scholarly journals Discovery of Novel Antigiardiasis Drug Candidates

2014 ◽  
Vol 58 (12) ◽  
pp. 7303-7311 ◽  
Author(s):  
Liudmila Kulakova ◽  
Andrey Galkin ◽  
Catherine Z. Chen ◽  
Noel Southall ◽  
Juan J. Marugan ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Standard Care ◽  
Parasitic Infection ◽  
The United States ◽  
The European Union ◽  
Current Standard ◽  
Content Type ◽  
Drug Candidates

ABSTRACTGiardiasis is a severe intestinal parasitic disease caused byGiardia lamblia, which inflicts many people in poor regions and is the most common parasitic infection in the United States. Current standard care drugs are associated with undesirable side effects, treatment failures, and an increasing incidence of drug resistance. As follow-up to a high-throughput screening of an approved drug library, which identified compounds lethal toG. lambliatrophozoites, we have determined the minimum lethal concentrations of 28 drugs and advanced 10 of them toin vivostudies in mice. The results were compared to treatment with the standard care drug, metronidazole, in order to identify drugs with equal or better anti-Giardiaactivities. Three drugs, fumagillin, carbadox, and tioxidazole, were identified. These compounds were also potent against metronidazole-resistant humanG. lambliaisolates (assemblages A and B), as determined inin vitroassays. Of these three compounds, fumagillin is currently an orphan drug used within the European Union to treat microsporidiosis in immunocompromised individuals, whereas carbadox and tioxidazole are used in veterinary medicine. A dose-dependent study of fumagillin in a giardiasis mouse model revealed that the effective dose of fumagillin was ∼100-fold lower than the metronidazole dose. Therefore, fumagillin may be advanced to further studies as an alternative treatment for giardiasis when metronidazole fails.

scholarly journals In VitroandIn VivoActivities of Zinc Linolenate, a Selective Antibacterial Agent againstHelicobacter pylori

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Yanqiang Huang ◽  
Xudong Hang ◽  
Xueqing Jiang ◽  
Liping Zeng ◽  
Jia Jia ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Therapeutic Potential ◽  
Combined Therapy ◽  
Peptic Ulcers ◽  
Current Standard ◽  
Gastric Diseases ◽  
Content Type ◽  
H Pylori

ABSTRACTHelicobacter pyloriis a major global pathogen, and its infection represents a key factor in the etiology of various gastric diseases, including gastritis, peptic ulcers, and gastric carcinoma. The efficacy of current standard treatment forH. pyloriinfection including two broad-spectrum antibiotics is compromised by toxicity toward the gut microbiota and the development of drug resistance, which will likely only be resolved through novel and selective antibacterial strategies. Here, we synthesized a small molecule, zinc linolenate (ZnLla), and investigated its therapeutic potential for the treatment ofH. pyloriinfection. ZnLla showed effective antibacterial activity against standard strains and drug-resistant clinical isolates ofH. pyloriin vitrowith no development of resistance during continuous serial passaging. The mechanisms of ZnLla action againstH. pyloriinvolved the disruption of bacterial cell membranes and generation of reactive oxygen species. In mouse models of multidrug-resistantH. pyloriinfection, ZnLla showedin vivokilling efficacy comparable and superior to the triple therapy approach when use as a monotherapy and a combined therapy with omeprazole, respectively. Moreover, ZnLla treatment induces negligible toxicity against normal tissues and causes minimal effects on both the diversity and composition of the murine gut microbiota. Thus, the high degree of selectivity of ZnLla forH. pyloriprovides an attractive candidate for novel targeted anti-H. pyloritreatment.

scholarly journals USA300 and USA500 Clonal Lineages of Staphylococcus aureus Do Not Produce a Capsular Polysaccharide Due to Conserved Mutations in the cap5 Locus

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Susan Boyle-Vavra ◽  
Xue Li ◽  
Md Tauqeer Alam ◽  
Timothy D. Read ◽  
Julia Sieth ◽  
...  
Keyword(s):  
United States ◽  
Staphylococcus Aureus ◽  
Capsular Polysaccharide ◽  
The United States ◽  
Whole Genome Sequence ◽  
Content Type ◽  
Capsule Production ◽  
Usa300 Strain

ABSTRACTThe surface capsular polysaccharide (CP) is a virulence factor that has been used as an antigen in several successful vaccines against bacterial pathogens. A vaccine has not yet been licensed againstStaphylococcus aureus, although two multicomponent vaccines that contain CP antigens are in clinical trials. In this study, we evaluated CP production in USA300 methicillin-resistantS. aureus(MRSA) isolates that have become the predominant community-associated MRSA clones in the United States. We found that all 167 USA300 MRSA and 50 USA300 methicillin-susceptibleS. aureus(MSSA) isolates were CP negative (CP−). Moreover, all 16 USA500 isolates, which have been postulated to be the progenitor lineage of USA300, were also CP−. Whole-genome sequence analysis of 146 CP−USA300 MRSA isolates revealed they all carry acap5locus with 4 conserved mutations compared with strain Newman. Genetic complementation experiments revealed that three of these mutations (in thecap5promoter,cap5Dnucleotide 994, andcap5Enucleotide 223) ablated CP production in USA300 and that Cap5E75 Asp, located in the coenzyme-binding domain, is essential for capsule production. All but three USA300 MSSA isolates had the same fourcap5mutations found in USA300 MRSA isolates. Most isolates with a USA500 pulsotype carried three of these four USA300-specific mutations, suggesting the fourth mutation occurred in the USA300 lineage. Phylogenetic analysis of thecaploci of our USA300 isolates as well as publicly available genomes from 41 other sequence types revealed that the USA300-specificcap5mutations arose sequentially inS. aureusin a common ancestor of USA300 and USA500 isolates.IMPORTANCEThe USA300 MRSA clone emerged as a community-associated pathogen in the United States nearly 20 years ago. Since then, it has rapidly disseminated and now causes health care-associated infections. This study shows that the CP-negative (CP−) phenotype has persisted among USA300 isolates and is a universal and characteristic trait of this highly successful MRSA lineage. It is important to note that a vaccine consisting solely of CP antigens would not likely demonstrate high efficacy in the U.S. population, where about half of MRSA isolates comprise USA300. Moreover, conversion of a USA300 strain to a CP-positive (CP+) phenotype is unlikelyin vivoorin vitrosince it would require the reversion of 3 mutations. We have also established that USA300 MSSA isolates and USA500 isolates are CP−and provide new insight into the evolution of the USA300 and USA500 lineages.

scholarly journals Ferrous Iron Is a Significant Component of Bioavailable Iron in Cystic Fibrosis Airways

mBio ◽  
2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Ryan C. Hunter ◽  
Fadi Asfour ◽  
Jozef Dingemans ◽  
Brenda L. Osuna ◽  
Tahoura Samad ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Ferrous Iron ◽  
Ferric Iron ◽  
Relative Proportion ◽  
Iron Oxidation ◽  
The United States ◽  
Environmental Parameter ◽  
Content Type

ABSTRACTChronic, biofilm-like infections by the opportunistic pathogenPseudomonas aeruginosaare a major cause of mortality in cystic fibrosis (CF) patients. While much is known aboutP. aeruginosafrom laboratory studies, far less is understood about what it experiencesin vivo. Iron is an important environmental parameter thought to play a central role in the development and maintenance ofP. aeruginosainfections, for both anabolic and signaling purposes. Previous studies have focused on ferric iron [Fe(III)] as a target for antimicrobial therapies; however, here we show that ferrous iron [Fe(II)] is abundant in the CF lung (~39 µM on average for severely sick patients) and significantly correlates with disease severity (ρ = −0.56,P= 0.004), whereas ferric iron does not (ρ = −0.28,P= 0.179). Expression of theP. aeruginosagenesbqsRS, whose transcription is upregulated in response to Fe(II), was high in the majority of patients tested, suggesting that increased Fe(II) is bioavailable to the infectious bacterial population. Because limiting Fe(III) acquisition inhibits biofilm formation byP. aeruginosain various oxicin vitrosystems, we also tested whether interfering with Fe(II) acquisition would improve biofilm control under anoxic conditions; concurrent sequestration of both iron oxidation states resulted in a 58% reduction in biofilm accumulation and 28% increase in biofilm dissolution, a significant improvement over Fe(III) chelation treatment alone. This study demonstrates that the chemistry of infected host environments coevolves with the microbial community as infections progress, which should be considered in the design of effective treatment strategies at different stages of disease.IMPORTANCEIron is an important environmental parameter that helps pathogens thrive in sites of infection, including those of cystic fibrosis (CF) patients. Ferric iron chelation therapy has been proposed as a novel therapeutic strategy for CF lung infections, yet until now, the iron oxidation state has not been measured in the host. In studying mucus from the infected lungs of multiple CF patients from Europe and the United States, we found that ferric and ferrous iron change in concentration and relative proportion as infections progress; over time, ferrous iron comes to dominate the iron pool. This information is relevant to the design of novel CF therapeutics and, more broadly, to developing accurate models of chronic CF infections.

scholarly journals Postantibiotic and Sub-MIC Effects of Exebacase (Lysin CF-301) Enhance Antimicrobial Activity againstStaphylococcus aureus

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Jun Taek Oh ◽  
Cara Cassino ◽  
Raymond Schuch
Keyword(s):  
Antimicrobial Activity ◽  
Cell Wall ◽  
The United States ◽  
Infection Model ◽  
Postantibiotic Effect ◽  
Content Type ◽  
Wall Ultrastructure ◽  
Bacterial Fitness

ABSTRACTCF-301 (exebacase) is a recombinantly produced bacteriophage-derived lysin (cell wall hydrolase) and is the first agent of this class to enter clinical development in the United States for treating bacteremia including endocarditis due toStaphylococcus aureus. Whereas rapid bactericidal activity is the hallmarkin vitroandin vivoresponse to CF-301 at exposures higher than the MIC, prolonged antimicrobial activity, mediated by cell wall damage, is predicted at concentrations less than the MIC. In the current study, a series ofin vitropharmacodynamic parameters, including the postantibiotic effect (PAE), postantibiotic sub-MIC effect (PA-SME), and sub-MIC effect (SME), were studied to determine how short-duration and sub-MIC CF-301 exposures affect the growth of surviving staphylococci and extend its antimicrobial activity. Mean PAE, PA-SME, and SME values up to 4.8, 9.3, and 9.8 h, respectively, were observed against 14 staphylococcal strains tested in human serum; growth delays were extended by 6 h in the presence of daptomycin. Exposures to CF-301 at sub-MIC levels as low as 0.001× to 0.01× MIC (∼1 to 10 ng/ml) resulted in aberrant cell wall ultrastructure, increased membrane permeability, dissipation of membrane potential, and inhibition of virulence phenotypes, including agglutination and biofilm formation. A mouse thigh infection model designed to study the PAE was used to confirm our findings and demonstratein vivogrowth delays of ≥19.3 h. Our findings suggest that at CF-301 concentrations less than the MIC during therapeutic use, sustained reductions in bacterial fitness and virulence may substantially enhance efficacy.

scholarly journals The Cyclic Peptide Ecumicin Targeting ClpC1 Is Active against Mycobacterium tuberculosis In Vivo

2014 ◽  
Vol 59 (2) ◽  
pp. 880-889 ◽  
Author(s):  
Wei Gao ◽  
Jin-Yong Kim ◽  
Jeffrey R. Anderson ◽  
Tatos Akopian ◽  
Seungpyo Hong ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
High Throughput Screening ◽  
Cyclic Peptide ◽  
Genome Mining ◽  
Subcutaneous Administration ◽  
Multiple Drug ◽  
Drug Resistant ◽  
Content Type

ABSTRACTDrug-resistant tuberculosis (TB) has lent urgency to finding new drug leads with novel modes of action. A high-throughput screening campaign of >65,000 actinomycete extracts for inhibition ofMycobacterium tuberculosisviability identified ecumicin, a macrocyclic tridecapeptide that exerts potent, selective bactericidal activity againstM. tuberculosisin vitro, including nonreplicating cells. Ecumicin retains activity against isolated multiple-drug-resistant (MDR) and extensively drug-resistant (XDR) strains ofM. tuberculosis. The subcutaneous administration to mice of ecumicin in a micellar formulation at 20 mg/kg body weight resulted in plasma and lung exposures exceeding the MIC. Complete inhibition ofM. tuberculosisgrowth in the lungs of mice was achieved following 12 doses at 20 or 32 mg/kg. Genome mining of lab-generated, spontaneous ecumicin-resistantM. tuberculosisstrains identified the ClpC1 ATPase complex as the putative target, and this was confirmed by a drug affinity response test. ClpC1 functions in protein breakdown with the ClpP1P2 protease complex. Ecumicin markedly enhanced the ATPase activity of wild-type (WT) ClpC1 but prevented activation of proteolysis by ClpC1. Less stimulation was observed with ClpC1 from ecumicin-resistant mutants. Thus, ClpC1 is a valid drug target againstM. tuberculosis, and ecumicin may serve as a lead compound for anti-TB drug development.

scholarly journals In Vivo Targeting of Clostridioides difficile Using Phage-Delivered CRISPR-Cas3 Antimicrobials

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Kurt Selle ◽  
Joshua R. Fletcher ◽  
Hannah Tuson ◽  
Daniel S. Schmitt ◽  
Lana McMillan ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Broad Spectrum ◽  
Bacterial Species ◽  
Bacterial Genome ◽  
The United States ◽  
Type I ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile is an important nosocomial pathogen that causes approximately 500,000 cases of C. difficile infection (CDI) and 29,000 deaths annually in the United States. Antibiotic use is a major risk factor for CDI because broad-spectrum antimicrobials disrupt the indigenous gut microbiota, decreasing colonization resistance against C. difficile. Vancomycin is the standard of care for the treatment of CDI, likely contributing to the high recurrence rates due to the continued disruption of the gut microbiota. Thus, there is an urgent need for the development of novel therapeutics that can prevent and treat CDI and precisely target the pathogen without disrupting the gut microbiota. Here, we show that the endogenous type I-B CRISPR-Cas system in C. difficile can be repurposed as an antimicrobial agent by the expression of a self-targeting CRISPR that redirects endogenous CRISPR-Cas3 activity against the bacterial chromosome. We demonstrate that a recombinant bacteriophage expressing bacterial genome-targeting CRISPR RNAs is significantly more effective than its wild-type parent bacteriophage at killing C. difficile both in vitro and in a mouse model of CDI. We also report that conversion of the phage from temperate to obligately lytic is feasible and contributes to the therapeutic suitability of intrinsic C. difficile phages, despite the specific challenges encountered in the disease phenotypes of phage-treated animals. Our findings suggest that phage-delivered programmable CRISPR therapeutics have the potential to leverage the specificity and apparent safety of phage therapies and improve their potency and reliability for eradicating specific bacterial species within complex communities, offering a novel mechanism to treat pathogenic and/or multidrug-resistant organisms. IMPORTANCE Clostridioides difficile is a bacterial pathogen responsible for significant morbidity and mortality across the globe. Current therapies based on broad-spectrum antibiotics have some clinical success, but approximately 30% of patients have relapses, presumably due to the continued perturbation to the gut microbiota. Here, we show that phages can be engineered with type I CRISPR-Cas systems and modified to reduce lysogeny and to enable the specific and efficient targeting and killing of C. difficile in vitro and in vivo. Additional genetic engineering to disrupt phage modulation of toxin expression by lysogeny or other mechanisms would be required to advance a CRISPR-enhanced phage antimicrobial for C. difficile toward clinical application. These findings provide evidence into how phage can be combined with CRISPR-based targeting to develop novel therapies and modulate microbiomes associated with health and disease.

scholarly journals Staphlyococcus aureus Phenol-Soluble Modulins Stimulate the Release of Proinflammatory Cytokines from Keratinocytes and Are Required for Induction of Skin Inflammation

2015 ◽  
Vol 83 (9) ◽  
pp. 3428-3437 ◽  
Author(s):  
Adnan K. Syed ◽  
Tamra J. Reed ◽  
Kaitlyn L. Clark ◽  
Blaise R. Boles ◽  
J. Michelle Kahlenberg
Keyword(s):  
Proinflammatory Cytokines ◽  
Skin Inflammation ◽  
The United States ◽  
Cytokine Release ◽  
Content Type ◽  
Colonization Model ◽  
Necessary And Sufficient

Staphylococcus aureusis a human commensal that colonizes the skin. While it is normally innocuous, it has strong associations with atopic dermatitis pathogenesis and has become the leading cause of skin and soft tissue infections in the United States. The factors that dictate the role ofS. aureusin disease are still being determined. In this work, we utilized primary keratinocyte culture and an epidermal murine colonization model to investigate the role ofS. aureusphenol-soluble modulins (PSMs) in proinflammatory cytokine release and inflammation induction. We demonstrated that many species ofStaphylococcusare capable of causing release of interleukin 18 (IL-18) from keratinocytes and thatS. aureusPSMs are necessary and sufficient to stimulate IL-18 release from keratinocytes independently of caspase 1. Further, after 7 days of epicutaneous exposure to wild-typeS. aureus, but notS. aureusΔpsm, we saw dramatic changes in gross pathology, as well as systemic release of proinflammatory cytokines. This work demonstrates the importance of PSM peptides inS. aureus-mediated inflammatory cytokine release from keratinocytesin vitroandin vivoand further implicates PSMs as important contributors to pathogenesis.

scholarly journals Identification of a New Amide-Containing Thiazole as a Drug Candidate for Treatment of Chagas' Disease

2014 ◽  
Vol 59 (3) ◽  
pp. 1398-1404 ◽  
Author(s):  
Guzmán Álvarez ◽  
Javier Varela ◽  
Eugenia Cruces ◽  
Marcelo Fernández ◽  
Martín Gabay ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Parasitic Infection ◽  
Preclinical Study ◽  
Drug Candidate ◽  
Pharmacological Characterization ◽  
Reference Drug ◽  
Content Type ◽  
Optimization Stage

ABSTRACTAlthough the parasitic infection Chagas' disease was described over 100 years ago, even now there are not suitable drugs. The available drugs nifurtimox and benznidazole have limited efficacies and tolerances, with proven mutagenic effects. Attempting to find appropriate drugs to deal with this problem, here we report on the development and pharmacological characterization of new amide-containing thiazoles. In the present study, we evaluated thein vitroandin vivoeffects of new candidates againstTrypanosoma cruzi, the etiological agent of Chagas' disease. The lead amide-containing thiazole derivative had potentin vitroactivity, an absence of bothin vitromutagenic andin vivoclastogenic effects, and excellentin vitroselectivity andin vivotolerance. The compound suppressed parasitemia in mice, modifying the anti-T. cruziantibodies like the reference drug, benznidazole, and displayed the lowest mortality among the tested drugs. The present evidence suggests that this compound is a promising anti-T. cruziagent surpassing the lead optimization stage in drug development and leading to a candidate for preclinical study.

scholarly journals rpoS-Regulated Core Genes Involved in the Competitive Fitness of Salmonella enterica Serovar Kentucky in the Intestines of Chickens

2014 ◽  
Vol 81 (2) ◽  
pp. 502-514 ◽  
Author(s):  
Ying Cheng ◽  
Adriana Ayres Pedroso ◽  
Steffen Porwollik ◽  
Michael McClelland ◽  
Margie D. Lee ◽  
...  
Keyword(s):  
United States ◽  
Salmonella Enterica ◽  
The United States ◽  
Differential Regulation ◽  
Metabolic Adaptation ◽  
Content Type ◽  
Metabolic Genes ◽  
Core Genes

ABSTRACTSalmonella entericaserovar Kentucky has become the most frequently isolated serovar from poultry in the United States over the past decade. Despite its prevalence in poultry, it causes few human illnesses in the United States. The dominance ofS. Kentucky in poultry does not appear to be due to single introduction of a clonal strain, and its reduced virulence appears to correlate with the absence of virulence genesgrvA,sseI,sopE, andsodC1. S. Kentucky's prevalence in poultry is possibly attributable to its metabolic adaptation to the chicken cecum. While there were no difference in the growth rate ofS. Kentucky andS. Typhimurium grown microaerophilically in cecal contents,S. Kentucky persisted longer when chickens were coinfected withS. Typhimurium. Thein vivoadvantage thatS. Kentucky has overS. Typhimurium appears to be due to differential regulation of coreSalmonellagenes via the stationary-phase sigma factorrpoS. Microarray analysis ofSalmonellagrown in cecal contentsin vitroidentified several metabolic genes and motility and adherence genes that are differentially activated inS. Kentucky. The contributions of four of these operons (mgl,prp,nar, andcsg) toSalmonellacolonization in chickens were assessed. Deletion ofmglandcsgreducedS. Kentucky persistence in competition studies in chickens infected with wild-type or mutant strains. Subtle mutations affecting differential regulation of coreSalmonellagenes appear to be important inSalmonella's adaptation to its animal host and especially forS. Kentucky's emergence as the dominant serovar in poultry.

scholarly journals Drug Efficacy Comparison of 3D Forming and Preforming Sphere Models with a Micropillar and Microwell Chip Platform

2019 ◽  
Vol 24 (4) ◽  
pp. 476-483 ◽  
Author(s):  
Il Doh ◽  
Yong-Jun Kwon ◽  
Bosung Ku ◽  
Dong Woo Lee
Keyword(s):  
High Throughput Screening ◽  
Drug Efficacy ◽  
High Sensitivity ◽  
Chemotherapeutic Agents ◽  
Cell Culture Model ◽  
Drug Candidates ◽  
Tumor Microenvironments ◽  
Culture Model

Hepatocellular carcinoma (HCC), a major histological subtype of liver cancer, is the third most common cause of cancer-related death worldwide. Currently, many curative standard treatments using target-specific chemotherapeutic agents are being developed. However, drug efficacy tests based on the 2D monolayer cell culture model do not effectively screen the best drug candidates because they do not accurately reflect in vivo tumor microenvironments. Thus, to select the best drug candidates or repositioning drugs, we developed new 3D in vitro hepatic tumor models, including 3D forming and preformed sphere models. A micropillar and microwell chip platform was used for the 3D in vitro liver cell-based model for high-throughput screening. We measured the efficacy of 60 drugs and sorted the most efficacious drugs by comparing the drug response of the 2D monolayer model with the 3D forming and preformed sphere models. Among the 60 drugs, 17 drugs (28.3%) showed a significant high efficacy in the 3D preformed sphere model, while 45 drugs (75%) showed an efficacy in the 2D model. We also calculated the IC50 values of the 17 drugs and found that 7 drugs exhibited a high sensitivity in HCC, which was in agreement with previous studies.

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