Ribotypes and antimicrobial susceptibility profiles of clinical Clostridioides difficile isolates: A multicenter, laboratory-based surveillance in Taiwan, 2019-2021

BACKGROUND

The clinical burden of Clostridioides difficile infections (CDIs) remains substantial globally. This study aimed to investigate the ribotypes (RTs) and antimicrobial susceptibility of C. difficile isolates collected in Taiwan.

METHODS

C. difficile isolates were prospectively collected from four medical centers in Taiwan from 2019 to 2021. In a reference laboratory, in vitro susceptibility to clindamycin, moxifloxacin, metronidazole, vancomycin, fidaxomicin, and rifaximin were tested, and ribotyping was conducted to determine their genetic diversity.

RESULTS

A total of 568 C. difficile isolates were included. Metronidazole resistance was not observed, and the susceptibility rate of vancomycin was 99.5 %. Clindamycin showed poor activity against these isolates, with a resistance rate of 74.8 %. Fidaxomicin exhibited potent activity and 97.4 % of isolates were inhibited at 0.25 μg/mL. Rifaximin MIC90 increased from 0.015 μg/mL in 2019 to 0.03 μg/mL in 2020 and 2021. Of 40 RTs identified, two predominant RTs were RT 078/126 (78, 14 %) and 014/020 (76, 13 %). RT 017, traditional harboring truncated tcdA, accounted for 3 % (20 isolates) and there was no isolate belonging to RT 027. The proportions of RT 078 increased from 11.2 % in 2019 to 17.1 % in 2021, and the predominance of RT 078/126 was more evident in central Taiwan.

CONCLUSIONS

Vancomycin, fidaxomicin, and metronidazole remain in vitro effective against clinical C. difficile isolates in Taiwan. The reservoirs and genetic relatedness of two major RTs with zoonotic potentials, RT 078/126 and 014/020, warrant further investigations.

[Fulminant Clostridioides difficile infection during treatment with FLT3 inhibitor for acute myeloid leukemia]

An 80-year-old man with FLT3-TKD mutation-positive acute myeloid leukemia (AML) relapsed during consolidation therapy with venetoclax/azacitidine and was started on gilteritinib as salvage therapy. On the day after treatment initiation, febrile neutropenia was observed, but the fever resolved promptly after initiation of antimicrobial therapy. On the fifth day after completion of antimicrobial therapy, the patient experienced fever and watery diarrhea over 10 times a day, and a diagnosis of Clostridioides difficile infection (CDI) was made based on stool examination. The patient was treated with intravenous metronidazole, but renal dysfunction, hypotension, and hypoxemia developed, and a CT scan showed pleural and intraperitoneal effusion, significant intestinal wall thickening, and intestinal dilatation. Fidaxomicin was started under general monitoring in the intensive care unit and response was achieved. The patient was discharged from the intensive care unit on the 18th day after the onset of CDI. We report this case not only due to the rarity of fulminant CDI during AML treatment, but also because it is a valuable example of effective treatment of fulminant CDI with fidaxomicin.

European Practice for CDI Treatment

Clostridioides difficile infection (CDI) remains a significant cause of morbidity and mortality worldwide. Historically, two antibiotics (metronidazole and vancomycin) and a recent third (fidaxomicin) have been used for CDI treatment; convincing data are now available showing that metronidazole is the least efficacious agent. The European Society of Clinical Microbiology and Infectious Diseases (ESCMID) management guidance for CDI were updated in 2021. This guidance document outlines the treatment options for a variety of CDI clinical scenarios and for non-antimicrobial management (e.g., faecal microbiota transplantation, FMT). One of the main changes is that metronidazole is no longer recommended as first-line CDI treatment. Rather, fidaxomicin is preferred on the basis of reduced recurrence rates with vancomycin as an acceptable alternative. Recommended options for recurrent CDI now include bezlotoxumab as well as FMT.A 2017 survey of 20 European countries highlighted variation internationally in CDI management strategies. A variety of restrictions were in place in 65% countries prior to use of new anti-CDI treatments, including committee/infection specialist approval or economic review/restrictions. This survey was repeated in November 2022 to assess the current landscape of CDI management practices in Europe. Of 64 respondents from 17 countries, national CDI guidelines existed in 14 countries, and 11 have already/plan to incorporate the ESCMID 2021 CDI guidance, though implementation has not been surveyed in 6. Vancomycin is the most commonly used first-line agent for the treatment of CDI (n = 42, 66%), followed by fidaxomicin (n = 30, 47%). Six (9%) respondents use metronidazole as first-line agent for CDI treatment, whereas 22 (34%) only in selected low-risk patient groups. Fidaxomicin is more likely to be used in high-risk patient groups. Availability of anti-CDI therapy influenced prescribing in six respondents (9%). Approval pre-prescription was required before vancomycin (n = 3, 5%), fidaxomicin (n = 10, 6%), bezlotoxumab (n = 11, 17%) and FMT (n = 10, 6%). Implementation of CDI guidelines is rarely audited.Novel anti-CDI agents are being evaluated; it is not yet clear what will be the roles of these agents. The treatment of recurrent CDI is particularly troublesome, and several different live biotherapeutics are being developed, in addition to FMT.

Phenolic Substitution in Fidaxomicin: A Semisynthetic Approach to Antibiotic Activity Across Species

Fidaxomicin (Fdx) is a natural product antibiotic with potent activity against Clostridioides difficile and other Gram-positive bacteria such as Mycobacterium tuberculosis. Only a few Fdx derivatives have been synthesized and examined for their biological activity in the 50 years since its discovery. Fdx has a well-studied mechanism of action, namely inhibition of the bacterial RNA polymerase. Yet, the targeted organisms harbor different target protein sequences, which poses a challenge for the rational development of new semisynthetic Fdx derivatives. We introduced substituents on the two phenolic hydroxy groups of Fdx and evaluated the resulting trends in antibiotic activity against M. tuberculosis, C. difficile, and the Gram-negative model organism Caulobacter crescentus. As suggested by the target protein structures, we identified the preferable derivatisation site for each organism. The derivative ortho-methyl Fdx also exhibited activity against the Gram-negative C. crescentus wild type, a first for fidaxomicin antibiotics. These insights will guide the synthesis of next-generation fidaxomicin antibiotics.

Transcriptional regulation of the fidaxomicin gene cluster and cellular development in Actinoplanes deccanensis YP-1 by the pleiotropic regulator MtrA

IMPORTANCE

Cascade regulation networks are almost present in various kinds of microorganisms, but locating and systematically elucidating specific pleiotropic regulators related to a certain gene cluster can be a tricky problem. Here, based on the promoter of the fidaxomicin pathway-specific regulator FadR1, we utilized a "DNA to Proteins" affinity purification method and captured a global regulator MtrA, which positively regulates fidaxomicin biosynthesis. In the mtrA overexpressed strain, the production of fidaxomicin was improved by 37% compared to the native strain. Then, we combined the "Protein to DNAs" affinity purification method (DAP-seq) with the results of RNA-seq and systematically elucidated the primary and secondary metabolic processes in which MtrA directly or indirectly participates. Thus, our work brought up a new way to improve fidaxomicin production from the perspective of global regulation and analyzed the regulatory mechanism of MtrA. Meanwhile, we provided a novel methodology for the research of cascade regulation networks and vital secondary metabolites.

Prevention and treatment of C. difficile in cancer patients

PURPOSE OF REVIEW

We provide an update on the recent literature on Clostridioides difficile infection (CDI) in cancer patients.

RECENT FINDINGS

Distinguishing between colonization and infection remains challenging in cancer patients. Many patients with negative toxin analysis are still treated for CDI, and some meet criteria for severe cases. The incidence of CDI is high in cancer patients, especially those with haematological malignancies. Disruption of the gut microbiome due to antibiotic consumption, chemotherapy and radiotherapy is the primary factor contributing to CDI development. The severity of CDI in cancer patients is often unclear due to the absence of well-defined severity criteria. Certain microbiome species predominance and specific ribotypes have been associated with worse outcomes. Whole genome sequencing could be helpful for differentiating recurrence from reinfection and exploring potential nosocomial transmission. While certain new drugs such as fidaxomicin or bezlotoxumab show promise, the optimal treatment and prevention strategies for CDI in cancer patients remain uncertain. Faecal microbiota transplantation (FMT) holds potential for reducing CDI recurrence rates.

SUMMARY

Further studies are needed to provide robust recommendations for diagnosis, grading severity, and therapeutic management of CDI in cancer patients. Recurrences are particularly concerning due to subsequent exposition to CDI risk factors.

Fidaxomicin treatment for Clostridioides difficile infection in patients with inflammatory bowel disease

BACKGROUND AND AIM

Although fidaxomicin is an effective first-line treatment for Clostridioides difficile infection, it has not been well studied in patients with inflammatory bowel disease. We aimed to assess the effectiveness of fidaxomicin for the treatment of C. difficile infection in patients with inflammatory bowel disease.

METHODS

This was a multicenter retrospective study of adults with inflammatory bowel disease and C. difficile infection treated with fidaxomicin with at least 3 months of follow up. The primary outcomes were treatment response, defined as resolution of C. difficile infection-attributed diarrhea and/or negative C. difficile infection stool test, and time to C. difficile infection recurrence after fidaxomicin.

RESULTS

Thirty-three patients (median age 42 years; 60.6% female) were included. Most patients had ulcerative colitis (26, 78.8%), were receiving treatment with a biologic or small molecule medication (19, 57.6%), and had a prior episode of C. difficile infection (26, 78.8%, median 2 episodes, range 0-15). Fidaxomicin led to resolution of C. difficile infection in 20 (60.6%) patients, with 6/20 (30.0%) developing a recurrence at a median of 55 days. Most patients who failed to respond to fidaxomicin underwent fecal microbiota transplantation (10/13, 76.9%) with resolution.

CONCLUSIONS

In this cohort of patients with inflammatory bowel disease and C. difficile infection, 60.6% responded to treatment with fidaxomicin. Of those who did not respond, fecal microbiota transplantation was an effective therapy.

Inhibition of selenoprotein synthesis is not the mechanism by which auranofin inhibits growth of Clostridioides difficile

Clostridioides difficile infections (CDIs) are responsible for a significant number of antibiotic-associated diarrheal cases. The standard-of-care antibiotics for C. difficile are limited to fidaxomicin and vancomycin, with the recently obsolete metronidazole recommended if both are unavailable. No new antimicrobials have been approved for CDI since fidaxomicin in 2011, despite varying rates of treatment failure among all standard-of-care drugs. Drug repurposing is a rational strategy to generate new antimicrobials out of existing therapeutics approved for other indications. Auranofin is a gold-containing anti-rheumatic drug with antimicrobial activity against C. difficile and other microbes. In a previous report, our group hypothesized that inhibition of selenoprotein biosynthesis was auranofin's primary mechanism of action against C. difficile. However, in this study, we discovered that C. difficile mutants lacking selenoproteins are still just as sensitive to auranofin as their respective wild-type strains. Moreover, we found that selenite supplementation dampens the activity of auranofin against C. difficile regardless of the presence of selenoproteins, suggesting that selenite's neutralization of auranofin is not because of compensation for a chemically induced selenium deficiency. Our results clarify the findings of our original study and may aid drug repurposing efforts in discovering the compound's true mechanism of action against C. difficile.

Biosynthetic Diversification of Fidaxomicin Aglycones by Heterologous Expression and Promoter Refactoring

Fidaxomicin (Dificid) is a commercial macrolide antibiotic for treating Clostridium difficile infection. Total synthesis of fidaxomicin and its aglycone had been achieved through different synthetic schemes. In this study, an alternative biological route to afford the unique 18-membered macrolactone aglycone of fidaxomicin was developed. The promoter refactored fidaxomicin biosynthetic gene cluster from Dactylosporangium aurantiacum was expressed in the commonly used host Streptomyces albus J1074, thereby delivering five structurally diverse fidaxomicin aglycones with the corresponding titers ranging from 4.9 to 15.0 mg L^-1. In general, these results validated a biological strategy to construct and diversify fidaxomicin aglycones on the basis of promoter refactoring and heterologous expression.

Clinically Approved Antibiotics from 2010 to 2022

This review discusses small molecule antibiotics approved for clinical use in the time frame 2010-2022. This time span saw the approval of four synthetic antibiotics (bedaquiline, pretomanid, delafloxacin, tedizolid), nine natural product derivatives (ceftaroline fosamil, cefiderocol, plazomicin, omadacycline, eravacycline, sarecycline, lefamulin, dalbavancin, oritavancin), and one natural product (fidaxomicin).

Repurposing of potential antiviral drugs against RNA-dependent RNA polymerase of SARS-CoV-2 by computational approach

The high incidences of COVID-19 cases are believed to be associated with high transmissibility rates, which emphasizes the need for the discovery of evidence-based antiviral therapies for curing the disease. The rationale of repurposing existing classes of antiviral small molecule therapeutics against SARS-CoV-2 infection has been expected to accelerate the tedious and expensive drug development process. While Remdesivir has been recently approved to be the first treatment option for specific groups of COVID-19 patients, combinatory therapy with potential antiviral drugs may be necessary to enhance the efficacy in different populations. Hence, a comprehensive list of investigational antimicrobial drug compounds such as Favipiravir, Fidaxomicin, Galidesivir, GC376, Ribavirin, Rifabutin, and Umifenovir were computationally evaluated in this study. We performed in silico docking and molecular dynamics simulation on the selected small molecules against RNA-dependent RNA polymerase, which is one of the key target proteins of SARS-CoV-2, using AutoDock and GROMACS. Interestingly, our results revealed that the macrocyclic antibiotic, Fidaxomicin, possesses the highest binding affinity with the lowest energy value of -8.97 kcal/mol binding to the same active sites of RdRp. GC376, Rifabutin, Umifenovir and Remdesivir were identified as the next best compounds. Therefore, the above-mentioned compounds could be considered good leads for further preclinical and clinical experimentations as potentially efficient antiviral inhibitors for combination therapies against SARS-CoV-2.

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.

Genome-based rational engineering of Actinoplanes deccanensis for improving fidaxomicin production and genetic stability

Microbial fermentation is currently still the major way to produce structural complicated clinical drugs. Yet, the low productivity and genetic instability of producing strains remain the bottlenecks in microbial pharmaceutical industry. Fidaxomicin is a microbial drug against the Clostridium difficile infection. Here, a genome-based combinatorial engineering strategy was established to improve both fidaxomicin production and the genetic stability of Actinoplanes deccanensis YP-1. Guided by genomic analysis, several genetic instability-associated elements were cumulatively deleted, generating a more genetically stable mutant. Further rational engineering approaches including elimination of a pigment pathway, duplication of the fidaxomicin gene cluster, overexpression of a positive regulator and optimization of the fermentation medium, led to an overall 27-folds improvement in fidaxomicin production. Taken together, the genome-based rational combinatorial engineering strategy was efficient to enhance the fidaxomicin production and ameliorate the genetic stability of YP-1, it can also be widely used in other industrial actinomycetes for strain improvement.

Safety and Efficacy of Fidaxomicin and Vancomycin in Children and Adolescents with Clostridioides (Clostridium) difficile Infection: A Phase 3, Multicenter, Randomized, Single-blind Clinical Trial (SUNSHINE)

BACKGROUND

Fidaxomicin, a narrow-spectrum antibiotic approved for Clostridioides (Clostridium) difficile infection (CDI) in adults, is associated with lower rates of recurrence than vancomycin; however, pediatric data are limited. This multicenter, investigator-blind, phase 3, parallel-group trial assessed the safety and efficacy of fidaxomicin in children.

METHODS

Patients aged <18 years with confirmed CDI were randomized 2:1 to 10 days of treatment with fidaxomicin (suspension or tablets, twice daily) or vancomycin (suspension or tablets, 4 times daily). Safety assessments included treatment-emergent adverse events. The primary efficacy end point was confirmed clinical response (CCR), 2 days after the end of treatment (EOT). Secondary end points included global cure (GC; CCR without CDI recurrence) 30 days after EOT (end of study; EOS). Plasma and stool concentrations of fidaxomicin and its active metabolite OP-1118 were measured.

RESULTS

Of 148 patients randomized, 142 were treated (30 <2 years old). The proportion of participants with treatment-emergent adverse events was similar with fidaxomicin (73.5%) and vancomycin (75.0%). Of 3 deaths in the fidaxomicin arm during the study, none were CDI or treatment related. The rate of CCR at 2 days after EOT was 77.6% (76 of 98 patients) with fidaxomicin and 70.5% (31 of 44) with vancomycin, whereas the rate of GC at EOS was significantly higher in participants receiving fidaxomicin (68.4% vs 50.0%; adjusted treatment difference, 18.8%; 95% confidence interval, 1.5%-35.3%). Systemic absorption of fidaxomicin and OP-1118 was minimal, and stool concentrations were high.

CONCLUSIONS

Compared with vancomycin, fidaxomicin was well tolerated and demonstrated significantly higher rates of GC in children and adolescents with CDI.

CLINICAL TRIALS REGISTRATION

NCT02218372.

Analysis of Clostridium difficile biofilms: imaging and antimicrobial treatment

Background

Clostridium difficile, a spore-forming Gram-positive anaerobic bacillus, is the most common causative agent of healthcare-associated diarrhoea. Formation of biofilms may protect C. difficile against antibiotics, potentially leading to treatment failure. Furthermore, bacterial spores or vegetative cells may linger in biofilms in the gut causing C. difficile infection recurrence.

Objectives

In this study, we evaluated and compared the efficacy of four antibiotics (fidaxomicin, surotomycin, vancomycin and metronidazole) in penetrating C. difficile biofilms and killing vegetative cells.

Methods

C. difficile biofilms grown initially for 48 or 72 h using the colony biofilm model were then treated with antibiotics at a concentration of 25 × MIC for 24 h. Vegetative cells and spores were enumerated. The effect of treatment on biofilm structure was studied by scanning electron microscopy (SEM). The ability of fidaxomicin and surotomycin to penetrate biofilms was studied using fluorescently tagged antibiotics.

Results

Both surotomycin and fidaxomicin were significantly more effective than vancomycin or metronidazole (P < 0.001) at killing vegetative cells in established biofilms. Fidaxomicin was more effective than metronidazole at reducing viable spore counts in biofilms (P < 0.05). Fluorescently labelled surotomycin and fidaxomicin penetrated C. difficile biofilms in < 1 h. After 24 h of treatment, SEM demonstrated that both fidaxomicin and surotomycin disrupted the biofilm structure, while metronidazole had no observable effect.

Conclusions

Fidaxomicin is effective in disrupting C. difficile biofilms, killing vegetative cells and decreasing spore counts.

Efficacy and safety of fidaxomicin for the treatment of Clostridioides (Clostridium) difficile infection in a randomized, double-blind, comparative Phase III study in Japan

We assessed the efficacy and safety of fidaxomicin, a narrow-spectrum macrocyclic antibiotic, for treating inpatients with Clostridioides (Clostridium) difficile infection (CDI) in Japan. The objective was to demonstrate the non-inferior efficacy of fidaxomicin versus vancomycin. This Phase III, vancomycin-controlled, double-blind, parallel-group study enrolled adults with CDI. Patients were randomly assigned to receive fidaxomicin (200 mg twice daily, orally) or vancomycin (125 mg four-times daily, orally) for 10 days. The primary endpoint was global cure rate of CDI (proportion of patients cured at end of treatment with no recurrence during 28-day follow-up). Non-inferiority margin of 10% was pre-specified. Two-hundred and twelve patients were randomized and received treatment at 82 hospitals. Global cure rate was 67.3% (70/104) with fidaxomicin and 65.7% (71/108) with vancomycin: difference 1.2% [95% confidence interval (CI) -11.3-13.7]. Non-inferiority was not demonstrated. Post-hoc analysis in full analysis set patients who received at least 3 days' treatment revealed a higher global cure rate for fidaxomicin [70/97 (72.2%)] than vancomycin [71/106 (67.0%)]: difference 4.6% (95% CI -7.9-17.1). Recurrence rate in the full analysis set for recurrence was lower in fidaxomicin- [17/87 (19.5%)] than vancomycin-treated [24/95 (25.3%)] patients. Adverse event incidences and profiles were similar for both treatments. Though non-inferiority was not demonstrated for fidaxomicin versus vancomycin, global cure rate was numerically higher and recurrence rate lower for fidaxomicin than vancomycin. Fidaxomicin could be an option for the treatment of CDI in an era of reduced antibiotic susceptibility, and to reduce the incidence of recurrence in Japanese patients. CLINICALTRIALS.

GOV IDENTIFIER

NCT02179658.

A Systematic Literature Review of Economic Evaluations of Antibiotic Treatments for Clostridium difficile Infection

BACKGROUND AND OBJECTIVE

Clostridium difficile infection (CDI) is associated with high management costs, particularly in recurrent cases. Fidaxomicin treatment results in lower recurrence rates than vancomycin and metronidazole, but has higher acquisition costs in Europe and the USA. This systematic literature review summarises economic evaluations (EEs) of fidaxomicin, vancomycin and metronidazole for treatment of CDI.

METHODS

Electronic databases (MEDLINE®, Embase, Cochrane Library) and conference proceedings (ISPOR, ECCMID, ICAAC and IDWeek) were searched for publications reporting EEs of fidaxomicin, vancomycin and/or metronidazole in the treatment of CDI. Reference bibliographies of identified manuscripts were also reviewed. Cost-effectiveness was evaluated according to the overall population of patients with CDI, as well as in subgroups with severe CDI or recurrent CDI, or those at higher risk of recurrence or mortality.

RESULTS

Overall, 27 relevant EEs, conducted from the perspective of 12 different countries, were identified. Fidaxomicin was cost-effective versus vancomycin and/or metronidazole in 14 of 24 EEs (58.3%), vancomycin was cost-effective versus fidaxomicin and/or metronidazole in five of 27 EEs (18.5%) and metronidazole was cost-effective versus fidaxomicin and/or vancomycin in two of 13 EEs (15.4%). Fidaxomicin was cost-effective versus vancomycin in most of the EEs evaluating specific patient subgroups. Key cost-effectiveness drivers were cure rate, recurrence rate, time horizon, drug costs and length and cost of hospitalisation.

CONCLUSIONS

In most EEs, fidaxomicin was demonstrated to be cost-effective versus metronidazole and vancomycin in patients with CDI. These results have relevance to clinical practice, given the high budgetary impact of managing CDI and increasing restrictions on healthcare budgets.

OTHER

This analysis was initiated and funded by Astellas Pharma Inc.

Cost-effectiveness analysis on the use of fidaxomicin and vancomycin to treat Clostridium difficile infection in France

BACKGROUND

Fidaxomicin is a macrocyclic antibiotic with proven efficacy against Clostridium difficile infection (CDI) in adults. It was licensed in France in 2012, but, due to higher acquisition costs compared with existing treatments, healthcare providers require information on its cost/benefit profile.

OBJECTIVE

To compare healthcare costs and health outcomes of fidaxomicin and vancomycin, as reference treatment for CDI.

METHODS

A Markov model was used to simulate the treatment pathway, over 1 year, of adult patients with CDI receiving fidaxomicin or vancomycin. Several patient sub-groups (severe CDI; recurrent CDI; concomitant antibiotics; cancer; renal failure; elderly) were evaluated. Cost-effectiveness was analyzed based on cure and recurrence rates derived from published randomized clinical trials comparing fidaxomicin and vancomycin, and costs calculated from the payer perspective using French hospitalization data and drug cost databases. Model outputs included costs in euros (reference year 2014) and health outcomes (recurrence; sustained cure rates). Alternative scenario and sensitivity analyses were performed using data from other clinical trials in CDI, including one conducted in real-life clinical practice in France.

RESULTS

Drug acquisition costs were €1,692 higher in fidaxomicin-treated patients, but this was offset by the lower hospitalization costs with fidaxomicin, which were reduced by €1,722. The reduction in the cost of hospitalization was driven by the significantly lower number of recurrences in fidaxomicin-treated patients, offsetting the acquisition cost of fidaxomicin in all sub-groups except recurrent CDI and concomitant antibiotics.

CONCLUSION

This study demonstrated that, despite higher acquisition costs, the lower recurrence rate with fidaxomicin resulted in cost savings or low incremental costs compared with vancomycin.

High in vitro activity of fidaxomicin against Clostridium difficile isolates from a university teaching hospital in China

BACKGROUND

Clostridium difficile infection (CDI) is a significant cause of morbidity and mortality in both the acute care setting and the wider healthcare system. The purpose of this study was to evaluate the in vitro activity of fidaxomicin against C. difficile isolates from a university teaching hospital in China.

METHODS

One hundred and one C. difficile isolates were collected and analyzed for toxin genes by multiplex PCR. The toxin gene positive strains were also typed by multilocus sequence typing (MLST) and PCR-ribotyping. The MICs of the isolates were determined against fidaxomicin, metronidazole, vancomycin, tigecycline and moxifloxacin, by the agar dilution method.

RESULTS

All the 101 isolates exhibited low MICs to fidaxomicin (0.032-1 mg/L), metronidazole (0.125-1 mg/L), vancomycin (0.25-2 mg/L) and tigecycline (0.016-0.5 mg/L). Tigecycline showed the lowest geometric mean MIC value (0.041 mg/L), followed by fidaxomicin (0.227 mg/L), metronidazole (0.345 mg/L), and vancomycin (0.579 mg/L). About 35% of the strains (n = 35) were resistant to moxifloxacin, and the resistance rate to moxifloxacin for A-B+CDT- isolates (85.0%) was much higher than that of A+B+CDT- (15.7%) and A-B-CDT- (29.2%) isolates (P < 0.001). The MIC values of fidaxomicin, metronidazole, vancomycin and moxifloxacin against the 3 ST1 isolates were higher than for other STs. All the 28 moxifloxacin-resistant toxigenic isolates carried a mutation either in gyrA or/and gyrB.

CONCLUSION

Fidaxomicin exhibited high antimicrobial activity against all C. difficile isolates tested, which shows promise as a new drug for treating Chinese CDI patients.

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.

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.

Successful Therapy of Severe Pseudomembranous Clostridium difficile Colitis Using a Combination of Fecal Microbiota Therapy and Fidaxomicin

OBJECTIVE

The aim of this work was to describe the use of a combination of fidaxomicin and fecal microbiota therapy (FMT) in Clostridium difficile infection (CDI).

CLINICAL PRESENTATION AND INTERVENTION

A 78-year-old female, who was admitted for surgery due to acute diverticulitis caused by postoperative complications and broad antibiotic therapy, developed CDI-induced colitis. Despite the introduction of metronidazole and vancomycin therapy, her clinical condition continued to deteriorate. She was transferred to the intensive care unit where FMT followed by fidaxomicin were performed because her C-reactive protein and leucocyte levels remained elevated. Further clinical improvement and the resolution of colitis was observed.

CONCLUSION

In this case, severe CDI colitis was successfully treated with the combination of FMT and fidaxomicin.

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.

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.

Comparison of the safety, tolerability, and pharmacokinetics of fidaxomicin in healthy Japanese and caucasian subjects

Background and Objectives

Fidaxomicin treatment of Clostridium difficile infection is known to produce minimal systemic exposure, as the antibacterial (antibiotic) remains primarily in the gut. In this randomized, double-blind, placebo-controlled study, the safety, tolerability, and pharmacokinetics of single and multiple ascending doses of fidaxomicin were evaluated in healthy Japanese and Caucasian subjects.

Methods

Thirty-six healthy subjects were randomly assigned in a 3:1 ratio to receive either fidaxomicin or placebo. Cohort 1 (100 mg) and Cohort 2 (200 mg) comprised 12 Japanese subjects each and Cohort 3 (200 mg) comprised 12 Caucasian subjects. Subjects received a single dose of the study drug on Day 1 and received multiple doses for 10 days after a wash-out period.

Results

After multiple 200 mg dosing of fidaxomicin, both mean maximum plasma concentrations (C_max) in Japanese (8.7 ± 5.3 ng/mL) and Caucasian (7.0 ± 3.7 ng/mL) subjects and the area under the concentration–time curve (AUC) were higher in Japanese subjects (58.5 ± 36.7 ng·h/mL) than in Caucasian subjects (37.6 ± 15.7 ng·h/mL), although variation in both groups was large. The mean fecal concentrations of fidaxomicin in Japanese and Caucasian subjects were 2669 and 2181 μg/g, respectively. The possibly study drug-related adverse events were diarrhea (n = 1), feeling hot (n = 1), and hypersomnia (n = 2), which were mild in severity.

Conclusions

In both Japanese and Caucasian subjects, fidaxomicin demonstrated similarly minimal systemic absorption, and was mainly excreted in feces. Fidaxomicin was safe and well-tolerated in all subjects.

The Co-identity of Lipiarmycin A3 and Tiacumicin B

The co-identity of the antibiotics lipiarmycin A3 obtained from Actinoplanes deccanensis and tiacumicin B obtained from Dactylosporangium aurantiacum was unambiguously demonstrated through a number of experimental means. Spectroscopic analyses performed on both the antibiotics themselves and on their derivatives showed no difference between the two series of compounds. Moreover, unambiguous confirmation of the postulated identity of the two compounds was achieved by chemical degradation of lipiarmycin A3 and isolation of (3S,4R)-pentane-1,3,4-triol triacetate whose relative configuration was assigned by comparison with the authentic erythro and threo pentane-1,3,4-triol triacetates, obtained by chemical synthesis.

Controversies Around Epidemiology, Diagnosis and Treatment of Clostridium difficile Infection

Clostridium difficile infection is a major public health problem. However, in recent years the epidemiology, risk factors, diagnosis, and treatment of C. difficile infection have undergone a significant change. The incidence of C. difficile has increased, not only in the healthcare sector but also in the community. Hospital-acquired infection and community-acquired disease have different risk factors, with the latter occurring in children and younger individuals without a history of antibiotic use or previous infections. From a clinician's perspective, a quick efficient diagnosis is required for patient treatment; however, the old method of using enzyme immunoassays is insensitive and not very specific. Recent literature around diagnostic testing for C. difficile infection suggests using PCR or a two-step algorithm to improve sensitivity and specificity. More failures and recurrence with metronidazole have led to treatment algorithms suggesting its use for mild infections and switching to vancomycin if there is no clinical improvement. Alternatively, if signs and symptoms suggest severe infection, then oral vancomycin is recommended as a first-line agent. The addition of a new but costly agent, fidaxomicin, has seen some disparity between the European and North American guidelines with regard to when it should be used. Lastly, rapid developments and good results with fecal microbial transplantation have also left clinicians wondering about its place in therapy. This article reviews the literature around some of the recent controversies in the field of C. difficile infection.

Antibacterials Developed to Target a Single Organism: Mechanisms and Frequencies of Reduced Susceptibility to the Novel Anti-Clostridium difficile Compounds Fidaxomicin and LFF571

Clostridium difficile is the most common cause of antibacterial-associated diarrhea. Clear clinical presentation and rapid diagnostics enable targeted therapy for C. difficile infection (CDI) to start quickly. CDI treatment includes metronidazole and vancomycin (VAN). Despite decades of use for CDI, no clinically meaningful resistance to either agent has emerged. Fidaxomicin (FDX), an RNA polymerase inhibitor, is also approved to treat CDI. Mutants with reduced susceptibility to FDX have been selected in vitro by single and multistep methods. Strains with elevated FDX minimum inhibitory concentrations (MICs) were also identified from FDX-treated patients in clinical trials. LFF571 is an exploratory agent that inhibits EF-Tu. In a proof-of-concept study, LFF571 was safe and effective for treating CDI. Spontaneous mutants with reduced susceptibility to LFF571 were selected in vitro in a single step, but not via serial passage. Although there are several agents in development for treatment of CDI, this review summarizes the frequencies and mechanisms of C. difficile mutants displaying reduced susceptibility to FDX or LFF71.

Susceptibility of Clostridium difficile Isolates of Varying Antimicrobial Resistance Phenotypes to SMT19969 and 11 Comparators

We determined the in vitro activity of SMT19969 and 11 comparators, including metronidazole, vancomycin, and fidaxomicin, against 107 C. difficile isolates of different antimicrobial resistance phenotypes. Fidaxomicin and SMT19969 were the most active. The fidaxomicin and SMT19969 geometric mean MICs were highest in ribotypes known to show multiple resistance. Coresistance to linezolid and moxifloxacin was evident in ribotypes 001, 017, 027, and 356. The high-level ceftriaxone resistance in ribotypes 356 and 018 was location linked.

[Antibiotic treatment of clostridial colitis]

The advantages and disadvantages of various antibiotics used in the treatment of Clostridium difficile infection (CDI) are compared with respect to their pharmacokinetic and pharmacodynamic properties. Recommendations are made for their optimal use in clinical practice. Metronidazole is suitable for the treatment of mild forms of CDI which are essentially self-limiting. Vancomycin kills clostridia reliably but the treatment is encumbered with considerable risk of recurrence. This can be decreased by shortening the treatment to seven days and then switching to a (pulse, taper, chaser) regimen to prevent recurrence or by active restoration of the intestinal ecosystem (fecal transplant). Fidaxomicin works faster than vancomycin and is associated with a lower risk of recurrence. Thus, it can be profitably used in patients with impending ileus and also in those whose medical condition does not allow prolonged treatment. The duration of fidaxomicin treatment could be reduced to as few as five days. Rifaximin does not have a clear place in the treatment of CDI because no compelling data are available on its efficacy in this disease. The risk of resistance is also important. Tigecycline is a promising antibiotic for parenteral use. According to the available data, it should be more effective than intravenous metronidazole which has been considered the drug of choice.Clostridial colitis is associated with intestinal dysmicrobia which is the major cause of recurrence. Severe dysmicrobia cannot be treated by antibiotics but only by gut flora restoration; stool transplant from a healthy donor is the only proven therapy for this condition.

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.

Subinhibitory concentrations of LFF571 reduce toxin production by Clostridium difficile

LFF571 is a novel semisynthetic thiopeptide antibacterial that is undergoing investigation for safety and efficacy in patients with moderate Clostridium difficile infections. LFF571 inhibits bacterial protein synthesis by interacting with elongation factor Tu (EF-Tu) and interrupting complex formation between EF-Tu and aminoacyl-tRNA. Given this mechanism of action, we hypothesized that concentrations of LFF571 below those necessary to inhibit bacterial growth would reduce steady-state toxin levels in C. difficile cultures. We investigated C. difficile growth and toxin A and B levels in the presence of LFF571, fidaxomicin, vancomycin, and metronidazole. LFF571 led to strain-dependent effects on toxin production, including decreased toxin levels after treatment with subinhibitory concentrations, and more rapid declines in toxin production than in inhibition of colony formation. Fidaxomicin, which is an RNA synthesis inhibitor, conferred a similar pattern to LFF571 with respect to toxin levels versus viable cell counts. The incubation of two toxigenic C. difficile strains with subinhibitory concentrations of vancomycin, a cell wall synthesis inhibitor, increased toxin levels in the supernatant over those of untreated cultures. A similar phenomenon was observed with one metronidazole-treated strain of C. difficile. These studies indicate that LFF571 and fidaxomicin generally result in decreased C. difficile toxin levels in culture supernatants, whereas treatment of some strains with vancomycin or metronidazole had the potential to increase toxin levels. Although the relevance of these findings remains to be studied in patients, reducing toxin levels with sub-growth-inhibitory concentrations of an antibiotic is hypothesized to be beneficial in alleviating symptoms.

[Clostridium difficile infecion--diagnostics, prevention and treatment]

Clostridium difficile is the most common cause of an antibiotic-associated diarrhoea. Frequency of Clostridium difficile infections (CDI) increased in the last decade. This study presents current preventive measure i.e. hand washing, disposable gloves. Additionally, the article presents diagnostic methods: detection glutamine dehydrogenase (GDH), toxins A and B, cytotoxicity neutralization test, polymerase chain reaction methods (PCR) i.e. nucleic acid amplification test (NAAT) and stool culture. Moreover available methods of treatment were presented depending on severity of CDI e.i. metronidazole, vancomycin, fidaxomicin, rifaximin. Furthermore, the review provides information about alternative methods of treatment in view of new hypervirulent strains of C. difficile and increasing resistance to commonly used antibiotics, including: fuscid acid, bacitracin, probiotics, non-toxigenic strains, immunoglobulins, monoclonal antibodies, vaccines, toxins binders and fecal transplant.

The co-identity of lipiarmycin A3 and tiacumicin B

The co-identity of the antibiotics lipiarmycin A3 obtained from Actinoplanes deccanensis and tiacumicin B obtained from Dactylosporangium aurantiacum was unambiguously demonstrated through a number of experimental means. Spectroscopic analyses performed on both the antibiotics themselves and on their derivatives showed no difference between the two series of compounds. Moreover, unambiguous confirmation of the postulated identity of the two compounds was achieved by chemical degradation of lipiarmycin A3 and isolation of (3S,4R)-pentane-1,3,4-triol triacetate whose relative configuration was assigned by comparison with the authentic erythro and threo pentane-1,3,4-triol triacetates, obtained by chemical synthesis.

Diarylacylhydrazones: Clostridium-selective antibacterials with activity against stationary-phase cells

Current antibiotics for treating Clostridium difficile infections (CDI), that is, metronidazole, vancomycin and more recently fidaxomicin, are mostly effective but treatment failure and disease relapse remain as significant clinical problems. The shortcomings of these agents are attributed to their low selectivity for C. difficile over normal gut microflora and their ineffectiveness against C. difficile spores. This Letter reports that certain diarylacylhydrazones identified during a high-throughput screening/counter-screening campaign show selective activity against two Clostridium species (C. difficile and Clostridium perfringens) over common gut commensals. Representative examples are shown to possess activity similar to vancomycin against clinical C. difficile strains and to kill stationary-phase C. difficile cells, which are responsible for spore production. Structure-activity relationships with additional synthesised analogues suggested a protonophoric mechanism may play a role in the observed activity/selectivity and this was supported by the well-known protonophore carbonyl cyanide m-chlorophenyl hydrazone (CCCP) showing selective anti-Clostridium effects and activity similar to diarylacylhydrazones against stationary-phase C. difficile cells. Two diarylacylhydrazones were shown to be non-toxic towards human FaDu and Hep G2 cells indicating that further studies with the class are warranted towards new drugs for CDI.

First experience with Fidaxomicin use--case report]

Clostridium difficile infection (CDI) is an increasingly problem in everyday clinical practice. The most important risk factor of this infection is antibiotics use. The incidence of Clostridium difficile associated diarrhea (CDAD) in patients after renal transplantation is estimated to be about 6% in the early postoperative period. Due to the applied immunosuppression and frequent infections requiring intensive, broad spectral antibiotics, the later prevalence of CDAD may remain at a similar level. Massive diarrhea caused by Clostridium difficile may lead to fluctuations in immunosuppressive drugs concentration, in renal transplant patients. The authors present a case study of a 23-year old patient after kidney transplantation from deceased donor, with diagnosed polymorphic PTLD (Post-Transplant Lymphoproliferative Disorder). During biological treatment with rituximab in this patient 4 recurrences of CDI were observed. In this article the clinical manifestation of recurrent CDAD are presented. The authors discuss therapeutic procedure with fidaxomicin use, its results and influence on immunosuppressive drugs concentration.

In vitro selection, via serial passage, of Clostridium difficile mutants with reduced susceptibility to fidaxomicin or vancomycin

OBJECTIVES

Current treatments for Clostridium difficile infection include vancomycin, metronidazole and fidaxomicin. LFF571 is an experimental agent undergoing evaluation in humans for the treatment of moderate C. difficile infection. Reduced susceptibility of C. difficile to fidaxomicin or LFF571 in vitro can be mediated by single point mutations in genes encoding the targets, whereas the mechanism(s) mediating reduced susceptibility to vancomycin in vitro remains elusive. To further characterize mechanisms reducing susceptibility of C. difficile to vancomycin, fidaxomicin or LFF571 in vitro, selections via serial passage at low cell density were performed, followed by whole-genome sequencing.

METHODS

C. difficile strain ATCC 43255 and three clinical isolates were subjected to 10 passages on medium containing a range of concentrations of fidaxomicin, LFF571 or vancomycin. Genomic DNA from isolates with reduced susceptibility was sequenced using Illumina Whole Genome Sequencing.

RESULTS

Clones exhibiting decreased susceptibility to fidaxomicin harboured mutations in rpoB and CD22120 (marR homologue). Clones exhibiting decreased susceptibility to vancomycin harboured mutations in rpoC and also in CD2725, CD3659 and sdaB, which encode a putative N-acetylglucosamine transferase, exonuclease and l-serine deaminase, respectively. All mutations resulted in non-synonymous substitutions. No clones with reduced susceptibility to LFF571 were selected in this study.

CONCLUSIONS

Reduced susceptibility to fidaxomicin and vancomycin was associated with mutations mediating target modifications (RNA polymerase and cell wall, respectively), as well as with mutations that may contribute to reduced susceptibility via other mechanisms. The MIC of LFF571 was unaffected for those mutants with reduced susceptibility to fidaxomicin or vancomycin.

Diagnosis and management of Clostridium difficile infection

Clostridium difficile infection (CDI) is increasing in frequency and severity in and out of the hospital, with a high probability of recurrence after treatment. The recent literature on CDI was reviewed using PubMed to include recent publications dealing with diagnosis and therapy. Real-time polymerase chain reaction is a sensitive and useful diagnostic test for CDI but there are growing concerns of false-positive test results if the rate of CDI is low in the patient population providing samples and/or if the population being studied commonly includes people with C difficile colonization. Recommended therapy of CDI includes oral metronidazole for milder cases of CDI and oral vancomycin or fidaxomicin for more severe cases, each given for 10 days. Colectomy is being performed more frequently in patients with fulminant CDI. For treatment of first recurrences the drug used in the first bout can be used again and for second recurrences longer courses of vancomycin often are given in a tapered dose or intermittently to allow gut flora reconstitution, or other treatments including fidaxomicin may be used. Bacteriotherapy with fecal transplantation is playing an increasing role in therapy of recurrent cases. Metagenomic studies of patients with CDI during successful therapy are needed to determine how best to protect the flora from assaults from antibacterial drugs and to develop optimal therapeutic approaches. Immunotherapy and immunoprophylaxis offer opportunities to prevent CDI, to speed up recovery from CDI, and to eliminate recurrent infection. Humanized monoclonal antitoxin antibodies and active immunization with vaccines against C difficile or its toxins are both in development and appear to be of potential value.

Renal impairment and clinical outcomes of Clostridium difficile infection in two randomized trials

BACKGROUND/AIMS

Patients with chronic kidney disease (CKD) have increased risk for Clostridium difficile infection (CDI) and for subsequent mortality. We determined the effect of CKD on response to treatment for CDI.

METHODS

This is a post hoc analysis of two randomized controlled phase 3 trials that enrolled patients with CDI. Patients received either fidaxomicin 200 mg b.i.d. or vancomycin 125 mg q.i.d. for 10 days. Univariate and multivariate analyses compared end points by treatment received and CKD stage.

RESULTS

At baseline, 27, 21, and 9% of the patients had stage 2 (60-89 ml/min/1.73 m(2)), stage 3 (30-59), and stage 4 or higher (<30) CKD. Cure rates were similar for normal (91%) and stage 2 CKD (92%), but declined to 80% for stage 3 and to 75% for stage 4 CKD (p < 0.001 for trend). Time to resolution of diarrhea (TTROD) increased with stage 3 and stage 4 CKD. CDI recurrence rates 4 weeks after treatment were 16, 20, 27, and 24% for normal, stage 2, stage 3, and stage 4 or higher CKD, respectively. Mortality increased with CKD stage. In multivariate analyses, stage 3 or higher CKD correlated with lower odds of cure, greater chance of recurrence, and lower odds of sustained response 28 days after treatment. Initial cure rates were similar in the vancomycin or fidaxomicin groups; however, the rate of recurrence was higher following vancomycin treatment independent of renal function. The presence of immunosuppression did not alter this effect.

CONCLUSION

Progressive CKD is associated with increased TTROD, lower cure rates, and higher recurrence rates with treatment of CDI.

Antimicrobial activity of LFF571 and three treatment agents against Clostridium difficile isolates collected for a pan-European survey in 2008: clinical and therapeutic implications

OBJECTIVES

In November 2008, a study was performed with support from the European Centre for Disease Prevention and Control (ECDC) to obtain an overview of Clostridium difficile infections (CDIs) in European hospitals. A collection of 398 C. difficile isolates obtained from this hospital-based survey was utilized to identify antimicrobial susceptibility patterns of common C. difficile PCR ribotypes across Europe.

METHODS

The MICs of three approved therapeutic agents (vancomycin, metronidazole and fidaxomicin) and LFF571 (a novel semi-synthetic thiopeptide antibiotic) were determined by the agar dilution method.

RESULTS

MICs of fidaxomicin and LFF571 were in general 2-4-fold lower than those of vancomycin and metronidazole. Isolates belonging to clade 2, including the hypervirulent ribotype 027, had one-dilution higher MIC50 and MIC90 values for fidaxomicin and metronidazole, whereas similar MIC values were observed for vancomycin and LFF571. Isolates belonging to C. difficile PCR ribotype 001 were more susceptible to fidaxomicin than other frequently found PCR ribotypes 014/020 and 078. Six isolates from three different countries had a metronidazole MIC of 2 mg/L. Four of the six isolates were characterized as PCR ribotype 001.

CONCLUSIONS

There was no evidence of in vitro resistance of C. difficile to any of the four agents tested. However, the results suggest type-specific differences in susceptibility for the treatment agents we investigated. Continuous surveillance of C. difficile isolates in Europe is needed to determine the possible clinical implications of ribotype-specific changes in susceptibility to therapeutic agents.

Cost-effectiveness analysis evaluating fidaxomicin versus oral vancomycin for the treatment of Clostridium difficile infection in the United States

OBJECTIVES

Fidaxomicin is a novel treatment for Clostridium difficile infections (CDIs). This new treatment, however, is associated with a higher acquisition cost compared with alternatives. The objective of this study was to evaluate the cost-effectiveness of fidaxomicin or oral vancomycin for the treatment of CDIs.

METHODS

We performed a cost-utility analysis comparing fidaxomicin with oral vancomycin for the treatment of CDIs in the United States by creating a decision analytic model from the third-party payer perspective.

RESULTS

The incremental cost-effectiveness ratio with fidaxomicin compared with oral vancomycin was $67,576/quality-adjusted life-year. A probabilistic Monte Carlo sensitivity analysis showed that fidaxomicin had an 80.2% chance of being cost-effective at a willingness-to-pay threshold of $100,000/quality-adjusted life-year. Fidaxomicin remained cost-effective under all fluctuations of both fidaxomicin and oral vancomycin costs. The decision analytic model was sensitive to variations in clinical cure and recurrence rates. Secondary analyses revealed that fidaxomicin was cost-effective in patients receiving concominant antimicrobials, in patients with mild to moderate CDIs, and when compared with oral metronidazole in patients with mild to moderate disease. Fidaxomicin was dominated by oral vancomycin if CDI was caused by the NAP1/Bl/027 Clostridium difficile strain and was dominant in institutions that did not compound oral vancomycin.

CONCLUSION

Results of our model showed that fidaxomicin may be a more cost-effective option for the treatment of CDIs when compared with oral vancomycin under most scenarios tested.

[New treatment options for infections with Clostridium difficile]

Currently available broad spectrum antibiotics are not sufficiently effective against recurrent Clostridium difficile infections (CDI). Donor faecal microbiota transplantation is a very effective treatment for second and recurrent infection but is time-consuming and requires careful screening of donors. The new narrow spectrum antibiotic fidaxomicin is a good alternative in a first CDI or a first recurrence, but treatment is expensive and there are no data on its effectiveness in a second or later recurrence. Fidaxomicin is less effective against infections caused by the Ribotype 027 strain, a virulent strain that is regularly encountered in the Netherlands. The effectiveness of various other promising narrow spectrum antibiotics is currently being investigated. Medications that support the gut flora or the immune system seem to offer new perspectives. Expectations for the currently available probiotic preparations and toxin binders are not high.

Fidaxomicin versus vancomycin for Clostridium difficile infection: meta-analysis of pivotal randomized controlled trials

Two recently completed phase 3 trials (003 and 004) showed fidaxomicin to be noninferior to vancomycin for curing Clostridium difficile infection (CDI) and superior for reducing CDI recurrences. In both studies, adults with active CDI were randomized to receive blinded fidaxomicin 200 mg twice daily or vancomycin 125 mg 4 times a day for 10 days. Post hoc exploratory intent-to-treat (ITT) time-to-event analyses were undertaken on the combined study 003 and 004 data, using fixed-effects meta-analysis and Cox regression models. ITT analysis of the combined 003/004 data for 1164 patients showed that fidaxomicin reduced persistent diarrhea, recurrence, or death by 40% (95% confidence interval [CI], 26%–51%; P < .0001) compared with vancomycin through day 40. A 37% (95% CI, 2%–60%; P = .037) reduction in persistent diarrhea or death was evident through day 12 (heterogeneity P = .50 vs 13–40 days), driven by 7 (1.2%) fidaxomicin versus 17 (2.9%) vancomycin deaths at <12 days. Low albumin level, low eosinophil count, and CDI treatment preenrollment were risk factors for persistent diarrhea or death at 12 days, and CDI in the previous 3 months was a risk factor for recurrence (all P < .01). Fidaxomicin has the potential to substantially improve outcomes from CDI.

Fidaxomicin for the treatment of Clostridium difficile infections

Clostridium difficile infection (CDI), also known as C. difficile-associated disease or diarrhoea (CDAD), is an important cause of hospital-acquired diarrhoea with disease severity ranging from mild diarrhoea to fulminant colitis. In addition, over 40% of new cases of CDI occur outside hospital. ▾ Fidaxomicin (Dificlir - Astellas), the first antibiotic in a new class called macrocyclics, has recently been licensed for the treatment of C. difficile infection in adults. Here we provide a brief overview of C. difficile infection and assess how fidaxomicin fits with current management strategies for treatment of such infections.

Fidaxomicin for Clostridium difficile-associated diarrhoea: epidemiological method for estimation of warranted price

BACKGROUND

Fidaxomicin is a macrocyclic antibiotic approved in 2011 by the US Food and Drug Administration for treatment of Clostridium difficile-associated diarrhoea (CDAD).

OBJECTIVE

Herein, we present an epidemiological method to estimate, on a case mix basis, and from the perspective of the US health system, the warranted (justifiable) price per day for fidaxomicin, as a percent of the wholesale acquisition cost (WAC) per day for fidaxomicin ($US280).

METHODS

Data from two randomized controlled studies (Optimer-003 [n = 596] and Optimer-004 [n = 509]) were used to discern the number-needed-to-treat (NNT = 7.1) for sustained clinical response. Sustained clinical response was defined as clinical response at the end of treatment, and survival without proven or suspected CDAD recurrence through 25 days beyond the end of treatment. National data for primary and secondary cases (the case mix) of CDAD (mean hospital length of stay [LOS], and mean cost) were derived from the 2009 US Healthcare Cost and Utilization Project. The method for attribution of hospital LOS for secondary cases of CDAD was derived from a study published by O'Brien et al. in 2007. Comparative regimens of vancomycin were: (i) injectable used orally, 125 mg four times daily (qid; WAC of $US6/day), with use of vancomycin hydrochloride (HCl) capsules, 125 mg qid (WAC of $US106/day) post-hospital discharge; (ii) vancomycin HCl capsules, 125 mg qid; and (iii) vancomycin HCl capsules, 250 mg qid (WAC of $US196/day). Findings are expressed in 2011 US dollars. The study perspective is that of the US health system.

RESULTS

The warranted price per day for fidaxomicin represented 95% of the WAC per day for fidaxomicin compared with use of injectable vancomycin (orally) 125 mg qid (with subsequent use of vancomycin HCl capsules, 125 mg qid post-hospital discharge); 109% of the WAC per day for fidaxomicin compared with use of vancomycin HCl capsules, 125 mg qid; and 141% of the WAC per day for fidaxomicin when compared with use of vancomycin HCl capsules, 250 mg qid.

CONCLUSION

From the perspective of the US health system, fidaxomicin represents value for money in the treatment of CDAD. The methodology employed in this research has application beyond antimicrobial pharmacotherapy.