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.

Evaluation of an immunochromatographic test for the detection of glutamate dehydrogenase for the diagnosis of Clostridioides (Clostridium) difficile infection in dogs

This study aimed to evaluate an immunochromatographic test used to detect glutamate dehydrogenase (GDH) for the diagnosis of Clostridium difficile infection (CDI) in dogs. Fecal samples of 119 diarrheic dogs were subjected to toxigenic culture as the "gold standard" method and to GDH detection (Ecodiagnostica, Brazil). Samples positive for toxigenic C. difficile strains and those positive in the GDH test were also subjected to A/B toxin detection using an enzyme immunoassay kit (C. difficile Tox A/B II, Techlab Inc., USA). Sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) were measured for GDH detection and compared with the toxigenic culture results. A total of 19 (15.9%) dogs were positive for toxigenic C. difficile. Of these, 10 (52.6%) dogs were positive for A/B toxins using the enzyme immunoassay kit and 18 (15.2%) were positive in the GDH test, leading to a sensitivity and NPV of 89.4% and 97.9%, respectively. Three animals, two of which were colonized with non-toxigenic strains, were positive for GDH, though not confirmed with CDI, resulting in a high specificity (97%) and PPV (85%). The results suggest that the lateral flow test for GDH detection could be a useful method for diagnosing CDI in dogs, similar to that previously described for humans and other animal species.

Safety and immunogenicity of different Clostridioides (Clostridium) difficile vaccine formulations in two early phase randomized studies of healthy adults aged 50-85 years

BACKGROUND

Two phase 1/phase 2 studies assessed 2 formulations of investigational bivalent Clostridioides (Clostridium) difficile vaccine (QS-21 adjuvanted toxoid and toxoid-alone) in healthy adults 50-85 years of age.

METHODS

The QS-21 adjuvanted toxoid vaccine study randomized subjects 3:1 to 100 μg QS-21-containing C difficile vaccine or placebo administered in a shortened-month (Months 0, 1, 3) or day (Days 1, 8, 30) regimen. The toxoid-alone vaccine study randomized subjects 3:3:1 to receive 100 or 200 μg unadjuvanted C difficile vaccine formulation or placebo in Stages 1 and 2 (sentinel cohorts of different age groups), and 3:1 to receive the selected dose of unadjuvanted C difficile vaccine formulation or placebo in Stage 3 (Days 1, 8, 30). Safety was the primary outcome for both studies. Immunogenicity was determined by measuring serum toxin A- and B-specific neutralizing antibodies.

RESULTS

In the day regimen, 10 reports across both studies of grade 3 injection site redness postdose 2 triggered predefined stopping rules. Local reactions in both studies were more common among vaccine versus placebo recipients. Injection site pain predominated and was generally mild in severity. Systemic events were infrequent and generally mild-to-moderate in severity. Adverse events were reported by 50.0%-75.0% and 16.7%-50.0% of subjects in the QS-21 and toxoid-alone studies, respectively. Immune responses peaked around Day 37 (shortened-month regimen) or between Day 15 and Month 2 (day regimen) and remained above baseline throughout follow-up.

CONCLUSIONS

Both formulations demonstrated robust immunogenicity. Both studies stopped early due to grade 3 injection site redness postdose 2 of the day regimen; neither formulation progressed to later stage development. Instead, an aluminum hydroxide-containing formulation of the vaccine candidate administered at 0, 1, and 6 months, which was safe and immunogenic in phase 1 and 2 studies, advanced to phase 3 studies.

Diarrhea in tube-fed hospitalized patients: Feeding formula is not the most common cause

BACKGROUND AND AIM

Clostridium difficile-associated diarrhea (CDAD) and enteral nutrition (EN)-associated diarrhea are the most common recognized etiologies of nosocomial diarrhea. However, in clinical practice, the data regarding how each etiology contributes to the diarrheal episodes are limited. We identify the causes and factors associated with post-feeding diarrhea.

METHODS

Using the data of patients enrolled in "Effect of Psyllium Fiber Supplementation on Diarrhea Incidence in Enteral Tube-Fed Patients: A Prospective, Randomized, and Controlled Trial", the randomized controlled trial showed no difference in diarrheal incidences between fiber-added and fiber-free formulas. Hence, we analyzed the data of all enrolled patients. The causes of diarrhea were classified according to pre-specified definitions. The factors associated with diarrhea were analyzed using logistic regression.

RESULTS

Diarrhea was found in 37.3% (n = 31/83). The most common cause was medication associated (61.3%). CDAD and EN-associated diarrhea were found in only 9.7% and 6.5%, respectively. Patients with baseline albumin <3 g/dL and underlying cerebrovascular disease were more likely to develop diarrhea (adjusted odds ratio 5.70, 95% confidence interval 1.79-20.51, and adjusted odds ratio 10.83, 95% confidence interval 2.96-48.57, respectively). Compared with those without diarrhea, the length of hospital stay in CDAD patients was significantly longer (+23.1 days, P = 0.02), a trend of longer hospital stay in patients with diarrhea from other causes was observed (+3.2 days, P = 0.096).

CONCLUSIONS

Our study found that the most common cause of post-feeding diarrhea is medication associated. Review and cessation of possible drugs should be undertaken before EN modification. CDAD accounts for <10% of diarrhea causes, but it impacts the clinical outcome and should be identified and treated properly.

Methicillin-Resistant Staphylococcus aureus-Associated Diarrhea in a Critically Ill Burn Patient

Described in surgical patients after antibiotic use in the 1950s and 1960s, Staphylococcus aureus (S. aureus) enterocolitis is a rare form of nosocomial diarrhea. However, S. aureus is not routinely tested like Clostridium difficile (C. difficile). We report a case of methicillin-resistant S. aureus (MRSA) enterocolitis found on stool culture in a 22-week pregnant female with a previously negative nasal MRSA culture, and a total burn surface area greater than 60%. She also developed necrotizing MRSA pneumonia and bacteremia. After starting broad-spectrum antibiotic for the necrotizing pneumonia with subsequent acute respiratory distress syndrome, the patient exhibited large voluminous diarrhea that tested positive for MRSA and negative for C. difficile in the stool culture. Similar to other reports of high-volume diarrhea, the diarrhea resolved quickly with enteral vancomycin. S. aureus should be considered along with C. difficile during the workup of nosocomial diarrhea, especially with exposure to broad-spectrum antibiotics in the critically ill patient.

Immunochromatographic test and ELISA for the detection of glutamate dehydrogenase (GDH) and A/B toxins as an alternative for the diagnosis of Clostridioides (Clostridium) difficile-associated diarrhea in foals and neonatal piglets

Considering the lack of studies evaluating the performance of commercially available methods for diagnosis of Clostridioides (Clostridium) difficile infection (CDI) in animals, the present study aimed to assess an immunochromatographic test for detection of glutamate dehydrogenase (GDH) and A/B toxins of C. difficile, also evaluated by an ELISA kit, in foals and neonatal piglets. Intestinal contents of 47 piglets and feces of 35 foals were tested to GDH antigen and A/B toxins in a lateral flow method (Ecodiagnostica, Brazil). Also, these samples were submitted to A/B toxin detection by an ELISA kit (C. difficile Tox A/B II, Techlab Inc., USA), using the toxigenic culture (TC) as the reference method. The GDH component of the lateral flow test showed sensitivity and negative predictive value (NPV) of 100% and a high specificity in samples of piglets (82.61%) and foals (100%). Detection of A/B toxins using the lateral flow test and the ELISA resulted in a specificity of 100% in samples of both species. On the other hand, the sensibility ranged from 54.2 to 90% for the ELISA and from 12.5 to 60% for the lateral flow test for piglets' and foals' samples, respectively. In conclusion, the present work suggests that the lateral flow test for GDH detection could be a useful method for diagnosing CDI in these species. On the other hand, the low sensitivity of the lateral flow test for A/B toxins might compromise its utility in piglets.

Evaluation of glutamate dehydrogenase (GDH) and toxin A/B rapid tests for Clostridioides (prev. Clostridium) difficile diagnosis in a university hospital in Minas Gerais, Brazil

Clostridioides (Clostridium) difficile is responsible for most cases of nosocomial diarrhea and, despite the high prevalence of the disease worldwide, the best laboratory diagnostic approach to diagnose C. difficile infection (CDI) is a subject of ongoing debate. Although the use of multiple tests is recommended, the cost of these algorithms commonly exceeds the affordability in some countries. Thus, to improve CDI diagnosis in a university hospital in Brazil, this study analyzed two immunochromatographic tests and one enzyme immunoassay (ELISA) to evaluate the detection of glutamate dehydrogenase (GDH) and A/B toxins of C. difficile. Stool samples of 89 adult patients presenting nosocomial diarrhea during hospitalization were included. The toxigenic culture was used as the reference method. GDH detection by both commercial tests showed high sensitivity (100%) and specificity (92.1%). On the other hand, toxin-based methods showed a sensitivity between 19.2 and 57.7%. In conclusion, the results suggest that rapid tests for GDH detection are not only suitable for CDI diagnosis as screening tests but also as a single method.

Clostridium difficile intervention timelines for diagnosis, isolation, and treatment

BACKGROUND

Developing timelines of nosocomial Clostridium difficile infection (CDI) is critical to improving control and preventive measures. The objective of this study was to provide data-driven estimates of CDI timelines of diagnosis, isolation, and treatment in a hospital setting.

METHODS

We obtained data for all CDI inpatients with symptoms onset occurring between January 1, 2013, and December 30, 2017, from St Joseph's Healthcare in Hamilton, Canada. We analyzed full empirical distributions of timelines associated with the diagnosis, isolation, and treatment of CDI.

RESULTS

A total of 683 inpatients with CDI symptoms were recorded, of which 243 cases were identified as health care-associated infection (HAI). The mean time intervals between the onset of CDI symptoms after admission and the release of laboratory results were 1.2 days and 1.9 days for the HAI and community-associated infection (CAI) patient groups, respectively. The mean time intervals from symptoms onset to the start of isolation were 1.5 days and 2.6 days for the corresponding patient groups. The initiation of treatment within 2 days of symptoms onset reduced the duration of first isolation (P value < .0001); however, the type of initial antibiotic used for CDI treatment was not associated with the duration of isolation.

CONCLUSIONS

Estimated timelines did not differ (P values > .6) between HAI and CAI patient groups with symptoms onset after admission. These estimates are useful for evaluating the effectiveness of CDI interventions.

A phase 1 randomized study assessing safety and immunogenicity of two 3-dose regimens of a Clostridium difficile vaccine in healthy older Japanese adults

BACKGROUND

Clostridium difficile infection (CDI) is a major global cause of nosocomial and community-acquired infections. Despite potentially severe or fatal complications and frequent recurrence, no preventive vaccine is currently available. This randomized, observer-blinded, placebo-controlled phase 1 study in older Japanese adults evaluated safety and immunogenicity of an investigational C difficile vaccine containing a mixture of genetically detoxified and chemically inactivated toxoids, A and B.

METHODS

Healthy Japanese adults aged 65 to 85 years were randomized in a 3:3:2 ratio to receive 100 or 200 μg of C difficile vaccine or placebo, respectively, at 0, 1, and 6 months (month regimen) or 1, 8, and 30 days (day regimen). The primary objective was safety evaluation. Vaccine immunogenicity, the secondary objective, was determined by assessing toxin A- and toxin B-specific neutralizing antibody levels in human sera.

RESULTS

Local reactions were reported by up to 33.3% of subjects per dose in the month regimen; percentages were generally higher in the 200-μg group. Such reactions were all mild or moderate in severity and generally transient. No adverse events in the month regimen led to subject withdrawal, and no serious adverse events were considered vaccine related. Further enrollment and dosing in the day regimen were discontinued after 3 subjects in the 100-μg group reported severe redness after dose 2. In the month regimen study arm, immune responses as measured by toxin-neutralizing antibody geometric mean concentrations, geometric mean fold rises, and proportions of subjects achieving prespecified fold rises were generally higher in the 200-μg group, peaked at month 7, and remained elevated at month 12.

CONCLUSIONS

The C difficile vaccine candidate was safe, well tolerated, and immunogenic when administered to healthy older Japanese adults at 0, 1, and 6 months. Results support continued development of the vaccine for the prevention of CDI. ClinicalTrials.gov identifier: NCT02725437.

Clostridium difficile-associated Diarrhea in Developing Countries: A Systematic Review and Meta-Analysis

Introduction

The prevalence of Clostridium difficile infection is rapidly increasing worldwide, but prevalence is difficult to estimate in developing countries where awareness, diagnostic resources, and surveillance protocols are limited. As diarrhea is the hallmark symptom, we conducted a systematic review and meta-analysis to determine the prevalence and incidence of C. difficile infection in patients in these regions who presented with diarrhea.

Methods

We conducted a systematic literature search of MEDLINE/PubMed, Scopus, and Latin-American and Caribbean Health Sciences Literature databases to identify and analyze data from recent studies providing prevalence or incidence rates of C. difficile-associated diarrhea in developing countries within four regions: Africa–Middle East, developing Asia, Latin America, and China. Our objectives were to determine the current prevalence and incidence density rates of first episodes of C. difficile-associated diarrhea in developing countries.

Results

Within the regions included in our analysis, prevalence of C. difficile infection in patients with diarrhea was 15% (95% CI 13–17%) (including community and hospitalized patients), with no significant difference across regions. The incidence of C. difficile infection in 17 studies including this information was 8.5 per 10,000 patient-days (95% CI 5.83–12.46). Prevalence was significantly higher in hospitalized patients versus community patients (p  = 0.0227).

Conclusion

Our prevalence estimate of 15% is concerning; however, low awareness and inconsistent diagnostic and surveillance protocols suggest this is markedly underestimated. Enhanced awareness and management of C. difficile infection in patients with diarrhea, along with improvements in infection control and surveillance practices, should be implemented to reduce prevalence of C. difficile-associated diarrhea in developing countries.

Funding

Pfizer Inc.

Electronic supplementary material

The online version of this article (10.1007/s40121-019-0231-8) contains supplementary material, which is available to authorized users.

Prevalence of Nosocomial Diarrhea Due to Adenoviruses 40 and 41 in a Paediatric Ward in Iran

BACKGROUND

Enteric adenoviruses 40 (Ad40) and adenovirus 41 (Ad41) have been shown to be a significant cause of paediatric gastroenteritis worldwide, but no data are available for nosocomial diarrhea due to adenovirus in Iran.

AIM

The present study was performed to determine the incidence of Ad40 and Ad41 in children less than five years with nosocomial diarrhea in Shahrekord, southwest Iran.

MATERIALS AND METHODS

Adenovirus was detected by polymerase chain reaction (PCR) in stool samples collected during one year (2010-2011) from children less than five years with nosocomial diarrhea admitted to a paediatric center in Shahrekord, Iran. Nosocomial diarrhea was defined as those occurring more than 72 hours after admission to hospital for non-diarrheal causes. PCR technique was used for investigation of Ad40 and Ad41.

RESULTS

In total of 100 samples, Ad40 and Ad41 DNA was found to be positive in 14/100 (14%), and 8/100 (8%) of diarrheic patients less than five years, respectively.

CONCLUSION

Ad40 and Ad41 are important causes of nosocomial diarrhea in less than five-year, hospitalized Iranian children.

N-CDAD in Canada: results of the Canadian Nosocomial Infection Surveillance Program 1997 N-CDAD Prevalence Surveillance Project

BACKGROUND

A 1996 preproject survey among Canadian Hospital Epidemiology Committee (CHEC) sites revealed variations in the prevention, detection, management and surveillance of Clostridium difficile-associated diarrhea (CDAD). Facilities wanted to establish national rates of nosocomially acquired CDAD (N-CDAD) to understand the impact of control or prevention measures, and the burden of N-CDAD on health care resources. The CHEC, in collaboration with the Laboratory Centre for Disease Control (Health Canada) and under the Canadian Nosocomial Infection Surveillance Program, undertook a prevalence surveillance project among selected hospitals throughout Canada.

OBJECTIVE

To establish national prevalence rates of N-CDAD.

METHODS

For six weeks in 1997, selected CHEC sites tested all diarrheal stools from inpatients for either C difficile toxin or C difficile bacteria with evidence of toxin production. Questionnaires were completed for patients with positive stool assays who met the case definitions.

RESULTS

Nineteen health care facilities in eight provinces participated in the project. The overall prevalence of N-CDAD was 13.0% (95% CI 9.5% to 16.5%). The mean number of N-CDAD cases were 66.3 cases/100,000 patient days (95% CI 37.5 to 95.1) and 5.9 cases/1000 patient admissions (95% CI 3.4 to 8.4). N-CDAD was found most frequently in older patients and those who had been hospitalized for longer than two weeks in medical or surgical wards.

CONCLUSIONS

This national prevalence surveillance project, which established N-CDAD rates, is useful as 'benchmark' data for Canadian health care facilities, and in understanding the patterns and impact of N-CDAD.