Surotomycin versus vancomycin for Clostridium difficile infection: Phase 2, randomized, controlled, double-blind, non-inferiority, multicentre trial

Fighting against Clostridioides difficile infection: Current medications

Clostridioides difficile (formerly Clostridium difficile) has been regarded as an 'urgent threat' and a significant global health problem, as life-threatening diarrhoea and refractory recurrence are common in patients with C. difficile infection (CDI). Unfortunately, the available anti-CDI drugs are limited. Recent guidelines recommend fidaxomicin and vancomycin as first-line drugs to treat CDI, bezlotoxumab to prevent recurrence, and faecal microbiota transplantation for rescue treatment. Currently, researchers are investigating therapeutic antibacterial drugs (e.g. teicoplanin, ridinilazole, ibezapolstat, surotomycin, cadazolid, and LFF571), preventive medications against recurrence (e.g. Rebyota, Vowst, VP20621, VE303, RBX7455, and MET-2), primary prevention strategies (e.g. vaccine, ribaxamase, and DAV132) and other anti-CDI medications in the preclinical stage (e.g. Raja 42, Myxopyronin B, and bacteriophage). This narrative review summarises current medications, including newly marketed drugs and products in development against CDI, to help clinicians treat CDI appropriately and to call for more research on innovation.

Functional and Metagenomic Evaluation of Ibezapolstat for Early Evaluation of Anti-Recurrence Effects in Clostridioides difficile Infection

Reduction of Clostridioides difficile infection (CDI) recurrence is an essential endpoint for CDI-directed antibiotic development that is often not evaluated until Phase III trials. The purpose of this project was to use a functional and metagenomic approach to predict the potential anti-CDI recurrence effect of ibezapolstat, a DNA polymerase IIIC inhibitor, in clinical development for CDI. As part of the Phase I ibezapolstat clinical study, stool samples were collected from 22 healthy volunteers, who were given either ibezapolstat or vancomycin. Stool samples were evaluated for microbiome changes and bile acid concentrations. Ibezapolstat 450 mg and vancomycin, but not ibezapolstat 300 mg, showed statistically significant changes in alpha diversity over time compared to that of a placebo. Beta diversity changes confirmed that microbiota were significantly different between study groups. Vancomycin had a more wide-ranging effect on the microbiome, characterized by an increased proportion of Gammaproteobacteria. Ibezapolstat demonstrated an increased proportion of Actinobacteria, including the Bifidobacteriaceae family. Using a linear regression analysis, vancomycin was associated with significant increases in primary bile acids as well as primary:secondary bile acid ratios. An overabundance of Enterobacteriaceae was most highly correlated with primary bile acid concentrations (r = 0.63; P < 0.0001). Using Phase I healthy volunteer samples, beneficial changes suggestive of a lower risk of CDI recurrence were associated with ibezapolstat compared to vancomycin. This novel omics approach may allow for better and earlier prediction of anti-CDI recurrence effects for antibiotics in the clinical development pipeline.

Antimicrobial Mechanisms and Clinical Application Prospects of Antimicrobial Peptides

Antimicrobial peptides are a type of small-molecule peptide that widely exist in nature and are components of the innate immunity of almost all living things. They play an important role in resisting foreign invading microorganisms. Antimicrobial peptides have a wide range of antibacterial activities against bacteria, fungi, viruses and other microorganisms. They are active against traditional antibiotic-resistant strains and do not easily induce the development of drug resistance. Therefore, they have become a hot spot of medical research and are expected to become a new substitute for fighting microbial infection and represent a new method for treating drug-resistant bacteria. This review briefly introduces the source and structural characteristics of antimicrobial peptides and describes those that have been used against common clinical microorganisms (bacteria, fungi, viruses, and especially coronaviruses), focusing on their antimicrobial mechanism of action and clinical application prospects.

European Society of Clinical Microbiology and Infectious Diseases: 2021 update on the treatment guidance document for Clostridioides difficile infection in adults

SCOPE

In 2009, the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) published the first treatment guidance document for Clostridioides difficile infection (CDI). This document was updated in 2014. The growing literature on CDI antimicrobial treatment and novel treatment approaches, such as faecal microbiota transplantation (FMT) and toxin-binding monoclonal antibodies, prompted the ESCMID study group on C. difficile (ESGCD) to update the 2014 treatment guidance document for CDI in adults.

METHODS AND QUESTIONS

Key questions on CDI treatment were formulated by the guideline committee and included: What is the best treatment for initial, severe, severe-complicated, refractory, recurrent and multiple recurrent CDI? What is the best treatment when no oral therapy is possible? Can prognostic factors identify patients at risk for severe and recurrent CDI and is there a place for CDI prophylaxis? Outcome measures for treatment strategy were: clinical cure, recurrence and sustained cure. For studies on surgical interventions and severe-complicated CDI the outcome was mortality. Appraisal of available literature and drafting of recommendations was performed by the guideline drafting group. The total body of evidence for the recommendations on CDI treatment consists of the literature described in the previous guidelines, supplemented with a systematic literature search on randomized clinical trials and observational studies from 2012 and onwards. The Grades of Recommendation Assessment, Development and Evaluation (GRADE) system was used to grade the strength of our recommendations and the quality of the evidence. The guideline committee was invited to comment on the recommendations. The guideline draft was sent to external experts and a patients' representative for review. Full ESCMID endorsement was obtained after a public consultation procedure.

RECOMMENDATIONS

Important changes compared with previous guideline include but are not limited to: metronidazole is no longer recommended for treatment of CDI when fidaxomicin or vancomycin are available, fidaxomicin is the preferred agent for treatment of initial CDI and the first recurrence of CDI when available and feasible, FMT or bezlotoxumab in addition to standard of care antibiotics (SoC) are preferred for treatment of a second or further recurrence of CDI, bezlotoxumab in addition to SoC is recommended for the first recurrence of CDI when fidaxomicin was used to manage the initial CDI episode, and bezlotoxumab is considered as an ancillary treatment to vancomycin for a CDI episode with high risk of recurrence when fidaxomicin is not available. Contrary to the previous guideline, in the current guideline emphasis is placed on risk for recurrence as a factor that determines treatment strategy for the individual patient, rather than the disease severity.

3-Hydroxy-4-methyldecanoic Acid-Containing Cyclotetradepsipeptides from an Endolichenic Beauveria sp

An investigation of an endolichenic Beauveria sp. led to the discovery of seven new cyclotetradepsipeptides, beauveamides A-G (2-8), along with the known beauverolide Ka (1). All incorporate a 3-hydroxy-4-methyldecanoic acid (HMDA) moiety in their structures. Their configuration was determined through Marfey's, J-based configuration analysis, and NMR computational methods, representing the first time that the stereostructures of HMDA-moiety-containing cyclotetradepsipeptides have been established. Compounds 1 and 2 exhibited protecting effects on HEI-OC1 cells at 10 μM, while 1, 4, and 5 could stimulate glucose uptake in cultured rat L6 myoblasts at 50 μM. Compound 1 showed dose-dependent activity in both L6 myoblasts and myotubes.

Surotomycin (A Novel Cyclic Lipopeptide) vs. Vancomycin for the Treatment of Clostridioides difficile Infection: A Systematic Review and Meta-analysis

Background:

Current guidelines recommend the use of vancomycin for the initial treatment of moderate to severe Clostridioides difficile Infection (CDI). Surotomycin, a novel antibiotic, has been utilized for the management of CDI with variable results.

Methods:

A systematic literature search was performed using the following electronic databases [Medline, Embase, google scholar and Cochrane] for eligible studies. Randomized controlled trials comparing Surotomycin with Vancomycin for the CDI treatment were included. Demographic variables and outcomes (CDI resolution, CDI recurrence, B1/NAP1/027-specific strain treatment, B1/NAP1/027-strain recurrence, death not related to treatment) were analyzed. The primary outcome was clinical cure rate defined as the resolution of CDI at the end of the 10-day drug course.

Results:

Three RCTs met the inclusion criteria with a total of 1280 patients with CDI who received either surotomycin 250 mg twice daily (642 patients) or vancomycin 125 mg four times daily (638 patients). Clinical cure rates after 10 days of treatment with either surotomycin or vancomycin were not significantly different (pooled OR: 0.89, 95% CI 0.66-1.18, p=0.41). Sustained clinical response at clinical follow-up and the overall recurrence of CDI were also not significantly different between the two groups – pooled OR 1.15 (95% CI 0.89-1.50, p=0.29) and pooled OR 0.74 (95%CI 0.52- 1.04, p=0.08), respectively. With regards to the NAP1/BI/027 strain, patients in the surotomycin group had significantly lower rates of recurrence compared to vancomycin (pooled OR 0.35, 95% CI 0.19-0.63, p<0.01).

Conclusion:

Surotomycin is non-inferior to vancomycin and offers a promising alternative for the treatment and prevention of C. diff infection.

Recent developments in the management of recurrent Clostridioides difficile infection

Clostridioides (formerly Clostridium) difficile is responsible for a substantial burden of nosocomial infection. Recurrent C. difficile infection (rCDI) remains a concern due to its high morbidity, mortality, and cost. Despite the updated 2017 IDSA C. difficile treatment guidelines, there remains a lack of well-studied preventive control measures and treatment modalities for rCDI. There are ongoing efforts to develop novel therapies, such as new antibiotics with a lesser impact on gut microbiota and more targeted therapies, such as bacteriotherapy. This mini review highlights key rCDI management updates, preventive measures and ongoing research on novel treatment strategies including bacteriotherapy.

Prevention of recurrent Clostridioides difficile infection: A systematic review of randomized controlled trials

Recurrent Clostridioides (formerly Clostridium) difficile infection (rCDI) is common, and patients who have had one recurrence are more likely to have multiple recurrences. Frequent recurrences have been associated with increased morbidity and mortality, high healthcare costs, and lower quality of life. In this review, we compare the efficacy of interventions designed to prevent rCDI. We performed a systematic review of the English literature, including randomized controlled trials (RCTs) that evaluated rCDI as an outcome. Studies were included irrespective of patient demographics, disease severity, type of intervention, comparator used, or time-point of outcome evaluation. We performed a comprehensive literature search with the assistance of a research librarian. Two reviewers independently extracted data and assessed risk of bias. Our search yielded 38 RCTs (8,102 participants). Nineteen RCTs (3,743 subjects) evaluated antibiotics, eight fecal microbiota transplantation (FMT) (582 subjects), three monoclonal antibodies (MAbs) (2,805 subjects), and eight probiotics, prebiotics, or non-antibiotic polymers (972 subjects). The antibiotic and FMT therapies that demonstrated efficacy in rCDI prevention included: fidaxomicin (when compared to a ten-day vancomycin course) and FMT administered by nasogastric tube (when compared to a fourteen-day vancomycin course and a fourteen-day vancomycin course plus bowel lavage). Actoxumab (MAb against C. difficile toxin A; CDA1) plus bezlotoxumab (MAb against C. difficile toxin B; CDB1) in combination or bezlotoxumab alone appeared to be more effective in preventing rCDI compared to actoxumab alone. Of the prebiotics, probiotics, and nonantibiotic polymers, oligofructose, Saccharomyces boulardii, and the nontoxigenic C. difficile strain M3 were the most efficacious for rCDI prevention. Thirty-eight RCTs (>8,000 participants) evaluating treatment modalities for CDI were examined for efficacy in prevention of rCDI. Several CDI-specific antibiotics, FMT modalities, monoclonal antibodies, and various prebiotics and probiotics demonstrated a reduction in risk of rCDI with the greatest risk reduction observed with FMT and monoclonal antibody therapy. It is notable that the comparators in these studies were very different from one another and the relative risk reduction of rCDI may not be directly comparable from one study to the next.

The perils of PCR-based diagnosis of Clostridioides difficile infections: Painful lessons from clinical trials

Diagnostic tests favoured to detect C. difficile infections (CDI) have undergone successive changes. The problem of over-diagnosis with polymerase chain reaction (PCR) testing is recognized in the clinical setting; here we discuss the parallel of the clinical trial setting. We summarize and discuss four examples of the impact of method used to diagnose CDI on clinical trial outcomes. Bezlotoxumab, a human monoclonal antibody neutralizing toxin B, was found to be protective against recurrent CDI (rCDI) in clinical trials. A post hoc analysis showed that the magnitude of the relative reduction in rCDI rates of bezlotoxumab over placebo in patients diagnosed with toxin-based testing was almost double that in patients diagnosed with PCR. SER-109, a microbiome therapeutic developed to prevent rCDI, showed promise in a phase 1b trial, but results were not replicated in a phase 2 trial in which diagnosis was in majority PCR-based. Surotomycin, an oral lipopeptide antibiotic, was found to be non-inferior to vancomycin in phase 2 study, but development was discontinued after unfavourable phase 3 results in which the majority of CDI were diagnosed by PCR. Finally, a C. difficile vaccine program for a toxoid vaccine developed by Sanofi/Pasteur was terminated after interim analysis of a phase 3 trial, in which CDI diagnosis was based solely on PCR. We highlighted the perils of using PCR alone in studies involving different aspects of C. difficile clinical research, including immunotherapies, microbiome-based therapies, treatments, and vaccines. The importance of designing C. difficile clinical trials with careful consideration to the diagnostic testing method cannot be overemphasized.

Ridinilazole for the treatment of Clostridioides difficile infection

INTRODUCTION

Ridinilazole is a novel antibiotic being developed for the treatment of Clostridioides difficile infection (CDI). Ridinilazole has completed two phase II trials and phase III trials which are denoted Ri-CoDIFy 1 and 2, are planned (ClinicalTrials.gov identifiers: NCT03595553 and NCT03595566). Areas covered: This article covers the chemistry, mechanism of action, in vitro microbiology versus C. difficile and host microbiota, pre-clinical and clinical efficacy, pharmacokinetics, pharmacodynamics and safety and tolerability of ridinilazole. Expert opinion: Ridinilazole is a novel antibiotic with ideal properties for the treatment of CDI. Given the promising results from the phase II clinical trial, ridinilazole may have the capability to lower the risk for CDI recurrence thus improving sustained clinical response rates - a current unmet medical need. Assuming a positive phase III trial, ridinilazole will enter a market with heightened awareness on the importance of prevention of CDI. This along with further research into the economic consequences and decreased patient quality of life associated with recurrent CDI, should provide clinicians with further evidence for the need for therapy that limits CDI recurrence and improves sustained clinical cure.

Building upon Nature's Framework: Overview of Key Strategies Toward Increasing Drug-Like Properties of Natural Product Cyclopeptides and Macrocycles

The pharmaceutical industry has focused mainly in the development of small-molecule entities intended for oral administration for the past decades. As a result, the majority of existing drugs address only a narrow range of biological targets. In the era of post-genomics, transcriptomics, and proteomics, there is an increasing interest on larger modulators of proteins that can span larger surfaces, access new therapeutic mechanisms of action, and provide greater target specificity. Traditional drug-like molecules developed using "rule-of-five" (Ro5) guidelines have been proven ineffective against a variety of challenging targets, such as protein-protein interactions, nucleic acid complexes, and antibacterial modalities. However, natural products are known to be effective at modulating such targets, leading to a renewed focus by medicinal chemists on investigating underrepresented chemical scaffolds associated with natural products. Here we describe recent efforts toward identification of novel natural cyclopeptides and macrocycles as well as selected medicinal chemistry strategies to increase drug-like properties or further exploration of their activity.

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.

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.

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.

Sub-lethal doses of surotomycin and vancomycin have similar effects on Clostridium difficile virulence factor production in vitro

PURPOSE

Clostridium difficile is an anaerobic spore-forming bacterial pathogen that causes a spectrum of illness severity ranging from mild diarrhoea to severe life-threatening pseudomembranous colitis. C. difficile infection (CDI) is antibiotic-associated and primarily mediated by two exotoxins, Toxins A and B. We and others have shown that some antibiotics stimulate Toxin A and B production by C. difficile in a strain-specific manner. Still, the effects of newer anti-C. difficile antibiotics on this process and spore formation remain to be investigated.

METHODOLOGY

Surotomycin (formally CB-183,315) is a novel, minimally absorbed, narrow-spectrum antibiotic. We determined the effects of surotomycin on C. difficile growth, toxin production and sporulation in historical and BI/NAP1/027 epidemic strains of C. difficile.Results/Key findings. While antibiotic free controls showed toxin production during the stationary phase growth, all strains exposed to sub-inhibitory concentrations of surotomycin and vancomycin demonstrated increased TcdA and TcdB production during early (log phase) growth by all strains. However, this effect was not observed at 24 or 48 h post-treatment by any of the C. difficile strains exposed to either antibiotic. Additionally, all doses of surotomycin and vancomycin suppressed spore formation in all tested strains.

CONCLUSION

In summary, these findings demonstrate that surotomycin and vancomycin have similar effects on exotoxin production and sporulation by C. difficile in vitro. Furthermore, since spores contribute to recurrent infection, the ability of surotomycin to suppress spore formation may explain its ability to disrupt the reinfection cycle in the clinical setting.

Management of Primary and Recurrent Clostridium difficile Infection: An Update

Background: Clostridium difficile infection (CDI) is one of the most common healthcare-associated infections (HAI) in the United States and Canada, and incidence rates have increased worldwide in recent decades. Currently, antibiotics are the mainstay treatments for both primary and recurrent CDI, but their efficacy is limited, prompting further therapies to be developed. Aim: This review summarizes current and emerging therapies in CDI management including antibiotics, fecal microbiota transplantation, monoclonal antibodies, spore-based therapies, and vaccinations.

New and emerging therapies in treatment of Clostridium difficile infection

Clostridium difficile infection (CDI) represents one of the most serious nosocomial infections that have grown dramatically over the past decade. Vancomycin and metronidazole are currently used as a standard therapy for CDI. Metronidazole is recommended as a first-line therapy for mild-to-moderate infections and vancomycin is mainly used for severe and/or refractory cases. However, studies have demonstrated that there are quite high CDI relapse rates with both of these medications, which represents a challenge for clinicians. Over the last decade, a number of newer and novel therapeutic options have emerged as promising alternatives to these standard CDI therapies. The following review provides the updated summaries of these newer therapeutic agents and their status in the treatment of CDI.

Novel Antimicrobials for the Treatment of Clostridium difficile Infection

The current picture of Clostridium difficile infection (CDI) is alarming with a mortality rate ranging between 3% and 15% and a CDI recurrence rate ranging from 12% to 40%. Despite the great efforts made over the past 10 years to face the CDI burden, there are still gray areas in our knowledge on CDI management. The traditional anti-CDI antimicrobials are not always adequate in addressing the current needs in CDI management. The aim of our review is to give an update on novel antimicrobials for the treatment of CDI, considering the currently available evidences on their efficacy, safety, molecular mechanism of action, and their probability to be successfully introduced into the clinical practice in the near future. We identified, through a PubMed search, 16 novel antimicrobial molecules under study for CDI treatment: cadazolid, surotomycin, ridinilazole, LFF571, ramoplanin, CRS3123, fusidic acid, nitazoxanide, rifampin, rifaximin, tigecycline, auranofin, NVB302, thuricin CD, lacticin 3147, and acyldepsipeptide antimicrobials. In comparison with the traditional anti-CDI antimicrobial treatment, some of the novel antimicrobials reviewed in this study offer several advantages, i.e., the favorable pharmacokinetic and pharmacodynamic profile, the narrow-spectrum activity against CD that implicates a low impact on the gut microbiota composition, the inhibitory activity on CD sporulation and toxins production. Among these novel antimicrobials, the most active compounds in reducing spore production are cadazolid, ridinilazole, CRS3123, ramoplanin and, potentially, the acyldepsipeptide antimicrobials. These antimicrobials may potentially reduce CD environment spread and persistence, thus reducing CDI healthcare-associated acquisition. However, some of them, i.e., surotomycin, fusidic acid, etc., will not be available due to lack of superiority versus standard of treatment. The most CD narrow-spectrum novel antimicrobials that allow to preserve microbiota integrity are cadazolid, ridinilazole, auranofin, and thuricin CD. In conclusion, the novel antimicrobial molecules under development for CDI have promising key features and advancements in comparison to the traditional anti-CDI antimicrobials. In the near future, some of these new molecules might be effective alternatives to fight CDI.

Clostridioides (Clostridium) difficile infection: current and alternative therapeutic strategies

Clostridioides difficile (C. difficile) has become a pathogen of worldwide importance considering that epidemic strains are disseminated in hospitals of several countries, where community-acquired infections act as a constant source of new C. difficile strains into hospitals. Despite the advances in the treatment of infections, more effective therapies against C. difficile are needed but, at the same time, these therapies should be less harmful to the resident gastrointestinal microbiota. The purpose of this review is to present a description of issues associated to C. difficile infection, a summary of current therapies and those in developmental stage, and a discussion of potential combinations that may lead to an increased efficacy of C. difficile infection treatment.

Advances in the diagnosis and treatment of Clostridium difficile infections

Clostridium difficile is a leading cause of antibiotic-associated diarrhea worldwide. The diagnosis of C. difficile infection (CDI) requires both clinical manifestations and a positive laboratory test for C. difficile and/or its toxins. While antibiotic therapy is the treatment of choice for CDI, there are relatively few classes of effective antibiotics currently available. Therefore, the development of novel antibiotics and/or alternative treatment strategies for CDI has received a great deal of attention in recent years. A number of emerging agents such as cadazolid, surotomycin, ridinilazole, and bezlotoxumab have demonstrated activity against C. difficile; some of these have been approved for limited clinical use and some are in clinical trials. In addition, other approaches such as early and accurate diagnosis of CDI as well as disease prevention are important for clinical management. While the toxigenic culture and the cell cytotoxicity neutralization assay are still recognized as the gold standard for the diagnosis of CDI, new diagnostic approaches such as nucleic acid amplification methods have become available. In this review, we will discuss both current and emerging diagnostic and therapeutic modalities for CDI.

Exploring ways to improve CDI outcomes

Clostridium difficile is an anaerobic spore-forming Gram-positive bacillus recognized as an evolving international health problem. Metronidazole and vancomycin were - until recently - the only drugs available to treat C. difficile infection (CDI). Better knowledge of the pathophysiology and the development of new drugs completely modified the management of initial episodes and recurrences of CDI. Fidaxomicin significantly reduced recurrences compared with vancomycin. New drugs are also currently evaluated (cadazolid, surotomycin, ridinilazole, rifaximin). Gut microbiota homeostasis was clearly shown to be a key determinant in recurrences as demonstrated by the development of gut microbiota transplantation and alternative microbiota substitution. Passive immunotherapy and vaccinal approaches are also currently being evaluated. In conclusion, CDI treatment has evolved with the development of new therapeutic pathways which now need to be implemented in international guidelines.

Existing and investigational therapies for the treatment of Clostridium difficile infection: A focus on narrow spectrum, microbiota-sparing agents

Despite intense international attention and efforts to reduce its incidence, Clostridium difficile infection (CDI) remains a significant concern for patients, clinicians, and healthcare organizations. It is costly for payers and disabling for patients. Furthermore, recurrent CDI is particularly difficult to manage, resulting in excess mortality, hospital length of stay, and other healthcare resource use. A greater understanding of the role of the gut microbiome has emphasized the importance of this diverse community in providing colonization resistance against CDI. The introduction of fidaxomicin, which has limited effect on the microflora has improved clinical outcomes in relation to disease recurrence. There are a number of other new agents in development, which appear to have a narrow spectrum of activity whilst exerting minimal effect on the microflora. Whilst the role of these emerging agents in the treatment of CDI is presently unclear, they appear to be promising candidates.

Antibiotic treatment for Clostridium difficile-associated diarrhoea in adults

BACKGROUND

Clostridium difficile (C. difficile) is recognized as a frequent cause of antibiotic-associated diarrhoea and colitis. This review is an update of a previously published Cochrane review.

OBJECTIVES

The aim of this review is to investigate the efficacy and safety of antibiotic therapy for C. difficile-associated diarrhoea (CDAD), or C. difficile infection (CDI), being synonymous terms.

SEARCH METHODS

We searched MEDLINE, EMBASE, CENTRAL and the Cochrane IBD Group Specialized Trials Register from inception to 26 January 2017. We also searched clinicaltrials.gov and clinicaltrialsregister.eu for ongoing trials.

SELECTION CRITERIA

Only randomised controlled trials assessing antibiotic treatment for CDI were included in the review.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed abstracts and full text articles for inclusion and extracted data. The risk of bias was independently rated by two authors. For dichotomous outcomes, we calculated the risk ratio (RR) and corresponding 95% confidence interval (95% CI). We pooled data using a fixed-effect model, except where significant heterogeneity was detected, at which time a random-effects model was used. The following outcomes were sought: sustained symptomatic cure (defined as initial symptomatic response and no recurrence of CDI), sustained bacteriologic cure, adverse reactions to the intervention, death and cost.

MAIN RESULTS

Twenty-two studies (3215 participants) were included. The majority of studies enrolled patients with mild to moderate CDI who could tolerate oral antibiotics. Sixteen of the included studies excluded patients with severe CDI and few patients with severe CDI were included in the other six studies. Twelve different antibiotics were investigated: vancomycin, metronidazole, fusidic acid, nitazoxanide, teicoplanin, rifampin, rifaximin, bacitracin, cadazolid, LFF517, surotomycin and fidaxomicin. Most of the studies were active comparator studies comparing vancomycin with other antibiotics. One small study compared vancomycin to placebo. There were no other studies that compared antibiotic treatment to a placebo or a 'no treatment' control group. The risk of bias was rated as high for 17 of 22 included studies. Vancomycin was found to be more effective than metronidazole for achieving symptomatic cure. Seventy-two per cent (318/444) of metronidazole patients achieved symptomatic cure compared to 79% (339/428) of vancomycin patients (RR 0.90, 95% CI 0.84 to 0.97; moderate quality evidence). Fidaxomicin was found to be more effective than vancomycin for achieving symptomatic cure. Seventy-one per cent (407/572) of fidaxomicin patients achieved symptomatic cure compared to 61% (361/592) of vancomycin patients (RR 1.17, 95% CI 1.04 to 1.31; moderate quality evidence). Teicoplanin may be more effective than vancomycin for achieving a symptomatic cure. Eightly-seven per cent (48/55) of teicoplanin patients achieved symptomatic cure compared to 73% (40/55) of vancomycin patients (RR 1.21, 95% CI 1.00 to 1.46; very low quality evidence). For other comparisons including the one placebo-controlled study the quality of evidence was low or very low due to imprecision and in many cases high risk of bias because of attrition and lack of blinding. One hundred and forty deaths were reported in the studies, all of which were attributed by study authors to the co-morbidities of the participants that lead to acquiring CDI. Although many other adverse events were reported during therapy, these were attributed to the participants' co-morbidities. The only adverse events directly attributed to study medication were rare nausea and transient elevation of liver enzymes. Recent cost data (July 2016) for a 10 day course of treatment shows that metronidazole 500 mg is the least expensive antibiotic with a cost of USD 13 (Health Warehouse). Vancomycin 125 mg costs USD 1779 (Walgreens for 56 tablets) compared to fidaxomicin 200 mg at USD 3453.83 or more (Optimer Pharmaceuticals) and teicoplanin at approximately USD 83.67 (GBP 71.40, British National Formulary).

AUTHORS' CONCLUSIONS

No firm conclusions can be drawn regarding the efficacy of antibiotic treatment in severe CDI as most studies excluded patients with severe disease. The lack of any 'no treatment' control studies does not allow for any conclusions regarding the need for antibiotic treatment in patients with mild CDI beyond withdrawal of the initiating antibiotic. Nonetheless, moderate quality evidence suggests that vancomycin is superior to metronidazole and fidaxomicin is superior to vancomycin. The differences in effectiveness between these antibiotics were not too large and the advantage of metronidazole is its far lower cost compared to the other two antibiotics. The quality of evidence for teicoplanin is very low. Adequately powered studies are needed to determine if teicoplanin performs as well as the other antibiotics. A trial comparing the two cheapest antibiotics, metronidazole and teicoplanin, would be of interest.

A Review of Experimental and Off-Label Therapies for Clostridium difficile Infection

In spite of increased awareness and the efforts taken to optimize Clostridium difficile infection (CDI) management, with the limited number of currently available antibiotics for C. difficile the halt of this increasing epidemic remains out of reach. There are, however, close to 80 alternative treatment methods with controversial anti-clostridial efficacy or in experimental phase today. Indeed, some of these therapies are expected to become acknowledged members of the recommended anti-CDI arsenal within the next few years. None of these alternative treatment methods can respond in itself to all the major challenges of CDI management, which are primary prophylaxis in the susceptible population, clinical cure of severe cases, prevention of recurrences, and forestallment of asymptomatic C. difficile carriage and in-hospital spread. Yet, the greater the variety of treatment choices on hand, the better combination strategies can be developed to reach these goals in the future. The aim of this article is to provide a comprehensive summary of these experimental and currently off-label therapeutic options.

Primary Outcomes From a Phase 3, Randomized, Double-Blind, Active-Controlled Trial of Surotomycin in Subjects With Clostridium difficile Infection

Background

Although the incidence of Clostridium difficile infection (CDI) is increasing, available CDI treatment options are limited in terms of sustained response after treatment. This phase 3 trial assessed the efficacy and safety of surotomycin, a novel bactericidal cyclic lipopeptide, versus oral vancomycin in subjects with CDI.

Methods

In this randomized, double-blind, active-controlled, multicenter, international trial, subjects with CDI confirmed by a positive toxin result were randomized to receive surotomycin (250 mg twice daily) or vancomycin (125 mg 4 times daily) orally for 10 days. The primary endpoints were clinical response at end of treatment and evaluation of surotomycin safety. The key secondary endpoints were clinical response over time and sustained clinical response through a 30- to 40-day follow-up period. Clostridium difficile infection recurrence during follow-up and time to diarrhea resolution were also analyzed.

Results

In total, 570 subjects were randomized and had confirmed CDI; 290 subjects received surotomycin and 280 subjects received vancomycin. Surotomycin clinical cure rates at end of treatment (surotomycin/vancomycin: 79.0%/83.6%; difference of −4.6%; 95% confidence interval, −11.0 to 1.9]), clinical response over time (stratified log-rank test, P = .832), and sustained clinical response at end of trial (Day 40–50) (60.6%/61.4%; difference of −0.8%; 95% CI, −8.8 to 7.1) in the microbiological modified intent to treat population did not meet noninferiority or superiority criteria versus vancomycin. Both treatments were generally well tolerated.

Conclusions

Surotomycin failed to meet the criteria for noninferiority versus vancomycin for the primary and key secondary endpoints in this trial.

Novel antibiotics in development to treat Clostridium difficile infection

PURPOSE OF REVIEW

Clostridium difficile infections (CDI) remain a challenge to treat clinically due primarily to limited number of antibiotics available and unacceptably high recurrence rates. Because of this, there has been significant demand for creating innovative therapeutics, which has resulted in the development of several novel antibiotics.

RECENT FINDINGS

This review updates seven different antibiotics that are currently in development to treat CDI including fidaxomicin, surotomycin, ridinilazole, ramoplanin, cadazolid, LFF571, and CRS3123. Available preclinical and clinical data are compared between these antibiotics.

SUMMARY

Many of these new antibiotics display almost ideal properties for antibiotics directed against CDI. Despite these properties, not all clinical development of these compounds has been successful. These studies have provided key insights into the pathogenesis of CDI and will continue to inform future drug development. Successful phase III clinical trials should result in several new and novel antibiotics to treat CDI.

Clostridium difficile infection: Updates in management

Clostridium difficile was first identified in 1978 as a diarrhea-causing bacterium in humans. In the last three decades, C. difficile infection (CDI) has reached an epidemic state, both in health care and community settings worldwide. There has been substantial progress in the field of CDI, including identification of novel risk factors, presence of CDI in individuals not considered at risk previously, and treatment options including new drugs, monoclonal antibodies, and fecal microbiota transplantation. This review discusses epidemiology, novel and traditional risk factors, and updates in management for CDI.