Bezlotoxumab for Prevention of Recurrent Clostridium difficile Infection

Status of vaccine research and development for Clostridium difficile

Clostridium difficile associated disease is fundamentally associated with dysbiosis of the gut microbiome as a consequence of antibiotic use. This is because this sporulating, obligate anaerobe germinates and proliferates rapidly in the dysbiotic gut, which is an indirect consequence of their use. During its growth, C. difficile produces two toxins, toxin A (TcdA) and toxin B (TcdB), which are responsible for the majority of clinical symptoms associated with the disease. Three parenterally delivered vaccines, based on detoxified or recombinant forms of these toxins, have undergone or are undergoing clinical trials. Each offers the opportunity to generate high titres of toxin neutralising antibodies. Whilst these data suggest these vaccines may reduce primary symptomatic disease, they do not in their current form reduce the capacity of the organism to persist and shed from the vaccinated host. The current progress of vaccine development is considered with advantages and limitations of each highlighted. In addition, several alternative approaches are described that seek to limit C. difficile germination, colonisation and persistence. It may yet prove that the most effective treatments to limit infection, disease and spread of the organism will require a combination of therapeutic approaches. The potential use and efficacy of these vaccines in low and middle income countries will be depend on the development of a cost effective vaccine and greater understanding of the distribution and extent of disease in these countries.

Epithelium-specific MyD88 signaling, but not DCs or macrophages, control acute intestinal infection with Clostridium difficile

Infection with Clostridium difficile is one of the major causes of health care acquired diarrhea and colitis. Signaling though MyD88 downstream of TLRs is critical for initiating the early protective host response in mouse models of C. difficile infection (CDI). In the intestine, MyD88 is expressed in various tissues and cell types, such as the intestinal epithelium and mononuclear phagocytes (MNP), including DC or macrophages. Using a genetic gain-of-function system, we demonstrate here that restricting functional MyD88 signaling to the intestinal epithelium, but also to MNPs is sufficient to protect mice during acute CDI by upregulation of the intestinal barrier function and recruitment of neutrophils. Nevertheless, we also show that mice depleted for CD11c-expressing MNPs in the intestine display no major defects in mounting an effective inflammatory response, indicating that the absence of these cells is irrelevant for inducing host protection during acute infection. Together, our results highlight the importance of epithelial-specific MyD88 signaling and demonstrate that although functional MyD88 signaling in DC and macrophages alone is sufficient to correct the phenotype of MyD88-deficiency, these cells do not seem to be essential for host protection in MyD88-sufficient animals during acute infection with C. difficile.

Current updates in management of Clostridium difficile infection in cancer patients

BACKGROUND

Clostridium difficile infection (CDI) is a significant health burden, now recognized as the leading cause of acquired diarrhea in patients receiving antibiotic therapy. Complications of infection with this pathogen include severe diarrhea, causing electrolyte imbalances, dehydration, hemodynamic instability, toxic megacolon, shock, and death. Hence it is extremely paramount to stay updated on management options for this infection, especially in cancer patients.

REVIEW

This article presents an in-depth review of literature on the treatment modalities available for CDI in cancer patients. Relevant articles highlighting therapeutic and symptomatic management of CDI patients with underlying malignancy have been summarized.

CONCLUSIONS

Despite the current options available, more studies are needed to assess the newer therapeutic options that are being employed for populations other than cancer patients.

2019 update of the WSES guidelines for management of Clostridioides (Clostridium) difficile infection in surgical patients

In the last three decades, Clostridium difficile infection (CDI) has increased in incidence and severity in many countries worldwide. The increase in CDI incidence has been particularly apparent among surgical patients. Therefore, prevention of CDI and optimization of management in the surgical patient are paramount. An international multidisciplinary panel of experts from the World Society of Emergency Surgery (WSES) updated its guidelines for management of CDI in surgical patients according to the most recent available literature. The update includes recent changes introduced in the management of this infection.

The Gut Microbiota Is Associated with Clearance of Clostridium difficile Infection Independent of Adaptive Immunity

Clostridium (Clostridioides) difficile, a Gram-positive, anaerobic bacterium, is the leading single cause of nosocomial infections in the United States. A major risk factor for Clostridium difficile infection (CDI) is prior exposure to antibiotics, as they increase susceptibility to CDI by altering the membership of the microbial community enabling colonization. The importance of the gut microbiota in providing protection from CDI is underscored by the reported 80 to 90% success rate of fecal microbial transplants in treating recurrent infections. Adaptive immunity, specifically humoral immunity, is also sufficient to protect from both acute and recurrent CDI. However, the role of the adaptive immune system in mediating clearance of C. difficile has yet to be resolved. Using murine models of CDI, we found that adaptive immunity is dispensable for clearance of C. difficile However, random forest analysis using only two members of the resident bacterial community correctly identified animals that would go on to clear the infection with 66.7% accuracy. These findings indicate that the indigenous gut microbiota independent of adaptive immunity facilitates clearance of C. difficile from the murine gastrointestinal tract.IMPORTANCEClostridium difficile infection is a major cause of morbidity and mortality in hospitalized patients in the United States. Currently, the role of the adaptive immune response in modulating levels of C. difficile colonization is unresolved. This work suggests that the indigenous gut microbiota is a main factor that promotes clearance of C. difficile from the GI tract. Our results show that clearance of C. difficile can occur without contributions from the adaptive immune response. This study also has implications for the design of preclinical studies testing the efficacy of vaccines on clearance of bacterial pathogens, as inherent differences in the baseline community structure of animals may bias findings.

Cadazolid for the treatment of Clostridium difficile infection: results of two double-blind, placebo-controlled, non-inferiority, randomised phase 3 trials

BACKGROUND

Cadazolid is a novel quinoxolidinone antibiotic developed for treating Clostridium difficile infection. We aimed to investigate the safety and efficacy of cadazolid compared with vancomycin in patients with C difficile infection.

METHODS

IMPACT 1 and IMPACT 2 were identically designed, multicentre, double-blind, placebo-controlled, non-inferiority, randomised phase 3 trials. IMPACT 1 was done in Australia, Brazil, Canada, France, Germany, Italy, the Netherlands, Peru, Poland, Romania, Spain, and the USA, and IMPACT 2 was done in Argentina, Belgium, Brazil, Canada, Chile, Croatia, Czech Republic, Greece, Hungary, Israel, Romania, Slovakia, South Korea, the UK, and the USA. Patients (aged 18 years or older) with mild-to-moderate or severe C difficile infection (diarrhoea with positive glutamate dehydrogenase and toxin A or B enzyme immunoassays) were randomly assigned (1:1) with a randomisation list stratified by centre and C difficile infection episode type (block size of four), and allocation was masked to investigators and participants. Patients received either oral cadazolid 250 mg twice daily with vancomycin-matching placebo capsule four times daily or oral vancomycin 125 mg four times a day with cadazolid-matching placebo suspension twice daily for 10 days, with 30 days of follow-up. The primary efficacy outcome was non-inferiority (margin -10%) of cadazolid versus vancomycin for clinical cure in the modified intention-to-treat and per-protocol populations. Clinical cure was defined as resolution of diarrhoea with no additional treatment for C difficile infection. These trials are registered with ClinicalTrials.gov, numbers NCT01987895 (IMPACT 1) and NCT01983683 (IMPACT 2).

FINDINGS

Between March 28, 2014, and March 24, 2017, for IMPACT 1, and Dec 13, 2013, and May 2, 2017, for IMPACT 2, 1263 participants were randomly assigned to receive cadazolid (306 in IMPACT 1 and 298 in IMPACT 2) or vancomycin (326 in IMPACT 1 and 311 in IMPACT 2). In the modified intention-to-treat population in IMPACT 1, 253 (84%) of 302 had clinical cure in the cadazolid group versus 271 (85%) of 318 in the vancomycin group. In IMPACT 2, 235 (81%) of 290 versus 258 (86%) of 301 had clinical cure. In the per-protocol population, 247 (88%) of 282 versus 264 (92%) of 288 had clinical cure in IMPACT 1 and 214 (87%) of 247 versus 237 (92%) of 259 in IMPACT 2. Non-inferiority for clinical cure to vancomycin was shown in IMPACT 1 but not in IMPACT 2 (IMPACT 1 treatment difference: -1·4 [95% CI -7·2 to 4·3] for modified intention to treat and -4·1 [-9·2 to 1·0] for per protocol; IMPACT 2: -4·7 [-10·7 to 1·3] for modified intention to treat and -4·9 [-10·4 to 0·6] for per protocol). The safety and tolerability profiles of the two antibiotics were similar.

INTERPRETATION

Cadazolid was safe and well tolerated but did not achieve its primary endpoint of non-inferiority to vancomycin for clinical cure in one of two phase 3 C difficile infection trials. Therefore, further commercial development of cadazolid for C difficile infection is unlikely.

FUNDING

Actelion Pharmaceuticals.

The Hypervirulent Strain of Clostridium Difficile: NAP1/B1/027 - A Brief Overview

Clostridium difficile is a gram-positive bacterium notorious for causing epidemic diarrhea globally with a significant health burden. The pathogen is clinically challenging with increasing antibiotic resistance and recurrence rate. We provide here an in-depth review of one particular strain/ribotype 027, commonly known as NAP1/B1/027 or North American pulsed-field gel electrophoresis type 1, restriction endonuclease analysis type B1, polymerase chain reaction ribotype 027, which has shown a much higher recurrence rate than other strains.

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.

Dismantling a Toxin to Disarm a Superbug

Clostridium difficile (Clostridioides difficile) is a toxin-producing, multidrug-resistant bacterium. Inhibiting the effects of toxins, which are responsible for the symptoms of disease, is viewed as a promising non-antibiotic approach to treat C. difficile infection (CDI). By inducing premature activation of toxins, Ivarsson and colleagues (Cell Chemical Biology 2018; http://doi.org/10.1016/j.chembiol.2018.10.002) uncover a clever new strategy to block toxin action.

Bezlotoxumab: A Review in Preventing Clostridium difficile Infection Recurrence

Bezlotoxumab (Zinplava™) is a fully human monoclonal antibody against Clostridium difficile toxin B indicated for the prevention of C. difficile infection (CDI) recurrence in patients with a high recurrence risk. It is the first agent approved for recurrence prevention and is administered as a single intravenous infusion in conjunction with standard-of-care (SoC) antibacterial treatment for CDI. In well-designed, placebo-controlled, phase 3 trials (MODIFY 1 and 2), a single infusion of bezlotoxumab, given in combination with SoC antibacterial therapy for CDI in adults, was effective in reducing CDI recurrence in the 12 weeks post-treatment, with this benefit being seen mainly in the patients at high recurrence risk. Bezlotoxumab did not impact the efficacy of the antibacterials being used to treat the CDI and, consistent with its benefits on CDI recurrence, appeared to reduce the need for subsequent antibacterials, thus minimizing further gut microbiota disruption. Longer term, there were no further CDI recurrences over 12 months' follow-up among patients who had received bezlotoxumab in MODIFY 2 and entered an extension substudy. Bezlotoxumab has low immunogenicity and is generally well tolerated, although the potential for heart failure in some patients requires consideration; cost-effectiveness data for bezlotoxumab are awaited with interest. Thus, a single intravenous infusion of bezlotoxumab during SoC antibacterial treatment for CDI is an emerging option for reducing CDI recurrence in adults at high risk of recurrence.

Hypoalbuminemia as predictor of recurrence of Clostridium difficile infection

Background

Novel drugs for Clostridium difficile (C. difficile) infections have been proven to reduce recurrent infections. Because of their high financial costs, identification of patients at high risk for recurrence is essential to provide optimal treatment. The ATLAS score’s ability to predict 90-day recurrence, disease complications and 1‑year all-cause mortality was evaluated.

Methods

144 consecutive symptomatic patients with positive stool test for C. difficile were enrolled. The ATLAS score (consisting of the variables age, temperature, leukocyte count, albumin, systemic antibiotics, serum creatinine) was calculated and patients were stratified into 4 subgroups according to their scores. A Cox regression model was used to estimate the extent to which ATLAS was associated with 90-day recurrence. Furthermore, the score was correlated with disease complications and one-year all-cause mortality.

Results

ATLAS was unable to predict 90-day recurrence (p = 0.064, HR 1.134 [0.993;1.295]), but performed well for disease complications (D = 0.382, p < 0.001, HR 1.547 [1.266;1.889]) and mortality (p < 0.001, HR 1.374 [1.194;1.583]). Serum albumin was the only parameter able to predict 90-day recurrence (p = 0.016, HR 0.958 [0.926;0.992]) and was also a predictor of disease complications (p < 0.001, HR 0.865[0.809;0.924]) and one-year all-cause mortality (p < 0.001, HR 0.923 [0.896;0.950]). A threshold of 33.1g/L (sensitivity = 56%, specificity = 80%, AUC 0.683) and 29.2g/L (sensitivity = 75%, specificity = 70%, AUC 0.763) of serum albumin could be identified to be predictive for 90-day recurrence and one-year all-cause mortality, respectively.

Conclusions

Serum albumin and ATLAS are predictors of disease complications and mortality, while only serum albumin is significantly associated with 90-day disease recurrence.

Clostridioides difficile therapeutics: guidelines and beyond

Clostridioides difficile infection (CDI) has become an increasingly common infection both within and outside of the hospital setting. The management of this infection has been evolving as we learn more about the role of the human microbiota in protecting us from this gastrointestinal opportunist. For many years the focus of treatment had been on eradication of the vegetative, toxin-producing form of the organism, with little regard for its collateral impact on the host's microbiota or risk of recurrence. With the marked increase in C. difficile disease, and, particularly, recurrent disease in the last decade, new guidelines are more focused on targeting and reducing collateral damage to the colonic microbiota. Immune-based strategies that manipulate the microbiota and provide a humoral response to toxins have now become mainstream. Newer strategies are needed to look beyond simply resolving the primary episode but are focused on delayed outcomes such as cure at 90 days, reduced morbidity and mortality, and patient quality of life. The purpose of this review is to familiarize readers with the most recent evidence-based guidelines for C. difficile management, and to describe the role of newer antimicrobials, immunological-, and microbiota-based therapeutics to prevent recurrence and improve the outcomes of people with CDI.

Novel therapies and preventative strategies for primary and recurrent Clostridium difficile infections

Clostridium difficile is the leading infectious cause of antibiotic-associated diarrhea and colitis. C. difficile infection (CDI) places a heavy burden on the healthcare system, with nearly half a million infections yearly and an approximate 20% recurrence risk after successful initial therapy. The high incidence has driven new research on improved prevention such as the emerging use of probiotics, intestinal microbiome manipulation during antibiotic therapies, vaccinations, and newer antibiotics that reduce the disruption of the intestinal microbiome. While the treatment of acute C. difficile is effective in most patients, it can be further optimized by adjuvant therapies that improve the initial treatment success and decrease the risk of subsequent recurrence. Finally, the high risk of recurrence has led to multiple emerging therapies that target toxin activity, recovery of the intestinal microbial community, and elimination of latent C. difficile in the intestine. In summary, CDIs illustrate the complex interaction among host physiology, microbial community, and pathogen that requires specific therapies to address each of the factors leading to primary infection and recurrence.

Nuts and Bolts of Fecal Microbiota Transplantation

Clostridium difficile infection (CDI) has become the leading cause of nosocomial infection in the United States with significant risk of both morbidity and mortality. While antimicrobial therapy forms the basis of treatment, there are several clinical scenarios in which antimicrobial therapy alone is insufficient. Evidence continues to show the safety and efficacy fecal microbiota transplantation (FMT) in recurrent and severe CDI. This review will outline FMT efficacy, safety, and indications and present practical advice for clinicians interested in best practices around delivery of FMT.

Monoclonal antibodies as anti-infective products: a promising future?

BACKGROUND

The paucity of licensed monoclonal antibodies (mAbs) in the infectious diseases arena strongly contrasts with the ready availability of these therapeutics for use in other conditions.

AIMS

This narrative review aims to assess the potential of monoclonal antibody-based interventions for infectious diseases.

SOURCES

A review of the literature via the Medline database was performed and complemented by published official documents on licensed anti-infective mAbs. In addition, ongoing trials were identified through a search of the clinical trial registration platform ClinicalTrials.gov.

CONTENT

We identified the few infections for which mAbs have been added to the therapeutic armamentarium and stressed their potential in representing a readily available protection tool against biothreats and newly emerging and reemerging infectious agents. In reviewing the historical context and main features of mAbs, we assert a potentially wider applicability and cite relevant examples of ongoing therapeutic developments. Factors hindering successful introduction of mAbs on a larger scale are outlined and thoughts are offered on how to possibly address some of these limitations.

IMPLICATIONS

mAbs may represent important tools in treating or preventing infections occurring with reasonably sufficient prevalence to justify demand and for which existing alternatives are not deemed fully adequate. Future initiatives need to address the prohibitive costs encountered in the development process. The feasibility of more large-scale administration of alternative modalities merits further exploration. In order to ensure optimal prospect of regulatory success, an early dialogue with competent authorities is encouraged.

Analysis of Treatment Outcomes for Recurrent Clostridium difficile Infections and Fecal Microbiota Transplantation in a Pediatric Hospital

BACKGROUND

Clostridium difficile infection (CDI) is one of the most common nosocomial infections in the United States, with an increasing incidence in children. Approximately 20% of pediatric patients develop recurrent infections. It's imperative to further analyze the incidence of recurrent CDI in the pediatric population and determine the most effective treatments. The primary goal of this study is to characterize children with recurrent CDI at our institution, including both hospital-acquired CDI (HA-CDI) and community-acquired CDI (CA-CDI) cases, summarize the various treatments utilized, including fecal microbiota transplant (FMT) and compare their success rates.

METHODS

A retrospective cohort study of pediatric patients 1-21 years of age treated for CDI at a single institution from January 2010 to December 2014 was performed.

RESULTS

There were 175 subjects with 215 separate episodes of CDI. Oral metronidazole was the most common initial treatment (145/207, 70%) followed by oral vancomycin (30/207, 15%), with recurrence rates of 30% (42/145) and 37% (11/30), respectively. Twenty-nine percent (63/215) of all initial CDI cases had at least 1 documented recurrence. Using multivariate analysis, subjects with HA-CDI were 2.6 times less likely to recur than those with CA-CDI (odds ratio: 0.39; 95% confidence interval: 0.18-0.85; P = 0.018). The overall success rate for FMT at our institution was 10/12 (83%).

CONCLUSIONS

Our data show that cases of HA-CDI were less likely to recur compared with CA-CDI. Although currently reserved for multiply-recurrent cases, FMT was highly successful in our small cohort. More studies on FMT should be conducted to further evaluate its usefulness in the treatment of recurrent CDI in children.

Clostridioides difficile Infection in Chronic Kidney Disease/End-Stage Renal Disease

Clostridioides difficile infection (CDI) is a major health-care burden and increasingly seen in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Increased antibiotic use, alteration in host defenses, and gastric acid suppression are some of the etiologies for increased risk of CDI in these populations. Patients with CKD/ESRD have a higher risk of initial episode, recurrence, and development of severe CDI than those without CKD or ESRD. Diagnosis and management of CDI in patients with CKD/ESRD are similar to that in the general population. The mortality, length of stay, and health-care costs are higher in patients with CDI and CKD/ESRD. Antimicrobial stewardship with reduction in antibiotic use along with infection-control measures such as contact isolation and hand hygiene with soap and water is essential in the control and prevention of CDI in patients with CKD/ESRD.

Comparison of the 2010 and 2017 Infectious Diseases Society of America guidelines on the diagnosis and treatment of Clostridium difficile infection

PURPOSE OF REVIEW

To highlights the key changes in the updated Infectious Diseases Society of America and Society for Healthcare Epidemiology of America guidelines with respect to the diagnosis and treatment of Clostridium difficile infection (CDI).

RECENT FINDINGS

CDI continues as a major threat to healthcare institutions and as a community-associated infection related primarily to antibiotic exposure. Infectious Diseases Society of America/Society for Healthcare Epidemiology of America produced extensive CDI guidelines in 2010; in 2018, updated guidance has been published. The new guidelines include key changes with respect to the treatment and diagnosis of CDI.

SUMMARY

Updated, evidence guidelines allow optimization of the diagnosis of CDI and the use of therapeutic interventions, in particular to reduce the risk of recurrent infection.

Prevention and Treatment of Clostridium difficile-Associated Diarrhea in Solid Organ Transplant Recipients

Clostridium difficile infection is a significant cause of morbidity and mortality in solid organ transplant recipients. Risk factors in this population include frequent hospitalizations, receipt of immunosuppressive agents, and intestinal dysbiosis triggered by several factors, including exposure to broad-spectrum antimicrobials. The incidence and potential for significant adverse outcomes among solid organ transplant recipients with C difficile infection highlight the evolving need for strategic C difficile infection risk factor modification and novel approaches to disease management in this patient population. This review focuses on current concepts related to the prevention and treatment of C difficile infection in solid organ transplant recipients.

Bezlotoxumab for the prevention of Clostridium difficile infection: a review of current evidence and safety profile

Clostridium difficile infection (CDI) is a leading nosocomial disease estimated to cause nearly half a million cases in the United States annually. Recurrent CDI (rCDI) affects ~25% of patients after completion of standard of care therapy and is associated with substantial health care costs and a negative impact on patient's overall markers of quality of life. Bezlotoxumab is the first of its kind monoclonal antibody directed against C. difficile toxin B and indicated for prevention of rCDI in at-risk patients. For the present review, we assessed English-language studies evaluating the clinical efficacy, safety, and pharmacokinetics of bezlotoxumab in humans. Relevant studies were obtained through PubMed, Embase, Cochrane database library, Web of Science, and clinicaltrials.gov. Overall, bezlotoxumab demonstrated a 40% relative reduction rate (absolute rate reduction of ~10%) and a number needed to treat of 10 patients with a favorable safety profile. Special populations, including the elderly, immunocompromised, and patients with end-stage renal disease were evaluated in post hoc analyses with a similarly favorable reduction in rCDI. This review presents and interprets the most recent safety data and the clinical application of bezlotoxumab, highlighting specific high-risk patient populations.

Host-targeted niclosamide inhibits C. difficile virulence and prevents disease in mice without disrupting the gut microbiota

Clostridium difficile is the leading cause of nosocomial diarrhea and colitis in the industrialized world. Disruption of the protective gut microbiota by antibiotics enables colonization by multidrug-resistant C. difficile, which secrete up to three different protein toxins that are responsible for the gastrointestinal sequelae. Oral agents that inhibit the damage induced by toxins, without altering the gut microbiota, are urgently needed to prevent primary disease and break the cycle of antibiotic-induced disease recurrence. Here, we show that the anthelmintic drug, niclosamide, inhibits the pathogenesis of all three toxins by targeting a host process required for entry into colonocytes by each toxin. In mice infected with an epidemic strain of C. difficile, expressing all three toxins, niclosamide reduced both primary disease and recurrence, without disrupting the diversity or composition of the gut microbiota. Given its excellent safety profile, niclosamide may address an important unmet need in preventing C. difficile primary and recurrent diseases.

Clostridium difficile causes diarrhea and colitis by producing up to three different protein toxins. Here, Tam et al. show that an anthelmintic drug, niclosamide, inhibits the pathogenesis of all three toxins by targeting a host process required for toxin entry into host cells, without disrupting the gut microbiota.

Development of Neutralizing and Non-neutralizing Antibodies Targeting Known and Novel Epitopes of TcdB of Clostridioides difficile

Clostridioides difficile is the causative bacterium in 15-20% of all antibiotic associated diarrheas. The symptoms associated with C. difficile infection (CDI) are primarily induced by the two large exotoxins TcdA and TcdB. Both toxins enter target cells by receptor-mediated endocytosis. Although different toxin receptors have been identified, it is no valid therapeutic option to prevent receptor endocytosis. Therapeutics, such as neutralizing antibodies, directly targeting both toxins are in development. Interestingly, only the anti-TcdB antibody bezlotoxumab but not the anti-TcdA antibody actoxumab prevented recurrence of CDI in clinical trials. In this work, 31 human antibody fragments against TcdB were selected by antibody phage display from the human naive antibody gene libraries HAL9/10. These antibody fragments were further characterized by in vitro neutralization assays. The epitopes of the neutralizing and non-neutralizing antibody fragments were analyzed by domain mapping, TcdB fragment phage display, and peptide arrays, to identify neutralizing and non-neutralizing epitopes. A new neutralizing epitope within the glucosyltransferase domain of TcdB was identified, providing new insights into the relevance of different toxin regions in respect of neutralization and toxicity.

Bezlotoxumab use as adjunctive therapy with the third fecal microbiota transplant in refractory recurrent Clostridium difficile colitis; a case report and concise literature review

Clostridium difficile is the most commonly reported pathogen to cause nosocomial infections in the United States with a high burden affecting morbidity, mortality and healthcare expenditure. The use of Fecal Microbiota Transplantation (FMT) is one of the current standard therapies for recurrent C. difficile infection (CDIr). One emerging promising approach is the use of monoclonal antibodies that bind to and neutralize C. difficile toxins such as Bezlotoxumab. We present the first case report on combining the third FMT with bezlotoxumab after the failure of standard-of-care antibiotics and two trials of FMT alone, with subsequent success in preventing the recurrence of refractory CDI for 12 weeks following treatment. This case highlights the need for further studies and guidelines to recommend the best combination among different treatment options and modalities.

Management of adult Clostridium difficile digestive contaminations: a literature review

Clostridium difficile infections (CDI) dramatically increased during the last decade and cause a major public health problem. Current treatments are limited by the high disease recurrence rate, severity of clinical forms, disruption of the gut microbiota, and colonization by vancomycin-resistant enterococci (VRE). In this review, we resumed current treatment options from official recommendation to promising alternatives available in the management of adult CDI, with regard to severity and recurring or non-recurring character of the infection. Vancomycin remains the first-line antibiotic in the management of mild to severe CDI. The use of metronidazole is discussed following the latest US recommendations that replaced it by fidaxomicin as first-line treatment of an initial episode of non-severe CDI. Fidaxomicin, the most recent antibiotic approved for CDI in adults, has several advantages compared to vancomycin and metronidazole, but its efficacy seems limited in cases of multiple recurrences. Innovative therapies such as fecal microbiota transplantation (FMT) and antitoxin antibodies were developed to limit the occurrence of recurrence of CDI. Research is therefore very active, and new antibiotics are being studied as surotomycin, cadazolid, and rinidazole.

Bezlotoxumab Is Associated With a Reduction in Cumulative Inpatient-Days: Analysis of the Hospitalization Data From the MODIFY I and II Clinical Trials

Background

Patients with recurrent Clostridium difficile infection (rCDI) are more likely to have a hospital readmission and spend increased time in inpatient settings compared with patients with primary CDI. MODIFY I and II demonstrated that bezlotoxumab significantly reduced rCDI vs placebo. A post hoc within-trial analysis assessed whether bezlotoxumab was associated with a reduction in cumulative inpatient-days.

Methods

Data were pooled from the MODIFY trials to estimate the cumulative hospitalized days summed over the 84-day follow-up period. We adjusted inpatient use data from pooled MODIFY I and II for survival and censoring to estimate 84-day cumulative inpatient-days, overall and for subgroups. Treatment effects were obtained using recycled predictions based on trial protocol and rCDI risk, and 95% confidence intervals were obtained using 1000 bootstrap replicates.

Results

Mean cumulative inpatient-days were greater in the placebo arm (14.1 days) vs the bezlotoxumab arm (12.1 days) in the overall population. The mean difference between treatment groups was 2.1 days (95% confidence interval, –0.4 to –3.7). This was consistent in participants with risk factors for rCDI: age ≥65 years, compromised immunity, severe CDI, prior CDI, and ribotype 027/078/244 infection. As the number of risk factors increased, bezlotoxumab resulted in greater reductions in the number of inpatient-days compared with placebo (difference: –1.2 days, –2.3 days, –2.5 days, and –3.0 days for 0, 1, 2, and ≥3 risk factors, respectively).

Conclusions

Bezlotoxumab was associated with a reduction in cumulative inpatient-days, suggesting that treatment with bezlotoxumab may substantially reduce rCDI-associated health care resource use.

Trial registrations. MODIFY I (MK-3415A-001, NCT01241552) and II (MK-3415A-002, NCT01513239)

Comparing fecal microbiota transplantation to standard-of-care treatment for recurrent Clostridium difficile infection: a systematic review and meta-analysis

BACKGROUND

The use of fecal microbiota transplantation (FMT) as a treatment option for recurrent Clostridium difficile infection (rCDI) is well established. Various studies have used different forms and administration routes for FMT. We performed a systemic review and meta-analysis to update the clinical knowledge about different FMT modalities for curing rCDI compared with medical treatment (MT).

PATIENTS AND METHODS

We searched PubMed and Medline from inception through 10 May 2018 for randomized control trials (RCTs) comparing FMT (fresh or frozen) versus MT. We used Cochrane Collaboration's Risk of Bias tool to assess bias in the RCTs. We estimated odds ratio (OR) with 95% confidence interval (CI) for each outcome using a random effects model. P values of less than 0.05 were considered significant.

RESULTS

We included seven RCTs comprising a total of 543 patients with recurrent CDI. There was a nonsignificant trend toward resolution of diarrhea following a single fresh FMT infusion compared with frozen FMT and MT (OR=2.45, 95% CI=0.78-7.71, P=0.12, I=69%). Subgroup analysis of fresh FMT vs. frozen FMT showed no difference between the two groups (OR=2.13, 95% CI=0.22-20.41, P=0.51, I=61%). Frozen FMT infusion through upper route versus lower route showed no difference (OR=0.62, 95% CI=0.15-2.54, P=0.51, I=0%). There was a nonsignificant trend favoring multiple treatments with FMT versus multiple courses of MT (OR=3.68, 95% CI=0.74-18.22, P=0.11, I=0%).

CONCLUSION

FMT is a promising treatment modality for rCDI compared with MT alone. Different forms and routes of FMT administration seem to be equally efficacious. In future, more well-designed RCTs directed at homogenous FMT preparation and delivery methods are required to validate these findings.

Cost-Effectiveness Analysis of Bezlotoxumab Added to Standard of Care Versus Standard of Care Alone for the Prevention of Recurrent Clostridium difficile Infection in High-Risk Patients in Spain

INTRODUCTION

Clostridium difficile infection (CDI) is the major cause of infectious nosocomial diarrhoea and is associated with considerable morbidity, mortality and economic impact. Bezlotoxumab administered in combination with standard of care (SoC) antibiotic therapy prevents recurrent CDI. This study assessed the cost-effectiveness of bezlotoxumab added to SoC, compared to SoC alone, to prevent the recurrence of CDI in high-risk patients from the Spanish National Health System perspective.

METHODS

A Markov model was used to simulate the natural history of CDI over a lifetime horizon in five populations of patients at high risk of CDI recurrence according to MODIFY trials: (1) ≥ 65 years old; (2) severe CDI; (3) immunocompromised; (4) ≥ 1 CDI episode in the previous 6 months; and (5) ≥ 65 years old and with ≥ 1 CDI episode in the previous 6 months. The incremental cost-effectiveness ratio (ICER) expressed as cost per quality-adjusted life-year (QALY) gained was calculated. Deterministic (DSA) and probabilistic sensitivity analyses (PSA) were performed.

RESULTS

In all patient populations (from 1 to 5), bezlotoxumab added to SoC reduced CDI recurrence compared to SoC alone by 26.4, 19.5, 21.2, 26.6 and 39.7%, respectively. The resulting ICERs for the respective subgroups were €12,724, €17,495, €9545, €7386, and €4378. The model parameters with highest impact on the ICER were recurrence rate (first), mortality, and utility values. The probability that bezlotoxumab was cost-effective at a willingness-to-pay threshold of €21,000/QALY was 85.5%, 54.1%, 86.0%, 94.5%, 99.6%, respectively.

CONCLUSION

The results suggest that bezlotoxumab added to SoC compared to SoC alone is a cost-effective treatment to prevent the recurrence of CDI in high-risk patients. The influence of changes in model parameters on DSA results was higher in patients  ≥ 65 years old, with severe CDI and immunocompromised. Additionally, PSA estimated that the probability of cost-effectiveness exceeded 85% in most subgroups.

FUNDING

Merck Sharp & Dohme Corp.

Oral vancomycin versus metronidazole for the treatment of Clostridioides difficile infection: Meta-analysis of randomized controlled trials

At present, vancomycin (VCM) and metronidazole (MNZ) are used for the first-line standard treatment of Clostridioides difficile infection (CDI). However, their differential use has not been sufficiently investigated. In this study, a meta-analysis on differences in the efficacy for CDI between VCM and MNZ was performed. Reports of randomized controlled studies using VCM or MNZ to treat CDI were surveyed. Meta-analysis was performed using the Mantel-Haenszel method and random-effects model, and the risk ratio and 95% confidence interval were calculated. Excluding overlapping reports, 1043 reports were extracted and 5 randomized controlled studies were extracted. There was no difference in therapeutic effects for CDI between VCM and MNZ (RR = 1.08, 95% CI (0.99-1.17), p = 0.09, I² = 37%). On subgroup analysis by the severity, there was no difference in the clinical effects for CDI between VCM and MNZ in non-severe cases (risk ratio: 1.09, 95% confidence interval: 1.00-1.19, p = 0.06), but the clinical effects of VCM were significantly higher than those of MNZ in severe cases (risk ratio: 1.19, 95% confidence interval: 1.02-1.39, p = 0.03). No significant difference was noted in the recurrence rate, incidence of adverse event, time to exhibit therapeutic effects, or judgment of the bacteriological effects. As the therapeutic effects of VCM were superior in severe CDI cases, VCM should be considered first in severe cases.

The use of faecal microbiota transplant as treatment for recurrent or refractory Clostridium difficile infection and other potential indications: joint British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS) guidelines

Interest in the therapeutic potential of faecal microbiota transplant (FMT) has been increasing globally in recent years, particularly as a result of randomised studies in which it has been used as an intervention. The main focus of these studies has been the treatment of recurrent or refractory Clostridium difficile infection (CDI), but there is also an emerging evidence base regarding potential applications in non-CDI settings. The key clinical stakeholders for the provision and governance of FMT services in the UK have tended to be in two major specialty areas: gastroenterology and microbiology/infectious diseases. While the National Institute for Health and Care Excellence (NICE) guidance (2014) for use of FMT for recurrent or refractory CDI has become accepted in the UK, clear evidence-based UK guidelines for FMT have been lacking. This resulted in discussions between the British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS), and a joint BSG/HIS FMT working group was established. This guideline document is the culmination of that joint dialogue.

Guideline for the Management of Clostridium Difficile Infection in Children and Adolescents With Cancer and Pediatric Hematopoietic Stem-Cell Transplantation Recipients

PURPOSE

The aim of this work was to develop a clinical practice guideline for the prevention and treatment of Clostridium difficile infection (CDI) in children and adolescents with cancer and pediatric hematopoietic stem-cell transplantation (HSCT) patients.

METHODS

An international multidisciplinary panel of experts in pediatric oncology and infectious diseases with patient advocate representation was convened. We performed systematic reviews of randomized controlled trials for the prevention or treatment of CDI in any population and considered the directness of the evidence to children with cancer and pediatric HSCT patients. We used the Grading of Recommendations Assessment, Development, and Evaluation approach to generate recommendations.

RESULTS

The panel made strong recommendations to administer either oral metronidazole or oral vancomycin for the initial treatment of nonsevere CDI and oral vancomycin for the initial treatment of severe CDI. Fidaxomicin may be considered in the setting of recurrent CDI. The panel suggested that probiotics not be routinely used for the prevention of CDI, and that monoclonal antibodies and probiotics not be routinely used for the treatment of CDI. A strong recommendation to not use fecal microbiota transplantation was made in this population. We identified key knowledge gaps and suggested directions for future research.

CONCLUSION

We present a guideline for the prevention and treatment of CDI in children and adolescents with cancer and pediatric HSCT patients. Future research should include randomized controlled trials that involve children with cancer and pediatric HSCT patients to improve the management of CDI in this population.

The Conserved Cys-2232 in Clostridioides difficile Toxin B Modulates Receptor Binding

Clostridioides difficile toxins TcdA and TcdB are large clostridial glucosyltransferases which are the main pathogenicity factors in C. difficile-associated diseases. Four highly conserved cysteines are present in all large clostridial glucosyltransferases. In this study we focused on the conserved cysteine 2232 within the combined repetitive oligopeptide domain of TcdB from reference strain VPI10463 (clade I). Cysteine 2232 is not present in TcdB from hypervirulent strain R20291 (clade II), where a tyrosine is found instead. Replacement of cysteine 2232 by tyrosine in TcdB_{V PI10463} reduced binding to the soluble fragments of the two known TcdB receptors, frizzled-2 (FZD2) and poliovirus receptor-like protein-3/nectin-3 (PVRL3). In line with this, TcdB_R20291 showed weak binding to PVRL3 in pull-down assays which was increased when tyrosine 2232 was exchanged for cysteine. Surprisingly, we did not observe binding of TcdB_R20291 to FZD2, indicating that this receptor is less important for this toxinotype. Competition assay with the receptor binding fragments (aa 1101–1836) of TcdB_{V PI10463} and TcdB_R20291, as well as antibodies newly developed by antibody phage display, revealed different characteristics of the yet poorly described delivery domain of TcdB harboring the second receptor binding region. In summary, we found that conserved Cys-2232 in TcdB indirectly contributes to toxin–receptor interaction.

Clostridium difficile control measures: current and future methods for prevention

INTRODUCTION

Clostridium difficile is the most common cause of healthcare associated infection, and C. difficile infection (CDI) is associated with significant costs, morbidity, and mortality. One obstacle to preventing CDI is lack of high quality data on interventions to prevent CDI. This has led some to focus on areas, such as method of hand hygiene, unlikely to impact CDI incidence as much as others, such as contact precautions. In addition, existing strategies, although effective, do have limitations. Another challenge is the ability to rapidly, and accurately, diagnose CDI. Given these obstacles, new strategies to effectively prevent CDI are imperative to improve patient outcomes. Areas covered: Evidence of the interventions recommended by international scientific societies will be reviewed, as well as ongoing research on new strategies, such as screening for asymptomatic C. difficile carriage, microbiota sparing agents, bacteriocins and vaccines. Expert commentary: Current measures to prevent CDI are effective, but have significant limitations. Contact precautions and antimicrobial stewardship are likely the most effective of current prevention recommendations. Diagnostic assay utilization plays a role as well. New strategies to prevent CDI are needed, and, fortunately, several are being studied. Most likely a combination of approaches will be necessary to optimize CDI prevention.

Clostridium difficile infection in oncology patients: epidemiology, pathophysiology, risk factors, diagnosis, and treatment

Clostridium difficile infection (CDI) is one of the most common healthcare-associated infections in the United States. Its incidence has been increasing in the recent years despite preventative measures. CDI increases annual expenses by 1.5 billion dollars. Cancer patients are at higher risk to acquire CDI, as explained by their frequent exposure to risk factors. CDI in cancer patients is associated with higher mortality rates and prolonged hospitalization. Furthermore, CDI affects the course of the disease by delaying treatments such as chemotherapy. Chemotherapeutics drugs are considered independent risk factors for CDI. This review discusses Clostridium difficile infection in cancer patients, including those who are receiving chemotherapy. Herein, we summarize recent data regarding the epidemiology, risk factors, including chemotherapy regimens, pathogenesis, diagnostic techniques and treatment options, including newer agents. Method: A literature search was performed using the PubMed and Google Scholar databases. The MeSH terms utilized in different combinations were 'clostridium difficile', 'neoplasia/cancer/oncology', 'chemotherapy', 'diagnosis', and 'treatment', in addition to looking up each treatment option individually to generate a comprehensive search. The articles were initially screened by title alone, followed by screening through abstracts. Full texts of pertinent articles (including letters to editors, case reports, case series, cohort studies, and clinical trials) were included in this review.

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

The rapid development of antimicrobial resistance is threatening mankind to such an extent that the World Health Organization expects more deaths from infections than from cancer in 2050 if current trends continue. To avoid this scenario, new classes of anti-infectives must urgently be developed. Antibiotics with new modes of action are needed, but other concepts are also currently being pursued. Targeting bacterial virulence as a means of blocking pathogenicity is a promising new strategy for disarming pathogens. Furthermore, it is believed that this new approach is less susceptible towards resistance development. In this review, recent examples of anti-infective compounds acting on several types of bacterial targets, e.g., adhesins, toxins and bacterial communication, are described.

Fecal Microbiota Transplantation for the Management of Clostridium difficile Infection

The clinical burden of Clostridium difficile infection (CDI) continues to grow. Despite the multitude of treatment options that have been developed and tested to combat the morbidity and death associated with CDI, recurrence remains common. As such, treatment modalities such as fecal microbiota transplantation (FMT) have become studied increasingly; FMT serves to transplant stool from carefully selected healthy subjects into C. difficile positive patients through a variety of delivery routes. In doing so, FMT is hypothesized to correct dysbiosis of the recipient gut microbiome addressing the root cause of the pathogenesis of C. difficile infection. A growing body of evidence shows FMT to be efficacious in this setting, and the study of FMT accordingly continues to evolve to identify novel indications for its utilization.

Clostridioides difficile Infection

Clostridioides difficile (formerly Clostridium difficile) infection is the most frequently identified health care-associated infection in the United States. C difficile has also emerged as a cause of community-associated diarrhea, resulting in increased incidence of community-associated infection. Clinical illness ranges in severity from mild diarrhea to fulminant colitis and death. Appropriate management of infection requires understanding of the various diagnostic assays and therapeutic options as well as relevant measures to infection prevention. This article provides updated recommendations regarding the prevention, diagnosis, and treatment of incident and recurrent C difficile infection.

Results From a Randomized, Placebo-Controlled Clinical Trial of a RBX2660-A Microbiota-Based Drug for the Prevention of Recurrent Clostridium difficile Infection

BACKGROUND

Despite advancements, recurrent Clostridium difficile infections (CDI) remain an urgent public health threat with insufficient response rates to currently approved antibiotic therapies. Microbiota-based treatments appear effective, but rigorous clinical trials are required to optimize dosing strategies and substantiate long-term safety.

METHODS

This randomized, double-blind, placebo-controlled phase 2B trial enrolled adults with 2 or more CDI recurrences to receive: 2 doses of RBX2660, a standardized microbiota-based drug (group A); 2doses of placebo (group B); or 1 dose of RBX2660 followed by 1 dose of placebo (group C). Efficacy was defined as prevention of recurrent CDI for 8 weeks following treatment. Participants who had a recurrence within 8 weeks were eligible to receive up to 2 open-label RBX2660 doses. The primary endpoint was efficacy for group A compared to group B. Secondary endpoints included the efficacy of group C compared to group B, combined efficacy in the blinded and open-label phases, and safety for 24 months.

RESULTS

The efficacy for groups A, B, and C were 61%, 45%, and 67%, respectively. The primary endpoint was not met (P = .152). One RBX2660 dose (group C) was superior to placebo (group B; P = .048), and the overall efficacy (including open-label response) for RBX2660-treated participants was 88.8%. Adverse events did not differ significantly among treatment groups.

CONCLUSIONS

One, but not 2, doses of RBX2660 was superior to placebo in this randomized, placebo-controlled trial. These data provide important insights for a larger phase 3 trial and continued clinical development of RBX2660.

CLINICAL TRIALS REGISTRATION

NCT02299570.

Clinical review of Clostridium difficile infection: an update on treatment and prevention

INTRODUCTION

Clostridium difficile infection (CDI) has become a significant healthcare-associated infection and is strongly associated with antibiotic use. Practice guidelines have recently been revised incorporating updated recommendations for diagnosis, treatment, and prevention.

AREAS COVERED

This review discusses updated aspects of CDI management. New and emerging pharmacologic options for treatment and prevention are reviewed.

EXPERT OPINION

Metronidazole is associated with lower rates of treatment success compared to vancomycin and should no longer be used as primary therapy for the first episode of CDI or recurrent disease. Vancomycin or fidaxomicin are now recommended for first-line therapy for most cases of CDI. Fecal microbiota transplant is effective and safe for the treatment of recurrent CDI. Evidence supports the use of fidaxomicin and bezlotoxumab for prevention of recurrent CDI; however, the costs associated with these therapies may limit their use. Validated risk prediction tools are needed to identify patients most likely to benefit from these treatments. Future advancements in microbiota targeting treatments will emerge as promising alternatives to standard CDI treatments. Antibiotic stewardship and infection control measures will remain essential components for CDI management.

Impact of early-life events on the susceptibility to Clostridium difficile colonisation and infection in the offspring of the pig

Clostridium difficile has been documented as a major cause of uncontrolled outbreaks of enteritis in neonatal pigs and antibiotic-associated infections in clinical settings. It belongs to the natural cohort of early colonisers of the gastrointestinal tract of pigs and can be detected in faeces up to two weeks post-partum. In older pigs, it often remains under the detection limit. Most neonatal pigs show no clinical signs of disease although C. difficile and its toxins can be detected at high levels in faeces. Increased mortality rates associated with C. difficile on pig farms are, so far, considered "spontaneous" and the predisposing factors are mostly not defined. The infection caused by C. difficile is multifactorial and it is likely that the repertoire of maternal factors, host physiology, the individually developing gut microbiota, co-infections and environmental stress define the conditions for disease development. In this addendum to our recently published work on CDI in neonatal piglets, we discuss the "early-life events" that influence C. difficile spread and infection in neonatal piglets.

A comprehensive approach for the patient with Clostridium difficile infection

During the last decade there have been many changes and advances in the research on Clostridium difficile infection (CDI). We have improved diagnostic and therapeutic tools and, at the same time, we have learned that the CDI implies, especially in the most vulnerable patients, an important morbidity. CDI has traditionally been undervalued and it is widely dispersed in hospitals. Surely, there is inertness in its management and there are also broad areas of improvement. If we add to this the high cost of the new drugs and the practical difficulties to implement the faecal microbiota transplant, we realize that we may not be taking full advantage of all the opportunities to improve patient's outcomes. The implementation of policies that favour the supervision of all CDI cases by an expert in infectious diseases will contribute to a better global management of this important disease.

Current clostridium difficile treatments: Lessons that need to be learned from the clinical trials

Clostridium difficile infection (CDI) is the most common infectious disease cause of nosocomial diarrhea in adults in developed countries. Judging from the clinical trials on drugs used in CDIs, no approved treatment for recurrences exists, possibly indicating that a combination of treatment approaches are mandatory especially in severe infections, with current studies not being fully representative. Among the new strategies researched intensively fidaxomicin is presented, which demonstrates reduced CDI recurrences. Moreover, biotherapeutic strategies, mainly fecal microbiota transplantation but also competitive inhibition with non-toxigenic strains of C. difficile, and finally monoclonal antibodies against C. difficile toxins which offer protection against recurrences. Careful interpretation of the results based on lessons learned from previous trials conducted seems crucial. Questions are raised regarding how the results of future studies regarding new strategies researched will be managed and interpreted especially with regard to recurrence management as relevant data must be monitored for at least 30 days after end of treatment.