scholarly journals Identification of a Small Molecule Inhibitor of the Aminoglycoside 6’-N-Acetyltransferase Type Ib [AAC(6’)-Ib] Using Mixture-Based Combinatorial Libraries

2017 ◽  
Author(s):  
Tung Tran ◽  
Kevin Chiem ◽  
Saumya Jani ◽  
Brock A. Arivett ◽  
David Lin ◽  
...  
Keyword(s):  
Galleria Mellonella ◽  
Combinatorial Libraries ◽  
Resistant Bacteria ◽  
Scanning Strategy ◽  
Gram Negative ◽  
Inhibition Of Growth ◽  
Molecule Inhibitor ◽  
Positional Scanning ◽  
Enzymatic Inhibitor

AbstractThe aminoglycoside 6′-N-acetyltransferase type Ib [AAC(6’)-Ib] is the most widely distributed enzyme among AAC(6’)-I-producing Gram-negative pathogens and confers resistance to clinically relevant aminoglycosides including amikacin. This enzyme is therefore ideal to target with enzymatic inhibitors that could overcome resistance to aminoglycosides. The search for inhibitors was carried out using mixture-based combinatorial libraries, the scaffold ranking approach, and the positional scanning strategy. A library with high inhibitory activity had pyrrolidine pentamine scaffold and was selected for further analysis. This library contained 738,192 compounds with functionalities derived from 26 different amino acids (R1, R2 and R3) and 42 different carboxylic acids (R4) in four R group functionalities. The most active compounds all contained S-phenyl (R1 and R3) and S-hydromethyl (R2) functionalities at three locations and differed at the R4 position. The compound containing 3-phenylbutyl at R4 (compound 206) was a robust enzymatic inhibitor in vitro, in combination with amikacin potentiated the inhibition of growth of three resistant bacteria in culture, and improved survival when used as treatment of Galleria mellonella infected with aac(6’)-Ib-harboring Klebsiella pneumoniae and Acinetobacter baumannii strains.

scholarly journals Enhanced immune activity of cytotoxic T-lymphocyte epitope analogs derived from positional scanning synthetic combinatorial libraries

Blood ◽  
2001 ◽  
Vol 97 (6) ◽  
pp. 1776-1786 ◽  
Author(s):  
Corinna La Rosa ◽  
Radhika Krishnan ◽  
Susan Markel ◽  
Jonathan P. Schneck ◽  
Richard Houghten ◽  
...  
Keyword(s):  
T Cell ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Combinatorial Libraries ◽  
Peptide Sequence ◽  
Ctl Epitopes ◽  
Ctl Epitope ◽  
Positional Scanning ◽  
Synthetic Combinatorial Libraries

The pp65495-503 cytotoxic T-lymphocyte (CTL) epitope from cytomegalovirus (CMV) is universally recognized among CMV+ individuals who express an allele of the human leukocyte antigen A (HLA-A*0201). The relative binding affinity of the epitope to HLA-A*0201 is moderate, and its increased activity might prove beneficial in its use as a CTL epitope vaccine. A new approach to enhance the activity of T-cell epitopes is the use of positional scanning synthetic combinatorial libraries (PS-SCLs). Using a nonamer PS-SCL, the pp65495-503 epitope was modified after screening a CMV-specific T-cell clone (TCC) (3-3F4) from which the native peptide sequence was derived. Two peptides with amino acid substitutions at P1, P3, P7, and P8 are between 103 and 104 more active than the native epitope. Although the native CTL epitope terminates as a free acid, both tetrasubstituted peptides only function as CTL epitopes when the carboxyl terminus is amidated. Selective substitution of the native sequence based on PS-SCL screening results identified 3 amidated monosubstituted and disubstituted peptides that are better recognized than the native epitope by TCCs from a cohort expressing HLA-A*0201. In vitro stimulation of peripheral blood mononuclear cells with each of the peptide epitope analogs stimulated memory CTLs, which recognized CMV-infected targets among a high percentage of CMV+ individuals. Binding studies of peptide analogs with HLA-Ig (immunoglobulin) dimers and 2 different TCCs correlated with in vitro lysis results. These data suggest that increasing the activity of CTL epitopes while maintaining broad recognition is possible, which holds promise for vaccine development in infectious disease and cancer.

scholarly journals Antibiotic Resistant Bacterial Isolates from Captive Green Turtles andIn VitroSensitivity to Bacteriophages

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Alessandro Delli Paoli Carini ◽  
Ellen Ariel ◽  
Jacqueline Picard ◽  
Lisa Elliott
Keyword(s):  
Rapid Evolution ◽  
Chelonia Mydas ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Green Turtles ◽  
Resistant Genes ◽  
Resistance Rates

This study aimed to test multidrug resistant isolates from hospitalised green turtles(Chelonia mydas)and their environment in North Queensland, Australia, forin vitrosusceptibility to bacteriophages. Seventy-one Gram-negative bacteria were isolated from green turtle eye swabs and water samples. Broth microdilution tests were used to determine antibiotic susceptibility. All isolates were resistant to at least two antibiotics, with 24% being resistant to seven of the eight antibiotics. Highest resistance rates were detected to enrofloxacin (77%) and ampicillin (69.2%). More than 50% resistance was also found to amoxicillin/clavulanic acid (62.5%), ceftiofur (53.8%), and erythromycin (53.3%). All the enriched phage filtrate mixtures resulted in the lysis of one or more of the multidrug resistant bacteria, includingVibrio harveyiandV. parahaemolyticus. These results indicate that antibiotic resistance is common in Gram-negative bacteria isolated from hospitalised sea turtles and their marine environment in North Queensland, supporting global concern over the rapid evolution of multidrug resistant genes in the environment. Using virulent bacteriophages as antibiotic alternatives would not only be beneficial to turtle health but also prevent further addition of multidrug resistant genes to coastal waters.

scholarly journals Synergistic Efficacy of Aedes aegypti Antimicrobial Peptide Cecropin A2 and Tetracycline against Pseudomonas aeruginosa

2017 ◽  
Vol 61 (7) ◽  
Author(s):  
Zhaojun Zheng ◽  
Nagendran Tharmalingam ◽  
Qingzhong Liu ◽  
Elamparithi Jayamani ◽  
Wooseong Kim ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Aedes Aegypti ◽  
Mammalian Cells ◽  
Galleria Mellonella ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Synergistic Activity ◽  
Content Type

ABSTRACT The increasing prevalence of antibiotic resistance has created an urgent need for alternative drugs with new mechanisms of action. Antimicrobial peptides (AMPs) are promising candidates that could address the spread of multidrug-resistant bacteria, either alone or in combination with conventional antibiotics. We studied the antimicrobial efficacy and bactericidal mechanism of cecropin A2, a 36-residue α-helical cationic peptide derived from Aedes aegypti cecropin A, focusing on the common pathogen Pseudomonas aeruginosa. The peptide showed little hemolytic activity and toxicity toward mammalian cells, and the MICs against most clinical P. aeruginosa isolates were 32 to 64 μg/ml, and its MICs versus other Gram-negative bacteria were 2 to 32 μg/ml. Importantly, cecropin A2 demonstrated synergistic activity against P. aeruginosa when combined with tetracycline, reducing the MICs of both agents by 8-fold. The combination was also effective in vivo in the P. aeruginosa/Galleria mellonella model (P < 0.001). We found that cecropin A2 bound to P. aeruginosa lipopolysaccharides, permeabilized the membrane, and interacted with the bacterial genomic DNA, thus facilitating the translocation of tetracycline into the cytoplasm. In summary, the combination of cecropin A2 and tetracycline demonstrated synergistic antibacterial activity against P. aeruginosa in vitro and in vivo, offering an alternative approach for the treatment of P. aeruginosa infections.

scholarly journals Development of in Vitro Resistance to Daptomycin in Enterococcus Faecium and Estimation of Its Fitness Cost

2020 ◽  
Author(s):  
Weiliang Zeng ◽  
Tao Chen ◽  
Qing Wu ◽  
Ye Xu ◽  
Kaihang Yu ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Resistance Mechanisms ◽  
Fitness Cost ◽  
Resistant Bacteria ◽  
Infection Model ◽  
Dynamic Resistance ◽  
Vancomycin Resistant

Abstract BackgroundDaptomycin has broad-spectrum antibacterial activity against Gram-positive pathogens, but recent studies have revealed cases where daptomycin has failed to treat multidrug-resistant bacteria, such as vancomycin-resistant Enterococcus faecium. However, the resistance evolution of E. faecium to daptomycin in vitro and fitness cost remain unclear. In this study, we sought to analyze the resistance development and mechanism of E. faecium to datomycin, and futher to investigate the relationship between daptomycin resistance and fitness cost.MethodsTo investigate the development of daptomycin resistance in E. faecium, 6 daptomycin-susceptible (DAP-S) clinical isolates, including 3 vancomycin-resistant E. faecium (VRE) and 3 vancomycin-susceptible E. faecium (VSE), were exposured to daptomycin in vitro by serial passage experiment. Then the different resistance mechanisms of daptomycin-resistant (DAP-R) mutants were analyzed by polymerase chain reaction (PCR), cytochrome C binding assay and transmission electron microscopy. Furthermore, we also estimated the changes of fitness cost among each highly DAP-R mutants by bacterial growth curve measurement, in vitro competition experiments, infection model of Galleria mellonella larvae and biofilm formation assays.ResultsIn vitro, a total of 21 DAP-R mutants with minimal inhibitory concentration (MIC) of 4 to 512 μg/mL were obtained, and these mutants carried more than one mutation of LiaFSR and YycFG system encoding genes. More positive charges were detected among highly DAP-R mutants than parent isolates, and the cell walls of SC1174-D and SC1762-D mutants were remarkly thicker than those of the parent isolates. In comparison with parent isolates, besides, the growth, competition ability and virulence were significantly reduced, while the biofilm formation capacity was markedly elevated among each highly DAP-R mutants.ConclusionsOur findings suggest that E. faecium isolates are able to rapidly acquire DAP resistance in vitro through different dynamic resistance mechanisms, which often accompany by significant fitness cost. Intriguingly, DAP and glycopeptide antibiotics may present collateral-sensitivity during E. faecium acquired DAP resistance in vitro.

scholarly journals Therapeutic Effect and Mechanisms of the Novel Monosulfactam 0073

2020 ◽  
Vol 64 (10) ◽  
Author(s):  
Ying Sun ◽  
Xueyuan Liao ◽  
Zhigang Huang ◽  
Yaliu Xie ◽  
Yanbin Liu ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Serial Passage ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Infection Model ◽  
The Novel ◽  
Gram Negative ◽  
Content Type

ABSTRACT This study aimed to evaluate the antimicrobial activity of the novel monosulfactam 0073 against multidrug-resistant Gram-negative bacteria in vitro and in vivo and to characterize the mechanisms underlying 0073 activity. The in vitro activities of 0073, aztreonam, and the combination with avibactam were assessed by MIC and time-kill assays. The safety of 0073 was evaluated using 3-(4,5-dimethylthizol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and acute toxicity assays. Murine thigh infection and pneumonia models were employed to define in vivo efficacy. A penicillin-binding protein (PBP) competition assay and confocal microscopy were conducted. The inhibitory action of 0073 against β-lactamases was evaluated by the half-maximal inhibitory concentration (IC50), and resistance development was evaluated via serial passage. The monosulfactam 0073 showed promising antimicrobial activity against Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii isolates producing metallo-β-lactamases (MBLs) and serine β-lactamases. In preliminary experiments, compound 0073 exhibited safety both in vitro and in vivo. In the murine thigh infection model and the pneumonia models in which infection was induced by P. aeruginosa and Klebsiella pneumoniae, 0073 significantly reduced the bacterial burden. Compound 0073 targeted several PBPs and exerted inhibitory effects against some serine β-lactamases. Finally, 0073 showed a reduced propensity for resistance selection compared with that of aztreonam. The novel monosulfactam 0073 exhibited increased activity against β-lactamase-producing Gram-negative organisms compared with the activity of aztreonam and showed good safety profiles both in vitro and in vivo. The underlying mechanisms may be attributed to the affinity of 0073 for several PBPs and its inhibitory activity against some serine β-lactamases. These data indicate that 0073 represents a potential treatment for infections caused by β-lactamase-producing multidrug-resistant bacteria.

scholarly journals Multiple Mechanisms of the Synthesized Antimicrobial Peptide TS against Gram-Negative Bacteria for High Efficacy Antibacterial Action In Vivo

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 60
Author(s):  
Rui Zhang ◽  
Xiaobo Fan ◽  
Xinglu Jiang ◽  
Mingyuan Zou ◽  
Han Xiao ◽  
...  
Keyword(s):  
Antimicrobial Peptide ◽  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Divalent Cations ◽  
Resistant Bacteria ◽  
Antibacterial Drug ◽  
Gram Negative Bacteria ◽  
Gram Negative

The emergence of drug-resistant bacteria emphasizes the urgent need for novel antibiotics. The antimicrobial peptide TS shows extensive antibacterial activity in vitro and in vivo, especially in gram-negative bacteria; however, its antibacterial mechanism is unclear. Here, we find that TS without hemolytic activity disrupts the integrity of the outer bacterial cell membrane by displacing divalent cations and competitively binding lipopolysaccharides. In addition, the antimicrobial peptide TS can inhibit and kill E. coli by disintegrating the bacteria from within by interacting with bacterial DNA. Thus, antimicrobial peptide TS’s multiple antibacterial mechanisms may not easily induce bacterial resistance, suggesting use as an antibacterial drug to be for combating bacterial infections in the future.

scholarly journals Lysophosphatidylcholine Potentiates Antibacterial Activity of Polymyxin B

2020 ◽  
Vol 64 (12) ◽  
Author(s):  
Jitender Yadav ◽  
Sana Ismaeel ◽  
Ayub Qadri
Keyword(s):  
Antibacterial Activity ◽  
Polymyxin B ◽  
Resistant Bacteria ◽  
Bacterial Membrane ◽  
Gram Negative Bacteria ◽  
Drug Resistant ◽  
Antibiotic Resistant ◽  
Gram Negative ◽  
Drug Resistant Bacteria

ABSTRACT Polymyxin B, used to treat infections caused by antibiotic-resistant Gram-negative bacteria, produces nephrotoxicity at its current dosage. We show that a combination of nonbactericidal concentration of this drug and lysophosphatidylcholine (LPC) potently inhibits growth of Salmonella and at least two other Gram-negative bacteria in vitro. This combination makes bacterial membrane porous and causes degradation of DnaK, the regulator of protein folding. Polymyxin B-LPC combination may be an effective and safer regimen against drug-resistant bacteria.

scholarly journals Combined Use of the Ab105-2фΔCI Lytic Mutant Phage and Different Antibiotics in Clinical Isolates of Multiresistant Acinetobacter Baumannii

2019 ◽  
Author(s):  
Lucia Blasco ◽  
Anton Ambroa ◽  
Maria Lopez ◽  
Laura Fernandez-Garcia ◽  
Ines Bleriot ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Acinetobacter Baumannii ◽  
Antimicrobial Agents ◽  
Galleria Mellonella ◽  
Resistant Bacteria ◽  
Lytic Phage ◽  
Drug Resistant Bacteria ◽  
Multiresistant Strains

The global health emergency caused by multi-drug resistant bacteria has led to the search for and development of new antimicrobial agents. Phage therapy is an abandoned antimicrobial therapy that has been resumed in recent years. In this study, we mutated a lysogenic phage from Acinetobacter baumannii into a lytic phage (Ab105-2phi&Delta;CI) showing antimicrobial activity against A.baumannii clinical strains (such as Ab177_GEIH-2000 which showed MICs to meropenem and imipenem of 32 &micro;g/ml and 16 &micro;g/ml, respectively as well as belonging to GEIH-REIPI Spanish Multicenter A. baumannii Study II 2000/2010, Umbrella Genbank Bioproject PRJNA422585). We then enhanced the time kill curves (in vitro) and in Galleria mellonella survival assays (in vivo) antimicrobial activity of the new lytic phage by combining it with carbapenem antibiotics (meropenem and imipenem). We observed in vitro, an antimicrobial synergistic effect (from 4 log to 7 log CFU/ml) with meropenem plus lytic phage in all combinations analysed (0.1, 1 and 10 MOI of Ab105-2phi&Delta;CI mutant as well as 1/4 and 1/8 MIC of meropenem). Moreover, we had a decrease in bacterial growth of 8 log CFU/ml for the combination of imipenem at 1/4 MIC plus lytic phage (Ab105-2phi&Delta;CI mutant) and of 4 log CFU/ml for the combination of imipenem at 1/8 MIC plus lytic phage (Ab105-2phi&Delta;CI mutant) in both MOI 1 and 10. These results were confirmed in in vivo (G. mellonella) obtaining a higher effectiveness in the combination of imipenem and Ab105-2phi&Delta;CI mutant (P&lt;0.05 by Log Rank-Matel Cox test). This approach could help to reduce the emergence of phage resistant bacteria and restore sensitivity to the antibiotics when used to combat multiresistant strains of Acinetobacter baumannii.

Efficient Synthesis and Antibacterial Profile of Bis(2-hydroxynaphthalene- 1,4-dione)

2020 ◽  
Vol 20 (2) ◽  
pp. 121-131 ◽  
Author(s):  
Juliana S. Novais ◽  
Aline C. Rosandiski ◽  
Carolina M. de Carvalho ◽  
Letícia S. de Saules Silva ◽  
Lais C. dos S. Velasco de Souza ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Public Health Problem ◽  
In Vitro Toxicity ◽  
Resistant Bacteria ◽  
Gram Positive ◽  
Healthy Human ◽  
Gram Negative ◽  
Methicillin Resistant

Background: Antibacterial resistance is a serious public health problem infecting millions in the global population. Currently, there are few antimicrobials on the market against resistant bacterial infections. Therefore, there is an urgent need for new therapeutic options against these strains. Objective: In this study, we synthesized and evaluated ten Bis(2-hydroxynaphthalene-1,4-dione) against Gram-positive strains, including a hospital Methicillin-resistant (MRSA), and Gram-negative strains. Method: The compounds were prepared by condensation of aldehydes and lawsone in the presence of different L-aminoacids as catalysts in very good yields. The compounds were submitted to antibacterial analysis through disk diffusion and Minimal Inhibitory Concentration (MIC) assays. Result: L-aminoacids have been shown to be efficient catalysts in the preparation of Bis(2- hydroxynaphthalene-1,4-dione) from 2-hydroxy-1,4-naphthoquinones and arylaldehydes in excellent yields of up to 96%. The evaluation of the antibacterial profile against Gram-positive strains (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. epidermidis ATCC 12228) also including a hospital Methicillin-resistant S. aureus (MRSA) and Gram-negative strains (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Klebsiella pneumoniae ATCC 4352), revealed that seven compounds showed antibacterial activity within the Clinical and Laboratory Standards Institute (CLSI) levels mainly against P. aeruginosa ATCC 27853 (MIC 8-128 µg/mL) and MRSA (MIC 32-128 µg/mL). In addition, the in vitro toxicity showed all derivatives with no hemolytic effects on healthy human erythrocytes. Furthermore, the derivatives showed satisfactory theoretical absorption, distribution, metabolism, excretion, toxicity (ADMET) parameters, and a similar profile to antibiotics currently in use. Finally, the in silico evaluation pointed to a structure-activity relationship related to lipophilicity for these compounds. This feature may help them in acting against Gram-negative strains, which present a rich lipid cell wall selective for several antibiotics. Conclusion: Our data showed the potential of this series for exploring new and more effective antibacterial activities in vivo against other resistant bacteria.

scholarly journals Small Molecule Inhibitor of Type Three Secretion System Belonging to a Class 2,4-disubstituted-4H-[1,3,4]-thiadiazine-5-ones Improves Survival and Decreases Bacterial Loads in an AirwayPseudomonas aeruginosaInfection in Mice

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Anna B. Sheremet ◽  
Naylia A. Zigangirova ◽  
Egor S. Zayakin ◽  
Sergei I. Luyksaar ◽  
Lydia N. Kapotina ◽  
...  
Keyword(s):  
Small Molecule ◽  
Small Molecule Inhibitor ◽  
Secretion System ◽  
Resistant Bacteria ◽  
Lung Pathology ◽  
Antibiotic Resistant ◽  
Molecule Inhibitor ◽  
Type Three Secretion System ◽  
Type Three Secretion

Pseudomonas aeruginosais a cause of high mortality in burn, immunocompromised, and surgery patients. High incidence of antibiotic resistance in this pathogen makes the existent therapy inefficient. Type three secretion system (T3SS) is a leading virulence system ofP. aeruginosathat actively suppresses host resistance and enhances the severity of infection. Innovative therapeutic strategies aiming at inhibition of type three secretion system ofP. aeruginosaare highly attractive, as they may reduce the severity of clinical manifestations and improve antibacterial immune responses. They may also represent an attractive therapy for antibiotic-resistant bacteria. Recently our laboratory developed a new small molecule inhibitor belonging to a class 2,4-disubstituted-4H-[1,3,4]-thiadiazine-5-ones, Fluorothiazinon (FT), that effectively suppressed T3SS in chlamydia and salmonellain vitroandin vivo.In this study, we evaluate the activity of FT towards antibiotic-resistant clinical isolates ofP. aeruginosaexpressing T3SS effectors ExoU and ExoS in an airway infection model. We found that FT reduced mortality and bacterial loads and decrease lung pathology and systemic inflammation. In addition, we show that FT inhibits the secretion of ExoT and ExoY, reduced bacteria cytotoxicity, and increased bacteria internalizationin vitro. Overall, FT shows a strong potential as an antibacterial therapy of antibiotic-resistantP. aeruginosainfection.

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