Can we identify patients at high risk of recurrent Clostridium difficile infection?

Fidaxomicin for treatment of Clostridium difficile infection in clinical practice: a prospective cohort study in a French University Hospital

PURPOSE

Two randomized controlled trials (RCTs) showed the non-inferiority of fidaxomicin compared with vancomycin for Clostridium difficile infection (CDI) treatment and its superiority regarding recurrence rate. The aim of this study was to evaluate fidaxomicin's efficacy in clinical practice.

METHODS

This single-center prospective cohort study included hospitalized patients treated with fidaxomicin for CDI. Demographic, clinical and biological data were collected. Primary outcome was efficacy of fidaxomicin (clinical cure, recurrence and global cure) at 10 weeks. Secondary outcome was efficacy among different subgroups.

RESULTS

Ninety-nine patients were included: 42 severe CDI, 16 complicated CDI and 41 recurrent CDI. Rates of clinical cure, recurrence and global cure were 87, 15 and 59%, respectively. Subgroup analysis showed a higher recurrence rate for patients with recurrent CDI compared with first episode (8 vs. 26%; p = 0.04). Binary toxin was associated with severe/complicated CDI (80 vs. 50%; p < 0.01) and recurrence (32 vs. 7%; p < 0.01). Fidaxomicin was used as a first line for 83% of the patients with recurrence and for only 52% of first episodes even though 86% had recurrence's risk factors.

CONCLUSION

Compared with RCTs, fidaxomicin in real world is used for patients with more severe and recurrent CDI, but clinical cure and recurrence rates were similar. Comparative studies are needed in these specific subgroups. Our data also illustrate clinicians' difficulty to define a "patient at risk for recurrence" among the first episodes. Finally, we showed that binary toxin could be important in the screening for severity and recurrence risks.

Cost-Effectiveness Analysis of Five Competing Strategies for the Management of Multiple Recurrent Community-Onset Clostridium difficile Infection in France

Background

Clostridium difficile infection (CDI) is characterized by high rates of recurrence, resulting in substantial health care costs. The aim of this study was to analyze the cost-effectiveness of treatments for the management of second recurrence of community-onset CDI in France.

Methods

We developed a decision-analytic simulation model to compare 5 treatments for the management of second recurrence of community-onset CDI: pulsed-tapered vancomycin, fidaxomicin, fecal microbiota transplantation (FMT) via colonoscopy, FMT via duodenal infusion, and FMT via enema. The model outcome was the incremental cost-effectiveness ratio (ICER), expressed as cost per quality-adjusted life year (QALY) among the 5 treatments. ICERs were interpreted using a willingness-to-pay threshold of €32,000/QALY. Uncertainty was evaluated through deterministic and probabilistic sensitivity analyses.

Results

Three strategies were on the efficiency frontier: pulsed-tapered vancomycin, FMT via enema, and FMT via colonoscopy, in order of increasing effectiveness. FMT via duodenal infusion and fidaxomicin were dominated (i.e. less effective and costlier) by FMT via colonoscopy and FMT via enema. FMT via enema compared with pulsed-tapered vancomycin had an ICER of €18,092/QALY. The ICER for FMT via colonoscopy versus FMT via enema was €73,653/QALY. Probabilistic sensitivity analysis with 10,000 Monte Carlo simulations showed that FMT via enema was the most cost-effective strategy in 58% of simulations and FMT via colonoscopy was favored in 19% at a willingness-to-pay threshold of €32,000/QALY.

Conclusions

FMT via enema is the most cost-effective initial strategy for the management of second recurrence of community-onset CDI at a willingness-to-pay threshold of €32,000/QALY.

Australasian Society of Infectious Diseases updated guidelines for the management of Clostridium difficile infection in adults and children in Australia and New Zealand

The incidence of Clostridium difficile infection (CDI) continues to rise, whilst treatment remains problematic due to recurrent, refractory and potentially severe nature of disease. The treatment of C. difficile is a challenge for community and hospital-based clinicians. With the advent of an expanding therapeutic arsenal against C. difficile since the last published Australasian guidelines, an update on CDI treatment recommendations for Australasian clinicians was required. On behalf of the Australasian Society of Infectious Diseases, we present the updated guidelines for the management of CDI in adults and children.

Disease Progression and Resolution in Rodent Models of Clostridium difficile Infection and Impact of Antitoxin Antibodies and Vancomycin

Clostridium difficile causes infections of the colon in susceptible patients. Specifically, gut dysbiosis induced by treatment with broad-spectrum antibiotics facilitates germination of ingested C. difficile spores, expansion of vegetative cells, and production of symptom-causing toxins TcdA and TcdB. The current standard of care for C. difficile infections (CDI) consists of administration of antibiotics such as vancomycin that target the bacterium but also perpetuate gut dysbiosis, often leading to disease recurrence. The monoclonal antitoxin antibodies actoxumab (anti-TcdA) and bezlotoxumab (anti-TcdB) are currently in development for the prevention of recurrent CDI. In this study, the effects of vancomycin or actoxumab/bezlotoxumab treatment on progression and resolution of CDI were assessed in mice and hamsters. Rodent models of CDI are characterized by an early severe phase of symptomatic disease, associated with high rates of morbidity and mortality; high intestinal C. difficile burden; and a disrupted intestinal microbiota. This is followed in surviving animals by gradual recovery of the gut microbiota, associated with clearance of C. difficile and resolution of disease symptoms over time. Treatment with vancomycin prevents disease initially by inhibiting outgrowth of C. difficile but also delays microbiota recovery, leading to disease relapse following discontinuation of therapy. In contrast, actoxumab/bezlotoxumab treatment does not impact the C. difficile burden but rather prevents the appearance of toxin-dependent symptoms during the early severe phase of disease, effectively preventing disease until the microbiota (the body's natural defense against C. difficile) has fully recovered. These data provide insight into the mechanism of recurrence following vancomycin administration and into the mechanism of recurrence prevention observed clinically with actoxumab/bezlotoxumab.

Utilization of Health Services Among Adults With Recurrent Clostridium difficile Infection: A 12-Year Population-Based Study

BACKGROUND Considerable efforts have been dedicated to developing strategies to prevent and treat recurrent Clostridium difficile infection (rCDI); however, evidence of the impact of rCDI on patient healthcare utilization and outcomes is limited. OBJECTIVE To compare healthcare utilization and 1-year mortality among adults who had rCDI, nonrecurrent CDI, or no CDI. METHODS We performed a nested case-control study among adult Kaiser Foundation Health Plan members from September 1, 2001, through December 31, 2013. We identified CDI through the presence of a positive laboratory test result and divided patients into 3 groups: patients with rCDI, defined as CDI in the 14-57 days after initial CDI; patients with nonrecurrent CDI; and patients who never had CDI. We conducted 3 matched comparisons: (1) rCDI vs no CDI; (2) rCDI vs nonrecurrent CDI; (3) nonrecurrent CDI vs no CDI. We followed patients for 1 year and compared healthcare utilization between groups, after matching patients on age, sex, and comorbidity. RESULTS We found that patients with rCDI consistently have substantially higher levels of healthcare utilization in various settings and greater 1-year mortality risk than both patients who had nonrecurrent CDI and patients who never had CDI. CONCLUSIONS Patients who develop an initial CDI are generally characterized by excess underlying, severe illness and utilization. However, patients with rCDI experience even greater adverse consequences of their disease than patients who do not experience rCDI. Our results further support the need for continued emphasis on identifying and using novel approaches to prevent and treat rCDI. Infect Control Hosp Epidemiol. 2016;1-8.

Determining the cause of recurrent Clostridium difficile infection using whole genome sequencing

Understanding the contribution of relapse and reinfection to recurrent Clostridium difficile infection (CDI) has implications for therapy and infection prevention, respectively. We used whole genome sequencing to determine the relation of C. difficile strains isolated from patients with recurrent CDI at an academic medical center in the United States. Thirty-five toxigenic C. difficile isolates from 16 patients with 19 recurrent CDI episodes with median time of 53.5days (range, 13-362) between episodes were whole genome sequenced on the Illumina MiSeq platform. In 84% (16) of recurrences, the cause of recurrence was relapse with prior strain of C. difficile. In 16% (3) of recurrent episodes, reinfection with a new strain of C. difficile was the cause. In conclusion, the majority of CDI recurrences at our institution were due to infection with the same strain rather than infection with a new strain.

Longitudinal survey of Clostridium difficile presence and gut microbiota composition in a Belgian nursing home

BACKGROUND

Increasing age, several co-morbidities, environmental contamination, antibiotic exposure and other intestinal perturbations appear to be the greatest risk factors for C. difficile infection (CDI). Therefore, elderly care home residents are considered particularly vulnerable to the infection. The main objective of this study was to evaluate and follow the prevalence of C. difficile in 23 elderly care home residents weekly during a 4-month period. A C. difficile microbiological detection scheme was performed along with an overall microbial biodiversity study of the faeces content by 16S rRNA gene analysis.

RESULTS

Seven out of 23 (30.4 %) residents were (at least one week) positive for C. difficile. C. difficile was detected in 14 out of 30 diarrhoeal samples (43.7 %). The most common PCR-ribotype identified was 027. MLVA showed that there was a clonal dissemination of C. difficile strains within the nursing home residents. 16S-profiling analyses revealed that each resident has his own bacterial imprint, which was stable during the entire study. Significant changes were observed in C. difficile positive individuals in the relative abundance of a few bacterial populations, including Lachnospiraceae and Verrucomicrobiaceae. A decrease of Akkermansia in positive subjects to the bacterium was repeatedly found.

CONCLUSIONS

A high C. difficile colonisation in nursing home residents was found, with a predominance of the hypervirulent PCR-ribotype 027. Positive C. difficile status is not associated with microbiota richness or biodiversity reduction in this study. The link between Akkermansia, gut inflammation and C. difficile colonisation merits further investigations.

A cost-effectiveness and budget impact analysis of first-line fidaxomicin for patients with Clostridium difficile infection (CDI) in Germany

PURPOSE

Clostridium difficile infection (CDI) represents a significant economic healthcare burden, especially the cost of recurrent disease. Fidaxomicin produced significantly lower recurrence rates and higher sustained cure rates in clinical trials. We evaluated the cost-effectiveness and budget impact of fidaxomicin compared with vancomycin in Germany in the first-line treatment of patient subgroups with CDI at increased risk of recurrence.

METHODS

A semi-Markov model was used to compare the cost-effectiveness and budget impact of fidaxomicin vs. vancomycin from a payer perspective in Germany. The model cycle length was 10 days. The time horizon was 1 year. Model inputs were probability of clinical cure, 30-day probability of recurrence, and 30-day attributable mortality based on evidence from two randomized controlled trials comparing fidaxomicin and vancomycin in patients with CDI. Cost-effectiveness outcomes were cost per quality-adjusted life year gained, cost per bed-day saved, and cost per recurrence avoided.

RESULTS

Despite higher drug acquisition costs, fidaxomicin was dominant in the cancer subgroup (less costly and more effective) and cost-effective in the other subgroups, with incremental cost-effectiveness ratios vs. vancomycin ranging from €26,900 to €44,500. Hospitalization costs of the first-line treatment of CDI with fidaxomicin vs. vancomycin were lower in every patient subgroup, resulting in budget impacts ranging from -€1325 (in patients ≥65 years) to -€2438 (in cancer patients). Reductions in the cost of treating recurrence with fidaxomicin ranged from -€574.32 per patient in those receiving concomitant antibiotics to -€1500.68 per patient in renally impaired patients.

CONCLUSIONS

In patient subgroups with CDI at increased recurrence risk, fidaxomicin was cost-effective vs. vancomycin, and less costly and more effective in patients with cancer.

Role of cephalosporins in the era of Clostridium difficile infection

The incidence of Clostridium difficile infection (CDI) in Europe has increased markedly since 2000. Previous meta-analyses have suggested a strong association between cephalosporin use and CDI, and many national programmes on CDI control have focused on reducing cephalosporin usage. Despite reductions in cephalosporin use, however, rates of CDI have continued to rise. This review examines the potential association of CDI with cephalosporins, and considers other factors that influence CDI risk. EUCLID (the EUropean, multicentre, prospective biannual point prevalence study of CLostridium difficile Infection in hospitalized patients with Diarrhoea) reported an increase in the annual incidence of CDI from 6.6 to 7.3 cases per 10 000 patient bed-days from 2011-12 to 2012-13, respectively. While CDI incidence and cephalosporin usage varied widely across countries studied, there was no clear association between overall cephalosporin prescribing (or the use of any particular cephalosporin) and CDI incidence. Moreover, variations in the pharmacokinetic and pharmacodynamic properties of cephalosporins of the same generation make categorization by generation insufficient for predicting impact on gut microbiota. A multitude of additional factors can affect the risk of CDI. Antibiotic choice is an important consideration; however, CDI risk is associated with a range of antibiotic classes. Prescription of multiple antibiotics and a long duration of treatment are key risk factors for CDI, and risk also differs across patient populations. We propose that all of these are factors that should be taken into account when selecting an antibiotic, rather than focusing on the exclusion of individual drug classes.

Development and Validation of a Clostridium difficile Health-related Quality-of-Life Questionnaire

GOALS AND BACKGROUND

Patients with Clostridium difficile infection (CDI) can experience long-term symptoms and poor quality of life due to the disease. Despite this, a health-related quality of life (HRQOL) instrument specific for patients with CDI does not exist. The aim of this study was to develop and validate a disease-specific instrument to assess HRQOL in patients with CDI.

STUDY

A systematic literature review was conducted to identify HRQOL instruments and questions related to general health (n=3) or gastrointestinal disease (n=12) potentially related to CDI HRQOL. Removing duplicate questions and using direct patient or clinician interviews, a 36-item survey was developed. The survey was then tested using 98 patients with CDI and compared with the RAND Short-Form 36 (SF-36) Health Survey. Psychometric analysis techniques were used to identify domains and remove redundant items.

RESULTS

Exploratory factor analysis identified 3 major domains (physical, mental, and social) with 4 associated subdomains. Survey overall and domain scores displayed good internal consistency (Cronbach α coefficient >0.87) and concurrent validity evidenced by significant correlation with SF-36 scores. The C. difficile survey scores were better able than the SF-36 to discriminate quality-of-life score differences in patients with primary versus recurrent CDI and increasing time since last episode of CDI. The final version contained 32 items related to the physical, mental, and social health of CDI patients.

CONCLUSION

The properties of the newly developed Cdiff32 should make it appropriate to assess changes over time in HRQOL in patients with CDI.

Association of Fidaxomicin with C. difficile Spores: Effects of Persistence on Subsequent Spore Recovery, Outgrowth and Toxin Production

BACKGROUND

We have previously shown that fidaxomicin instillation prevents spore recovery in an in-vitro gut model, whereas vancomycin does not. The reasons for this are unclear. Here, we have investigated persistence of fidaxomicin and vancomycin on C. difficile spores, and examined post-antibiotic exposure spore recovery, outgrowth and toxin production.

METHODS

Prevalent UK C. difficile ribotypes (n = 10) were incubated with 200mg/L fidaxomicin, vancomycin or a non-antimicrobial containing control for 1 h in faecal filtrate or Phosphate Buffered Saline. Spores were washed three times with faecal filtrate or phosphate buffered saline, and residual spore-associated antimicrobial activity was determined by bioassay. For three ribotypes (027, 078, 015), antimicrobial-exposed, faecal filtrate-washed spores and controls were inoculated into broth. Viable vegetative and spore counts were enumerated on CCEYL agar. Percentage phase bright spores, phase dark spores and vegetative cells were enumerated by phase contrast microscopy at 0, 3, 6, 24 and 48 h post-inoculation. Toxin levels (24 and 48h) were determined by cell cytotoxicity assay.

RESULTS

Fidaxomicin, but not vancomycin persisted on spores of all ribotypes following washing in saline (mean = 10.1mg/L; range = 4.0-14mg/L) and faecal filtrate (mean = 17.4mg/L; 8.4-22.1mg/L). Outgrowth and proliferation rates of vancomycin-exposed spores were similar to controls, whereas fidaxomicin-exposed spores showed no vegetative cell growth after 24 and 48 h. At 48h, toxin levels averaged 3.7 and 3.3 relative units (RU) in control and vancomycin-exposed samples, respectively, but were undetectable in fidaxomicin-exposed samples.

CONCLUSION

Fidaxomicin persists on C. difficile spores, whereas vancomycin does not. This persistence prevents subsequent growth and toxin production in vitro. This may have implications on spore viability, thereby impacting CDI recurrence and transmission rates.

Ridinilazole: a novel therapy for Clostridium difficile infection

Clostridium difficile infection (CDI) is the leading cause of infectious healthcare-associated diarrhoea. Recurrent CDI increases disease morbidity and mortality, posing a high burden to patients and a growing economic burden to the healthcare system. Thus, there exists a significant unmet and increasing medical need for new therapies for CDI. This review aims to provide a concise summary of CDI in general and a specific update on ridinilazole (formerly SMT19969), a novel antibacterial currently under development for the treatment of CDI. Owing to its highly targeted spectrum of activity and ability to spare the normal gut microbiota, ridinilazole provides significant advantages over metronidazole and vancomycin, the mainstay antibiotics for CDI. Ridinilazole is bactericidal against C. difficile and exhibits a prolonged post-antibiotic effect. Furthermore, treatment with ridinilazole results in decreased toxin production. A phase 1 trial demonstrated that oral ridinilazole is well tolerated and specifically targets clostridia whilst sparing other faecal bacteria. Phase 2 and 3 trials will hopefully further our understanding of the clinical utility of ridinilazole for the treatment of CDI.

Clearance of Vancomycin-Resistant Enterococcus Concomitant With Administration of a Microbiota-Based Drug Targeted at Recurrent Clostridium difficile Infection

Background. Vancomycin-resistant Enterococcus (VRE) is a major healthcare-associated pathogen and a well known complication among transplant and immunocompromised patients. We report on stool VRE clearance in a post hoc analysis of the Phase 2 PUNCH CD study assessing a microbiota-based drug for recurrent Clostridium difficile infection (CDI).

Methods. A total of 34 patients enrolled in the PUNCH CD study received 1 or 2 doses of RBX2660 (microbiota suspension). Patients were requested to voluntarily submit stool samples at baseline and at 7, 30, and 60 days and 6 months after the last administration of RBX2660. Stool samples were tested for VRE using bile esculin azide agar with 6 µg/mL vancomycin and Gram staining. Vancomycin resistance was confirmed by Etest.

Results. VRE status (at least 1 test result) was available for 30 patients. All stool samples for 19 patients (63.3%, mean age 61.7 years, 68% female) tested VRE negative. Eleven patients (36.7%, mean age 75.5 years, 64% female) were VRE positive at the first test (baseline or 7-day follow-up). Of these patients, 72.7%, n = 8 converted to negative as of the last available follow-up (30 or 60 days or 6 months). Of the other 3: 1 died (follow-up data not available); 1 patient remained positive at all follow-ups; 1 patient retested positive at 6 months with negative tests during the interim.

Conclusions. Although based on a small sample size, this secondary analysis demonstrated the possibility of successfully converting a high percentage of VRE-positive patients to negative in a recurrent CDI population with RBX2660.

Structural and functional changes within the gut microbiota and susceptibility to Clostridium difficile infection

Alteration of the gut microbial community structure and function through antibiotic use increases susceptibility to colonization by Clostridium difficile and other enteric pathogens. However, the mechanisms that mediate colonization resistance remain elusive. As the leading definable cause of infectious diarrhea, toxigenic C. difficile represents a burden for patients and health care systems, underscoring the need for better diagnostics and treatment strategies. Next-generation sequence data has increased our understanding of how the gut microbiota is influenced by many factors including diet, disease, aging and drugs. However, a microbial-based biomarker differentiating C. difficile infection from antibiotic-associated diarrhea has not been identified. Metabolomics profiling, which is highly responsive to changes in physiological conditions, have shown promise in differentiating subtle disease phenotypes that exhibit a nearly identical microbiome community structure, suggesting metabolite-based biomarkers may be an ideal diagnostic for identifying patients with CDI. This review focuses on the current understanding of structural and functional changes to the gut microbiota during C. difficile infection obtained from studies assessing the microbiome and metabolome of samples from patients and murine models.

Impact on toxin production and cell morphology in Clostridium difficile by ridinilazole (SMT19969), a novel treatment for C. difficile infection

OBJECTIVES

Ridinilazole (SMT19969) is a narrow-spectrum, non-absorbable antimicrobial with activity against Clostridium difficile undergoing clinical trials. The purpose of this study was to assess the pharmacological activity of ridinilazole and assess the effects on cell morphology.

METHODS

Antibiotic killing curves were performed using the epidemic C. difficile ribotype 027 strain, R20291, using supra-MIC (4× and 40×) and sub-MIC (0.125×, 0.25× and 0.5×) concentrations of ridinilazole. Following exposure, C. difficile cells were collected for cfu counts, toxin A and B production, and morphological changes using scanning electron and fluorescence microscopy. Human intestinal cells (Caco-2) were co-incubated with ridinilazole-treated C. difficile growth medium to determine the effects on host inflammatory response (IL-8).

RESULTS

Treatment at supra-MIC concentrations (4× and 40× MIC) of ridinilazole resulted in a significant reduction in vegetative cells over 72 h (4 log difference, P < 0.01) compared with controls without inducing spore formation. These results correlated with a 75% decrease in toxin A production (P < 0.05) and a 96% decrease in toxin B production (P < 0.05). At sub-MIC levels (0.5× MIC), toxin A production was reduced by 91% (P < 0.01) and toxin B production was reduced by 100% (P < 0.001), which resulted in a 74% reduction in IL-8 release compared with controls (P < 0.05). Sub-MIC (0.5×)-treated cells formed filamentous structures ∼10-fold longer than control cells. Following fluorescence labelling, the cell septum was not forming in sub-MIC-treated cells, yet the DNA was dividing.

CONCLUSIONS

Ridinilazole had robust killing effects on C. difficile that significantly reduced toxin production and attenuated the inflammatory response. Ridinilazole also elicited significant cell division effects suggesting a potential mechanism of action.

Economic burden of primary compared with recurrent Clostridium difficile infection in hospitalized patients: a prospective cohort study

BACKGROUND

Few studies have investigated the additional healthcare costs of recurrent C. difficile infection (CDI).

AIM

To quantify inpatient treatment costs for CDI and length of stay among hospitalized patients with primary CDI only, compared with CDI patients who experienced recurrent CDI.

METHODS

This was a prospective, observational cohort study of hospitalized adult patients with primary CDI followed for three months to assess for recurrent CDI episodes. Total and CDI-attributable hospital length of stay (LOS) and hospitalization costs were compared among patients who did or did not experience at least one recurrent CDI episode.

FINDINGS

In all, 540 hospitalized patients aged 62±17 years (42% males) with primary CDI were enrolled, of whom 95 patients (18%) experienced 101 recurrent CDI episodes. CDI-attributable median (interquartile range) LOS and costs (in US$) increased from 7 (4-13) days and $13,168 (7,525-24,456) for patients with primary CDI only versus 15 (8-25) days and $28,218 (15,050-47,030) for patients with recurrent CDI (P<0.0001, each). Total hospital median LOS and costs increased from 11 (6-22) days and $20,693 (11,287-41,386) for patients with primary CDI only versus 24 (11-48) days and $45,148 (20,693-82,772) for patients with recurrent CDI (P<0.0001, each). The median cost of pharmacological treatment while hospitalized was $60 (23-200) for patients with primary CDI only (N=445) and $140 (30-260) for patients with recurrent CDI (P=0.0013).

CONCLUSION

This study demonstrated that patients with CDI experience a significant healthcare economic burden attributed to CDI. Economic costs and healthcare burden increased significantly for patients with recurrent CDI.

Clostridium difficile infection

Infection of the colon with the Gram-positive bacterium Clostridium difficile is potentially life threatening, especially in elderly people and in patients who have dysbiosis of the gut microbiota following antimicrobial drug exposure. C. difficile is the leading cause of health-care-associated infective diarrhoea. The life cycle of C. difficile is influenced by antimicrobial agents, the host immune system, and the host microbiota and its associated metabolites. The primary mediators of inflammation in C. difficile infection (CDI) are large clostridial toxins, toxin A (TcdA) and toxin B (TcdB), and, in some bacterial strains, the binary toxin CDT. The toxins trigger a complex cascade of host cellular responses to cause diarrhoea, inflammation and tissue necrosis - the major symptoms of CDI. The factors responsible for the epidemic of some C. difficile strains are poorly understood. Recurrent infections are common and can be debilitating. Toxin detection for diagnosis is important for accurate epidemiological study, and for optimal management and prevention strategies. Infections are commonly treated with specific antimicrobial agents, but faecal microbiota transplants have shown promise for recurrent infections. Future biotherapies for C. difficile infections are likely to involve defined combinations of key gut microbiota.

Principles of DNA-Based Gut Microbiota Assessment and Therapeutic Efficacy of Fecal Microbiota Transplantation in Gastrointestinal Diseases

Fecal microbiota transplantation (FMT), a process by which the normal gastrointestinal microbiota is restored, has demonstrated extraordinary cure rates for Clostridium difficile infection and low recurrence. The community of microorganisms within the human gut (or microbiota) is critical to health status and functions; therefore, together with the rise of FMT, the gastrointestinal microbiota has emerged as a 'virtual' organ with a level of complexity comparable to that of any other organ system and capable to compete with powerful known antibiotics for the treatment of several disorders. Although treatment protocols, donor selection, stool preparation and delivery methods varied widely, with a few reports following an identical protocol, FMT has diffused to other areas where the alterations of the gut microbiota ecology (or dysbiosis) have been theorized to play a causative role, including inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), among several other extra-intestinal disorders (i.e. metabolic syndrome and obesity, multiple sclerosis, cardiovascular diseases). FMT can be relatively simple to perform, but a number of challenges need to be overcome before this procedure is widely accepted in clinical practice, and currently, there is no consensus between the various gastrointestinal organizations and societies regarding the FMT procedure. In this article, we describe the modern high-throughput sequencing techniques to characterize the composition of gut microbiota and the potential for therapeutics by manipulating microbiota with FMT in several gastrointestinal disorders (C. difficile-associated diarrhea, IBD and IBS), with a look on the potential future directions of FMT.

Fecal Microbial Transplants Reduce Antibiotic-resistant Genes in Patients With Recurrent Clostridium difficile Infection

Patients with recurrent C. difficile infection harbor large numbers of microbes with antibiotic resistance genes. Fecal microbial transplantation eradicates pathogenic organisms and eliminates antibiotic-resistance genes suggesting this may be a viable treatment option to eradicate multidrug resistant bacteria from patients.

Background. Recurrent Clostridium difficile infection (RCDI) is associated with repeated antibiotic treatment and the enhanced growth of antibiotic-resistant microbes. This study tested the hypothesis that patients with RCDI would harbor large numbers of antibiotic-resistant microbes and that fecal microbiota transplantation (FMT) would reduce the number of antibiotic-resistant genes.

Methods. In a single center study, patients with RCDI (n = 20) received FMT from universal donors via colonoscopy. Stool samples were collected from donors (n = 3) and patients prior to and following FMT. DNA was extracted and shotgun metagenomics performed. Results as well as assembled libraries from a healthy cohort (n = 87) obtained from the Human Microbiome Project were aligned against the NCBI bacterial taxonomy database and the Comprehensive Antibiotic Resistance Database. Results were corroborated through a DNA microarray containing 354 antibiotic resistance (ABR) genes.

Results. RCDI patients had a greater number and diversity of ABR genes compared with donors and healthy controls. Beta-lactam, multidrug efflux pumps, fluoroquinolone, and antibiotic inactivation ABR genes were increased in RCDI patients, although donors primarily had tetracycline resistance. RCDI patients were dominated by Proteobacteria with Escherichia coli and Klebsiella most prevalent. FMT resulted in a resolution of symptoms that correlated directly with a decreased number and diversity of ABR genes and increased Bacteroidetes and Firmicutes with reduced Proteobacteria. ABR gene profiles were maintained in recipients for up to a year following FMT.

Conclusions. RCDI patients have increased numbers of antibiotic-resistant organisms. FMT is effective in the eradication of pathogenic antibiotic-resistant organisms and elimination of ABR genes.

Clostridium difficile infection: A brief update on emerging therapies

PURPOSE

Established and investigational antibiotic, monoclonal antibody, vaccine, and microbe-based approaches to the prevention and treatment of Clostridium difficile infection (CDI) are reviewed.

SUMMARY

CDI is increasingly prevalent in the United States and other countries, particularly among hospitalized patients and the elderly, who are at high risk for potentially fatal CDI-related enterotoxic diarrhea. Established therapies for CDI such as vancomycin and metronidazole (an off-label use) are limited by poor efficacy and high recurrence rates. An investigational antibiotic with potent in vitro activity against all C. difficile strains (including the hypervirulent BI/NAP1/027 strain) has yielded encouraging results in early clinical trials. Another promising approach involves the use of monoclonal antibodies with selective activity against toxins responsible for CDI-associated diarrhea; in a small Phase II clinical trial, a single monoclonal antibody infusion in combination with vancomycin or metronidazole therapy was more effective than antibiotic therapy alone in preventing CDI relapse. Other emerging approaches to CDI treatment and prophylaxis include the use of vaccines against C. difficile toxins (several C. difficile-targeted vaccines are under development in Europe and the United States); microbe-based strategies such as fecal microbiota transplants, "microbial ecosystem therapeutics," and probiotic supplements; and an investigational encapsulated form of β-lactamase designed to prevent C. difficile colonization from progressing to CDI.

CONCLUSION

The current antibiotic therapies for CDI, mainly vancomycin and (off-label) metronidazole and the newer agent fidaxomicin, have limitations with respect to efficacy, recurrence rates, and adverse effects, but a variety of promising approaches are emerging.

Stability and recovery of DIFICID(®) (Fidaxomicin) 200-mg crushed tablet preparations from three delivery vehicles, and administration of an aqueous dispersion via nasogastric tube

Fidaxomicin is approved for the treatment of adults with Clostridium difficile–associated diarrhea, many of whom have difficulty swallowing an intact tablet. The study objective was to evaluate the stability and recovery of crushed DIFICID^® (fidaxomicin) 200-mg tablets dispersed in water, applesauce, or Ensure^® brand liquid nutritional supplement, and to determine the recovery of fidaxomicin from the administration of an aqueous dispersion of a crushed DIFICID^® tablet through a nasogastric (NG) tube. DIFICID^® tablets were crushed and dispersed in water, applesauce, or Ensure^®. The stability and recovery of fidaxomicin were evaluated over 24 h in these vehicles. In a separate experiment, the ability to recover a full dose of fidaxomicin when administering as an aqueous dispersion through an NG tube was assessed. When DIFICID^® tablets were crushed and dispersed in water, the active ingredient, fidaxomicin, was stable for up to 2 h at room temperature. Additionally, it was stable for up to 24 h in dispersions with applesauce or Ensure^®. Recovery of fidaxomicin after crushing and dispersing in any of the three vehicles studied ranged from 95 to 108 %, which is within the normal range of individual tablet variability. When crushed, dispersed in water, and administered through an NG tube, the average recovery of fidaxomicin was 96 %. Stability and recovery of fidaxomicin were confirmed when DIFICID^® tablets were crushed and dispersed in water, applesauce, or Ensure^®. In addition, administration of an aqueous dispersion of a crushed tablet through an NG tube is supported by acceptable recovery of fidaxomicin.

Fecal microbiota transplantation for Clostridium difficile infection: back to the future

INTRODUCTION

Clostridium difficile infection (CDI) is a leading cause of diarrhea in the industrialized world. The estimated costs of this infection are impressive: over 3.2 billion dollars annually in the US. The introduction of fecal microbiota transplantation (FMT) to clinical practice can be considered a Copernican Revolution. The rationale of this approach consists of correcting the imbalance of the organisms dwelling in the gut by reintroducing a normal flora.

AREAS COVERED

This review focuses on the indication for FMT in CDI; it examines in-depth the most relevant aspects of the techniques used, and the safety and efficacy of this new 'old' therapy.

EXPERT OPINION

Authoritative guidelines about the management of CDI strongly recommend FMT for multiple recurrent episodes of infection by C. difficile unresponsive to repeated antibiotic treatment. The cure rates are about 90%, with no serious adverse events having been reported. The main concerns are the long-term outcomes, lack of a standardized procedure for the delivery of donor material, and a cultural barrier to the transplantation of fecal microbiota. A promising solution to some of these problems could be the use of a more acceptable administration route of fecal material, namely, oral capsules.

Successful Fecal Microbiota Transplantation as an Initial Therapy for Clostridium difficile Infection on an Outpatient Basis

A 64-year-old woman developed diarrhea after taking clindamycin for a dental infection. We diagnosed her with Clostridium difficile infection (CDI) and performed fecal microbiota transplantation (FMT) as the initial therapy using colonoscopy on an outpatient basis. The frequency of her bowel movements decreased from 10 times per day to two times per day three days after the procedure. The key component of FMT is to restructure the protective microbiome of the natural intestinal flora. We consider that FMT could be used as an effective first-line therapy for CDI if the efficacy and safety of this procedure is established in the future.

Novel approaches to treating Clostridium difficile-associated colitis

Clostridium difficile is being recognized as a growing threat to many health-care systems. Epidemiology data shows that infection rates are soaring and the disease burden is increasing. Despite the efficacy of standard treatments, it is becoming evident that novel therapeutics will be required to tackle this disease. These new treatments aim to enhance the intestinal microbial barrier, activate the immune system and neutralize the toxins that mediate this disease. Many of these therapies are still in the beginning stages of investigation, however, in the next few years, more clinical data will become available to help implement many of these exciting new therapeutic approaches.

Molecular characteristics of Clostridium difficile strains from patients with a first recurrence more than 8 weeks after the primary infection

BACKGROUND/PURPOSE

Nearly all published studies of recurrent Clostridium difficile infections (CDI) report recurrent CDI within 8 weeks after the primary infection. This study explored the molecular characteristics of C. difficile isolates from the first recurrent CDI more than 8 weeks after the primary infection.

METHODS

Consecutive hospitalized patients with a recurrent CDI more than 8 weeks after a primary infection were enrolled prospectively from January 2008 to February 2011. All C. difficile isolates of the primary and recurrent infections were collected and subjected to polymerase chain reaction ribotyping and antimicrobial susceptibility testing.

RESULTS

There were 62 cases of CDI in this study, which included 32 cases (51.6%) of recurrence due to the same ribotype of C. difficile, 26 (41.9%) cases due to a different ribotype, and four (6.5%) cases with 2-4 recurrences due to the same or different strains. One hundred and forty C. difficile isolates were obtained, which included 62 primary CDI isolates and 78 recurrent isolates. Ribotype 020 was the most common C. difficile strain in primary and recurrent infections. Ribotype 001 accounted for 15.4% (10/78) of recurrent infections and 3.2% (2/62) of primary infections (p = 0.0447). The minimum inhibitory concentration at 90% (MIC₉₀) values of linezolid, moxifloxacin, and clindamycin against type 001 strains were much higher, compared to the three other common ribotypes.

CONCLUSION

Recurrent CDI more than 8 weeks after a primary infection can be caused by the same or different C. difficile ribotype at similar percentages. Ribotype 001 C. difficile strains, which have a lower susceptibility to antimicrobials, were isolated more frequently in patients with a recurrent CDI.

Clinical and Healthcare Burden of Multiple Recurrences of Clostridium difficile Infection

BACKGROUND

Clostridium difficile infection (CDI) is associated with a high risk of recurrence (rCDI). Few studies have focused on multiple recurrences. To evaluate the potential of novel treatments targeting recurrence, we assessed the burden and severity of rCDI.

METHODS

This was a retrospective cohort of adults diagnosed with CDI in a hospital in Sherbrooke, Canada (1998-2013). An rCDI episode was defined by the reappearance of diarrhea leading to a treatment, with or without a positive toxin assay, within 14-60 days after the previous episode.

RESULTS

We included 1527 patients. The probability of developing a first rCDI was 25% (354/1418); a second, 38% (128/334); a third, 29% (35/121); and a fourth or more, 27% (9/33). Two or more rCDIs were observed in 9% (128/1389) of patients. The risk of a first recurrence fluctuated over time, but there was no such variation for second or further recurrences. The proportion of severe cases decreased (47% for initial episodes, 31% for first recurrences, 25% for second, 17% for third), as did the risk of complicated CDI (5.8% to 2.8%). The severity and risk of complications of first recurrences decreased over time, while oral vancomycin was used more systemically. A hospital admission was needed for 34% (148/434) of recurrences.

CONCLUSIONS

This study documented the clinical and healthcare burden of rCDI: 34% of patients with rCDI needed admission, 28% developed severe CDI, and 4% developed a complication. Secular changes in the severity of recurrences could reflect variations in the predominant strain, or better management.

Safety and Durability of RBX2660 (Microbiota Suspension) for Recurrent Clostridium difficile Infection: Results of the PUNCH CD Study

BACKGROUND

Managing recurrent Clostridium difficile infection (CDI) presents a significant challenge for clinicians and patients. Fecal microbiota transplantation (FMT) is a highly effective therapy for recurrent CDI, yet availability of a standardized, safe, and effective product has been lacking. Our aim in this study was to assess the safety and effectiveness of RBX2660 (microbiota suspension), a commercially prepared FMT drug manufactured using standardized processes and available in a ready-to-use format.

METHODS

Patients with at least 2 recurrent CDI episodes or at least 2 severe episodes resulting in hospitalization were enrolled in a prospective, multicenter open-label study of RBX2660 administered via enema. Intensive surveillance for adverse events (AEs) was conducted daily for 7 days following treatment and then at 30 days, 60 days, 3 months, and 6 months. The primary objective was product-related AEs. A secondary objective was CDI-associated diarrhea resolution at 8 weeks.

RESULTS

Of the 40 patients enrolled at 11 centers in the United States between 15 August 2013 and 16 December 2013, 34 received at least 1 dose of RBX2660 and 31 completed 6-month follow-up. Overall efficacy was 87.1% (16 with 1 dose and 11 with 2 doses). Of 188 reported AEs, diarrhea, flatulence, abdominal pain/cramping, and constipation were most common. The frequency and severity of AEs decreased over time. Twenty serious AEs were reported in 7 patients; none were related to RBX2660 or its administration.

CONCLUSIONS

Among patients with recurrent or severe CDI, administration of RBX2660 via enema appears to be safe and effective.

CLINICAL TRIALS REGISTRATION

NCT01925417.

Regulation of Clostridium difficile Spore Formation by the SpoIIQ and SpoIIIA Proteins

Sporulation is an ancient developmental process that involves the formation of a highly resistant endospore within a larger mother cell. In the model organism Bacillus subtilis, sporulation-specific sigma factors activate compartment-specific transcriptional programs that drive spore morphogenesis. σ^G activity in the forespore depends on the formation of a secretion complex, known as the “feeding tube,” that bridges the mother cell and forespore and maintains forespore integrity. Even though these channel components are conserved in all spore formers, recent studies in the major nosocomial pathogen Clostridium difficile suggested that these components are dispensable for σ^G activity. In this study, we investigated the requirements of the SpoIIQ and SpoIIIA proteins during C. difficile sporulation. C. difficile spoIIQ, spoIIIA, and spoIIIAH mutants exhibited defects in engulfment, tethering of coat to the forespore, and heat-resistant spore formation, even though they activate σ^G at wildtype levels. Although the spoIIQ, spoIIIA, and spoIIIAH mutants were defective in engulfment, metabolic labeling studies revealed that they nevertheless actively transformed the peptidoglycan at the leading edge of engulfment. In vitro pull-down assays further demonstrated that C. difficile SpoIIQ directly interacts with SpoIIIAH. Interestingly, mutation of the conserved Walker A ATP binding motif, but not the Walker B ATP hydrolysis motif, disrupted SpoIIIAA function during C. difficile spore formation. This finding contrasts with B. subtilis, which requires both Walker A and B motifs for SpoIIIAA function. Taken together, our findings suggest that inhibiting SpoIIQ, SpoIIIAA, or SpoIIIAH function could prevent the formation of infectious C. difficile spores and thus disease transmission.

The bacterial spore-forming pathogen Clostridium difficile is a leading cause of nosocomial infections in the United States and represents a significant threat to healthcare systems around the world. As an obligate anaerobe, C. difficile must form spores in order to survive exit from the gastrointestinal tract. Accordingly, spore formation is essential for C. difficile disease transmission. Since the mechanisms controlling this process remain poorly characterized, we analyzed the importance of highly conserved secretion channel components during C. difficile sporulation. In the model organism Bacillus subtilis, this channel had previously been shown to function as a “feeding tube” that allows the mother cell to nurture the developing forespore and sustain transcription in the forespore. We show here that conserved components of this structure in C. difficile are dispensable for forespore transcription, although they are important for completing forespore engulfment and retaining the protective spore coat around the forespore, in contrast with B. subtilis. The results of our study suggest that targeting these conserved proteins could prevent C. difficile spore formation and thus disease transmission.

Economic assessment of fidaxomicin for the treatment of Clostridium difficile infection (CDI) in special populations (patients with cancer, concomitant antibiotic treatment or renal impairment) in Spain

The objective of this paper was to assess the cost-utility of fidaxomicin versus vancomycin in the treatment of Clostridium difficile infection (CDI) in three specific CDI patient subgroups: those with cancer, treated with concomitant antibiotic therapy or with renal impairment. A Markov model with six health states was developed to assess the cost-utility of fidaxomicin versus vancomycin in the patient subgroups over a period of 1 year from initial infection. Cost and outcome data used to parameterise the model were taken from Spanish sources and published literature. The costs were from the Spanish hospital perspective, in Euros (€) and for 2013. For CDI patients with cancer, fidaxomicin was dominant versus vancomycin [gain of 0.016 quality-adjusted life-years (QALYs) and savings of €2,397 per patient]. At a cost-effectiveness threshold of €30,000 per QALY gained, the probability that fidaxomicin was cost-effective was 96 %. For CDI patients treated with concomitant antibiotic therapy, fidaxomicin was the dominant treatment versus vancomycin (gain of 0.014 QALYs and savings of €1,452 per patient), with a probability that fidaxomicin was cost-effective of 94 %. For CDI patients with renal impairment, fidaxomicin was also dominant versus vancomycin (gain of 0.013 QALYs and savings of €1,432 per patient), with a probability that fidaxomicin was cost-effective of 96 %. Over a 1-year time horizon, when fidaxomicin is compared to vancomycin in CDI patients with cancer, treated with concomitant antibiotic therapy or with renal impairment, the use of fidaxomicin would be expected to result in increased QALYs for patients and reduced overall costs.

A small-molecule antivirulence agent for treating Clostridium difficile infection

Clostridium difficile infection (CDI) is a worldwide health threat that is typically triggered by the use of broad-spectrum antibiotics, which disrupt the natural gut microbiota and allow this Gram-positive anaerobic pathogen to thrive. The increased incidence and severity of disease coupled with decreased response, high recurrence rates, and emergence of multiple antibiotic-resistant strains have created an urgent need for new therapies. We describe pharmacological targeting of the cysteine protease domain (CPD) within the C. difficile major virulence factor toxin B (TcdB). Through a targeted screen with an activity-based probe for this protease domain, we identified a number of potent CPD inhibitors, including one bioactive compound, ebselen, which is currently in human clinical trials for a clinically unrelated indication. This drug showed activity against both major virulence factors, TcdA and TcdB, in biochemical and cell-based studies. Treatment in a mouse model of CDI that closely resembles the human infection confirmed a therapeutic benefit in the form of reduced disease pathology in host tissues that correlated with inhibition of the release of the toxic glucosyltransferase domain (GTD). Our results show that this non-antibiotic drug can modulate the pathology of disease and therefore could potentially be developed as a therapeutic for the treatment of CDI.

WSES guidelines for management of Clostridium difficile infection in surgical patients

In the last two decades there have been dramatic changes in the epidemiology of Clostridium difficile infection (CDI), with increases in incidence and severity of disease in many countries worldwide. The incidence of CDI has also increased in surgical patients. Optimization of management of C difficile, has therefore become increasingly urgent. An international multidisciplinary panel of experts prepared evidenced-based World Society of Emergency Surgery (WSES) guidelines for management of CDI in surgical patients.

Recurrent Clostridium difficile infection: From colonization to cure

Clostridium difficile infection (CDI) is increasingly prevalent, dangerous and challenging to prevent and manage. Despite intense national and international attention the incidence of primary and of recurrent CDI (PCDI and RCDI, respectively) have risen rapidly throughout the past decade. Of major concern is the increase in cases of RCDI resulting in substantial morbidity, morality and economic burden. RCDI management remains challenging as there is no uniformly effective therapy, no firm consensus on optimal treatment, and reliable data regarding RCDI-specific treatment options is scant. Novel therapeutic strategies are critically needed to rapidly, accurately, and effectively identify and treat patients with, or at-risk for, RCDI. In this review we consider the factors implicated in the epidemiology, pathogenesis and clinical presentation of RCDI, evaluate current management options for RCDI and explore novel and emerging therapies.

Novel riboswitch-binding flavin analog that protects mice against Clostridium difficile infection without inhibiting cecal flora

Novel mechanisms of action and new chemical scaffolds are needed to rejuvenate antibacterial drug discovery, and riboswitch regulators of bacterial gene expression are a promising class of targets for the discovery of new leads. Herein, we report the characterization of 5-(3-(4-fluorophenyl)butyl)-7,8-dimethylpyrido[3,4-b]quinoxaline-1,3(2H,5H)-dione (5FDQD)-an analog of riboflavin that was designed to bind riboswitches that naturally recognize the essential coenzyme flavin mononucleotide (FMN) and regulate FMN and riboflavin homeostasis. In vitro, 5FDQD and FMN bind to and trigger the function of an FMN riboswitch with equipotent activity. MIC and time-kill studies demonstrated that 5FDQD has potent and rapidly bactericidal activity against Clostridium difficile. In C57BL/6 mice, 5FDQD completely prevented the onset of lethal antibiotic-induced C. difficile infection (CDI). Against a panel of bacteria representative of healthy bowel flora, the antibacterial selectivity of 5FDQD was superior to currently marketed CDI therapeutics, with very little activity against representative strains from the Bacteroides, Lactobacillus, Bifidobacterium, Actinomyces, and Prevotella genera. Accordingly, a single oral dose of 5FDQD caused less alteration of culturable cecal flora in mice than the comparators. Collectively, these data suggest that 5FDQD or closely related analogs could potentially provide a high rate of CDI cure with a low likelihood of infection recurrence. Future studies will seek to assess the role of FMN riboswitch binding to the mechanism of 5FDQD antibacterial action. In aggregate, our results indicate that riboswitch-binding antibacterial compounds can be discovered and optimized to exhibit activity profiles that merit preclinical and clinical development as potential antibacterial therapeutic agents.

Randomised clinical trial: faecal microbiota transplantation by colonoscopy vs. vancomycin for the treatment of recurrent Clostridium difficile infection

BACKGROUND

Faecal microbiota transplantation (FMT) from healthy donors is considered an effective treatment against recurrent Clostridium difficile infection.

AIM

To study the effect of FMT via colonoscopy in patients with recurrent C. difficile infection compared to the standard vancomycin regimen.

METHODS

In an open-label, randomised clinical trial, we assigned subjects with recurrent C. difficile infection to receive: FMT, short regimen of vancomycin (125 mg four times a day for 3 days), followed by one or more infusions of faeces via colonoscopy; or vancomycin, vancomycin 125 mg four times daily for 10 days, followed by 125-500 mg/day every 2-3 days for at least 3 weeks. The latter treatment did not include performing colonoscopy. The primary end point was the resolution of diarrhoea related to C. difficile infection 10 weeks after the end of treatments.

RESULTS

The study was stopped after a 1-year interim analysis. Eighteen of the 20 patients (90%) treated by FMT exhibited resolution of C. difficile-associated diarrhoea. In FMT, five of the seven patients with pseudomembranous colitis reported a resolution of diarrhoea. Resolution of C. difficile infection occurred in 5 of the 19 (26%) patients in vancomycin (P < 0.0001). No significant adverse events were observed in either of the study groups.

CONCLUSIONS

Faecal microbiota transplantation using colonoscopy to infuse faeces was significantly more effective than vancomycin regimen for the treatment of recurrent C. difficile infection. The delivery of donor faeces via colonoscopy has the potential to optimise the treatment strategy in patients with pseudomembranous colitis.

Effectiveness of fecal-derived microbiota transfer using orally administered capsules for recurrent Clostridium difficile infection

BACKGROUND

Clostridium difficile infection (CDI), a complication of antibiotic-induced injury to the gut microbiome, is a prevalent and dangerous cause of infectious diarrhea. Antimicrobial therapy for CDI is typically effective for acute symptoms, but up to one third of patients later experience recurrent CDI. Fecal-derived microbiota transplantation (FMT) can ameliorate the underlying dysbiosis and is highly effective for recurrent CDI. Traditional methods of FMT are limited by patient discomfort, risk and inefficient procedures. Many individuals with recurrent CDI have extensive comorbidities and advanced age. Widespread use of FMT requires strategies that are non-invasive, scalable and applicable across healthcare settings.

METHODS

A method to facilitate microbiota transfer was developed. Fecal samples were collected and screened for potential pathogens. Bacteria were purified, concentrated, cryopreserved and formulated into multi-layered capsules. Capsules were administered to patients with recurrent CDI, who were then monitored for 90 days.

RESULTS

Thirteen women and six men with recurrent CDI were provided with microbiota transfer with orally administered capsules. The procedure was well tolerated. Thirteen individuals responded to a single course. Four patients were cured after a second course. There were 2 failures. The cumulative clinical cure rate of 89% is similar to the rates achieved with reported fecal-derived transplantation procedures.

CONCLUSIONS

Recurrent CDI represents a profound dysbiosis and a debilitating chronic disease. Stable cure can be achieved by restoring the gut microbiome with an effective, well-tolerated oral capsule treatment. This strategy of microbiota transfer can be widely applied and is particularly appropriate for frail patients.

A randomised phase 1 study to investigate safety, pharmacokinetics and impact on gut microbiota following single and multiple oral doses in healthy male subjects of SMT19969, a novel agent for Clostridium difficile infections

BACKGROUND

Clostridium difficile infection (CDI) is a leading cause of diarrhoea in health care settings with symptoms ranging from mild and self-limiting to life threatening. SMT19969 is a novel, non-absorbable antibiotic currently under development for the treatment of CDI. Here we report the results from a Phase I study.

METHODS

A double-blind, randomized, placebo-controlled study assessing safety and tolerability of single and multiple oral doses of SMT19969 in healthy volunteers. Pharmacokinetic assessments included blood and faecal sampling. The effect of food on systemic exposure and analysis of the gut microbiota were also included.

RESULTS

Fifty-six healthy male subjects were enrolled. Following single oral doses of up to 2,000 mg in the fasted state, plasma concentrations of SMT19969 were generally below the lower limit of quantification. In the fed state levels ranged from 0.102 to 0.296 ng/mL after single dosing and after repeat dosing at Day 10 from 0.105 to 0.305 ng/mL. Following single and multiple oral doses of SMT19969, mean daily faecal concentrations increased with increasing dose level and were significantly above the typical MIC range for C. difficile (0.06-0.5 μg/mL). At 200 mg BID, mean (± SD) faecal concentrations of 1,466 (±547) μg/g and 1,364 (±446) μg/g were determined on days 5 and 10 of dosing respectively. No notable metabolites were detected in faeces. Overall, all doses of SMT19969 were well tolerated both as single oral doses or BID oral doses for 10 days. The majority (88%) of adverse events (AEs) were classified as gastrointestinal disorders and were mild in severity, resolving without treatment. The gut microbiota was analysed in the multiple dose groups with minimal changes observed in the bacterial groups analysed except for total clostridia which were reduced to below the limit of detection by day 4 of dosing.

CONCLUSIONS

Oral administration of SMT19969 was considered safe and well tolerated and was associated with negligible plasma concentrations after single and multiple doses. In addition, minimal disruption of normal gut microbiota was noted, confirming the highly selective spectrum of the compound. These results support the further clinical development of SMT19969 as an oral therapy for CDI.

TRIAL REGISTRATION

Current Controlled Trials. ISRCTN10858225 .

A prediction model for Clostridium difficile recurrence

Background

Clostridium difficile infection (CDI) is a growing problem in the community and hospital setting. Its incidence has been on the rise over the past two decades, and it is quickly becoming a major concern for the health care system. High rate of recurrence is one of the major hurdles in the successful treatment of C. difficile infection. There have been few studies that have looked at patterns of recurrence. The studies currently available have shown a number of risk factors associated with C. difficile recurrence (CDR); however, there is little consensus on the impact of most of the identified risk factors.

Methods

Our study was a retrospective chart review of 198 patients diagnosed with CDI via Polymerase Chain Reaction (PCR) from January 2009 to Jun 2013. In our study, we decided to use a machine learning algorithm called the Random Forest (RF) to analyze all of the factors proposed to be associated with CDR. This model is capable of making predictions based on a large number of variables, and has outperformed numerous other models and statistical methods.

Results

We came up with a model that was able to accurately predict the CDR with a sensitivity of 83.3%, specificity of 63.1%, and area under curve of 82.6%. Like other similar studies that have used the RF model, we also had very impressive results.

Conclusions

We hope that in the future, machine learning algorithms, such as the RF, will see a wider application.

SMT19969 for Clostridium difficile infection (CDI): in vivo efficacy compared with fidaxomicin and vancomycin in the hamster model of CDI

OBJECTIVES

SMT19969 is a novel narrow-spectrum antimicrobial under development for the treatment of Clostridium difficile infection (CDI). The objectives were to assess the relative efficacies of SMT19969, vancomycin and fidaxomicin in the hamster model of CDI.

METHODS

Hamsters were infected with either C. difficile BI1 (ribotype 027) or C. difficile 630 (ribotype 012) prior to treatment with vehicle, SMT19969, fidaxomicin or vancomycin for 5 days. Animals were further monitored through to day 28 and survival recorded. Plasma and gastrointestinal concentrations of SMT19969 following single and repeat administration in infected hamsters were determined.

RESULTS

Following infection with C. difficile BI1, treatment with SMT19969, vancomycin and fidaxomicin resulted in 100% survival during the 5 day dosing period, with 90%-100% of animals receiving SMT19969 and fidaxomicin surviving during the post-dosing follow-up period. Whilst protective during treatment, onset of mortality was observed on day 11 in animals treated with vancomycin, with a 10% survival recorded by day 28. Similar results were observed for SMT19969 and vancomycin following infection with C. difficile 630, with day 28 survival rates of 80%-100% and 0%, respectively. Fidaxomicin protected animals infected with C. difficile 630 from mortality during dosing, although day 28 survival rates varied from 0% to 40% depending on dose. Plasma levels of SMT19969 were typically below the limit of quantification, but levels in the gastrointestinal tract remained far in excess of the MIC.

CONCLUSIONS

These data show that SMT19969 is highly effective at treating both acute infection and preventing recurrent disease and support continued investigation of SMT19969 as a potential therapy for CDI.

In vitro susceptibility of Clostridium difficile to SMT19969 and comparators, as well as the killing kinetics and post-antibiotic effects of SMT19969 and comparators against C. difficile

OBJECTIVES

SMT19969 is a novel antimicrobial under clinical development for the treatment of Clostridium difficile infection (CDI). The objective was to determine the comparative susceptibility of 82 C. difficile clinical isolates (which included ribotype 027 isolates and isolates with reduced metronidazole susceptibility) to SMT19969, fidaxomicin, vancomycin and metronidazole and to determine the killing kinetics and post-antibiotic effects of SMT19969, fidaxomicin and vancomycin against C. difficile.

METHODS

MICs were determined by agar incorporation. Killing kinetics and post-antibiotic effects were determined against C. difficile BI1, 630 and 5325 (ribotypes 027, 012 and 078, respectively).

RESULTS

SMT19969 showed potent inhibition of C. difficile (MIC90=0.125 mg/L) and was markedly more active than either metronidazole (MIC90 = 8 mg/L) or vancomycin (MIC90 = 2 mg/L). There were no differences in susceptibility to SMT19969 between different ribotypes. Fidaxomicin was typically one doubling dilution more active than SMT19969 and both agents maintained activity against isolates with reduced susceptibility to metronidazole. In addition, SMT19969 was bactericidal against the C. difficile strains tested, with reductions in viable counts to below the limit of detection by 24 h post-inoculation. Vancomycin was bacteriostatic against all three strains. Fidaxomicin was bactericidal although reduced killing was observed at concentrations <20 × MIC against C. difficile BI1 (ribotype 027) compared with other strains tested.

CONCLUSIONS

These data demonstrate that SMT19969 is associated with potent and bactericidal activity against the strains tested and support further investigation of SMT19969 as potential therapy for CDI.

Risk factors for recurrent Clostridium difficile infection: a systematic review and meta-analysis

OBJECTIVE

An estimated 20-30% of patients with primary Clostridium difficile infection (CDI) develop recurrent CDI (rCDI) within 2 weeks of completion of therapy. While the actual mechanism of recurrence remains unknown, a variety of risk factors have been suggested and studied. The aim of this systematic review and meta-analysis was to evaluate current evidence on the risk factors for rCDI.

DESIGN

We searched MEDLINE and 5 other databases for subject headings and text related to rCDI. All studies investigating risk factors of rCDI in a multivariate model were eligible. Information on study design, patient population, and assessed risk factors were collected. Data were combined using a random-effects model and pooled relative risk ratios (RRs) were calculated.

RESULTS

A total of 33 studies (n=18,530) met the inclusion criteria. The most frequent independent risk factors associated with rCDI were age≥65 years (risk ratio [RR], 1.63; 95% confidence interval [CI], 1.24-2.14; P=.0005), additional antibiotics during follow-up (RR, 1.76; 95% CI, 1.52-2.05; P<.00001), use of proton-pump inhibitors (PPIs) (RR, 1.58; 95% CI, 1.13-2.21; P=.008), and renal insufficiency (RR, 1.59; 95% CI, 1.14-2.23; P=.007). The risk was also greater in patients previously on fluoroquinolones (RR, 1.42; 95% CI, 1.28-1.57; P<.00001).

CONCLUSIONS

Multiple risk factors are associated with the development of rCDI. Identification of modifiable risk factors and judicious use of antibiotics and PPI can play an important role in the prevention of rCDI.

Predictors and outcomes of readmission for Clostridium difficile in a national sample of medicare beneficiaries

BACKGROUND

Rates of Clostridium difficile (CD) infections are increasing. Elderly patients may be at particular risk of recurrent CD infection. Little is known about the risk for CD readmission specifically in this age group.

METHODS

A 5% random sample of Medicare data (2009-2011) was queried for patients surviving a hospitalization for CD by ICD-9 code. Demographic (age, sex, gender), clinical (Elixhauser index, gastrointestinal comorbidities), and hospitalization (length of stay, ICU admission) characteristics as well as exposure to antibiotics and interim non-CD hospitalization were compared for those with and without a readmission for CD. A multivariable survival analysis was used to determine predictors of readmission.

RESULTS

Of 7,564 patients surviving a CD hospitalization, 8.5% were readmitted with CD in a median of 25 days (interquartile range (IQR) 14-57). In multivariable survival analyses, interim non-CD hospital exposure was the strongest predictor of CD readmission (hazard ration (HR) 3.75 95%, confidence interval (CI) 3.2-4.42). Oral and intravenous/intramuscular (IV/IM) antibiotic use, Elixhauser index, and CD as the primary diagnosis also increased the risk of CD readmission. Discharge to hospice, long-term care or a skilled nursing facility decreased the odds of CD readmission.

CONCLUSION

Hospital exposure and antibiotic use put elderly patients at risk of CD readmission. Exposure to these factors should be minimized in the immediate post discharge period.

Missed diagnosis of Clostridium difficile infection; a prospective evaluation of unselected stool samples

BACKGROUND

Clostridium difficile infection (CDI) is the leading cause of hospital-acquired diarrhoea in developed countries, however a high proportion of CDI episodes go undiagnosed, either because physicians do not request identification of toxigenic C. difficile or microbiologists do not perform the appropriate tests.

OBJECTIVE

To investigate the clinical characteristics of patients with CDI within a non-selected population and to determine risk factors for clinical underdiagnosis.

METHODS

We conducted a prospective study in which systematic testing for toxigenic C. difficile on all diarrhoeic stool samples was performed regardless of the clinician's request. Patients aged >2 years positive for toxigenic C. difficile and diarrhoea were enrolled (Jan-June 2013) and monitored at least 2 months after their last episode.

RESULTS

We identified 204 cases of CDI, of which three-quarters were healthcare-associated. Most cases were mild to moderate (83.8%), the recurrence rate was 16.2%, and CDI-related mortality was low (2.5%). A significant proportion (12.7%) of CDI cases would have been missed owing to lack of clinical suspicion. Community-acquired cases and young age were risk factors for clinical underdiagnosis.

CONCLUSION

Our data support the introduction of a systematic search for toxigenic C. difficile in all diarrhoeic stools from inpatients and outpatients older than 2 years.

Ethical dilemmas in antibiotic treatment: focus on the elderly

Maximal antibiotic treatment for all patients suspected of harbouring a bacterial infection is non-viable, because it will rapidly induce resistance and exhaust this finite resource. This raises two ethical dilemmas: the question of whether we are justified in increasing the danger to a present, named, patient so as to benefit future, unknown, patients; and whether we are allowed to do so without asking the present patient for consent. Although the considerations for healthy elderly patients are similar to younger adults, the answers are complex when addressing patients with dementia, severely reduced quality of life and at end of life. We argue that a public debate on the balance between benefit to a present patient versus harm to future patients should be conducted. Such a debate should include examinations of scenarios in which antibiotic treatment does not gain any benefit in a patient with infection: at the end of life; in situations in which resistance is such that empirical antibiotic treatment seldom matches the susceptibilities of the pathogen; and in patients with no quality of life. An explicit cost-benefit model, incorporating quality of life and risk of resistance, in computerized decision support might obviate a clinician's need to deal with these difficult issues at bedside.

Synthetic polymers active against Clostridium difficile vegetative cell growth and spore outgrowth

Nylon-3 polymers (poly-β-peptides) have been investigated as synthetic mimics of host-defense peptides in recent years. These polymers are attractive because they are much easier to synthesize than are the peptides themselves, and the polymers resist proteolysis. Here we describe in vitro analysis of selected nylon-3 copolymers against Clostridium difficile, an important nosocomial pathogen that causes highly infectious diarrheal disease. The best polymers match the human host-defense peptide LL-37 in blocking vegetative cell growth and inhibiting spore outgrowth. The polymers and LL-37 were effective against both the epidemic 027 ribotype and the 012 ribotype. In contrast, neither vancomycin nor nisin inhibited outgrowth for the 012 ribotype. The best polymer was less hemolytic than LL-37. Overall, these findings suggest that nylon-3 copolymers may be useful for combatting C. difficle.