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Chittams-Miles AE, Malik A, Purcell EB, Muratori C. Nanosecond pulsed electric fields increase antibiotic susceptibility in methicillin-resistant Staphylococcus aureus. Microbiol Spectr 2024; 12:e0299223. [PMID: 38092563 PMCID: PMC10783032 DOI: 10.1128/spectrum.02992-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/31/2023] [Indexed: 01/13/2024] Open
Abstract
IMPORTANCE We have found that treatment with short electric pulses potentiates the effects of multiple antibiotics against methicillin-resistant Staphylococcus aureus. By reducing the dose of antibiotic necessary to be effective, co-treatment with electric pulses could amplify the effects of standard antibiotic dosing to treat S. aureus infections such as skin and soft-tissue infections (SSTIs). SSTIs are accessible to physical intervention and are good candidates for electric pulse co-treatment, which could be adopted as a step-in wound and abscess debridement.
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Affiliation(s)
- Alexandra E. Chittams-Miles
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, USA
- Biomedical Sciences Program, Old Dominion University, Norfolk, Virginia, USA
| | - Areej Malik
- Biomedical Sciences Program, Old Dominion University, Norfolk, Virginia, USA
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, USA
| | - Erin B. Purcell
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, USA
| | - Claudia Muratori
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, USA
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, USA
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2
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Pruitt EL, Zhang R, Ross DH, Ashford NK, Chen X, Alonzo F, Bush MF, Werth BJ, Xu L. Elucidating the impact of bacterial lipases, human serum albumin, and FASII inhibition on the utilization of exogenous fatty acids by Staphylococcus aureus. mSphere 2023; 8:e0036823. [PMID: 38014966 PMCID: PMC10732024 DOI: 10.1128/msphere.00368-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/26/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Incorporation of host-derived exogenous fatty acids (eFAs), particularly unsaturated fatty acids (UFAs), by Staphylococcus aureus could affect the bacterial membrane fluidity and susceptibility to antimicrobials. In this work, we found that glycerol ester hydrolase (Geh) is the primary lipase hydrolyzing cholesteryl esters and, to a lesser extent, triglycerides and that human serum albumin (HSA) could serve as a buffer of eFAs, where low levels of HSA facilitate the utilization of eFAs but high levels of HSA inhibit it. The fact that the type II fatty acid synthesis (FASII) inhibitor, AFN-1252, leads to an increase in UFA content even in the absence of eFA suggests that membrane property modulation is part of its mechanism of action. Thus, Geh and/or the FASII system look to be promising targets to enhance S. aureus killing in a host environment by restricting eFA utilization or modulating membrane properties, respectively.
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Affiliation(s)
- Emily L. Pruitt
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | - Dylan H. Ross
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | | | - Xi Chen
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Matthew F. Bush
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Brian J. Werth
- Department of Pharmacy, University of Washington, Seattle, Washington, USA
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
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Ledger EVK, Sabnis A, Edwards AM. Polymyxin and lipopeptide antibiotics: membrane-targeting drugs of last resort. MICROBIOLOGY (READING, ENGLAND) 2022; 168:001136. [PMID: 35118938 PMCID: PMC8941995 DOI: 10.1099/mic.0.001136] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
The polymyxin and lipopeptide classes of antibiotics are membrane-targeting drugs of last resort used to treat infections caused by multi-drug-resistant pathogens. Despite similar structures, these two antibiotic classes have distinct modes of action and clinical uses. The polymyxins target lipopolysaccharide in the membranes of most Gram-negative species and are often used to treat infections caused by carbapenem-resistant species such as Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa. By contrast, the lipopeptide daptomycin requires membrane phosphatidylglycerol for activity and is only used to treat infections caused by drug-resistant Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. However, despite having distinct targets, both antibiotic classes cause membrane disruption, are potently bactericidal in vitro and share similarities in resistance mechanisms. Furthermore, there are concerns about the efficacy of these antibiotics, and there is increasing interest in using both polymyxins and daptomycin in combination therapies to improve patient outcomes. In this review article, we will explore what is known about these distinct but structurally similar classes of antibiotics, discuss recent advances in the field and highlight remaining gaps in our knowledge.
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Affiliation(s)
- Elizabeth V. K. Ledger
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Akshay Sabnis
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Andrew M. Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
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Johnston RD, Woodall BM, Harrison J, Campagna SR, Fozo EM. Removal of peptidoglycan and inhibition of active cellular processes leads to daptomycin tolerance in Enterococcus faecalis. PLoS One 2021; 16:e0254796. [PMID: 34297729 PMCID: PMC8301656 DOI: 10.1371/journal.pone.0254796] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 07/04/2021] [Indexed: 11/19/2022] Open
Abstract
Daptomycin is a cyclic lipopeptide antibiotic used in the clinic for treatment of severe enterococcal infections. Recent reports indicate that daptomycin targets active cellular processes, specifically, peptidoglycan biosynthesis. Within, we examined the efficacy of daptomycin against Enterococcus faecalis under a range of environmental growth conditions including inhibitors that target active cellular processes. Daptomycin was far less effective against cells in late stationary phase compared to cells in exponential phase, and this was independent of cellular ATP levels. Further, the addition of either the de novo protein synthesis inhibitor chloramphenicol or the fatty acid biosynthesis inhibitor cerulenin induced survival against daptomycin far better than controls. Alterations in metabolites associated with peptidoglycan synthesis correlated with protection against daptomycin. This was further supported as removal of peptidoglycan induced physiological daptomycin tolerance, a synergistic relation between daptomycin and fosfomycin, an inhibitor of the fist committed step peptidoglycan synthesis, was observed, as well as an additive effect when daptomycin was combined with ampicillin, which targets crosslinking of peptidoglycan strands. Removal of the peptidoglycan of Enterococcus faecium, Staphylococcus aureus, and Bacillus subtilis also resulted in significant protection against daptomycin in comparison to whole cells with intact cell walls. Based on these observations, we conclude that bacterial growth phase and metabolic activity, as well as the presence/absence of peptidoglycan are major contributors to the efficacy of daptomycin.
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Affiliation(s)
- Rachel D. Johnston
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, United States of America
| | - Brittni M. Woodall
- Department of Chemistry, University of Tennessee, Knoxville, TN, United States of America
| | - Johnathan Harrison
- Department of Microbiology, University of Tennessee, Knoxville, TN, United States of America
| | - Shawn R. Campagna
- Department of Chemistry, University of Tennessee, Knoxville, TN, United States of America
- Biological and Small Molecule Mass Spectrometry Core, University of Tennessee, Knoxville, TN, United States of America
| | - Elizabeth M. Fozo
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, United States of America
- Department of Microbiology, University of Tennessee, Knoxville, TN, United States of America
- * E-mail:
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Rowe SE, Beam JE, Conlon BP. Recalcitrant Staphylococcus aureus Infections: Obstacles and Solutions. Infect Immun 2021; 89:e00694-20. [PMID: 33526569 PMCID: PMC8090968 DOI: 10.1128/iai.00694-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Antibiotic treatment failure of Staphylococcus aureus infections is very common. In addition to genetically encoded mechanisms of antibiotic resistance, numerous additional factors limit the efficacy of antibiotics in vivo Identifying and removing the barriers to antibiotic efficacy are of major importance, as even if new antibiotics become available, they will likely face the same barriers to efficacy as their predecessors. One major obstacle to antibiotic efficacy is the proficiency of S. aureus to enter a physiological state that is incompatible with antibiotic killing. Multiple pathways leading to antibiotic tolerance and the formation of tolerant subpopulations called persister cells have been described for S. aureus Additionally, S. aureus is a versatile pathogen that can infect numerous tissues and invade a variety of cell types, of which some are poorly penetrable to antibiotics. It is therefore unlikely that there will be a single solution to the problem of recalcitrant S. aureus infection. Instead, specific approaches may be required for targeting tolerant cells within different niches, be it through direct targeting of persister cells, sensitization of persisters to conventional antibiotics, improved penetration of antibiotics to particular niches, or any combination thereof. Here, we examine two well-described reservoirs of antibiotic-tolerant S. aureus, the biofilm and the macrophage, the barriers these environments present to antibiotic efficacy, and potential solutions to the problem.
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Affiliation(s)
- Sarah E Rowe
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jenna E Beam
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Brian P Conlon
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Abstract
The nares of one in three humans are colonized by Staphylococcus aureus. In these environments, and arguably on all mucosal surfaces, bacteria encounter fatty acids with antimicrobial properties. Our study uncovers that S. aureus releases membrane vesicles (MVs) that act as decoys to protect the bacterium against antimicrobial fatty acids (AFAs). The AFA-neutralizing effects of MVs were neither strain specific nor restricted to one particular AFA. Hence, MVs may represent “public goods” playing an overlooked role in shaping bacterial communities in AFA-rich environments such as the skin and nose. Intriguingly, in addition to MV biogenesis, S. aureus modulates MV composition in response to exposure to AFAs, including an increased release of lipoproteins. These MVs strongly stimulate the innate immunity via Toll-like receptor 2 (TLR2). TLR2-mediated inflammation, which helps to fight infections, may exacerbate inflammatory disorders like atopic dermatitis. Our study highlights intricate immune responses preventing infections from colonizing bacteria. Staphylococcus aureus is a major pathogen, which colonizes one in three otherwise healthy humans. This significant spread of S. aureus is largely due to its ability to circumvent innate immune responses, including antimicrobial fatty acids (AFAs) on the skin and in nasal secretions. In response to AFAs, S. aureus swiftly induces resistance mechanisms, which have yet to be completely elucidated. Here, we identify membrane vesicle (MV) release as a resistance strategy used by S. aureus to sequester host-specific AFAs. MVs protect S. aureus against a wide array of AFAs. Strikingly, beside MV production, S. aureus modulates MV composition upon exposure to AFAs. MVs purified from bacteria grown in the presence of linoleic acid display a distinct protein content and are enriched in lipoproteins, which strongly activate Toll-like receptor 2 (TLR2). Cumulatively, our findings reveal the protective capacities of MVs against AFAs, which are counteracted by an increased TLR2-mediated innate immune response. IMPORTANCE The nares of one in three humans are colonized by Staphylococcus aureus. In these environments, and arguably on all mucosal surfaces, bacteria encounter fatty acids with antimicrobial properties. Our study uncovers that S. aureus releases membrane vesicles (MVs) that act as decoys to protect the bacterium against antimicrobial fatty acids (AFAs). The AFA-neutralizing effects of MVs were neither strain specific nor restricted to one particular AFA. Hence, MVs may represent “public goods” playing an overlooked role in shaping bacterial communities in AFA-rich environments such as the skin and nose. Intriguingly, in addition to MV biogenesis, S. aureus modulates MV composition in response to exposure to AFAs, including an increased release of lipoproteins. These MVs strongly stimulate the innate immunity via Toll-like receptor 2 (TLR2). TLR2-mediated inflammation, which helps to fight infections, may exacerbate inflammatory disorders like atopic dermatitis. Our study highlights intricate immune responses preventing infections from colonizing bacteria.
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Kronenberger T, de Oliveira Fernades P, Drumond Franco I, Poso A, Gonçalves Maltarollo V. Ligand- and Structure-Based Approaches of Escherichia coli FabI Inhibition by Triclosan Derivatives: From Chemical Similarity to Protein Dynamics Influence. ChemMedChem 2019; 14:1995-2004. [PMID: 31670463 PMCID: PMC6916556 DOI: 10.1002/cmdc.201900415] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/03/2019] [Indexed: 12/20/2022]
Abstract
Enoyl-acyl carrier protein reductase (FabI) is the limiting step to complete the elongation cycle in type II fatty acid synthase (FAS) systems and is a relevant target for antibacterial drugs. E. coli FabI has been employed as a model to develop new inhibitors against FAS, especially triclosan and diphenyl ether derivatives. Chemical similarity models (CSM) were used to understand which features were relevant for FabI inhibition. Exhaustive screening of different CSM parameter combinations featured chemical groups, such as the hydroxy group, as relevant to distinguish between active/decoy compounds. Those chemical features can interact with the catalytic Tyr156. Further molecular dynamics simulation of FabI revealed the ionization state as a relevant for ligand stability. Also, our models point the balance between potency and the occupancy of the hydrophobic pocket. This work discusses the strengths and weak points of each technique, highlighting the importance of complementarity among approaches to elucidate EcFabI inhibitor's binding mode and offers insights for future drug discovery.
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Affiliation(s)
- Thales Kronenberger
- Department of Medical Oncology and Pneumology, Internal Medicine VIIIUniversity Hospital of TübingenOtfried-Müller-Strasse 1472076TübingenGermany
- School of PharmacyUniversity of Eastern Finland Faculty of Health SciencesKuopio70211Finland
| | - Philipe de Oliveira Fernades
- Departamento de Produtos Farmacêuticos, Faculdade de FarmáciaUniversidade Federal de Minas GeraisAv. Antônio Carlos6627Pampulha, Belo Horizonte, MG, 31270-901Brazil
- Departamento de Química, Instituto de Ciências ExatasUniversidade Federal de Minas GeraisAv. Antônio Carlos6627 –Pampulha, Belo Horizonte, MG, 31270-901Brazil
| | - Isabella Drumond Franco
- Departamento de Produtos Farmacêuticos, Faculdade de FarmáciaUniversidade Federal de Minas GeraisAv. Antônio Carlos6627Pampulha, Belo Horizonte, MG, 31270-901Brazil
| | - Antti Poso
- Department of Medical Oncology and Pneumology, Internal Medicine VIIIUniversity Hospital of TübingenOtfried-Müller-Strasse 1472076TübingenGermany
- School of PharmacyUniversity of Eastern Finland Faculty of Health SciencesKuopio70211Finland
| | - Vinícius Gonçalves Maltarollo
- Departamento de Produtos Farmacêuticos, Faculdade de FarmáciaUniversidade Federal de Minas GeraisAv. Antônio Carlos6627Pampulha, Belo Horizonte, MG, 31270-901Brazil
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RexAB is essential for the mutagenic repair of Staphylococcus aureus DNA damage caused by co-trimoxazole. Antimicrob Agents Chemother 2019:AAC.00944-19. [PMID: 31591116 PMCID: PMC6879246 DOI: 10.1128/aac.00944-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Co-trimoxazole (SXT) is a combination therapeutic that consists of sulfamethoxazole and trimethoprim that is increasingly used to treat skin and soft-tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA). However, the use of SXT is limited to the treatment of low-burden, superficial S. aureus infections and its therapeutic value is compromised by the frequent emergence of resistance. As a first step towards the identification of approaches to enhance the efficacy of SXT, we examined the role of bacterial DNA repair in antibiotic susceptibility and mutagenesis. We found that mutants lacking the DNA repair complex RexAB had a modest 2-fold lower SXT MIC than wild-type strains but were killed 50-5000-fold more efficiently by the combination antibiotic at the breakpoint concentration. SXT-mediated DNA damage occurred via both thymidine limitation and the generation of reactive oxygen species, and triggered induction of the SOS response in a RexAB-dependent manner. SOS induction was associated with a 50% increase in the mutation rate, which may contribute to emergence of resistant strains during SXT therapy. In summary, this work determined that SXT caused DNA damage in S. aureus via both thymidine limitation and oxidative stress, which was repaired by the RexAB complex, leading to induction of the mutagenic SOS response. Small molecule inhibitors of RexAB could therefore have therapeutic value by increasing the efficacy of SXT and decreasing the emergence of drug-resistance during treatment of infections caused by S. aureus.
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