1). Of 197 children with eligible data, recurrence occurred in 18 (9.1%); baseline toxin A+B concentration was significantly higher in patients with versus without recurrence (3,946.7 vs. 283.3 pg/mL, P=0.026) (Figure 2).

Conclusion

Higher stool toxin concentrations are present in children with baseline severe CDI, a CDI-attributable severe outcome, or recurrence compared with children without these presentations. Quantification of stool toxin concentration may be helpful in identifying severe CDI and predicting CDI outcomes, which could help guide decisions about clinical management.

Disclosures

Larry K. Kociolek, MD, MSCI, Merck: Grant/Research Support Timothy J. Savage, MD, MPH, MSc, UCB: Contract to Brigham and Women's Hospital Alice Banz, PhD, biomerieux: Simoa assays were performed by bioMerieux, and A.B. is an employee of bioMerieux Kevin W. Garey, PharmD, MS, Acurx: Grant/Research Support|cidara: Advisor/Consultant|cidara: Grant/Research Support|Paratek: Grant/Research Support|Seres Health: Grant/Research Support|Summit: Grant/Research Support Ciaran P. Kelly, n/a, Artugen: Advisor/Consultant|Facile Therapeutics: Advisor/Consultant|Ferring Pharma: Advisor/Consultant|Finch: Advisor/Consultant|Finch: Advisor/Consultant|First Light Biosciences: Advisor/Consultant|First Light Biosciences: Ownership Interest|Milky Way Biosciences: Advisor/Consultant|Milky Way Biosciences: Grant/Research Support|Pfizer: Advisor/Consultant|Seres Therapeutics: Advisor/Consultant|Summit Therapeutics: Advisor/Consultant.

Higher In Vivo Fecal Concentrations of Clostridioides difficile Toxins A and B in Patients With North American Pulsed-Field Gel Electrophoresis Type 1/Ribotype 027 Strain Infection

Ultrasensitive, quantitative Clostridioides difficile stool toxin measurement demonstrated significantly higher concentrations of toxins A and B in patients infected with the North American pulsed-field gel electrophoresis type 1/ribotype 027 (NAP-1/027) strain compared with other strains, providing in vivo confirmation of the in vitro association between NAP-1/027 and elevated toxin production.

Development of the invasive candidiasis discharge [I Can discharge] model: a mixed methods analysis

Patients with invasive candidiasis (IC) have complex medical and infectious disease problems that often require continued care after discharge. This study aimed to assess echinocandin use at hospital discharge and develop a transition of care (TOC) model to facilitate discharge for patients with IC. This was a mixed method study design that used epidemiologic assessment to better understand echinocandin use at hospital discharge TOC. Using grounded theory methodology focused on patients given echinocandins during their last day of hospitalization, a TOC model for patients with IC, the invasive candidiasis [I Can] discharge model was developed to better understand discharge barriers. A total of 33% (1405/4211) echinocandin courses were continued until the last day of hospitalization. Of 536 patients chosen for in-depth review, 220 (41%) were discharged home, 109 (20%) were transferred, and 207 (39%) died prior to discharge. Almost half (46%, 151/329) of patients discharged alive received outpatient echinocandin therapy. Independent predictors for outpatient echinocandin use were osteomyelitis (OR, 4.1; 95% CI, 1.1-15.7; p = 0.04), other deep-seated infection (OR, 4.4; 95% CI, 1.7-12.0; p = 0.003), and non-home discharge location (OR, 3.9, 95% CI, 2.0-7.7; p < 0.001). The I Can discharge model was developed encompassing four distinct themes which was used to identify potential barriers to discharge. Significant echinocadin use occurs at hospital discharge TOC. The I Can discharge model may help clinical, policy, and research decision-making processes to facilitate smoother and earlier hospital discharges.

Stool Toxin Concentration Does Not Distinguish Clostridioides difficile Infection from Colonization in Children Less Than 3 Years of Age

In a prospective cohort study, stools from children <3 years with and without diarrhea who were Clostridioides difficile nucleic acid amplification test-positive underwent ultrasensitive and quantitative toxin measurement. Among 37 cases and 46 controls, toxin concentration distributions overlapped substantially. Toxin concentration alone does not distinguish C. difficile infection from colonization in young children.