Efficacy of Bezlotoxumab in Trial Participants Infected With Clostridioides difficile Strain BI Associated With Poor Outcomes.

BACKGROUND: Bezlotoxumab reduced rates of recurrent Clostridioides difficile infection (rCDI) vs placebo in Monoclonal Antibodies for C. difficile Therapy (MODIFY) I/II trial participants receiving antibacterial drug treatment for CDI. A secondary objective of MODIFY I/II was to assess bezlotoxumab's efficacy against C. difficile strains associated with increased rates of morbidity and mortality. METHODS: In this post-hoc analysis of pooled MODIFY I/II data, efficacy endpoints were assessed in participants infected with restriction endonuclease analysis BI and non-BI strains of C. difficile at study entry. Treatment outcomes were compared between participants receiving bezlotoxumab (alone or with actoxumab [B, B+A]) and those receiving no bezlotoxumab (placebo or actoxumab [P, A]). RESULTS: From 2559 randomized participants, C. difficile was isolated from 1588 (67.2%) baseline stool samples. Participants with BI strains (n = 328) were older and had more risk factors for rCDI than non-BI strain participants (n = 1260). There were no differences in initial clinical cure rate between BI and non-BI strains in either group. The rCDI rate for BI strains treated with bezlotoxumab was lower than for the no bezlotoxumab group (B, B+A vs P, A: 23.6% vs 43.9%) and was also lower for the non-BI strains (B, B+A vs P, A: 21.4% vs 36.1%). Rates of 30-day CDI-associated rehospitalization were greater with BI vs non-BI strains in both groups. CONCLUSIONS: Infection with BI strains of C. difficile predicted poor outcomes in the MODIFY I/II trials. Bezlotoxumab (alone or with actoxumab) treatment was effective both in BI and non-BI subpopulations.

Bezlotoxumab for the Prevention of Recurrent Clostridioides difficile Infection: 12-Month Observational Data From the Randomized Phase III Trial, MODIFY II.

From Monoclonal Antibodies for C. difficile Therapy II, no participants (n = 0/69) with a sustained clinical cure through 12 weeks following bezlotoxumab infusion experienced recurrent Clostridioides difficile infection (rCDI) after 9 months (versus actoxumab + bezlotoxumab, n = 2/65; versus placebo, n = 1/34). Bezlotoxumab's efficacy appears to be due to prevention rather than delayed onset of rCDI. Clinical Trials Registration. NCT01513239.

Effect of Endogenous Clostridioides difficile Toxin Antibodies on Recurrence of C. difficile Infection.

BACKGROUND: Endogenous antibodies (eAbs) against Clostridioides (Clostridium) difficile toxins may protect against recurrence of C. difficile infection (rCDI). This hypothesis was tested using placebo group data from MODIFY (Monoclonal Antibodies for C. difficile Therapy) I and II (NCT01241552 and NCT01513239, respectively), global, randomized phase 3 trials that assessed the efficacy and safety of the antitoxin monoclonal antibodies bezlotoxumab and actoxumab in participants receiving antibiotic therapy for CDI. METHODS: A placebo infusion (normal saline) was administered on study day 1. Serum samples were collected on day 1, week 4, and week 12, and eAb-A and eAb-B titers were measured by 2 validated electrochemiluminescence immunoassays. Rates of initial clinical cure and rCDI were summarized by eAb titer category (low, medium, high) at each time point. RESULTS: Serum eAb titers were available from a total of 773 participants. The proportion of participants with high eAb-A and eAb-B titers increased over time. Rates of initial clinical cure were similar across eAb titer categories. There was no correlation between eAb-A titers and rCDI rate at any time point. However, there was a negative correlation between rCDI and eAb-B titer on day 1 and week 4. rCDI occurred in 22% of participants with high eAb-B titers at baseline compared with 35% with low or medium titers (P = .015). CONCLUSIONS: Higher eAb titers against toxin B, but not toxin A, were associated with protection against rCDI. These data are consistent with the observed efficacy of bezlotoxumab, and lack of efficacy of actoxumab, in the MODIFY trials. CLINICAL TRIALS REGISTRATION: NCT01241552 and NCT01513239.

Bezlotoxumab for Prevention of Recurrent Clostridium difficile Infection.

BACKGROUND: Clostridium difficile is the most common cause of infectious diarrhea in hospitalized patients. Recurrences are common after antibiotic therapy. Actoxumab and bezlotoxumab are human monoclonal antibodies against C. difficile toxins A and B, respectively. METHODS: We conducted two double-blind, randomized, placebo-controlled, phase 3 trials, MODIFY I and MODIFY II, involving 2655 adults receiving oral standard-of-care antibiotics for primary or recurrent C. difficile infection. Participants received an infusion of bezlotoxumab (10 mg per kilogram of body weight), actoxumab plus bezlotoxumab (10 mg per kilogram each), or placebo; actoxumab alone (10 mg per kilogram) was given in MODIFY I but discontinued after a planned interim analysis. The primary end point was recurrent infection (new episode after initial clinical cure) within 12 weeks after infusion in the modified intention-to-treat population. RESULTS: In both trials, the rate of recurrent C. difficile infection was significantly lower with bezlotoxumab alone than with placebo (MODIFY I: 17% [67 of 386] vs. 28% [109 of 395]; adjusted difference, -10.1 percentage points; 95% confidence interval [CI], -15.9 to -4.3; P<0.001; MODIFY II: 16% [62 of 395] vs. 26% [97 of 378]; adjusted difference, -9.9 percentage points; 95% CI, -15.5 to -4.3; P<0.001) and was significantly lower with actoxumab plus bezlotoxumab than with placebo (MODIFY I: 16% [61 of 383] vs. 28% [109 of 395]; adjusted difference, -11.6 percentage points; 95% CI, -17.4 to -5.9; P<0.001; MODIFY II: 15% [58 of 390] vs. 26% [97 of 378]; adjusted difference, -10.7 percentage points; 95% CI, -16.4 to -5.1; P<0.001). In prespecified subgroup analyses (combined data set), rates of recurrent infection were lower in both groups that received bezlotoxumab than in the placebo group in subpopulations at high risk for recurrent infection or for an adverse outcome. The rates of initial clinical cure were 80% with bezlotoxumab alone, 73% with actoxumab plus bezlotoxumab, and 80% with placebo; the rates of sustained cure (initial clinical cure without recurrent infection in 12 weeks) were 64%, 58%, and 54%, respectively. The rates of adverse events were similar among these groups; the most common events were diarrhea and nausea. CONCLUSIONS: Among participants receiving antibiotic treatment for primary or recurrent C. difficile infection, bezlotoxumab was associated with a substantially lower rate of recurrent infection than placebo and had a safety profile similar to that of placebo. The addition of actoxumab did not improve efficacy. (Funded by Merck; MODIFY I and MODIFY II ClinicalTrials.gov numbers, NCT01241552 and NCT01513239 .).

A randomized, double-blind trial investigating the efficacy of caspofungin versus amphotericin B deoxycholate in the treatment of invasive candidiasis in neonates and infants younger than 3 months of age.

OBJECTIVES: Investigate the efficacy of caspofungin in participants <3 months of age with invasive Candida infection (ICI). METHODS: This multicentre, randomized, double-blind, comparator-controlled, Phase 2 study (protocol MK0991-064; NCT01945281) enrolled participants <3 months of age with culture-confirmed ICI within 96 h of study entry. Participants were randomly assigned 2:1 to once-daily intravenous 2 mg/kg caspofungin or intravenous 1 mg/kg amphotericin B deoxycholate (dAMB). The primary endpoint was fungal-free survival (FFS) 2 weeks after treatment in the full-analysis-set (FAS) population, defined as participants with culture-confirmed ICI who received ≥1 dose of therapy. Planned enrolment was 90 participants. RESULTS: Fifty-one participants were enrolled; 49 received treatment (caspofungin, n=33; dAMB, n=16); 2 additional participants did not have confirmed infections at study entry. The study was terminated after ∼ 3.5 years because of low enrolment. Forty-seven participants were included in the FAS population (caspofungin, n=31; dAMB, n=16). FFS rate at 2 weeks after treatment was 71.0% (22/31) in the caspofungin arm and 68.8% (11/16) in the dAMB arm [difference, stratified by weight, - 0.9% (95% CI, - 24.3%-27.7%)]. Adverse events developed in 84.8% (28/33) of participants in the caspofungin arm and 100% (16/16) in the dAMB arm. CONCLUSIONS: Among neonates and infants with confirmed ICI, FFS at 2 weeks was similar in the caspofungin and dAMB treatment arms. A smaller proportion of participants who received caspofungin experienced adverse events.

Analysis of C. difficile infection-related outcomes in European participants in the bezlotoxumab MODIFY I and II trials.

The MODIFY I/II trials demonstrated that bezlotoxumab, a human monoclonal antibody against Clostridioides difficile toxin B, given during antibiotic treatment for Clostridioides difficile infection (CDI) significantly reduced C. difficile recurrence (rCDI) in adults at high risk for rCDI. Efficacy of CDI-directed intervention may depend on ribotype regional epidemiology, and patient characteristics. This post hoc analysis assessed the efficacy of bezlotoxumab in the subgroup of MODIFY I/II trial participants enrolled in Europe. Data from the bezlotoxumab (10 mg/kg single intravenous infusion) and placebo (0.9% saline) groups from MODIFY I/II were compared to assess initial clinical cure (ICC), rCDI, all-cause, and CDI-associated rehospitalizations within 30 days of discharge, and mortality through 12 weeks post-infusion. Of 1554 worldwide participants, 606 were from Europe (bezlotoxumab n = 313, 51%; placebo n = 292; 48%). Baseline characteristics were generally similar across groups, although there were more immunocompromised participants in the bezlotoxumab group (27.2%) compared with placebo (20.1%). Fifty-five percent of participants were female, and 86% were hospitalized at randomization. The rate of ICC was similar between treatment groups. The rate of rCDI in the bezlotoxumab group was lower compared with placebo among European participants overall, and among those with ≥ 1 risk factor for rCDI. Bezlotoxumab reduced 30-day CDI-associated rehospitalizations compared with placebo. These results are consistent with overall results from the MODIFY trials and demonstrate that bezlotoxumab reduces rCDI and CDI-associated rehospitalizations in European patients with CDI. MODIFY I/II (NCT01241552 and NCT01513239).

A time-to-event analysis of the exposure-response relationship for bezlotoxumab concentrations and CDI recurrence.

Bezlotoxumab is a monoclonal antibody approved for the prevention of recurrent Clostridium difficile infection (rCDI). In a previous exposure-response (E-R) analysis of bezlotoxumab exposure and rCDI, based on data from two phase 3 trials in participants who received placebo or bezlotoxumab 10 mg/kg, rCDI was treated as a binary endpoint and discontinued subjects were imputed as not having rCDI, resulting in an apparent positive E-R trend between rCDI rates and bezlotoxumab exposure. Therefore, a time-to-event (TTE) analysis was applied to investigate the E-R relationship, accounting for the time to rCDI occurrence and participant discontinuation. A TTE model, applying a time-dependent hazard function and right-censoring of data based on rCDI, discontinuation, or study end was developed. Exposure effects and covariates effects were evaluated as predictors affecting the hazard. The TTE model consisted of a Gompertz function with age, endogenous immunoglobulin G to C. difficile toxin B (IgG-B), history of CDI, hospitalization, sex, Charlson Comorbidity Index, and concomitant use of systemic antibiotics affecting the hazard. Exposure effects were characterized with a maximum effect (Emax) E-R relationship on the baseline parameter, and bezlotoxumab exposures achieved at the 10 mg/kg dose were found to be on the plateau of the E-R curve. Endogenous IgG-B significantly impacted the Emax, indicating that low-titer participants derive a greater benefit from bezlotoxumab treatment compared with high-titer participants. The results support the conclusions of the previous E-R analysis, where exposures achieved at the 10 mg/kg dose are on the plateau of the E-R curve.

Bezlotoxumab for prevention of Clostridium difficile infection recurrence: Distinguishing relapse from reinfection with whole genome sequencing.

BACKGROUND: Bezlotoxumab has been shown to prevent Clostridium difficile infection recurrence (rCDI) in high-risk patients. METHODS: We used whole genome sequencing to estimate the impact of bezlotoxumab on same-strain relapse or new-strain reinfection in MODIFY I/II trials. Reinfection with a new strain and relapse with the same strain were differentiated by the comparison of ribotype (RT) and pair-wise single-nucleotide whole genome sequencing (WGS) variations (PWSNV). Relapse was assigned if the baseline RT and the RT isolated during rCDI were the same, and if PWSNVs were ≤ 2. Reinfection was assigned if the baseline RT and the RT isolated during rCDI were different, or if the RT was the same but PWSNVs were > 10. Unknown status was assigned if the RT was the same but PWSNVs were 3-10. RESULTS: 259 rCDI events were evaluable (50 [19.3%] reinfection; 198 [76.4%] relapse). The proportion of relapses was higher for ribotype 027 (84.5%) compared with other ribotypes (74.1%). Cumulative incidence of relapse was significantly lower for bezlotoxumab versus no bezlotoxumab (p < 0.0001), with a non-significant trend towards reduction for reinfection (p = 0.14). CONCLUSION: Bezlotoxumab treatment significantly reduced the rate of CDI relapse versus a regimen without bezlotoxumab. (NCT01241552/NCT01513239).

Population Pharmacokinetics and Pharmacodynamics of Bezlotoxumab in Adults with Primary and Recurrent Clostridium difficile Infection.

The fully human monoclonal antibody bezlotoxumab is indicated for preventing the recurrence of Clostridioides difficile (formerly Clostridium difficile) infection (CDI) in adults who receive antibacterial treatment for CDI and who are at high risk for a CDI recurrence. The efficacy and safety of 10-mg/kg of body weight bezlotoxumab were demonstrated in two phase 3 trials: the MODIFY I (ClinicalTrials.gov registration number NCT01241552) and MODIFY II (ClinicalTrials.gov registration number NCT01513239) trials. Here, a population pharmacokinetic (popPK) analysis, performed using data from the MODIFY I and II trials (n = 1,515) and from three phase 1 trials (n = 72) to characterize bezlotoxumab pharmacokinetics (PK) in phase 3 clinical trial participants and in healthy subjects, is reported. A stepwise covariate search was conducted to identify factors influencing PK. Post hoc-estimated bezlotoxumab exposures from the popPK model were used to conduct an exposure-response analysis for CDI recurrence. Bezlotoxumab PK were described by a two-compartment model with linear elimination and allometric scaling for clearance and the volume of distribution by body weight. Although the final popPK model included gender, ethnicity (Japanese descent), race (black versus nonblack), and albumin level as significant covariates, the impact of these factors was not clinically meaningful, based on the totality of the PK and clinical experience. Exposure-response analysis of CDI recurrence demonstrated a similar low rate of CDI recurrence over the entire range of exposures achieved in the phase 3 trials, indicating that exposures were on the maximal response plateau of the exposure-response curve. Overall, the analyses confirmed the appropriateness of the 10-mg/kg dose across the phase 3 trial population with no dose adjustments necessary over a broad demographic background.

Cost-effectiveness of Bezlotoxumab Compared With Placebo for the Prevention of Recurrent Clostridium difficile Infection.

Background: Clostridium difficile infection (CDI) is the most commonly recognized cause of recurrent diarrhea. Bezlotoxumab, administered concurrently with antibiotics directed against C. difficile (standard of care [SoC]), has been shown to reduce the recurrence of CDI, compared with SoC alone. This study aimed to assess the cost-effectiveness of bezlotoxumab administered concurrently with SoC, compared with SoC alone, in subgroups of patients at risk of recurrence of CDI. Methods: A computer-based Markov health state transition model was designed to track the natural history of patients infected with CDI. A cohort of patients entered the model with either a mild/moderate or severe CDI episode, and were treated with SoC antibiotics together with either bezlotoxumab or placebo. The cohort was followed over a lifetime horizon, and costs and utilities for the various health states were used to estimate incremental cost-effectiveness ratios (ICERs). Both deterministic and probabilistic sensitivity analyses were used to test the robustness of the results. Results: The cost-effectiveness model showed that, compared with placebo, bezlotoxumab was associated with 0.12 quality-adjusted life-years (QALYs) gained and was cost-effective in preventing CDI recurrences in the entire trial population, with an ICER of $19824/QALY gained. Compared with placebo, bezlotoxumab was also cost-effective in the subgroups of patients aged ≥65 years (ICER of $15298/QALY), immunocompromised patients (ICER of $12597/QALY), and patients with severe CDI (ICER of $21430/QALY). Conclusions: Model-based results demonstrated that bezlotoxumab was cost-effective in the prevention of recurrent CDI compared with placebo, among patients receiving SoC antibiotics for treatment of CDI.

Bezlotoxumab for Prevention of Recurrent Clostridium difficile Infection in Patients at Increased Risk for Recurrence.

Background: Bezlotoxumab is a human monoclonal antibody against Clostridium difficile toxin B indicated to prevent C. difficile infection (CDI) recurrence (rCDI) in adults at high risk for rCDI. This post hoc analysis of pooled monocolonal antibodies for C.difficile therapy (MODIFY) I/II data assessed bezlotoxumab efficacy in participants with characteristics associated with increased risk for rCDI. Methods: The analysis population was the modified intent-to-treat population who received bezlotoxumab or placebo (n = 1554) by risk factors for rCDI that were prespecified in the statistical analysis plan: age ≥65 years, history of CDI, compromised immunity, severe CDI, and ribotype 027/078/244. The proportion of participants with rCDI in 12 weeks, fecal microbiota transplant procedures, 30-day all cause and CDI-associated hospital readmissions, and mortality at 30 and 90 days after randomization were presented. Results: The majority of enrolled participants (75.6%) had ≥1 risk factor; these participants were older and a higher proportion had comorbidities compared with participants with no risk factors. The proportion of placebo participants who experienced rCDI exceeded 30% for each risk factor compared with 20.9% among those without a risk factor, and the rCDI rate increased with the number of risk factors (1 risk factor: 31.3%; ≥3 risk factors: 46.1%). Bezlotoxumab reduced rCDI, fecal microbiota transplants, and CDI-associated 30-day readmissions in participants with risk factors for rCDI. Conclusions: The risk factors prespecified in the MODIFY statistical analysis plan are appropriate to identify patients at high risk for rCDI. While participants with ≥3 risk factors had the greatest reduction of rCDI with bezlotoxumab, those with 1 or 2 risk factors may also benefit. Clinical Trials Registration: NCT01241552 (MODIFY I) and NCT01513239 (MODIFY II).

Efficacy of bezlotoxumab based on timing of administration relative to start of antibacterial therapy for Clostridium difficile infection.

Background: The fully human monoclonal antibody bezlotoxumab binds Clostridioides (Clostridium) difficile toxin B and reduces recurrence rates in patients with C. difficile infection (CDI) receiving antibacterial treatment for a primary or recurrent episode. Objectives: To investigate whether the timing of bezlotoxumab administration relative to the onset of antibacterial treatment affected clinical outcome in the Phase 3 trials MODIFY I (NCT01241552) and MODIFY II (NCT01513239). Methods: Initial clinical cure and CDI recurrence rates of participants who received bezlotoxumab or placebo were summarized by timing of infusion relative to the start of antibacterial drug treatment for CDI: 0-2, 3-4 and ≥5 days after onset. Results: Of 1554 total participants, 649 (41.8%), 469 (30.1%) and 436 (28.1%) received an infusion 0-2, 3-4 and ≥5 days after onset of antibacterial treatment for CDI, respectively. Regardless of timing of administration, there were no differences in initial clinical cure rates between participants receiving bezlotoxumab (range 77.8% to 81.4%) or placebo (77.8% to 81.7%). Bezlotoxumab efficacy was unaffected by timing of administration; rates of CDI recurrence were lower versus placebo in all subgroups (range 19.3% to 22.8% for bezlotoxumab and 31.7% to 35.8% for placebo). Timing of administration also had no effect on time to resolution of diarrhoea, which was achieved by the end of antibacterial treatment in ∼95% of participants in both bezlotoxumab and placebo groups. Conclusions: Bezlotoxumab is effective in preventing CDI recurrence and can be administered at any time before ending antibacterial drug treatment.

The effect of bezlotoxumab for prevention of recurrent Clostridium difficile infection (CDI) in Japanese patients.

Recurrent Clostridium difficile infection is considered as a significant health care burden. The global study (MODIFY II) of antibody treatment (bezlotoxumab) for the prevention of recurrent C. difficile infection includes Japanese patients (95 subjects); The aim of this subgroup analysis is to report the data obtained from Japanese patients. Patients with C. difficile infection receiving standard of care antibiotic treatment and a single infusion of bezlotoxumab 10 mg/kg, actoxumab 10 mg/kg + bezlotoxumab 10 mg/kg or placebo. Recurrent C. difficile infection through Week 12 was evaluated. In the Full Analysis Set (93 subjects), 91% were older than 65 years of age and 93% were hospitalized at the time of study entry. The standard of care antibiotic for C. difficile infection was metronidazole for 57 subjects and vancomycin for 36 subjects. The recurrent C. difficile infection rate was 46% in the placebo, 21% in the bezlotoxumab (p = 0.0197) and 28% in the actoxumab + bezlotoxumab group. No additive recurrent C. difficile infection-reducing effect with the addition of actoxumab was demonstrated. There were no events representing safety concern in bezlotoxumab. Among 54 clinical isolates of C. difficile as a baseline culture in Japanese patients, the common ribotypes were 052 (28%), 018 (19%), 002 (15%) and 369 (9%). It showed distinctly different distribution from that in the United States and Europe. The superior effect of bezlotoxumab 10 mg/kg in the prevention of recurrent C. difficile infection suggests that the agent will be useful in the rapidly aging Japanese society.

Thirty-Day Readmissions in Hospitalized Patients Who Received Bezlotoxumab With Antibacterial Drug Treatment for Clostridium difficile Infection.

Clinical Trials Registration: NCT01241552 (MODIFY I) and NCT01513239 (MODIFY II).

Antibodies to Toxin B Are Protective Against Clostridium difficile Infection Recurrence.

BACKGROUND: Although newer studies have evaluated risk factors for recurrent Clostridium difficile infection (CDI), the vast majority did not measure important biomarkers such as endogenous anti-toxin A and anti-toxin B antibody levels. METHODS: Data from the placebo group of a phase 2 trial testing monoclonal antibodies to C. difficile toxins A and B for preventing CDI recurrence (rCDI) were analyzed to assess risk factors associated with rCDI. Patients with symptomatic CDI taking metronidazole or vancomycin were enrolled. The primary outcome was rCDI within 84 days of treatment start. Univariate and multivariate logistic regression was used to examine associations between potential risk factors and rCDI. At baseline, demographic and clinical characteristics were recorded; endogenous antibody levels were assessed using 2 enzyme-linked immunosorbent assays. RESULTS: A predictor of recurrence was age ≥65 years, and an antibody-mediated immune response to toxin B appears to be protective against rCDI. CONCLUSIONS: Our findings demonstrate the importance of clinical as well as immunological risk factors in rCDI and provide more robust evidence for the protective effects of antibody to toxin B in the prevention of rCDI. CLINICAL TRIALS REGISTRATION: NCT00350298.

Double-Blind, Placebo-Controlled Study of Bezlotoxumab in Children Receiving Antibacterial Treatment for Clostridioides difficile Infection (MODIFY III).

BACKGROUND: Therapies to prevent recurrence of Clostridioides difficile infection (CDI) in pediatric patients are needed. Bezlotoxumab is a fully human monoclonal antibody approved for prevention of recurrent CDI in adults. We assessed the pharmacokinetics, safety, tolerability, and efficacy of bezlotoxumab in pediatric patients. METHODS: MODIFY III was a multicenter, double-blind, placebo-controlled study of bezlotoxumab in children (1 to <18 years) receiving antibacterial treatment for CDI. Participants were randomized 3:1 to receive a single infusion of bezlotoxumab (10 mg/kg) or placebo and were stratified by age at randomization (cohort 1: 12 to <18 years, cohort 2: 1 to <12 years). The primary objective was to characterize bezlotoxumab pharmacokinetics to support dose selection for pediatric patients; the primary endpoint was the area under the bezlotoxumab serum concentration-time curve (AUC0-inf). Safety, tolerability, and efficacy were monitored for 12 weeks post-infusion. RESULTS: A total of 148 participants were randomized and 143 were treated: 107 with bezlotoxumab and 36 with placebo (cohort 1 n = 60, cohort 2 n = 83; median age 9.0 years); 52.4% of participants were male and 80.4% were white. Geometric mean ratios (90% CI) for bezlotoxumab AUC0-inf were 1.06 (0.95, 1.18) and 0.82 (0.75, 0.89) h * µg/mL for cohorts 1 and 2, respectively. Bezlotoxumab 10 mg/kg was generally well-tolerated with an adverse event profile similar to placebo, including no treatment discontinuations due to adverse events. CDI recurrence was low and comparable for bezlotoxumab (11.2%) and placebo (14.7%). CONCLUSIONS: The results of this study support the bezlotoxumab dose of 10 mg/kg for pediatric patients. TRIAL REGISTRATION: NCT03182907 at ClinicalTrials.gov.

Corrigendum to: Renal Impairment, C. difficile Recurrence, and the Differential Effect of Bezlotoxumab: A Post Hoc Analysis of Pooled Data From 2 Randomized Clinical Trials.

[This corrects the article DOI: 10.1093/ofid/ofaa248.].

Global Landscape of Clostridioides Difficile Phylogeography, Antibiotic Susceptibility, and Toxin Polymorphisms by Post-Hoc Whole-Genome Sequencing from the MODIFY I/II Studies.

INTRODUCTION: Clostridioides (Clostridium) difficile infection, the leading cause of healthcare-associated diarrhea, represents a significant burden on global healthcare systems. Despite being a global issue, information on C. difficile from a global perspective is lacking. The aim of this study is to model the global phylogeography of clinical C. difficile. METHODS: Using samples collected from the MODIFY I and II studies (NCT01241552, NCT01513239), we performed whole-genome sequencing of 1501 clinical isolates including 37 novel sequence types (STs), representing the largest worldwide collection to date. RESULTS: Our data showed ribotypes, multi-locus sequence typing clades, and whole-genome phylogeny were in good accordance. The clinical C. difficile genome was found to be more conserved than previously reported (61% core genes), and modest recombination rates of 1.4-5.0 were observed across clades. We observed a significant continent distribution preference among five C. difficile clades (Benjamini-Hochberg corrected Fisher's exact test P < 0.01); moreover, weak association between geographic and genetic distance among ribotypes suggested sources beyond healthcare-related transmission. Markedly different trends of antibiotic susceptibility among lineages and regions were identified, and three novel mutations (in pyridoxamine 5'-phosphate oxidase family protein: Tyr130Ser, Tyr130Cys, and a promoter SNP) associated with metronidazole-reduced susceptibility were discovered on a nim-related gene and its promotor by genome-wide association study. Toxin gene polymorphisms were shown to vary within and between prevalent ribotypes, and novel severe mutations were found on the tcdC toxin regulator protein. CONCLUSION: Our systematic characterization of a global set of clinical trial C. difficile isolates from infected individuals demonstrated the complexity of the genetic makeup of this pathogenic organism. The geographic variability of clades, variability in toxin genes, and mutations associated with antibiotic susceptibility indicate a highly complex interaction of C. difficile between host and environment. This dataset will provide a useful resource for validation of findings and future research of C. difficile.