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1.
Infect Immun ; 92(4): e0001824, 2024 Apr 09.
Article in English | MEDLINE | ID: mdl-38514468

ABSTRACT

Borrelia burgdorferi, the spirochetal agent of Lyme disease, utilizes a variety of strategies to evade and suppress the host immune response, which enables it to chronically persist in the host. The resulting immune response is characterized by unusually strong IgM production and a lack of long-term protective immunity. Previous studies in mice have shown that infection with B. burgdorferi also broadly suppresses host antibody responses against unrelated antigens. Here, we show that mice infected with B. burgdorferi and concomitantly immunized with recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein had an abrogated antibody response to the immunization. To further define how long this humoral immune suppression lasts, mice were immunized at 2, 4, and 6 weeks post-infection. Suppression of host antibody production against the SARS-CoV-2 spike protein peaked at 2 weeks post-infection but continued for all timepoints measured. Antibody responses against the SARS-CoV-2 spike protein were also assessed following antibiotic treatment to determine whether this immune suppression persists or resolves following clearance of B. burgdorferi. Host antibody production against the SARS-CoV-2 spike protein returned to baseline following antibiotic treatment; however, anti-SARS-CoV-2 IgM remained high, comparable to levels found in B. burgdorferi-infected but untreated mice. Thus, our data demonstrate restored IgG responses following antibiotic treatment but persistently elevated IgM levels, indicating lingering effects of B. burgdorferi infection on the immune system following treatment.


Subject(s)
Borrelia burgdorferi , Lyme Disease , Spike Glycoprotein, Coronavirus , Mice , Humans , Animals , Immunity, Humoral , Immunoglobulin M , Anti-Bacterial Agents , Antibodies, Bacterial
2.
Cell Rep Med ; 4(11): 101253, 2023 11 21.
Article in English | MEDLINE | ID: mdl-37918405

ABSTRACT

Colonization of the gut and airways by pathogenic bacteria can lead to local tissue destruction and life-threatening systemic infections, especially in immunologically compromised individuals. Here, we describe an mRNA-based platform enabling delivery of pathogen-specific immunoglobulin A (IgA) monoclonal antibodies into mucosal secretions. The platform consists of synthetic mRNA encoding IgA heavy, light, and joining (J) chains, packaged in lipid nanoparticles (LNPs) that express glycosylated, dimeric IgA with functional activity in vitro and in vivo. Importantly, mRNA-derived IgA had a significantly greater serum half-life and a more native glycosylation profile in mice than did a recombinantly produced IgA. Expression of an mRNA encoded Salmonella-specific IgA in mice resulted in intestinal localization and limited Peyer's patch invasion. The same mRNA-LNP technology was used to express a Pseudomonas-specific IgA that protected from a lung challenge. Leveraging the mRNA antibody technology as a means to intercept bacterial pathogens at mucosal surfaces opens up avenues for prophylactic and therapeutic interventions.


Subject(s)
Mucous Membrane , Peyer's Patches , Mice , Animals , Immunoglobulin A , Antibodies, Monoclonal
3.
Pharmaceutics ; 15(2)2023 Jan 29.
Article in English | MEDLINE | ID: mdl-36839766

ABSTRACT

Lung metastasis is a leading cause of cancer-related deaths. Here, we show that intranasal delivery of our engineered CpG-coated tumor antigen (Tag)-encapsulated nanoparticles (NPs)-nasal nano-vaccine-significantly reduced lung colonization by intravenous challenge of an extra-pulmonary tumor. Protection against tumor-cell lung colonization was linked to the induction of localized mucosal-associated effector and resident memory T cells as well as increased bronchiolar alveolar lavage-fluid IgA and serum IgG antibody responses. The nasal nano-vaccine-induced T-cell-mediated antitumor mucosal immune response was shown to increase tumor-specific production of IFN-γ and granzyme B by lung-derived CD8+ T cells. These findings demonstrate that our engineered nasal nano-vaccine has the potential to be used as a prophylactic approach prior to the seeding of tumors in the lungs, and thereby prevent overt lung metastases from existing extra pulmonary tumors.

4.
Pharmaceuticals (Basel) ; 17(1)2023 Dec 28.
Article in English | MEDLINE | ID: mdl-38256885

ABSTRACT

A hallmark of effective cancer treatment is the prevention of tumor reoccurrence and metastasis to distal organs, which are responsible for most cancer deaths. However, primary tumor resection is expected to be curative as most solid tumors have been shown both experimentally and clinically to accelerate metastasis to distal organs including the lungs. In this study, we evaluated the efficacy of our engineered nasal nano-vaccine (CpG-NP-Tag) in reducing accelerated lung metastasis resulting from primary tumor resection. Cytosine-phosphate-guanine oligonucleotide [CpG ODN]-conjugated nanoparticle [NP] encapsulating tumor antigen [Tag] (CpG-NP-Tag) was manufactured and tested in vivo using a syngeneic mouse mammary tumor model following intranasal delivery. We found that our nasal nano-vaccine (CpG-NP-Tag), compared to control NPs administered after primary mammary tumor resection, significantly reduced lung metastasis in female BALB/c mice subjected to surgery (surgery mice). An evaluation of vaccine efficacy in both surgery and non-surgery mice revealed that primary tumor resection reduces CD11b+ monocyte-derived suppressor-like cell accumulation in the lungs, allowing increased infiltration of vaccine-elicited T cells (IFN-γ CD8+ T cells) in the lungs of surgery mice compared to non-surgery mice. These findings suggest that the combination of the target delivery of a nasal vaccine in conjunction with the standard surgery of primary tumors is a plausible adjunctive treatment against the establishment of lung metastasis.

5.
J Med Chem ; 65(6): 4481-4495, 2022 03 24.
Article in English | MEDLINE | ID: mdl-35175750

ABSTRACT

TNP-2198, a stable conjugate of a rifamycin pharmacophore and a nitroimidazole pharmacophore, has been designed, synthesized, and evaluated as a novel dual-targeted antibacterial agent for the treatment of microaerophilic and anaerobic bacterial infections. TNP-2198 exhibits greater activity than a 1:1 molar mixture of the parent drugs and exhibits activity against strains resistant to both rifamycins and nitroimidazoles. A crystal structure of TNP-2198 bound to a Mycobacterium tuberculosis RNA polymerase transcription initiation complex reveals that the rifamycin portion of TNP-2198 binds to the rifamycin binding site on RNAP and the nitroimidazole portion of TNP-2198 interacts directly with the DNA template-strand in the RNAP active-center cleft, forming a hydrogen bond with a base of the DNA template strand. TNP-2198 is currently in Phase 2 clinical development for the treatment of Helicobacter pylori infection, Clostridioides difficile infection, and bacterial vaginosis.


Subject(s)
Helicobacter Infections , Helicobacter pylori , Nitroimidazoles , Rifamycins , Anaerobiosis , DNA-Directed RNA Polymerases , Humans , Nitroimidazoles/pharmacology
6.
J Med Chem ; 64(14): 10155-10166, 2021 07 22.
Article in English | MEDLINE | ID: mdl-34191513

ABSTRACT

A major antimicrobial resistance mechanism in Gram-negative bacteria is the production of ß-lactamase enzymes. The increasing emergence of ß-lactamase-producing multi-drug-resistant "superbugs" has resulted in increases in costly hospital Emergency Department (ED) visits and hospitalizations due to the requirement for parenteral antibiotic therapy for infections caused by these difficult-to-treat bacteria. To address the lack of outpatient treatment, we initiated an iterative program combining medicinal chemistry, biochemical testing, microbiological profiling, and evaluation of oral pharmacokinetics. Lead optimization focusing on multiple smaller, more lipophilic active compounds, followed by an exploration of oral bioavailability of a variety of their respective prodrugs, provided 36 (VNRX-7145/VNRX-5236 etzadroxil), the prodrug of the boronic acid-containing ß-lactamase inhibitor 5 (VNRX-5236). In vitro and in vivo studies demonstrated that 5 restored the activity of the oral cephalosporin antibiotic ceftibuten against Enterobacterales expressing Ambler class A extended-spectrum ß-lactamases, class A carbapenemases, class C cephalosporinases, and class D oxacillinases.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Discovery , Enterobacteriaceae/drug effects , beta-Lactamase Inhibitors/pharmacology , beta-Lactamases/metabolism , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Dose-Response Relationship, Drug , Enterobacteriaceae/enzymology , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , beta-Lactamase Inhibitors/chemical synthesis , beta-Lactamase Inhibitors/chemistry
7.
Antimicrob Agents Chemother ; 65(8): e0055221, 2021 07 16.
Article in English | MEDLINE | ID: mdl-34001510

ABSTRACT

There is an urgent need for oral agents to combat resistant Gram-negative pathogens. Here, we describe the characterization of VNRX-5236, a broad-spectrum boronic acid ß-lactamase inhibitor (BLI), and its orally bioavailable etzadroxil prodrug, VNRX-7145. VNRX-7145 is being developed in combination with ceftibuten, an oral cephalosporin, to combat strains of Enterobacterales expressing extended-spectrum ß-lactamases (ESBLs) and serine carbapenemases. VNRX-5236 is a reversible covalent inhibitor of serine ß-lactamases, with inactivation efficiencies on the order of 104 M-1 · sec-1, and prolonged active site residence times (t1/2, 5 to 46 min). The spectrum of inhibition includes Ambler class A ESBLs, class C cephalosporinases, and class A and D carbapenemases (KPC and OXA-48, respectively). Rescue of ceftibuten by VNRX-5236 (fixed at 4 µg/ml) in isogenic strains of Escherichia coli expressing class A, C, or D ß-lactamases demonstrated an expanded spectrum of activity relative to oral comparators, including investigational penems, sulopenem, and tebipenem. VNRX-5236 rescued ceftibuten activity in clinical isolates of Enterobacterales expressing ESBLs (MIC90, 0.25 µg/ml), KPCs (MIC90, 1 µg/ml), class C cephalosporinases (MIC90, 1 µg/ml), and OXA-48-type carbapenemases (MIC90, 1 µg/ml). Frequency of resistance studies demonstrated a low propensity for recovery of resistant variants at 4× the MIC of the ceftibuten/VNRX-5236 combination. In vivo, whereas ceftibuten alone was ineffective (50% effective dose [ED50], >128 mg/kg), ceftibuten/VNRX-7145 administered orally protected mice from lethal septicemia caused by Klebsiella pneumoniae producing KPC carbapenemase (ED50, 12.9 mg/kg). The data demonstrate potent, broad-spectrum rescue of ceftibuten activity by VNRX-5236 in clinical isolates of cephalosporin-resistant and carbapenem-resistant Enterobacterales.


Subject(s)
Cephalosporins , beta-Lactamase Inhibitors , Animals , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Bacterial Proteins , Carbapenems/pharmacology , Ceftibuten , Cephalosporins/pharmacology , Mice , Microbial Sensitivity Tests , Serine , beta-Lactamase Inhibitors/pharmacology , beta-Lactamases/genetics
8.
J Infect Dis ; 224(8): 1394-1397, 2021 10 28.
Article in English | MEDLINE | ID: mdl-33588433

ABSTRACT

Coadministration of human secretory IgA (sIgA) together with subtherapeutic vancomycin enhanced survival in the Clostridioides difficile infection (CDI) hamster model. Vancomycin (5 or 10 mg/kg × 5 days) plus healthy donor plasma sIgA/monomeric IgA (TID × 21 days) or hyperimmune sIgA/monomeric IgA (BID × 13 days) enhanced survival. Survival was improved compared to vancomycin alone, P = .018 and .039 by log-rank Mantel-Cox, for healthy and hyperimmune sIgA, respectively. Passive immunization with sIgA (recombinant human secretory component plus IgA dimer/polymer from pooled human plasma) can be administered orally and prevents death in a partially treated CDI hamster model.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Clostridioides difficile , Clostridium Infections/therapy , Immunoglobulin A, Secretory/therapeutic use , Immunotherapy/methods , Vancomycin/therapeutic use , Animals , Cricetinae , Humans , Immunoglobulin A , Immunologic Factors
9.
BMC Microbiol ; 20(1): 27, 2020 02 05.
Article in English | MEDLINE | ID: mdl-32024477

ABSTRACT

BACKGROUND: Clostridioides difficile infections have become more frequently diagnosed and associated with greater disease severity, which has resulted in an increase burden on the healthcare system. These increases are attributed to the increased prevalence of hypervirulent strains encompassing select ribotypes. These epidemic ribotypes were characterized as hypervirulent due to higher in vitro spore and toxin production, as well as increased incidence, severity and mortality within patients. However, it is unclear whether epidemic ribotypes are truly more virulent than non-epidemic ribotypes in vivo. Furthermore, there is conflicting evidence about the ability of a strain's in vitro phenotype to be predictive of their in vivo virulence. The goals of the current studies were to determine if epidemic ribotypes are more virulent than other ribotypes in animal models, and whether the in vitro virulence phenotype of an isolate or ribotype predict in vivo virulence. RESULTS: To determine if epidemic strains were truly more virulent than other non-epidemic strains, the in vivo virulence of 13 C. difficile isolates (7 non-epidemic and 6 epidemic ribotype isolates) were determined in murine and hamster models of CDI. The isolates of epidemic ribotype of C. difficile were found to be more virulent in both the murine and hamster models than non-epidemic isolates. In particular, the group of epidemic ribotypes of C. difficile had lower LD50 values in hamsters. The increased severity of disease was associated with higher levels of Toxin A and Toxin B production found in fecal samples, but not numbers of organisms recovered. The isolates were further characterized for their in vitro virulence phenotypes, e.g. toxin production, growth rates, spore formation and adherence of spores to intestinal epithelial cell lines. Although there were higher levels of toxins produced and greater adherence for the group of epidemic ribotypes, the in vitro profiles of individual isolates were not always predictive of their in vivo virulence. CONCLUSIONS: Overall, the group of epidemic ribotypes of C. difficile were more virulent in vivo despite individual isolates having similar phenotypes to the non-epidemic isolates in vitro.


Subject(s)
Clostridioides difficile/classification , Clostridioides difficile/pathogenicity , Clostridium Infections/mortality , Ribotyping/methods , Animals , Bacterial Adhesion , Bacterial Proteins/metabolism , Bacterial Toxins/metabolism , Caco-2 Cells , Clostridioides difficile/genetics , Clostridium Infections/epidemiology , Clostridium Infections/microbiology , Cricetinae , Disease Models, Animal , Enterotoxins/metabolism , Epidemics , Feces/chemistry , Female , Humans , Lethal Dose 50 , Male , Mice , Mortality , Virulence
10.
Article in English | MEDLINE | ID: mdl-31636067

ABSTRACT

Fluoroquinolone treatments induce dysbiosis of the intestinal microbiota, resulting in loss of resistance to colonization by exogenous bacteria such as Clostridioides difficile that may cause severe diarrhea in humans and lethal infection in hamsters. We show here that DAV131A, a charcoal-based adsorbent, decreases the intestinal levels of the fluoroquinolone antibiotics levofloxacin and ciprofloxacin in hamsters, protects their intestinal microbiota, and prevents lethal infection by C. difficile.


Subject(s)
Charcoal/administration & dosage , Clostridioides difficile , Clostridium Infections/prevention & control , Administration, Oral , Adsorption , Animals , Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/pharmacokinetics , Ciprofloxacin/adverse effects , Ciprofloxacin/pharmacokinetics , Clostridioides difficile/pathogenicity , Disease Models, Animal , Dysbiosis/chemically induced , Dysbiosis/metabolism , Dysbiosis/prevention & control , Fluoroquinolones/adverse effects , Fluoroquinolones/pharmacokinetics , Gastrointestinal Microbiome/drug effects , Levofloxacin/adverse effects , Levofloxacin/pharmacokinetics , Male , Mesocricetus
11.
PLoS One ; 14(8): e0220646, 2019.
Article in English | MEDLINE | ID: mdl-31415582

ABSTRACT

C. difficile is an endospore-forming pathogen, which is becoming a common cause of microbial health-care associated gastrointestinal disease in the United States. Both healthy and symptomatic patients can shed C. difficile spores into the environment, which can survive for long periods, being resistant to desiccation, heat, and disinfectants. In healthcare facilities, environmental contamination with C. difficile is a major concern as a potential source of exposure to this pathogen and risk of disease in susceptible patients. Although hospital-acquired infection is recognized, community-acquired infection is an increasingly recognized health problem. Primary care clinics may be a significant source of exposure to this pathogen; however, there are limited data about presence of environmental C. difficile within clinics. To address the potential for primary care clinics as a source of environmental exposure to virulent C. difficile, we measured the frequency of environmental contamination with spores in clinic examination rooms and hospital rooms in Dallas-Fort Worth (DFW) area of Texas. The ribotypes and presence of toxin genes from some environmental isolates were compared. Our results indicate primary care clinics have higher frequencies of contamination than hospitals. After notification of the presence of C. difficile spores in the clinics and an educational discussion to emphasize the importance of this infection and methods of infection prevention, environmental contamination in clinics was reduced on subsequent sampling to that found in hospitals. Thus, primary care clinics can be a source of exposure to virulent C. difficile, and recognition of this possibility can result in improved infection prevention, potentially reducing community-acquired C. difficile infections and subsequent disease.


Subject(s)
Clostridioides difficile/isolation & purification , Clostridium Infections/prevention & control , Cross Infection/prevention & control , Health Facilities , Humans , Primary Health Care , Texas
12.
Sci Rep ; 9(1): 2904, 2019 02 27.
Article in English | MEDLINE | ID: mdl-30814582

ABSTRACT

In Gram-negative bacterial sepsis, production of excess pro-inflammatory cytokines results in hyperinflammation and tissue injury. Anti-inflammatory cytokines such as IL-10 inhibit inflammation and enhance tissue healing. Here, we report a novel approach to treat septicemia associated with intra-abdominal infection in a murine model by delicately balancing pro- and anti-inflammatory cytokines. A novel oligosaccharide compound AVR-25 selectively binds to the TLR4 protein (IC50 = 0.15 µM) in human peripheral blood monocytes and stimulates IL-10 production. Following the cecal ligation and puncture (CLP) procedure, intravenous dosing of AVR-25 (10 mg/kg, 6-12 h post-CLP) alone and in combination with antibiotic imipenem protected both young adult (10-12 week old) and aged (16-18 month old) mice against polymicrobial infection, organ dysfunction, and death. Proinflammatory cytokines (TNF-α, MIP-1, i-NOS) were decreased significantly and restoration of tissue damage was observed in all organs. A decrease in serum C-reactive protein (CRP) and bacterial colony forming unit (CFU) confirmed improved bacterial clearance. Together, these findings demonstrate the therapeutic ability of AVR-25 to mitigate the storm of inflammation and minimize tissue injury with high potential for adjunctive therapy in intra-abdominal sepsis.


Subject(s)
Aging/physiology , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Chitin/therapeutic use , Gram-Negative Bacterial Infections/drug therapy , Intraabdominal Infections/drug therapy , Leukocytes, Mononuclear/drug effects , Oligosaccharides/therapeutic use , Sepsis/prevention & control , Animals , Cecum/surgery , Cells, Cultured , Chitin/chemistry , Cytokines/metabolism , Disease Models, Animal , Gram-Negative Bacterial Infections/complications , Humans , Inflammation Mediators/metabolism , Intraabdominal Infections/complications , Leukocytes, Mononuclear/physiology , Mice , Mice, Inbred C57BL , Oligosaccharides/chemistry , Sepsis/etiology , Toll-Like Receptor 4/metabolism
13.
Toxins (Basel) ; 11(2)2019 02 06.
Article in English | MEDLINE | ID: mdl-30736358

ABSTRACT

Toxin-induced Clostridium difficile infection (CDI) is a major disease characterized by severe diarrhea and high morbidity rates. The aim with this study was to develop an alternative drug for the treatment of CDI. Cows were repeatedly immunized to establish specific immunoglobulin G and A titers against toxins A (TcdA) and B (TcdB) and against C. difficile cells in mature milk or colostrum. The effect of three different concentrations of anti-C. difficile whey protein isolates (anti-CD-WPI) and the standard of care antibiotic vancomycin were investigated in an animal model of CD infected hamsters (6 groups, with 10 hamsters each). WPI obtained from the milk of exactly the same cows pre-immunization and a vehicle group served as negative controls. The survival of hamsters receiving anti-CD-WPI was 50, 80 and 100% compared to 10 and 0% for the control groups, respectively. Vancomycin suppressed the growth of C. difficile and thus protected the hamsters at the time of administration, but 90% of these hamsters nevertheless died shortly after discontinuation of treatment. In contrast, the surviving hamsters of the anti-CD-WPI groups survived the entire study period, although they were treated for only 75 h. The specific antibodies not only inactivated the toxins for initial suppression of CDI, but also provoked the inhibition of C. difficile growth after discontinuation, thus preventing recurrence. Oral administration of anti-CD-WPI is a functional therapy of CDI in infected hamsters for both primary treatment and prevention of recurrence. Thus, anti-CD-WPI could address the urgent unmet medical need for treating and preventing recurrent CDI in humans.


Subject(s)
Antibodies/therapeutic use , Bacterial Proteins/immunology , Bacterial Toxins/immunology , Clostridium Infections/therapy , Enterotoxins/immunology , Whey Proteins/therapeutic use , Animals , Bacterial Vaccines/administration & dosage , Cattle , Clostridium Infections/prevention & control , Cricetinae , Disease Models, Animal , Female , Male , Milk/immunology , Pregnancy
14.
Article in English | MEDLINE | ID: mdl-30670434

ABSTRACT

Lantibiotics present an attractive scaffold for the development of novel antibiotics. We report here a novel lantibiotic for the treatment of Clostridium difficile infection. The lead compounds were selected from a library of over 700 single- and multiple-substitution variants of the lantibiotic mutacin 1140 (MU1140). The best performers in vitro and in vivo were further used to challenge Golden Syrian hamsters orally in a Golden Syrian hamster model of Clostridium difficile-associated disease (CDAD) in a dose-response format, resulting in the selection of OG716 as the lead compound. This lantibiotic was characterized by a 50% effective dose of 23.85 mg/kg of body weight/day (10.97 µmol/kg/day) in this model. Upon oral administration of the maximum feasible dose (≥1,918 mg/kg/day), no observable toxicities or side effects were noted, and no effect on intestinal motility was observed. Compartmentalization to the gastrointestinal tract was confirmed. MU1140-derived variants offer a large pipeline for the development of novel antibiotics for the treatment of several indications and are particularly attractive considering their novel mechanism of action. Based on the currently available data, OG716 has an acceptable profile for further development for the treatment of CDAD.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteriocins/pharmacology , Clostridium Infections/drug therapy , Administration, Oral , Animals , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/chemistry , Bacteriocins/administration & dosage , Bacteriocins/adverse effects , Bacteriocins/chemistry , Biological Availability , Cecum/microbiology , Clostridium Infections/mortality , Colony Count, Microbial , Dose-Response Relationship, Drug , Female , Gastric Emptying/drug effects , Male , Maximum Tolerated Dose , Mesocricetus , Rats, Wistar
15.
Article in English | MEDLINE | ID: mdl-30061286

ABSTRACT

Antibiotic disruption of the intestinal microbiota favors colonization by Clostridium difficile Using a charcoal-based adsorbent to decrease intestinal antibiotic concentrations, we studied the relationship between antibiotic concentrations in feces and the intensity of dysbiosis and quantified the link between this intensity and mortality. We administered either moxifloxacin (n = 70) or clindamycin (n = 60) to hamsters by subcutaneous injection from day 1 (D1) to D5 and challenged them with a C. difficile toxigenic strain at D3 Hamsters received various doses of a charcoal-based adsorbent, DAV131A, to modulate intestinal antibiotic concentrations. Gut dysbiosis was evaluated at D0 and D3 using diversity indices determined from 16S rRNA gene profiling. Survival was monitored until D16 We analyzed the relationship between fecal antibiotic concentrations and dysbiosis at the time of C. difficile challenge and studied their capacity to predict subsequent death of the animals. Increasing doses of DAV131A reduced fecal concentrations of both antibiotics, lowered dysbiosis, and increased survival from 0% to 100%. Mortality was related to the level of dysbiosis (P < 10-5 for the change of Shannon index in moxifloxacin-treated animals and P < 10-9 in clindamycin-treated animals). The Shannon diversity index and unweighted UniFrac distance best predicted death, with areas under the receiver operating curve (ROC) of 0.89 (95% confidence interval [CI], 0.82, 0.95) and 0.95 (0.90, 0.98), respectively. Altogether, moxifloxacin and clindamycin disrupted the diversity of the intestinal microbiota with a dependency on the DAV131A dose; mortality after C. difficile challenge was related to the intensity of dysbiosis in similar manners with the two antibiotics.


Subject(s)
Anti-Bacterial Agents/adverse effects , Clostridium Infections/drug therapy , Clostridium Infections/mortality , Dysbiosis/chemically induced , Animals , Anti-Bacterial Agents/therapeutic use , Clindamycin/therapeutic use , Clostridioides difficile/drug effects , Clostridioides difficile/pathogenicity , Cricetinae , Dysbiosis/mortality , Gastrointestinal Microbiome/drug effects , Male , Mesocricetus , Moxifloxacin/therapeutic use
16.
PLoS One ; 13(6): e0197467, 2018.
Article in English | MEDLINE | ID: mdl-29894469

ABSTRACT

Lantibiotics continue to offer an untapped pipeline for the development of novel antibiotics. We report here the discovery of a novel lantibiotic for the treatment of C. difficile infection (CDI). The leads were selected from a library of over 300 multiple substitution variants of the lantibiotic Mutacin 1140 (MU1140). Top performers were selected based on testing for superior potency, solubility, manufacturability, and physicochemical and/or metabolic stability in biologically-relevant systems. The best performers in vitro were further evaluated orally in the Golden Syrian hamster model of CDAD. In vivo testing ultimately identified OG716 as the lead compound, which conferred 100% survival and no relapse at 3 weeks post infection. MU1140-derived variants are particularly attractive for further clinical development considering their novel mechanism of action.


Subject(s)
Bacteriocins/administration & dosage , Clostridioides difficile/drug effects , Clostridium Infections/drug therapy , Animals , Clostridioides difficile/pathogenicity , Clostridium Infections/microbiology , Cricetinae , Disease Models, Animal , Humans , Mesocricetus
17.
Front Microbiol ; 9: 415, 2018.
Article in English | MEDLINE | ID: mdl-29615987

ABSTRACT

Lantibiotics offer an untapped pipeline for the development of novel antibiotics to treat serious Gram-positive (+) infections including Clostridium difficile. Mutacin 1140 (MU1140) is a lantibiotic produced by Streptococcus mutans and acts via a novel mechanism of action, which may limit the development of resistance. This study sought to identify a lead compound for the treatment of C. difficile associated diarrhea (CDAD). Compounds were selected from a saturation mutagenesis library of 418 single amino acid variants of MU1140. Compounds were produced by small scale fermentation, purified, characterized and then subjected to a panel of assays aimed at identifying the best performers. The screening assays included: in vitro susceptibility testing [MIC against Micrococcus luteus, Clostridium difficile, vancomycin-resistant enterococci (VRE), Staphylococcus aureus, Streptococcus pneumonia, Mycobacterium phlei, and Pseudomonas aeruginosa; cytotoxicity screening on HepG2 hepatocytes; in vitro pharmacological profiling with the Safety Screen 44TM, metabolic and chemical stability in biologically relevant fluids (FaSSGF, FaSSIF and serum); and efficacy in vivo]. Several lantibiotic compounds had better MIC against C. difficile, compared to vancomycin, but not against other bacterial species tested. The Safety Screen 44TMin vitro pharmacological profiling assay suggested that this class of compounds has relatively low overall toxicity and that compound OG253 (MU1140, Phe1Ile) is not likely to present inadvertent off-target effects, as evidenced by a low promiscuity score. The in vitro cytotoxicity assay also indicated that this class of compounds was characterized by low toxicity; the EC50 of OG253 was 636 mg/mL on HepG2 cells. The half-life in simulated gastric fluid was >240 min. for all compound tested. The stability in simulated intestinal fluid ranged between a half-life of 5 min to >240 min, and paralleled the half-life in serum. OG253 ultimately emerged as the lead compound based on superior in vivo efficacy along with an apparent lack of relapse in a hamster model of infection. The lessons learned from this report are applicable to therapeutic lanthipeptides in general and may assist in the design of novel molecules with improved pharmacological, therapeutic and physicochemical profiles. The data presented also support the continued clinical development of OG253 as a novel antibiotic against CDAD that could prevent recurrence of the infection.

18.
Article in English | MEDLINE | ID: mdl-29038270

ABSTRACT

The recently approved combination of meropenem and vaborbactam (Vabomere) is highly active against Gram-negative pathogens, especially Klebsiella pneumoniae carbapenemase (KPC)-producing, carbapenem-resistant Enterobacteriaceae We evaluated the efficacy of meropenem-vaborbactam against three clinically relevant isolates in a murine pyelonephritis model. The data indicate that the combination of meropenem and vaborbactam significantly increased bacterial killing compared to that with the untreated controls. These data suggest that this combination may have utility in the treatment of complicated urinary tract infections due to KPC-producing, carbapenem-resistant Enterobacteriaceae.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Boronic Acids/therapeutic use , Carbapenem-Resistant Enterobacteriaceae/drug effects , Escherichia coli/drug effects , Klebsiella pneumoniae/drug effects , Meropenem/therapeutic use , Pyelonephritis/drug therapy , Urinary Tract Infections/drug therapy , beta-Lactamase Inhibitors/therapeutic use , Animals , Bacterial Proteins/metabolism , Carbapenem-Resistant Enterobacteriaceae/isolation & purification , Disease Models, Animal , Drug Combinations , Humans , Klebsiella pneumoniae/isolation & purification , Klebsiella pneumoniae/metabolism , Mice , Microbial Sensitivity Tests , Pyelonephritis/microbiology , Urinary Tract Infections/microbiology , beta-Lactamases/metabolism
19.
Article in English | MEDLINE | ID: mdl-28739791

ABSTRACT

Lowering the gut exposure to antibiotics during treatments can prevent microbiota disruption. We evaluated the effects of an activated charcoal-based adsorbent, DAV131A, on the fecal free moxifloxacin concentration and mortality in a hamster model of moxifloxacin-induced Clostridium difficile infection. A total of 215 hamsters receiving moxifloxacin subcutaneously (day 1 [D1] to D5) were orally infected at D3 with C. difficile spores. They received various doses (0 to 1,800 mg/kg of body weight/day) and schedules (twice a day [BID] or three times a day [TID]) of DAV131A (D1 to D8). Moxifloxacin concentrations and C. difficile counts were determined at D3, and mortality was determined at D12 We compared mortality rates, moxifloxacin concentrations, and C. difficile counts according to DAV131A regimen and modeled the links between DAV131A regimen, moxifloxacin concentration, and mortality. All hamsters that received no DAV131A died, but none of those that received 1,800 mg/kg/day died. Significant dose-dependent relationships between DAV131A dose and (i) mortality, (ii) moxifloxacin concentration, and (iii) C. difficile count were evidenced. Mathematical modeling suggested that (i) lowering the moxifloxacin concentration at D3, which was 58 µg/g (95% confidence interval [CI] = 50 to 66 µg/g) without DAV131A, to 17 µg/g (14 to 21 µg/g) would reduce mortality by 90%; and (ii) this would be achieved with a daily DAV131A dose of 703 mg/kg (596 to 809 mg/kg). In this model of C. difficile infection, DAV131A reduced mortality in a dose-dependent manner by decreasing the fecal free moxifloxacin concentration.


Subject(s)
Clostridioides difficile/pathogenicity , Clostridium Infections/chemically induced , Dysbiosis/chemically induced , Enterocolitis, Pseudomembranous/chemically induced , Fluoroquinolones/adverse effects , Gastrointestinal Microbiome/drug effects , Gastrointestinal Tract/drug effects , Animals , Charcoal/pharmacology , Clostridium Infections/drug therapy , Cricetinae , Disease Models, Animal , Dose-Response Relationship, Drug , Enterocolitis, Pseudomembranous/drug therapy , Enterocolitis, Pseudomembranous/mortality , Fluoroquinolones/pharmacology , Gastrointestinal Tract/microbiology , Moxifloxacin
20.
Article in English | MEDLINE | ID: mdl-28167541

ABSTRACT

Based upon knowledge of the hydrolytic profile of major ß-lactamases found in Gram-negative bacteria, we tested the efficacy of the combination of ceftazidime-avibactam (CAZ-AVI) with aztreonam (ATM) against carbapenem-resistant enteric bacteria possessing metallo-ß-lactamases (MBLs). Disk diffusion and agar-based antimicrobial susceptibility testing were initially performed to determine the in vitro efficacy of a unique combination of CAZ-AVI and ATM against 21 representative Enterobacteriaceae isolates with a complex molecular background that included blaIMP, blaNDM, blaOXA-48, blaCTX-M, blaAmpC, and combinations thereof. Time-kill assays were conducted, and the in vivo efficacy of this combination was assessed in a murine neutropenic thigh infection model. By disk diffusion assay, all 21 isolates were resistant to CAZ-AVI alone, and 19/21 were resistant to ATM. The in vitro activity of CAZ-AVI in combination with ATM against diverse Enterobacteriaceae possessing MBLs was demonstrated in 17/21 isolates, where the zone of inhibition was ≥21 mm. All isolates demonstrated a reduction in CAZ-AVI agar dilution MICs with the addition of ATM. At 2 h, time-kill assays demonstrated a ≥4-log10-CFU decrease for all groups that had CAZ-AVI with ATM (8 µg/ml) added, compared to the group treated with CAZ-AVI alone. In the murine neutropenic thigh infection model, an almost 4-log10-CFU reduction was noted at 24 h for CAZ-AVI (32 mg/kg every 8 h [q8h]) plus ATM (32 mg/kg q8h) versus CAZ-AVI (32 mg/kg q8h) alone. The data presented herein require us to carefully consider this new therapeutic combination to treat infections caused by MBL-producing Enterobacteriaceae.


Subject(s)
Anti-Bacterial Agents/pharmacology , Azabicyclo Compounds/pharmacology , Aztreonam/pharmacology , Ceftazidime/pharmacology , Enterobacteriaceae Infections/drug therapy , Enterobacteriaceae/drug effects , Animals , Colony Count, Microbial , Cyclophosphamide , Drug Administration Schedule , Drug Combinations , Drug Therapy, Combination , Enterobacteriaceae/enzymology , Enterobacteriaceae/genetics , Enterobacteriaceae/growth & development , Enterobacteriaceae Infections/microbiology , Female , Gene Expression , Humans , Klebsiella Infections/complications , Klebsiella Infections/drug therapy , Klebsiella Infections/microbiology , Klebsiella pneumoniae/drug effects , Klebsiella pneumoniae/enzymology , Klebsiella pneumoniae/genetics , Klebsiella pneumoniae/growth & development , Mice , Microbial Sensitivity Tests , Neutropenia/chemically induced , Neutropenia/complications , Neutropenia/drug therapy , Neutropenia/microbiology , Plasmids/chemistry , Plasmids/metabolism , Soft Tissue Infections/complications , Soft Tissue Infections/drug therapy , Soft Tissue Infections/microbiology , Thigh , beta-Lactam Resistance/drug effects , beta-Lactam Resistance/genetics , beta-Lactamases/genetics , beta-Lactamases/metabolism
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