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Targeting Helicobacter pylori for antibacterial drug discovery with novel therapeutics. Curr Opin Microbiol 2022; 70:102203. [PMID: 36156373 DOI: 10.1016/j.mib.2022.102203] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 08/11/2022] [Accepted: 08/16/2022] [Indexed: 01/25/2023]
Abstract
Helicobacter pylori is an important human pathogen with increasing antimicrobial resistance to standard-of-care antibiotics. Treatment generally includes a combination of classical broad-spectrum antibiotics and a proton-pump inhibitor, which often leads to perturbation of the gut microbiome and the potential for the development of antibiotic resistance. In this review, we examine reports, primarily from the past decade, on the discovery of new anti-H. pylori therapeutics, including approaches to develop narrow-spectrum and mechanistically unique antibiotics to treat these infections in their gastric niche. Compound series that target urease, respiratory complex I, and menaquinone biosynthesis are discussed in this context, along with bivalent antibiotic approaches that suppress resistance development. With increases in the understanding of the unique physiology of H. pylori and technological advances in the field of antibacterial drug discovery, there is a clear promise that novel therapeutics can be developed to effectively treat H. pylori infections.
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2
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Jain E, Zaenker EI, Hoffman PS, Warren CA. In vitro activity of amixicile against T. vaginalis from clinical isolates. Parasitol Res 2022; 121:2453-2455. [PMID: 35676563 PMCID: PMC9745912 DOI: 10.1007/s00436-022-07567-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/31/2022] [Indexed: 12/15/2022]
Abstract
Trichomoniasis is a sexually transmitted infection in humans caused by the protozoan Trichomonas vaginalis, the leading causative agent of vaginitis in women and urethritis in men worldwide. Metronidazole is the standard treatment for trichomoniasis, with tinidazole as the second line. There are currently no FDA-approved non-nitroimidazole alternative treatments for resistant strains. This study compares the efficacy of a newly synthesized non-nitroimidazole oral drug, amixicile, to that of both metronidazole and the synthetic precursor of amixicile, nitazoxanide with in vitro sensitivity testing. One standard strain from ATCC and three patient-isolated strains of T. vaginalis were used to compare treatments under anaerobic conditions. The minimum inhibitory concentration for metronidazole, nitazoxanide, and amixicile were 12.5 μM, 100 μM, and 6.25 μM, respectively. These results suggest that amixicile may be highly active against T. vaginalis and warrants further investigation as a potential alternative to metronidazole in the treatment of trichomoniasis.
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Affiliation(s)
- Eisha Jain
- Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Edna I. Zaenker
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, VA
| | - Paul S. Hoffman
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, VA
| | - Cirle A. Warren
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, VA
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Gui Q, Lyons DJ, Deeb JG, Belvin BR, Hoffman PS, Lewis JP. Non-human Primate Macaca mulatta as an Animal Model for Testing Efficacy of Amixicile as a Targeted Anti-periodontitis Therapy. FRONTIERS IN ORAL HEALTH 2022; 2:752929. [PMID: 35048063 PMCID: PMC8757802 DOI: 10.3389/froh.2021.752929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 09/30/2021] [Indexed: 01/15/2023] Open
Abstract
Periodontitis is an inflammatory condition triggered by selected oral microbiota; thus treatment strategies should be aimed at reducing the abundance of the pathogenic bacteria. An obstacle to preclinical testing of such strategies is the availability of reliable animal models. Here, a non-human primate (NHP), Macaca mulatta, was used to examine the effectiveness of a novel antimicrobial, amixicile, which inhibits pyruvate–ferredoxin oxidoreductase (PFOR) present in anaerobic bacteria. Animals were assessed for their periodontal health, including radiography, clinical attachment loss (CAL), presence of plaque (PI), bleeding on probing (BOP) and pocket depth (PD), and sampled for saliva, gingival crevicular fluid (GCF), and subgingival plaque to determine their baseline clinical status. Amixicile was then administered for 2 weeks (40 mg/kg/day) and the animals were monitored for periodontal health immediately after the antibiotic treatment, then at 1 month-, 3 months-, and 6-months posttreatment. Microbial species present in plaque and saliva were determined through 16S rDNA sequencing. Baseline assessment of the microbiome has shown a significant proportion of bacteria belonging to the Streptococcus, Haemophilus, Porphyromonas, Gemella, and Fusobacterium genera. The abundance of Porphyromonas and Fusobacterium was reduced following treatment with amixicile, whereas that of Escherichia, Haemophilus, and Gemella were elevated. CAL, PD, and BOP were also significantly reduced following the treatment. In conclusion, the NHP model proves useful for preclinical studies of strategies targeting selected members of the oral microbiome. We show that amixicile reduces the levels of anaerobic bacteria under in vivo conditions, correlating with a reduction in CAL, PD, and BOP, thus validating its usefulness as an antimicrobial strategy.
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Affiliation(s)
- Qin Gui
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, United States
| | - Denver J Lyons
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, United States.,Department of Periodontics, Virginia Commonwealth University, Richmond, VA, United States
| | - Janina Golob Deeb
- Department of Periodontics, Virginia Commonwealth University, Richmond, VA, United States
| | - B Ross Belvin
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, United States
| | - Paul S Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, United States
| | - Janina P Lewis
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, VA, United States.,Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, United States.,Department of Biochemistry, Virginia Commonwealth University, Richmond, VA, United States
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4
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Gui Q, Ramsey KW, Hoffman PS, Lewis JP. Amixicile depletes the ex vivo periodontal microbiome of anaerobic bacteria. J Oral Biosci 2020; 62:195-204. [PMID: 32278683 DOI: 10.1016/j.job.2020.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 12/23/2022]
Abstract
OBJECTIVES Although periodontal diseases result from overgrowth of anaerobic bacteria, the effect of a specific knockdown of anaerobes on the disease outcome has yet to be examined. We have reported that amixicile, a non-toxic, readily bioavailable, and novel antimicrobial, specifically targets selected oral anaerobes through inhibition of the activity of pyruvate ferredoxin oxidoreductase (PFOR), a major enzyme mediating oxidative decarboxylation of pyruvate. METHODS Here, we generated an ex vivo microbiome derived from gingival pockets of human subjects with chronic periodontal disease and evaluated the efficacy of amixicile in generating a specific knockdown of anaerobic bacteria present in the microbiome. RESULTS Our bioinformatics analysis identified PFOR-like coding capacity in over 100 genomes available from the HOMD database. Many of those bacteria were present in our ex vivo microbiome. Significantly, the anaerobic pathogens relying on PFOR for energy generation were specifically reduced in abundance following treatment with amixicile while non-PFOR bacteria were spared. Specifically, Prevotella, Veillonella, Slackia, Porphyromonas, Treponema, Megasphera, and Atobium were reduced in abundance. Such treatment resulted in the conversion of a microbiome resembling a microbiome derived from sites with periodontal disease to one resembling a microbiome present at healthy sites. We also compared the inhibitory spectrum of amixicile to that of metronidazole and showed that the antibiotics have a similar inhibitory spectrum. CONCLUSIONS This work further demonstrates that amixicile has the potential to reverse and prevent the outgrowth of anaerobic pathogens observed in subjects with periodontal disease.
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Affiliation(s)
- Qin Gui
- Philips Institute for Oral Health Research, Virginia Commonwealth University, 521 North 11th Street, Richmond, VA, 23298, USA.
| | - Kane W Ramsey
- Philips Institute for Oral Health Research, Virginia Commonwealth University, 521 North 11th Street, Richmond, VA, 23298, USA; Department of Periodontics, Virginia Commonwealth University, 521 North 11th Street, Richmond, VA, 23298, USA.
| | - Paul S Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA.
| | - Janina P Lewis
- Philips Institute for Oral Health Research, Virginia Commonwealth University, 521 North 11th Street, Richmond, VA, 23298, USA; Department of Microbiology and Immunology, Virginia Commonwealth University, 521 North 11th Street, Richmond, VA, 23298, USA; Department of Biochemistry Virginia Commonwealth University, Richmond, VA, USA.
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5
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Gui Q, Hoffman PS, Lewis JP. Amixicile targets anaerobic bacteria within the oral microbiome. J Oral Biosci 2019; 61:226-235. [PMID: 31706024 PMCID: PMC7550198 DOI: 10.1016/j.job.2019.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 10/13/2019] [Accepted: 10/21/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVES Anaerobic bacteria are the major causative agents of periodontal disease. However, so far, targeted therapy aimed at reducing those pathogens has not been widely implemented. We have previously reported on a novel antimicrobial, amixicile, that targets anaerobic bacteria through inhibition of the function of the major anaerobic metabolic enzyme pyruvate ferredoxin oxidoreductase (PFOR), while not affecting aerotolerant organisms. It effectively inhibited the growth of oral anaerobes both in monocultures as well as in mixed in vitro mixed cultured however, amixicile's activity in in vivo-like conditions remained to be established. METHODS Here, we expand our study using an ex vivo oral microbiome combined with metagenomic sequencing to determine the effect of amixicile treatment on the composition of the microbiome and compare it to that of metronidazole. RESULTS Our results show that in the complex microbiomes, anaerobic bacteria are selectively inhibited, while the growth of aerotolerant ones, such as Streptococcus, Klebsiella, Neisseria, and Rothia is unaffected. Veillonella was the most abundant anaerobic genus in our ex vivo microbiome, and we observed complete inhibition of its growth. In addition, growth of other anaerobes, Fusobacterium and Prevotella, was significantly inhibited. It is noteworthy that a change in abundance of bacteriophages, such as Siphoviridae and Myoviridae, associated with the oral microbiome was observed. CONCLUSIONS Collectively, our data expand on the so far reported inhibitory spectrum of amixicile and demonstrates that it inhibits anaerobic bacteria, including both clinical isolates and laboratory strains.
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Affiliation(s)
- Qin Gui
- Philips Institute of Oral Health Research, Richmond, VA, USA
| | - Paul S Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
| | - Janina P Lewis
- Philips Institute of Oral Health Research, Richmond, VA, USA; Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA, USA; Department of Biochemistry, Virginia Commonwealth University, Richmond, VA, USA.
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Bartelt LA, Bolick DT, Kolling GL, Stebbins E, Huston CD, Guerrant RL, Hoffman PS. Amixicile Reduces Severity of Cryptosporidiosis but Does Not Have In Vitro Activity against Cryptosporidium. Antimicrob Agents Chemother 2018; 62:e00718-18. [PMID: 30297368 PMCID: PMC6256802 DOI: 10.1128/aac.00718-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 09/28/2018] [Indexed: 12/13/2022] Open
Abstract
Cryptosporidium species cause significant morbidity in malnourished children. Nitazoxanide (NTZ) is the only approved treatment for cryptosporidiosis, but NTZ has diminished effectiveness during malnutrition. Here, we show that amixicile, a highly selective water-soluble derivative of NTZ diminishes Cryptosporidium infection severity in a malnourished mouse model despite a lack of direct anticryptosporidial activity. We suggest that amixicile, by tamping down anaerobes associated with intestinal inflammation, reverses weight loss and indirectly mitigates infection-associated pathology.
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Affiliation(s)
- Luther A Bartelt
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Center for Gastrointestinal Biology and Disease, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - David T Bolick
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Glynis L Kolling
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Erin Stebbins
- Division of Infectious Diseases, Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Christopher D Huston
- Division of Infectious Diseases, Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Richard L Guerrant
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Paul S Hoffman
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
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Reed LA, O'Bier NS, Oliver LD, Hoffman PS, Marconi RT. Antimicrobial activity of amixicile against Treponema denticola and other oral spirochetes associated with periodontal disease. J Periodontol 2018; 89:1467-1474. [PMID: 29958324 DOI: 10.1002/jper.17-0185] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 04/29/2018] [Accepted: 05/30/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Periodontal disease is a polymicrobial infection characterized by inflammation of the gingiva, alveolar bone resorption and tooth loss. As periodontal disease progresses, oral treponemes (spirochetes) become dominant bacteria in periodontal pockets. Oral treponemes are anaerobes and all encode the enzyme pyruvate-ferredoxin oxidoreductase (PFOR) which catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA. Here we assess the susceptibility of oral treponemes to amixicile (AMIX), a novel inhibitor of PFOR. METHODS The minimum inhibitory concentration (MIC) of AMIX against several oral treponeme species was determined. The impact of AMIX on processes relevant to virulence including motility, H2 S production, and complement evasion were determined. RESULTS The growth of all oral treponeme species tested was inhibited by AMIX with MIC concentrations (MIC) ranging from 0.5-1.5 μg/mL. AMIX significantly reduced motility, caused a dose-dependent decrease in hydrogen sulfide production and increased sensitivity to killing by human complement (i.e., serum sensitivity). CONCLUSIONS AMIX is effective in vitro in inhibiting growth and other processes central to virulence. AMIX could serve could serve as a new selective therapeutic tool for the treatment of periodontal disease.
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Affiliation(s)
- Lucas A Reed
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA
| | - Nathaniel S O'Bier
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA
| | - Lee D Oliver
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA
| | - Paul S Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, VA
| | - Richard T Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA
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Gil F, Calderón IL, Fuentes JA, Paredes-Sabja D. Clostridioides (Clostridium) difficile infection: current and alternative therapeutic strategies. Future Microbiol 2018; 13:469-482. [PMID: 29464969 DOI: 10.2217/fmb-2017-0203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Clostridioides difficile (C. difficile) has become a pathogen of worldwide importance considering that epidemic strains are disseminated in hospitals of several countries, where community-acquired infections act as a constant source of new C. difficile strains into hospitals. Despite the advances in the treatment of infections, more effective therapies against C. difficile are needed but, at the same time, these therapies should be less harmful to the resident gastrointestinal microbiota. The purpose of this review is to present a description of issues associated to C. difficile infection, a summary of current therapies and those in developmental stage, and a discussion of potential combinations that may lead to an increased efficacy of C. difficile infection treatment.
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Affiliation(s)
- Fernando Gil
- Microbiota-Host Interactions & Clostridia Research Group, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, 8370035, Chile
| | - Iván L Calderón
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, 8370035, Chile
| | - Juan A Fuentes
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, 8370035, Chile
| | - Daniel Paredes-Sabja
- Microbiota-Host Interactions & Clostridia Research Group, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, 8370035, Chile
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9
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Hutcherson JA, Sinclair KM, Belvin BR, Gui Q, Hoffman PS, Lewis JP. Amixicile, a novel strategy for targeting oral anaerobic pathogens. Sci Rep 2017; 7:10474. [PMID: 28874750 PMCID: PMC5585216 DOI: 10.1038/s41598-017-09616-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 07/24/2017] [Indexed: 01/27/2023] Open
Abstract
The oral microflora is composed of both health-promoting as well as disease-initiating bacteria. Many of the disease-initiating bacteria are anaerobic and include organisms such as Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Tannerella forsythia. Here we investigated a novel therapeutic, amixicile, that targets pyruvate:ferredoxin oxidoreductase (PFOR), a major metabolic enzyme involved in energy generation through oxidative decarboxylation of pyruvate. PFOR is present in these anaerobic pathogenic bacteria and thus we hypothesized that amixicile would effectively inhibit their growth. In general, PFOR is present in all obligate anaerobic bacteria, while oral commensal aerobes, including aerotolerant ones, such as Streptococcus gordonii, use pyruvate dehydrogenase to decarboxylate pyruvate. Accordingly, we observed that growth of the PFOR-containing anaerobic periodontal pathogens, grown in both monospecies as well as multispecies broth cultures was inhibited in a dose-dependent manner while that of S. gordonii was unaffected. Furthermore, we also show that amixicile is effective against these pathogens grown as monospecies and multispecies biofilms. Finally, amixicile is the first selective therapeutic agent active against bacteria internalized by host cells. Together, the results show that amixicile is an effective inhibitor of oral anaerobic bacteria and as such, is a good candidate for treatment of periodontal diseases.
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Affiliation(s)
- Justin A Hutcherson
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Kathryn M Sinclair
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Benjamin R Belvin
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
- Department of Biochemistry, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Qin Gui
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Paul S Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA
| | - Janina P Lewis
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.
- Department of Biochemistry, Virginia Commonwealth University, Richmond, Virginia, USA.
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Fehér C, Soriano A, Mensa J. A Review of Experimental and Off-Label Therapies for Clostridium difficile Infection. Infect Dis Ther 2017; 6:1-35. [PMID: 27910000 PMCID: PMC5336415 DOI: 10.1007/s40121-016-0140-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Indexed: 12/16/2022] Open
Abstract
In spite of increased awareness and the efforts taken to optimize Clostridium difficile infection (CDI) management, with the limited number of currently available antibiotics for C. difficile the halt of this increasing epidemic remains out of reach. There are, however, close to 80 alternative treatment methods with controversial anti-clostridial efficacy or in experimental phase today. Indeed, some of these therapies are expected to become acknowledged members of the recommended anti-CDI arsenal within the next few years. None of these alternative treatment methods can respond in itself to all the major challenges of CDI management, which are primary prophylaxis in the susceptible population, clinical cure of severe cases, prevention of recurrences, and forestallment of asymptomatic C. difficile carriage and in-hospital spread. Yet, the greater the variety of treatment choices on hand, the better combination strategies can be developed to reach these goals in the future. The aim of this article is to provide a comprehensive summary of these experimental and currently off-label therapeutic options.
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Affiliation(s)
- Csaba Fehér
- Department of Infectious Diseases, Hospital Clínic of Barcelona, Barcelona, Spain.
| | - Alex Soriano
- Department of Infectious Diseases, Hospital Clínic of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- University of Barcelona, Barcelona, Spain
| | - Josep Mensa
- Department of Infectious Diseases, Hospital Clínic of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
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Role of Serum Amyloid A, Granulocyte-Macrophage Colony-Stimulating Factor, and Bone Marrow Granulocyte-Monocyte Precursor Expansion in Segmented Filamentous Bacterium-Mediated Protection from Entamoeba histolytica. Infect Immun 2016; 84:2824-32. [PMID: 27456830 DOI: 10.1128/iai.00316-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/18/2016] [Indexed: 02/07/2023] Open
Abstract
Intestinal segmented filamentous bacteria (SFB) protect from ameba infection, and protection is transferable with bone marrow dendritic cells (BMDCs). SFB cause an increase in serum amyloid A (SAA), suggesting that SAA might mediate SFB's effects on BMDCs. Here we further explored the role of bone marrow in SFB-mediated protection. Transient gut colonization with SFB or SAA administration alone transiently increased the H3K27 histone demethylase Jmjd3, persistently increased bone marrow Csf2ra expression and granulocyte monocyte precursors (GMPs), and protected from ameba infection. Pharmacologic inhibition of Jmjd3 H3K27 demethylase activity during SAA treatment or blockade of granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling in SFB-colonized mice prevented GMP expansion, decreased gut neutrophils, and blocked protection from ameba infection. These results indicate that alteration of the microbiota and systemic exposure to SAA can influence myelopoiesis and susceptibility to amebiasis via epigenetic mechanisms. Gut microbiota-marrow communication is a previously unrecognized mechanism of innate protection from infection.
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12
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Synthesis and Antimicrobial Evaluation of Amixicile-Based Inhibitors of the Pyruvate-Ferredoxin Oxidoreductases of Anaerobic Bacteria and Epsilonproteobacteria. Antimicrob Agents Chemother 2016; 60:3980-7. [PMID: 27090174 DOI: 10.1128/aac.00670-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 04/11/2016] [Indexed: 01/04/2023] Open
Abstract
Amixicile is a promising derivative of nitazoxanide (an antiparasitic therapeutic) developed to treat systemic infections caused by anaerobic bacteria, anaerobic parasites, and members of the Epsilonproteobacteria (Campylobacter and Helicobacter). Amixicile selectively inhibits pyruvate-ferredoxin oxidoreductase (PFOR) and related enzymes by inhibiting the function of the vitamin B1 cofactor (thiamine pyrophosphate) by a novel mechanism. Here, we interrogate the amixicile scaffold, guided by docking simulations, direct PFOR inhibition assays, and MIC tests against Clostridium difficile, Campylobacter jejuni, and Helicobacter pylori Docking simulations revealed that the nitro group present in nitazoxanide interacts with the protonated N4'-aminopyrimidine of thiamine pyrophosphate (TPP). The ortho-propylamine on the benzene ring formed an electrostatic interaction with an aspartic acid moiety (B456) of PFOR that correlated with improved PFOR-inhibitory activity and potency by MIC tests. Aryl substitution with electron-withdrawing groups and substitutions of the propylamine with other alkyl amines or nitrogen-containing heterocycles both improved PFOR inhibition and, in many cases, biological activity against C. difficile Docking simulation results correlate well with mechanistic enzymology and nuclear magnetic resonance (NMR) studies that show members of this class of antimicrobials to be specific inhibitors of vitamin B1 function by proton abstraction, which is both novel and likely to limit mutation-based drug resistance.
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