A phase 3 study evaluating the lot consistency, immunogenicity, safety, and tolerability of a Clostridioides difficile vaccine in healthy adults 65 to 85 years of age

BACKGROUND

A toxoid-based Clostridioides difficile vaccine is currently in development. Here, we report lot-to-lot consistency, immunogenicity, safety, and tolerability of 3 C difficile vaccine doses in healthy older adults.

METHODS

This phase 3, placebo-controlled study randomized (1:1:1:1) healthy adults 65 to 85 years of age to 1 of 3 C difficile vaccine lots or placebo. Participants received C difficile vaccine (200 μg total toxoid) or placebo (Months 0, 1, 6). The primary immunogenicity objective was lot-to-lot consistency (2-sided 95 % CIs within 0.5 and 2 for comparisons of geometric mean concentration [GMC] ratios) for toxins A- and B-specific neutralizing antibody levels 1 month after Dose 3. Safety outcomes included local reactions and systemic events ≤7 days after vaccination, adverse events (AEs), and serious AEs (SAEs).

RESULTS

Of 1317 enrolled participants, 1218 completed the study. C difficile vaccine immunogenicity was consistent across lots, with neutralizing antibody responses 1 month after Dose 3 for both toxin A (GMC [95 % CI]: lot 1, 878.8 [786.3, 982.2]; lot 2, 873.0 [779.2, 978.1]; lot 3, 872.9 [782.6, 973.5]) and toxin B (lot 1, 5823.9 [5041.0, 6728.4]; lot 2, 5462.8 [4733.4, 6304.7]; lot 3, 5426.0 [4724.4, 6231.8]). Two-sided 95 % CIs for GMC ratios were within 0.5 and 2 for toxins A and B, indicating lot-to-lot consistency was achieved. C difficile vaccine was well tolerated, with similar rates of local reactions and systemic events among vaccine lots. AE and SAE rates were similar across C difficile vaccine (36.5 % and 4.5 %, respectively) and placebo (35.3 % and 6 %).

CONCLUSIONS

Three doses (Months 0,1,6) of toxoid-based C difficile vaccine induced robust neutralizing antibody responses and were well tolerated in healthy participants 65 to 85 years of age. Lot-to-lot consistency was excellent, indicating the manufacturing process for this C difficile vaccine formulation was well controlled.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03579459.

Descriptive Study of Gut Microbiota in Infected and Colonized Subjects by Clostridiodes difficile

Clostridiodes difficile can lead to a range of situations from the absence of symptoms (colonization) to severe diarrhea (infection). Disruption of gut microbiota provides an ideal environment for infection to occur. Comparison of gut microbiota of infected and colonized subjects could provide relevant information on susceptible groups or protectors to the development of infection, since the presence of certain genera could be related to the inhibition of transition from a state of colonization to infection. Through high-throughput sequencing of 16S rDNA gene, we performed alpha and beta diversity and composition studies on 15 infected patients (Group CDI), 15 colonized subjects (Group P), and 15 healthy controls (Group CTLR). A loss of alpha diversity and richness and a different structure have been evidenced in the CDI and P groups with respect to the CTRL group, but without significant differences between the first two. In CDI and P groups, there was a strong decrease in phylum Firmicutes and an expansion of potential pathogens. Likewise, there was a loss of inhibitory genus of C. difficile germination in infected patients that were partially conserved in colonized subjects. Therefore, infected and colonized subjects presented a gut microbiota that was completely different from that of healthy controls, although similar to each other. It is in composition where we found that colonized subjects, especially in minority genera, presented differences with respect to those infected.

Laxative Use Does Not Preclude Diagnosis or Reduce Disease Severity in Clostridiodes difficile Infection

BACKGROUND

To optimize utility of laboratory testing for Clostridiodes difficile infection (CDI), the 2017 Infectious Diseases Society of America-Society for Healthcare Epidemiology of America (IDSA-SHEA) clinical practice guidelines recommend excluding patients from stool testing for C. difficile if they have received laxatives within the preceding 48 hours. Sparse data support this recommendation.

METHODS

Patients with new-onset diarrhea (≥3 bowel movements in any 24-hour period in the 48 hours before stool collection) and a positive stool C. difficile nucleic acid amplification test were enrolled. Laxative use within 48 hours before stool testing, severity of illness (defined by 4 distinct scoring methods), and clinical outcomes were recorded.

RESULTS

209 patients with CDI were studied, 65 of whom had received laxatives. There were no significant differences in the proportion of patients meeting severe CDI criteria by 4 severity scoring methods in patients receiving versus not receiving laxatives (66.2% vs 56.3%, respectively; P = .224) by IDSA-SHEA, the primary scoring system. Similar rates of serious outcomes attributable to CDI, including death, intensive care unit admission, and colectomy, were observed in the laxative and no laxative groups.

CONCLUSIONS

Our study found similar rates of severe CDI and serious CDI-attributable clinical outcomes in CDI-diagnosed patients who did or did not receive laxatives. Precluding recent laxative users from CDI testing, as proposed by the IDSA-SHEA guideline, carries a potential for harm due to delayed diagnosis and treatment.

The Association Between the Frequency of Interruptions in Antibiotic Exposure and the Risk of Health Care-Associated Clostridiodes difficile Infection

Background

Although antibiotic use is an established risk factor for health care-associated Clostridiodes difficile infection, estimates of the association between infection and antibiotic use vary, depending upon how antibiotic exposure is measured.

Objectives

The purpose of this study was to explore the association between the frequency of interruptions in antibiotic exposure and the risk of health care-associated C difficile infection.

Methods

A retrospective chart review cohort study was conducted of all inpatients between 2011and 2016 from a single academic health center who received at least 1 dose of a systemic antibacterial for a cumulative duration of >3 days and ≤30 days. The measures of antibiotic exposure examined were duration—cumulative total calendar days of antibiotics therapy—and continuity—the frequency of interruptions in antibiotic exposure that was defined as the number of antibiotic treatment courses.

Results

A total of 52,445/227,967 (23%) patients received antibacterial therapy for >3 days and ≤30 days during their hospitalization. Of these, 1161 out of 52,445 (2.21%) were patients with health care-associated C difficile infection. An adjusted multivariable logistic regression analysis revealed that the risk of C difficile increased with longer cumulative days (odds ratio = 2.7; comparison of >12 days to ≤5 days) and fewer interruptions of antibiotic treatment (odds ratio = 0.78; comparison of >3 discrete antibiotic treatment courses to 1 course or continuous antibiotic treatment course; all P values < 0.05).

Conclusions

For patients who received the same number of cumulative days of therapy, the patients who had more frequently interrupted courses of antibiotic therapy were less likely to experience health care-associated C difficile infection. (Curr Ther Res Clin Exp. 2020; 81:XXX–XXX)

Refining the Galleria mellonella Model by Using Stress Marker Genes to Assess Clostridioides difficile Infection and Recuperation during Phage Therapy

The Galleria mellonella is an effective model for probing Clostridioides difficile interactions with phages. Despite valuable insights from this model, the larvae are not easily amenable to assessing detailed clinical responses to either bacteria or phages. Here, larval survival, colonisation and toxin levels were compared to expression profiles of 17 G. mellonella stress genes to monitor Clostridiodes difficile infection (CDI), and recuperation during phage therapy. The larvae were infected with a ribotype 014/020 isolate and treated with an optimised phage cocktail. Larvae treated prophylactically with phages and the phage-control larval group were protected, showing the highest survival, and low C. difficile colonisation and toxin rates, compared to co-infection, remedial and bacterial-control larval groups. Expression of growth (9) and reproduction (2) genes were enhanced within prophylaxis and phage-control larval groups compared to the co-infection, remedial and bacterial control groups. In contrast, expression of infection (2), humoral (1) and cellular (3) immunity genes declined in the prophylactic and phage-control groups but increased in the co-infection, remedial and bacterial control larvae. The molecular markers augment the survival, colonisation and toxin data and allow detailed monitoring of CDI and recovery. This data support the use of stress marker genes as tools to analyse clinical symptoms in this model.

Diagnostic stewardship of Clostridioides difficile polymerase chain reaction results from syndromic diarrhea panel and implications for patient outcomes

BACKGROUND

A syndromic gastrointestinal pathogen panel (GIP) was implemented in May 2018. All positive (+) GIP and standard-of-care (SOC) C. difficile results were reviewed.

METHODS

A single-center audit of adult patients with GIP results was conducted May-December 2018. We reviewed GIP(+)/SOC(+/-) and GIP(-)/SOC(-) tests (control group) for clinical outcomes.

RESULTS

We reviewed 269 GIP(+) patients. Of 119 GIP(+)/SOC(+) patients, 44 (37%) were positive by toxin A/B enzyme immunoassay, and 75 (63%) by PCR only. Thirty-day mortality and re-admission were not significantly different between groups. CDI rates within 6 months were not significantly different between GIP(+)/SOC(-) and controls (p-value = 0.39). Those with initial SOC(+) tests had more true CDI events within 6 months, compared to controls (p-values < 0.001).

CONCLUSIONS

Forty percent of patients with GIP(+) C. difficile were (-) by SOC test, suggesting that true CDI was not present. Additional PCR-based testing may not impact outcomes.