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Fidaxomicin (Fdx) is widely used to treat Clostridioides difficile ( Cdiff ) infections, but the molecular basis of its narrow-spectrum activity in the human gut microbiome remains unknown. Cdiff infections are a leading cause of nosocomial deaths 1 . Fidaxomicin, which inhibits RNA polymerase, targets Cdiff with minimal effects on gut commensals, reducing recurrence of Cdiff infection 2 , 3 . Here we present the cryo-electron microscopy structure of Cdiff RNA polymerase in complex with fidaxomicin and identify a crucial fidaxomicin-binding determinant of Cdiff RNA polymerase that is absent in most gut microbiota such as Proteobacteria and Bacteroidetes. By combining structural, biochemical, genetic and bioinformatic analyses, we establish that a single residue in Cdiff RNA polymerase is a sensitizing element for fidaxomicin narrow-spectrum activity. Our results provide a blueprint for targeted drug design against an important human pathogen. Structural analysis of Clostridioides difficile RNA polymerase in complex with fidaxomicin combined with biochemical, genetic and bioinformatic analyses identifies a key residue that determines fidaxomicin sensitivity.

The emergence of drug‐resistant viruses and novel strains necessitates the rapid development of novel antiviral therapies. This need was particularly demanding during the COVID‐19 pandemic. While de novo drug development is a time‐consuming process, repurposing existing approved medications offers a more expedient approach. In our prior in silico screening of the DrugBank database, fidaxomicin emerged as a potential SARS‐CoV‐2 papain‐like protease inhibitor. This study extends those findings by investigating fidaxomicin‘s antiviral properties in vitro. Our results support further exploration of fidaxomicin as a therapeutic candidate against SARS‐CoV‐2, given its promising in vitro antiviral activity and favorable safety profile.

Fidaxomicin is an oral narrow-spectrum novel 18-membered macrocyclic antibiotic that was initially approved in 2011 by the US FDA for the treatment of infections (CDI) in adults. In February 2020, the FDA approved fidaxomicin for the treatment of CDI in children age >6 months. In adults, fidaxomicin is as efficacious as vancomycin in treating CDI and reduces the risk of recurrent CDI. An investigator-blinded, randomized, multicenter, multinational clinical trial comparing the efficacy and safety of fidaxomicin with vancomycin in children was recently published confirming similar findings as previously reported in adults. Fidaxomicin is the first FDA-approved treatment for CDI in children and offers a promising option for reducing recurrent CDI in this population.

Given the crucial roles of carbohydrates in energy supply, biochemical processes, signaling events and the pathogenesis of several diseases, the development of carbohydrate analogues, called glycomimetics, is a key research area in Glycobiology, Pharmacology, and Medicinal Chemistry. Among the many structural transformations explored, the replacement of endo- and exocyclic oxygen atoms by carbon (carbasugars) or heteroatoms, such as nitrogen (aza- and iminosugars), phosphorous (phosphasugars), sulfur (thiosugars), selenium (selenosugars) or tellurium (tellurosugars) have garnered significant attention. These isosteric substitutions can modulate the carbohydrate bioavailability, stability, and bioactivity, while introducing new properties, such as redox activity, interactions with pathological lectins and enzymes, or cytotoxic effects. In this manuscript we have focused on three major families of glycomimetics: thio-, seleno-, and tellurosugars. We provide a comprehensive review of the most relevant synthetic pathways leading to substitutions primarily at the endocyclic and glycosidic positions. The scope includes metal-catalyzed reactions, organocatalysis, electro- and photochemical transformations, free-radical processes, and automated syntheses. Additionally, mechanistic insights, stereoselectivity, and biological properties are also discussed. The structural diversity and promising bioactivities of these glycomimetics underscore their significance in this research area.

Infection with Clostridium difficile is the primary infective cause of antibiotic-associated diarrhoea. We aimed to compare efficacy and safety of fidaxomicin and vancomycin to treat patients with C difficile infection in Europe, Canada, and the USA. In this multicentre, double-blind, randomised, non-inferiority trial, we enrolled patients from 45 sites in Europe and 41 sites in the USA and Canada between April 19, 2007, and Dec 11, 2009. Eligible patients were aged 16 years or older with acute, toxin-positive C difficile infection. Patients were randomly allocated (1:1) to receive oral fidaxomicin (200 mg every 12 h) or oral vancomycin (125 mg every 6 h) for 10 days. The primary endpoint was clinical cure, defined as resolution of diarrhoea and no further need for treatment. An interactive voice-response system and computer-generated randomisation schedule gave a randomisation number and medication kit number for each patient. Participants and investigators were masked to treatment allocation. Non-inferiority was prespecified with a margin of 10%. Modified intention-to-treat and per-protocol populations were analysed. This study is registered with ClinicalTrials.gov, number NCT00468728. Of 535 patients enrolled, 270 were assigned fidaxomicin and 265 vancomycin. After 26 patients were excluded, 509 were included in the modified intention-to-treat (mITT) population. 198 (91·7%) of 216 patients in the per-protocol population given fidaxomicin achieved clinical cure, compared with 213 (90·6%) of 235 given vancomycin, meeting the criterion for non-inferiority (one-sided 97·5% CI −4·3%). Non-inferiority was also shown for clinical cure in the mITT population, with 221 (87·7%) of 252 patients given fidaxomicin and 223 (86·8%) of 257 given vancomycin cured (one-sided 97·5% CI −4·9%). In most subgroup analyses of the primary endpoint in the mITT population, outcomes in the two treatment groups did not differ significantly; although patients receiving concomitant antibiotics for other infections had a higher cure rate with fidaxomicin (46 [90·2%] of 51) than with vancomycin (33 [73·3%] of 45; p=0·031). Occurrence of treatment-emergent adverse events did not differ between groups. 20 (7·6%) of 264 patients given at least one dose of fidaxomicin and 17 (6·5%) of 260 given vancomycin died. Fidaxomicin could be an alternative treatment for infection with C difficile, with similar efficacy and safety to vancomycin. Optimer Pharmaceuticals.

In this randomized trial of fidaxomicin as compared with vancomycin in 629 patients, oral fidaxomicin was shown to be noninferior to oral vancomycin in the treatment of C. difficile infection and was associated with lower rates of recurrence. Clostridium difficile infection generally occurs after exposure to broad-spectrum antibiotics. The incidence and severity of C. difficile infection are increasing. The increases have been ascribed to the emergence of a hypervirulent C. difficile strain, known variously as North American Pulsed Field type 1 (NAP1), restriction-endonuclease analysis (REA) type BI, or polymerase-chain-reaction ribotype 027 (referred to collectively as the NAP1/BI/027 strain). 1 – 4 Furthermore, the rates of death associated with C. difficile infection are rising, 5 – 7 and the infection is occurring in populations that were previously considered to be at low risk, such as young, healthy persons living in the community and . . .

The emergence of antimicrobic-resistant infectious pathogens and the consequent rising in the incidence and prevalence of demises caused by or associated to infections which are not sensitive to drug treatments is one of today's major global health challenges. Antimicrobial resistance (AMR) can bring to therapeutic failure, infection’s persistence and risk of serious illness, in particular in vulnerable populations such as the elderly, patients with neoplastic diseases or the immunocompromised. It is assessed that AMR will induce until 10 million deaths per year by 2050, becoming the leading cause of disease-related deaths. The World Health Organisation (WHO) and the United Nations General Assembly urgently call for new measures to combat the phenomenon. Research and development of new antimicrobial agents has decreased due to market failure. However, promising results are coming from new alternative therapeutic strategies such as monoclonal antibodies, microbiome modulators, nanomaterial-based therapeutics, vaccines, and phages. This narrative review aimed to analyse the benefits and weaknesses of alternative therapeutic strategies to antibiotics which treat multidrug-resistant bacterial infections.

In clinical practice, imiquimod is used to treat Human Papillomavirus (HPV)-related lesions, such as condyloma and Cervical Intraepithelial Neoplasia (CIN). Metronidazole is the most commonly prescribed antibiotic for bacterial vaginosis. The study developed biodegradable imiquimod- and metronidazole-loaded nanofibrous mats and assessed their effectiveness for the topical treatment of cervical cancer, a type of HPV-related lesion. Nanofibers of two distinct poly[(d,l)-lactide- -glycolide] (PLGA)-to-drug ratios (6:1 and 4:1) were manufactured through the electrospinning technology. The in vitro release behavior of imiquimod and metronidazole was evaluated via an elution method, while the in vivo discharge behavior was evaluated on a mice model. Additionally, a model of cervical cancer was established using C57BL/6J mice, and it was utilized to evaluate the efficacy of drug-eluting nanofibers through in vivo testing. Mice afflicted with cervical cancer were separated into three distinct groups for the study: The mice in Group A served as the control and received no treatment. Group B received treatment with pure PLGA nanofibers (no drugs loaded), whereas Group C received treatment with nanofibers loaded with imiquimod and metronidazole. Post implantation, the variations in tumor sizes of rats receiving the implantation of drug-eluting nanofibers were monitored. The experimental data show that drug-eluting nanofibers could discharge in vitro high concentrations of imiquimod and metronidazole for exceeding 30 days. In vivo, each membrane consistently released elevated concentrations of imiquimod/metronidazole at the intended site in mice over a four-week period, with minimal systemic drug concentration detected in the bloodstream. The mice treated with drug-loaded nanofibers displayed noticeably reduced tumor volumes compared to both the control group and the group treated with pristine nanofibers. Histological examination revealed the absence of any discernible tissue inflammation. Biodegradable nanofibers with a sustainable release of imiquimod and metronidazole demonstrated their effectiveness and lasting impact of treating mice with cervical cancer.

Recurrence of Clostridium difficile infection (CDI) occurs in approximately 25% of successfully treated patients. Two phase 3 randomized, double-blind trials were conducted at 154 sites in the United States, Canada, and Europe to compare fidaxomicin vs vancomycin in treating CDI. Patients with CDI received fidaxomicin 200 mg twice daily or vancomycin 125 mg 4 times daily for 10 days. The primary end point was clinical cure of CDI at end of treatment, and a secondary end point was recurrence during the 28 days following clinical cure. In all, 1164 subjects were enrolled, of which a subgroup of 128 in the per-protocol population had another recent episode of CDI prior to the CDI diagnosis at study enrollment. In the analysis of this subgroup, initial response to therapy was similar for both drugs (>90% cure). However, recurrence within 28 days occurred in 35.5% of patients treated with vancomycin and 19.7% of patients treated with fidaxomicin (-15.8% difference; 95% confidence interval, -30.4% to -0.3%; P = .045). Early recurrence (within 14 days) was reported in 27% of patients treated with vancomycin and 8% of patients treated with fidaxomicin (P = .003). In patients with a first recurrence of CDI, fidaxomicin was similar to vancomycin in achieving a clinical response at end of therapy but superior in preventing a second recurrence within 28 days. Clinical Trials Registration. NCT00314951 and NCT00468728.

Natural products have multifarious bioactivities against bacteria, fungi, viruses, cancers and other diseases due to their diverse structures. Nearly 65% of anticancer drugs are natural products or their derivatives. Thus, natural products play significant roles in clinical cancer therapy. With the development of biosynthetic technologies, an increasing number of natural products have been discovered and developed as candidates for clinical cancer therapy. Here, we aim to summarize the anticancer natural products approved from 1950 to 2021 and discuss their molecular mechanisms. We also describe the available synthetic biology tools and highlight their applications in the development of natural products.