Efficacy and Safety of Investigational Microbiome Drug SER-109 for Treatment of Recurrent Clostridioides difficile Infection

Background: Antibiotics targeted against Clostridioides difficile bacteria are necessary, but insufficient, to achieve a durable clinical response because they have no effect on C. difficile spores that germinate within a disrupted microbiome. ECOSPOR-III evaluated SER-109, an investigational, biologically derived microbiome therapeutic of purified Firmicute spores for treatment of rCDI. Herein, we present the interim analysis in the ITT population at 8 and 12 weeks. Methods: Adults ≥18 years with rCDI (≥3 episodes in 12 months) were screened at 75 US and CAN sites. CDI was defined as ≥3 unformed stools per day for <48 hours with a positive C. difficile assay. After completion of 10–21 days of vancomycin or fidaxomicin, adults with symptom resolution were randomized 1:1 to SER-109 (4 capsules × 3 days) or matching placebo and stratified by age (≥ or <65 years) and antibiotic received. Primary objectives were safety and efficacy at 8 weeks. Primary efficacy endpoint was rCDI (recurrent toxin+ diarrhea requiring treatment); secondary endpoints included efficacy at 12 weeks after dosing. Results: Overall, 287 participants were screened and 182 were randomized (59.9% female; mean age, 65.5 years). The most common reason for screen failure was a negative C. difficile toxin assay. A significantly lower proportion of SER-109 participants had rCDI after dosing compared to placebo at week 8 (11.1% vs 41.3%, respectively; relative risk [RR], 0.27; 95% confidence interval [CI], 0.15–0.51; p-value <0.001). Efficacy rates were significantly higher with SER-109 vs placebo in both stratified age groups (Figure 1). SER-109 was well-tolerated with a safety profile similar to placebo. The most common treatment-emergent adverse events (TEAEs) were gastrointestinal and were mainly mild to moderate. No serious TEAEs, infections, deaths, or drug discontinuations were deemed related to study drug. Conclusions: SER-109, an oral live microbiome therapeutic, achieved high rates of sustained clinical response with a favorable safety profile. By enriching for Firmicute spores, SER-109 achieves high efficacy while mitigating risk of transmitting infectious agents, beyond donor screening alone. SER-109 represents a major paradigm shift in the clinical management of patients with recurrent CDI. Clinicaltrials.gov Identifier NCT03183128. These data were previously presented as a late breaker at American College of Gastroenterology 2020.Funding: Seres TherapeuticsDisclosures: None

Admission Screening for Clostridium difficile Infection (CDI) in Bone Marrow Transplant Populations

Background:Clostridium difficile infection (CDI) is the most common healthcare-associated infection (HAI) and is often associated with increased medical costs and longer lengths of hospital stay. Previous studies have highlighted that hematopoietic stem cell transplant (HSCT) recipients are at an increased risk for CDI of up to 33% from other hospitalized patients. Studies have also supported the prevalence of asymptomatic colonization with C. difficile among HSCT patients. Asymptomatic colonization with C. difficile is a significant risk factor for transmission of infection to other patients developing hospital onset (HO-CDI). Therefore, targeted infection prevention efforts, such as early identification of patients with community-onset (CO-CDI) and patients with asymptomatic colonization with CDI in HSCT patients, may be effective in reducing the occurrence of HO-CDI. We discuss the CDI admission screening protocol in Emory University Hospital’s (EUH) bone marrow transplant (BMT) unit. Methods: As part of an infection prevention initiative, a CDI screening protocol was implemented in December 2018 for all patients that admitted to the EUH inpatient BMT unit. Upon admission, patients were screened for CO-CDI symptoms, specifically loose or unformed stools. A C. difficile toxin assay PCR would be collected within the first 3 calendar days of admission for all patients screened. Patients with symptoms were placed on isolation precautions pending results of the C. difficile toxin assay. If a patient had a positive C. difficile toxin assay result, isolation precautions would be maintained for the duration of hospitalization regardless of symptoms. Patients who are were unable to produce a stool specimen on the first 3 days of admission were excluded from the screening protocol. Patients with positive C. difficile toxin assay PCRs were classified as CO-CDI and were treated. Results: Since implementation of the CDI screening protocol, 109 CDI events were identified from January 2019 to October 2019. Moreover, 79% of positive C. difficile toxin assays were collected within the first 3 calendar days of admission. HO-CDI has decreased from 78% in 2018 to 21% during the designated time frame. Conclusions: CDI screening upon admission of BMT populations has shown a decrease among HO-CDI by early identification of CO-CDI and CO asymptomatic colonization with C. difficile. This early identification has allowed rapid implementation of infection preventions precautions, thus reducing risk of unit-based transmission.Funding: NoneDisclosures: None

High Agreement Between an Ultrasensitive Clostridioides difficile Toxin Assay and a C. difficile Laboratory Algorithm Utilizing GDH-and-Toxin Enzyme Immunoassays and Cytotoxin Testing

ABSTRACT The Singulex Clarity C. diff toxins A/B (Clarity) assay is an automated, ultrasensitive immunoassay for the detection of Clostridioides difficile toxins in stool. In this study, the performance of the Clarity assay was compared to that of a multistep algorithm using an enzyme immunoassay (EIA) for detection of glutamate dehydrogenase (GDH) and toxins A and B arbitrated by a semiquantitative cell cytotoxicity neutralization assay (CCNA). The performance of the assay was evaluated using 211 residual deidentified stool samples tested with a GDH-and-toxin EIA (C. Diff Quik Chek Complete; Techlab), with GDH-and-toxin discordant samples tested with CCNA. The stool samples were stored at –80°C before being tested with the Clarity assay. For samples discordant between Clarity and the standard-of-care algorithm, the samples were tested with PCR (Xpert C. difficile; Cepheid), and chart review was performed. The testing algorithm resulted in 34 GDH+/toxin+, 53 GDH−/toxin−, and 124 GDH+/toxin− samples, of which 39 were CCNA+ and 85 were CCNA−. Clarity had 96.2% negative agreement with GDH−/toxin− samples, 100% positive agreement with GDH+/toxin+ samples, and 95.3% agreement with GDH+/toxin−/CCNA− samples. The Clarity result was invalid for one sample. Clarity agreed with 61.5% of GDH+/toxin−/CCNA+ samples, 90.0% of GDH+/toxin−/CCNA+ (high-positive) samples, and 31.6% of GDH+/toxin−/CCNA+ (low-positive) samples. The Singulex Clarity C. diff toxins A/B assay demonstrated high agreement with a testing algorithm utilizing a GDH-and-toxin EIA and CCNA. This novel automated assay may offer an accurate, stand-alone solution for C. difficile infection (CDI) diagnostics, and further prospective clinical studies are merited.

Monitoring the 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) modification in eukaryotic tRNAs via the gamma-toxin endonuclease

ABSTRACTThe post-transcriptional modification of tRNA at the wobble position is a universal process occurring in all domains of life. In eukaryotes, the wobble uridine of particular tRNAs is transformed to the 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) modification which is critical for proper mRNA decoding and protein translation. However, current methods to detect mcm5s2U are technically challenging and/or require specialized instrumental expertise. Here, we show that gamma-toxin endonuclease from the yeast Kluyveromyces lactis can be used as a probe for assaying mcm5s2U status in the tRNA of diverse eukaryotic organisms ranging from protozoans to mammalian cells. The assay couples the mcm5s2U-dependent cleavage of tRNA by gamma-toxin with standard molecular biology techniques such as Northern blot analysis or quantitative PCR to monitor mcm5s2U levels in multiple tRNA isoacceptors. The results gained from the gamma-toxin assay reveals the evolutionary conservation of the mcm5s2U modification across eukaryotic species. Moreover, we have employed the gamma-toxin assay to verify uncharacterized eukaryotic Trm9 and Trm112 homologs that catalyze the formation of mcm5s2U. These findings demonstrate the use of gamma-toxin as a detection method to monitor mcm5s2U status in diverse eukaryotic cell types for cellular, genetic and biochemical studies.

Estimating Local Costs Associated WithClostridium difficileInfection Using Machine Learning and Electronic Medical Records

BACKGROUNDReported per-patient costs ofClostridium difficileinfection (CDI) vary by 2 orders of magnitude among different hospitals, implying that infection control officers need precise, local analyses to guide rational decision making between interventions.OBJECTIVEWe sought to comprehensively estimate changes in length of stay (LOS) attributable to CDI at a single urban tertiary-care facility using only data automatically extractable from the electronic medical record (EMR).METHODSWe performed a retrospective cohort study of 171,938 visits spanning a 7-year period. In total, 23,968 variables were extracted from EMR data recorded within 24 hours of admission to train elastic-net regularized logistic regression models for propensity score matching. To address time-dependent bias (reverse causation), we separately stratified comparisons by time of infection, and we fit multistate models.RESULTSThe estimated difference in median LOS for propensity-matched cohorts varied from 3.1 days (95% CI, 2.2–3.9) to 10.1 days (95% CI, 7.3–12.2) depending on the case definition; however, dependency of the estimate on time to infection was observed. Stratification by time to first positive toxin assay, excluding probable community-acquired infections, showed a minimum excess LOS of 3.1 days (95% CI, 1.7–4.4). Under the same case definition, the multistate model averaged an excess LOS of 3.3 days (95% CI, 2.6–4.0).CONCLUSIONSIn this study, 2 independent time-to-infection adjusted methods converged on similar excess LOS estimates. Changes in LOS can be extrapolated to marginal dollar costs by multiplying by average costs of an inpatient day. Infection control officers can leverage automatically extractable EMR data to estimate costs of CDI at their own institutions.Infect Control Hosp Epidemiol.2017;38:1478–1486

Use of culture- and ELISA-based toxin assay for detecting Clostridium difficile, a neglected pathogen: A single-center study from a tertiary care setting

INTRODUCTION: Clostridium difficile is a Gram-positive spore-bearing anaerobic bacillus increasingly associated with both community- and hospital-acquired colitis and diarrhea. It is the most common identifiable bacterial cause of healthcare-associated diarrhea associated with antibiotic use and one of the most common anaerobic infections. The diagnosis of C. difficile infection includes detection of toxin A/B in stool specimens by direct enzyme immunoassay, culture of pathogen from the stool specimens using a selective agar Cycloserine-Cefoxitin fructose agar (CCFA), tissue culture assay, and detection of glutamate dehydrogenase an enzyme produced by C. difficile. With few reports from India on this disease, the present study was planned to throw more light on the prevalence and utility of laboratory diagnostic methods for C. difficile-associated diarrhea (CDAD). MATERIAL AND METHODS: After taking approval from the Ethics Committee, 150 patients with antibiotic-associated diarrhea were taken as a study group and fifty patients with exposure to antibiotics but who did not develop diarrhea were taken as controls. Stool specimen was processed for both culture on CCFA and toxin detection by IVD Tox A + B ELISA. RESULTS: Only four specimens were culture positive, whereas 13 were ELISA positive. All culturepositive isolates were toxigenic. C. difficile was neither isolated nor its toxin detected in the control group. Culture- and toxin-based assays may not detect all cases of CDAD. CONCLUSION: Based on the results of the present study, culture does not provide any additional yield over toxin assay. Better diagnostic modalities would be required to prove CDAD.