lff571 and Enterocolitis--Pseudomembranous

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.. 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.. 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.. 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.

Topics: Aminoglycosides; Anti-Bacterial Agents; Clostridioides difficile; Clostridium Infections; Cross Infection; Enterocolitis, Pseudomembranous; Europe; Fidaxomicin; Humans; Metronidazole; Microbial Sensitivity Tests; Multilocus Sequence Typing; Polymerase Chain Reaction; Ribotyping; Thiazoles; Treatment Outcome; Vancomycin

Clostridium difficile (C. difficile) is a Gram positive, anaerobic bacterium that infects the lumen of the large intestine and produces toxins. This results in a range of syndromes from mild diarrhea to severe toxic megacolon and death. Alarmingly, the prevalence and severity of C. difficile infection are increasing; thus, associated morbidity and mortality rates are rising. 4-Aminothiazolyl analogues of the antibiotic natural product GE2270 A (1) were designed, synthesized, and optimized for the treatment of C. difficile infection. The medicinal chemistry effort focused on enhancing aqueous solubility relative to that of the natural product and previous development candidates (2, 3) and improving antibacterial activity. Structure-activity relationships, cocrystallographic interactions, pharmacokinetics, and efficacy in animal models of infection were characterized. These studies identified a series of dicarboxylic acid derivatives, which enhanced solubility/efficacy profile by several orders of magnitude compared to previously studied compounds and led to the selection of LFF571 (4) as an investigational new drug for treating C. difficile infection.

Topics: Animals; Anti-Bacterial Agents; Clostridioides difficile; Cricetinae; Crystallography, X-Ray; Enterococcus; Enterocolitis, Pseudomembranous; Escherichia coli Proteins; Female; Male; Mesocricetus; Mice; Microbial Sensitivity Tests; Models, Molecular; Molecular Structure; Peptide Elongation Factor Tu; Rats; Rats, Sprague-Dawley; Solubility; Staphylococcus aureus; Streptococcus pyogenes; Structure-Activity Relationship; Thiazoles; Water

The in vitro activities of LFF571, a novel analog of GE2270A that inhibits bacterial growth by binding with high affinity for protein synthesis elongation factor Tu, fidaxomicin, and 10 other antimicrobial agents were determined against 50 strains of Clostridium difficile and 630 other anaerobic and aerobic organisms of intestinal origin. LFF571 possesses potent activity against C. difficile and most other Gram-positive anaerobes (MIC(90), ≤ 0.25 μg/ml), with the exception of bifidobacteria and lactobacilli. The MIC(90)s for aerobes, including enterococci, Staphylococcus aureus (as well as methicillin-resistant S. aureus [MRSA] isolates), Streptococcus pyogenes, and other streptococci were 0.06, 0.125, 2, and 8 μg/ml, respectively. Comparatively, fidaxomicin showed variable activity against Gram-positive organisms: MIC(90)s against C. difficile, Clostridium perfringens, and Bifidobacterium spp. were 0.5, ≤ 0.015, and 0.125 μg/ml, respectively, but >32 μg/ml against Clostridium ramosum and Clostridium innocuum. MIC(90) for S. pyogenes and other streptococci was 16 and >32 μg/ml, respectively. LFF571 and fidaxomicin were generally less active against Gram-negative anaerobes.

Topics: Aminoglycosides; Anti-Bacterial Agents; Bacteria, Aerobic; Bacteria, Anaerobic; Clostridioides difficile; Enterocolitis, Pseudomembranous; Fidaxomicin; Humans; Intestines; Microbial Sensitivity Tests; Microbial Viability; Peptide Elongation Factor Tu; Protein Biosynthesis; Species Specificity; Thiazoles

LFF571 is a novel semisynthetic thiopeptide antibiotic with potent activity against a variety of Gram-positive pathogens, including Clostridium difficile. In vivo efficacy of LFF571 was compared to vancomycin in a hamster model of C. difficile infection (CDI). Infection was induced in Golden Syrian hamsters using a toxigenic strain of C. difficile. Treatment started 24 h postinfection and consisted of saline, vancomycin, or LFF571. Cox regression was used to analyze survival data from a cohort of animals evaluated across seven serial experimental groups treated with vancomycin at 20 mg/kg, LFF571 at 5 mg/kg, or vehicle alone. Survival was right censored; animals were not observed beyond day 21. At death or end of study, cecal contents were tested for C. difficile toxins A and B. In summary, the data showed that 5 mg/kg LFF571 decreased the risk of death by 79% (P < 0.0001) and 69% (P = 0.0022) compared with saline and 20 mg/kg vancomycin, respectively. Further analysis of the pooled data indicated that the survival benefit of LFF571 treatment at 5 mg/kg compared to vancomycin at 20 mg/kg was due primarily to a decrease in the risk of recurrence after end of treatment. Animals successfully treated with LFF571 or vancomycin had no detectable C. difficile toxin. Overall, LFF571 was more efficacious at the end of the study, at a lower dose, and with fewer recurrences, than vancomycin in the hamster model of CDI. LFF571 is being assessed in humans for safety and efficacy in the treatment of C. difficile infections.

Topics: Animals; Anti-Bacterial Agents; Bacterial Proteins; Bacterial Toxins; Clostridioides difficile; Cricetinae; Enterocolitis, Pseudomembranous; Enterotoxins; Male; Mesocricetus; Recurrence; Thiazoles; Vancomycin

LFF571 is a novel semisynthetic thiopeptide and potent inhibitor of Gram-positive bacteria. We report that the antibacterial activity of LFF571 against Clostridium difficile is due to inhibition of translation. Single-step mutants of C. difficile with reduced susceptibility to LFF571 were selected at frequencies of <4.5 × 10(-11) to 1.2 × 10(-9). Sequencing revealed a G260E substitution in the thiopeptide-binding pocket of elongation factor Tu. Importantly, this mutation did not confer cross-resistance to clinically used antimicrobials. These results support the development of LFF571 as a treatment for C. difficile infection.

Topics: Anti-Bacterial Agents; Binding Sites; Clostridioides difficile; Drug Resistance, Bacterial; Enterocolitis, Pseudomembranous; Humans; Microbial Sensitivity Tests; Peptide Chain Elongation, Translational; Peptide Elongation Factor Tu; Protein Structure, Tertiary; Thiazoles