scholarly journals Isolation of Phage Lysins That Effectively KillPseudomonas aeruginosain Mouse Models of Lung and Skin Infection

2019 ◽  
Vol 63 (7) ◽  
Author(s):  
Assaf Raz ◽  
Anna Serrano ◽  
Anaise Hernandez ◽  
Chad W. Euler ◽  
Vincent A. Fischetti
Keyword(s):  
Outer Membrane ◽  
Bacterial Infections ◽  
Skin Infection ◽  
Therapeutic Potential ◽  
Treatment Options ◽  
Opportunistic Pathogen ◽  
Infection Model ◽  
Gram Negative ◽  
Content Type ◽  
Phage Lysins

ABSTRACTMultidrug resistance (MDR) is rapidly increasing in prevalence among isolates of the opportunistic pathogenPseudomonas aeruginosa, leaving few treatment options. Phage lysins are cell wall hydrolases that have a demonstrated therapeutic potential against Gram-positive pathogens; however, the outer membrane of Gram-negative bacteria prevents most lysins from reaching the peptidoglycan, making them less effective as therapeutics. Nevertheless, a few lysins from Gram-negative bacterial phage can penetrate the bacterial outer membrane with the aid of an amphipathic tail found in the molecule’s termini. In this work, we took a phylogenetic approach to systematically identify those lysins fromP. aeruginosaphage that would be most effective therapeutically. We isolated and performed preliminary characterization of 16 lysins and chose 2 lysins, PlyPa03 and PlyPa91, which exhibited >5-log killing activity againstP. aeruginosaand other Gram-negative pathogens (particularlyKlebsiellaandEnterobacter). These lysins showed rapid killing kinetics and were active in the presence of high concentrations of salt and urea and under pH conditions ranging from 5.0 to 10.0. Activity was not inhibited in the presence of the pulmonary surfactant beractant (Survanta). While neither enzyme was active in 100% human serum, PlyPa91 retained activity in low serum concentrations. The lysins were effective in the treatment of aP. aeruginosaskin infection in a mouse model, and PlyPa91 protected mice in a lung infection model, making these lysins potential drug candidates for Gram-negative bacterial infections of the skin or respiratory mucosa.

scholarly journals ZN148 Is a Modular Synthetic Metallo-β-Lactamase Inhibitor That Reverses Carbapenem Resistance in Gram-Negative Pathogens In Vivo

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Ørjan Samuelsen ◽  
Ove Alexander Høgmoen Åstrand ◽  
Christopher Fröhlich ◽  
Adam Heikal ◽  
Susann Skagseth ◽  
...  
Keyword(s):  
Active Site ◽  
Therapeutic Potential ◽  
Treatment Options ◽  
Carbapenem Resistance ◽  
Functional Space ◽  
Bactericidal Effect ◽  
Gram Negative ◽  
Content Type

ABSTRACT Carbapenem-resistant Gram-negative pathogens are a critical public health threat and there is an urgent need for new treatments. Carbapenemases (β-lactamases able to inactivate carbapenems) have been identified in both serine β-lactamase (SBL) and metallo-β-lactamase (MBL) families. The recent introduction of SBL carbapenemase inhibitors has provided alternative therapeutic options. Unfortunately, there are no approved inhibitors of MBL-mediated carbapenem-resistance and treatment options for infections caused by MBL-producing Gram-negatives are limited. Here, we present ZN148, a zinc-chelating MBL-inhibitor capable of restoring the bactericidal effect of meropenem and in vitro clinical susceptibility to carbapenems in >98% of a large international collection of MBL-producing clinical Enterobacterales strains (n = 234). Moreover, ZN148 was able to potentiate the effect of meropenem against NDM-1-producing Klebsiella pneumoniae in a murine neutropenic peritonitis model. ZN148 showed no inhibition of the human zinc-containing enzyme glyoxylase II at 500 μM, and no acute toxicity was observed in an in vivo mouse model with cumulative dosages up to 128 mg/kg. Biochemical analysis showed a time-dependent inhibition of MBLs by ZN148 and removal of zinc ions from the active site. Addition of exogenous zinc after ZN148 exposure only restored MBL activity by ∼30%, suggesting an irreversible mechanism of inhibition. Mass-spectrometry and molecular modeling indicated potential oxidation of the active site Cys221 residue. Overall, these results demonstrate the therapeutic potential of a ZN148-carbapenem combination against MBL-producing Gram-negative pathogens and that ZN148 is a highly promising MBL inhibitor that is capable of operating in a functional space not presently filled by any clinically approved compound.

scholarly journals Reinforcing Lipid A Acylation on the Cell Surface of Acinetobacter baumannii Promotes Cationic Antimicrobial Peptide Resistance and Desiccation Survival

mBio ◽  
2015 ◽  
Vol 6 (3) ◽  
Author(s):  
Joseph M. Boll ◽  
Ashley T. Tucker ◽  
Dustin R. Klein ◽  
Alexander M. Beltran ◽  
Jennifer S. Brodbelt ◽  
...  
Keyword(s):  
Health Care ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Lipid A ◽  
Treatment Options ◽  
Cationic Antimicrobial Peptide ◽  
Gram Negative ◽  
Content Type ◽  
Hospital Environments ◽  
Lipid A Biosynthesis

ABSTRACTAcinetobacter baumanniiis an emerging Gram-negative pathogen found in hospitals and intensive care units. In order to persist in hospital environments,A. baumanniiwithstands desiccative conditions and can rapidly develop multidrug resistance to conventional antibiotics. Cationic antimicrobial peptides (CAMPs) have served as therapeutic alternatives because they target the conserved lipid A component of the Gram-negative outer membrane to lyse the bacterial cell. However, many Gram-negative pathogenic bacteria, includingA. baumannii, fortify their outer membrane with hepta-acylated lipid A to protect the cell from CAMP-dependent cell lysis. Whereas inEscherichia coliandSalmonella, increased production of the outer membrane acyltransferase PagP results in formation of protective hepta-acylated lipid A, which reinforces the lipopolysaccharide portion of the outer membrane barrier,A. baumanniidoes not carry a gene that encodes a PagP homolog. Instead,A. baumanniihas evolved a PagP-independent mechanism to synthesize protective hepta-acylated lipid A. Taking advantage of a recently adaptedA. baumanniigenetic recombineering system, we characterized two putative acyltransferases inA. baumanniidesignated LpxLAb(A. baumanniiLpxL) and LpxMAb(A. baumanniiLpxM), which transfer one and two lauroyl (C12:0) acyl chains, respectively, during lipid A biosynthesis. Hepta-acylation ofA. baumanniilipid A promoted resistance to vertebrate and polymyxin CAMPs, which are prescribed as last-resort treatment options. Intriguingly, our analysis also showed that LpxMAb-dependent acylation of lipid A is essential forA. baumanniidesiccation survival, a key resistance mechanism for survival in hospital environments. Compounds that inhibit LpxMAb-dependent hepta-acylation of lipid A could act synergistically with CAMPs to provide innovative transmission prevention strategies and treat multidrug-resistant infections.IMPORTANCEAcinetobacter baumanniiinfections can be life threatening, and disease can progress in a variety of host tissues. Current antibiotic regimen and disinfectant strategies have failed to limit nosocomialA. baumanniiinfections. Instead, the rate ofA. baumanniiinfection among health care communities has skyrocketed due to the bacterium's adaptability. Its aptitude for survival over extended periods on inanimate objects, such as catheters, respirators, and surfaces in intensive care units, or on the hands of health care workers and its ability to rapidly develop antibiotic resistance makeA. baumanniia threat to health care communities. Emergence of multidrug- and extremely drug-resistantA. baumanniiillustrates the ineffectiveness of current prevention and treatment options. Our analysis to understand howA. baumanniiresists cationic antimicrobial peptide (CAMP)-mediated and desiccative killing revealed two lipid A acyltransferases that produce protective hepta-acylated lipid A. Our work suggests that inhibiting lipid A biosynthesis by targeting the acyltransferase LpxMAb(A. baumanniiLpxM) could provide a novel target to combat this pathogen.

scholarly journals Characterization of an Acinetobacter baumanniilptDDeletion Strain: Permeability Defects and Response to Inhibition of Lipopolysaccharide and Fatty Acid Biosynthesis

2015 ◽  
Vol 198 (4) ◽  
pp. 731-741 ◽  
Author(s):  
Jade Bojkovic ◽  
Daryl L. Richie ◽  
David A. Six ◽  
Christopher M. Rath ◽  
William S. Sawyer ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Bacterial Infections ◽  
Lipid A ◽  
Fatty Acid Biosynthesis ◽  
Cell Permeability ◽  
Growth Defect ◽  
Gram Negative ◽  
Content Type ◽  
Chemical Inhibition

ABSTRACTLipid A on the Gram-negative outer membrane (OM) is synthesized in the cytoplasm by the Lpx pathway and translocated to the OM by the Lpt pathway. SomeAcinetobacter baumanniistrains can tolerate the complete loss of lipopolysaccharide (LPS) resulting from the inactivation of early LPS pathway genes such aslpxC. Here, we characterized a mutant deleted forlptD, which encodes an OM protein that mediates the final translocation of fully synthesized LPS to the OM. Cells lackinglptDhad a growth defect comparable to that of anlpxCdeletion mutant under the growth conditions tested but were more sensitive to hydrophobic antibiotics, revealing a more significant impact on cell permeability from impaired LPS translocation than from the loss of LPS synthesis. Consistent with this, ATP leakage andN-phenyl-1-naphthylamine (NPN) fluorescence assays indicated a more severe impact oflptDdeletion than oflpxCdeletion on inner and outer membrane permeability, respectively. Targeted liquid chromatography-mass spectrometry (LCMS) analysis of LPS intermediates from UDP-3-O-R-3-hydroxylauroyl-N-acetyl-α-d-glucosamine through lipid IVAshowed that the loss of LptD caused an accumulation of lipid IVA. This suggested that pathway intermediate accumulation or mislocalization caused by the blockage of later LPS pathway steps impacts envelope integrity. Supporting this notion, chemical inhibition of lipid A precursor enzymes, including LpxC and FabB/F, in thelptDdeletion strain partially rescued growth and permeability defects.IMPORTANCENew antibiotics to treat Gram-negative bacterial infections are urgently needed. Inhibition of LPS biosynthesis is attractive because this would impact viability and cell permeability. Therefore, a better understanding of this pathway is important, especially in strains such asA. baumanniiATCC 19606, where LPS biosynthesis is not essentialin vitro. We show that ATCC 19606 also survives the loss of the final translocation of LPS into the OM (lptDdeletion). Intriguingly, this impaired cell envelope integrity more than the loss of LPS biosynthesis (lpxCdeletion), presumably due to the accumulation of toxic intermediates. Supporting this, chemical inhibition of LPS biosynthesis partially reversed this permeability defect. This extends our understanding of the LPS machinery and provides insights into potential interrelationships of the target steps along this important pathway.

scholarly journals Azidothymidine Produces Synergistic Activity in Combination with Colistin against Antibiotic-Resistant Enterobacteriaceae

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
Yanmin Hu ◽  
Yingjun Liu ◽  
Anthony Coates
Keyword(s):  
Bacterial Infections ◽  
Therapeutic Potential ◽  
Infection Model ◽  
Synergistic Activity ◽  
Antibiotic Resistant ◽  
Content Type ◽  
E Coli ◽  
Broth Microdilution Method ◽  
Peritoneal Infection ◽  
Time Kill

ABSTRACT Bacterial infections remain a leading killer worldwide, which is worsened by the continuous emergence of antibiotic resistance. In particular, antibiotic-resistant Enterobacteriaceae are prevalent and extremely difficult to treat. Repurposing existing drugs and improving the therapeutic potential of existing antibiotics represent an attractive novel strategy. Azidothymidine (AZT) is an antiretroviral drug which is used in combination with other antivirals to prevent and to treat HIV/AIDS. AZT is also active against Gram-negative bacteria but has not been developed for that purpose. Here, we investigated the in vitro and in vivo efficacy of AZT in combination with colistin against antibiotic-resistant Enterobacteriaceae, including strains producing extended-spectrum beta-lactamases (ESBLs) or New Delhi metallo-beta-lactamase 1 (NDM) or carrying mobilized colistin resistance (mcr-1). The MIC was determined using the broth microdilution method. The combined effect of AZT and colistin was examined using the checkerboard method and time-kill analysis. A murine peritoneal infection model was used to test the therapeutic effect of the combination of AZT and colistin. The fractional inhibitory concentration index from the checkerboard assay demonstrated that AZT synergized with colistin against 61% and 87% of ESBL-producing Escherichia coli and Klebsiella pneumoniae strains, respectively, 100% of NDM-1-producing strains, and 92% of mcr-1-producing E. coli strains. Time-kill analysis demonstrated significant synergistic activities when AZT was combined with colistin. In a murine peritoneal infection model, AZT in combination with colistin showed augmented activities of both drugs in the treatment of NDM-1 K. pneumoniae and mcr-1 E. coli infections. The AZT and colistin combination possesses a potential to be used coherently to treat antibiotic-resistant Enterobacteriaceae infections.

scholarly journals Successful Development of Bacteriocins into Therapeutic Formulation for Treatment of MRSA Skin Infection in a Murine Model

2020 ◽  
Vol 64 (12) ◽  
Author(s):  
Kirill V. Ovchinnikov ◽  
Christian Kranjec ◽  
Tage Thorstensen ◽  
Harald Carlsen ◽  
Dzung B. Diep
Keyword(s):  
Skin Infection ◽  
Therapeutic Potential ◽  
Multidrug Resistant ◽  
Penicillin G ◽  
Infection Model ◽  
Component Mixture ◽  
Antibiotic Resistant ◽  
Content Type ◽  
Infection Treatment

ABSTRACT The emergence of antibiotic-resistant pathogens has caused a serious worldwide problem in infection treatment in recent years. One of the pathogens is methicillin-resistant Staphylococcus aureus (MRSA), which is a major cause of skin and soft tissue infections. Alternative strategies and novel sources of antimicrobials to solve antibiotic resistance problems are urgently needed. In this study, we explored the potential of two broad-spectrum bacteriocins, garvicin KS and micrococcin P1, in skin infection treatments. The two bacteriocins acted synergistically with each other and with penicillin G in killing MRSA in vitro. The MICs of the antimicrobials in the three-component mixture were 40 ng/ml for micrococcin P1 and 2 μg/ml for garvicin KS and penicillin G, which were 62, 16, and at least 1,250 times lower than their MICs when assessed individually. To assess its therapeutic potential further, we challenged the three-component formulation in a murine skin infection model with the multidrug-resistant luciferase-tagged MRSA Xen31, a strain derived from the clinical isolate S. aureus ATCC 33591. Using the tagged-luciferase activity as a reporter for the presence of Xen31 in wounds, we demonstrated that the three-component formulation was efficient in eradicating the pathogen from treated wounds. Furthermore, compared to Fucidin cream, which is an antibiotic commonly used in skin infection treatments, our formulation was also superior in terms of preventing resistance development.

scholarly journals Potentiation of Antibiotic Activity by a Novel Cationic Peptide: Potency and Spectrum of Activity of SPR741

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
David Corbett ◽  
Andrew Wise ◽  
Tara Langley ◽  
Kirsty Skinner ◽  
Emily Trimby ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Fusidic Acid ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Permeability Barrier ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Conventional Antibiotics

ABSTRACTNovel approaches for the treatment of multidrug-resistant Gram-negative bacterial infections are urgently required. One approach is to potentiate the efficacy of existing antibiotics whose spectrum of activity is limited by the permeability barrier presented by the Gram-negative outer membrane. Cationic peptides derived from polymyxin B have been used to permeabilize the outer membrane, granting antibiotics that would otherwise be excluded access to their targets. We assessed thein vitroefficacies of combinations of SPR741 with conventional antibiotics againstEscherichia coli,Klebsiella pneumoniae, andAcinetobacter baumannii. Of 35 antibiotics tested, the MICs of 8 of them were reduced 32- to 8,000-fold againstE. coliandK. pneumoniaein the presence of SPR741. The eight antibiotics, azithromycin, clarithromycin, erythromycin, fusidic acid, mupirocin, retapamulin, rifampin, and telithromycin, had diverse targets and mechanisms of action. AgainstA. baumannii, similar potentiation was achieved with clarithromycin, erythromycin, fusidic acid, retapamulin, and rifampin. Susceptibility testing of the most effective antibiotic-SPR741 combinations was extended to 25 additional multidrug-resistant or clinical isolates ofE. coliandK. pneumoniaeand 17 additionalA. baumanniiisolates in order to rank the potentiated antibiotics. SPR741 was also able to potentiate antibiotics that are substrates of the AcrAB-TolC efflux pump inE. coli, effectively circumventing the contribution of this pump to intrinsic antibiotic resistance. These studies support the further development of SPR741 in combination with conventional antibiotics for the treatment of Gram-negative bacterial infections.

scholarly journals Paenipeptin Analogues Potentiate Clarithromycin and Rifampin against mcr-1-Mediated Polymyxin-Resistant Escherichia coli In Vivo

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Sun Hee Moon ◽  
Yihong Kaufmann ◽  
En Huang
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Resistance ◽  
Outer Membrane ◽  
Infection Model ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Log Reduction

ABSTRACT Polymyxin resistance mediated by the mcr-1 gene threatens the last-resort antibiotics. Linear lipopeptide paenipeptin analogues 1 and 15 disrupted the outer membrane of Gram-negative pathogens and potentiated clarithromycin and rifampin against mcr-1-positive Escherichia coli from the FDA-CDC Antimicrobial Resistance Isolate Bank. In the presence of paenipeptin, clarithromycin and rifampin resulted in over 3-log reduction of E. coli in vitro. Moreover, paenipeptin-antibiotic combinations significantly reduced E. coli in a murine thigh infection model.

scholarly journals Protection againstStaphylococcus aureusColonization and Infection by B- and T-Cell-Mediated Mechanisms

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Fan Zhang ◽  
Olivia Ledue ◽  
Maria Jun ◽  
Cibelly Goulart ◽  
Richard Malley ◽  
...  
Keyword(s):  
T Cell ◽  
Soft Tissue ◽  
Bacterial Infections ◽  
Vaccine Development ◽  
Pathological Condition ◽  
Treatment Options ◽  
Immune Defense ◽  
Invasive Infection ◽  
Content Type ◽  
Increased Risk

ABSTRACTStaphylococcus aureusis a major cause of morbidity and mortality worldwide.S. aureuscolonizes 20 to 80% of humans at any one time and causes a variety of illnesses. Strains that are resistant to common antibiotics further complicate management.S. aureusvaccine development has been unsuccessful so far, largely due to the incomplete understanding of the mechanisms of protection against this pathogen. Here, we studied the role of different aspects of adaptive immunity induced by anS. aureusvaccine in protection againstS. aureusbacteremia, dermonecrosis, skin abscess, and gastrointestinal (GI) colonization. We show that, depending on the challenge model, the contributions of vaccine-inducedS. aureus-specific antibody and Th1 and Th17 responses to protection are different: antibodies play a major role in reducing mortality duringS. aureusbacteremia, whereas Th1 or Th17 responses are essential for prevention ofS. aureusskin abscesses and the clearance of bacteria from the GI tract. Both antibody- and T-cell-mediated mechanisms contribute to prevention ofS. aureusdermonecrosis. Engagement of all three immune pathways results in the most robust protection under each pathological condition. Therefore, our results suggest that eliciting multipronged humoral and cellular responses toS. aureusantigens may be critical to achieve effective and comprehensive immune defense against this pathogen.IMPORTANCES. aureusis a leading cause of healthcare- and community-associated bacterial infections.S. aureuscauses various illnesses, including bacteremia, meningitis, endocarditis, pneumonia, osteomyelitis, sepsis, and skin and soft tissue infections.S. aureuscolonizes between 20 and 80% of humans; carriers are at increased risk for infection and transmission to others. The spread of multidrug-resistant strains limits antibiotic treatment options. Vaccine development againstS. aureushas been unsuccessful to date, likely due to an inadequate understanding about the mechanisms of immune defense against this pathogen. The significance of our work is in illustrating the necessity of generating multipronged B-cell, Th1-, and Th17-mediated responses toS. aureusantigens in conferring enhanced and broad protection againstS. aureusinvasive infection, skin and soft tissue infection, and mucosal colonization. Our work thus, provides important insights for future vaccine development against this pathogen.

scholarly journals Efficacy of Humanized Cefiderocol Exposures over 72 Hours against a Diverse Group of Gram-Negative Isolates in the Neutropenic Murine Thigh Infection Model

2018 ◽  
Vol 63 (2) ◽  
pp. e01040-18 ◽  
Author(s):  
Sean M. Stainton ◽  
Marguerite L. Monogue ◽  
Masakatsu Tsuji ◽  
Yoshinori Yamano ◽  
Roger Echols ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Infection Model ◽  
Diverse Group ◽  
Gram Negative ◽  
Content Type ◽  
Adaptive Resistance

ABSTRACT Herein, we evaluated sustainability of humanized exposures of cefiderocol in vivo over 72 h against pathogens with cefiderocol MICs of 0.5 to 16 μg/ml in the neutropenic murine thigh model. In Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae displaying MICs of 0.5 to 8 μg/ml (n = 11), sustained kill was observed at 72 h among 9 isolates. Postexposure MICs revealed a single 2-dilution increase in one animal compared with controls (1/54 samples, 1.8%) at 72 h. Adaptive resistance during therapy was not observed.

scholarly journals Reversal of Azole Resistance inCandida albicansby Sulfa Antibacterial Drugs

2017 ◽  
Vol 62 (3) ◽  
Author(s):  
Hassan E. Eldesouky ◽  
Abdelrahman Mayhoub ◽  
Tony R. Hazbun ◽  
Mohamed N. Seleem
Keyword(s):  
Treatment Options ◽  
Antifungal Drugs ◽  
Infection Model ◽  
Azole Resistance ◽  
Global Public Health ◽  
Sulfa Drugs ◽  
Antibacterial Drugs ◽  
Content Type

ABSTRACTInvasive candidiasis presents an emerging global public health challenge due to the emergence of resistance to the frontline treatment options, such as fluconazole. Hence, the identification of other compounds capable of pairing with fluconazole and averting azole resistance would potentially prolong the clinical utility of this important group. In an effort to repurpose drugs in the field of antifungal drug discovery, we explored sulfa antibacterial drugs for the purpose of reversing azole resistance inCandida. In this study, we assembled and investigated a library of 21 sulfa antibacterial drugs for their ability to restore fluconazole sensitivity inCandida albicans. Surprisingly, the majority of assayed sulfa drugs (15 of 21) were found to exhibit synergistic relationships with fluconazole by checkerboard assay with fractional inhibitory concentration index (ΣFIC) values ranging from <0.0312 to 0.25. Remarkably, five sulfa drugs were able to reverse azole resistance in a clinically achievable range. The structure-activity relationships (SARs) of the amino benzene sulfonamide scaffold as antifungal agents were studied. We also identified the possible mechanism of the synergistic interaction of sulfa antibacterial drugs with azole antifungal drugs. Furthermore, the ability of sulfa antibacterial drugs to inhibitCandidabiofilm by 40%in vitrowas confirmed. In addition, the effects of sulfa-fluconazole combinations onCandidagrowth kinetics and efflux machinery were explored. Finally, using aCaenorhabditis elegansinfection model, we demonstrated that the sulfa-fluconazole combination does possess potent antifungal activityin vivo, reducingCandidain infected worms by ∼50% compared to the control.

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