Polyclonal activation of an IgA subclass against Staphylococcus aureus cell membrane antigen in post-methicillin-resistant S.aureus infection glomerulonephritis

As the burden of antibacterial resistance worsens and treatment options become narrower, rhodomyrtone—a novel natural antibiotic agent with a new antibacterial mechanism—could replace existing antibiotics for the treatment of infections caused by multi-drug resistant Gram-positive bacteria. In this study, rhodomyrtone was detected within the cell by means of an easy an inexpensive method. The antibacterial effects of rhodomyrtone were investigated on epidemic methicillin-resistant Staphylococcus aureus. Thin-layer chromatography demonstrated the entrapment and accumulation of rhodomyrtone within the bacterial cell wall and cell membrane. The incorporation of radiolabelled precursors revealed that rhodomyrtone inhibited the synthesis of macromolecules including DNA, RNA, proteins, the cell wall, and lipids. Following the treatment with rhodomyrtone at MIC (0.5–1 µg/mL), the synthesis of all macromolecules was significantly inhibited (p ≤ 0.05) after 4 h. Inhibition of macromolecule synthesis was demonstrated after 30 min at a higher concentration of rhodomyrtone (4× MIC), comparable to standard inhibitor compounds. In contrast, rhodomyrtone did not affect lipase activity in staphylococci—both epidemic methicillin-resistant S. aureus and S. aureus ATCC 29213. Interfering with the synthesis of multiple macromolecules is thought to be one of the antibacterial mechanisms of rhodomyrtone.

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Telavancin, a Multifunctional Lipoglycopeptide, Disrupts both Cell Wall Synthesis and Cell Membrane Integrity in Methicillin-Resistant Staphylococcus aureus

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.3.1127-1134.2005 ◽

2005 ◽

Vol 49 (3) ◽

pp. 1127-1134 ◽

Cited By ~ 291

Author(s):

Deborah L. Higgins ◽

Ray Chang ◽

Dmitri V. Debabov ◽

Joey Leung ◽

Terry Wu ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Membrane Potential ◽

Cell Membrane ◽

Bactericidal Activity ◽

Bacterial Cell ◽

Cell Membrane Potential ◽

Gram Positive ◽

Methicillin Resistant ◽

Bacterial Cell Membrane

ABSTRACTThe emergence and spread of multidrug-resistant gram-positive bacteria represent a serious clinical problem. Telavancin is a novel lipoglycopeptide antibiotic that possesses rapid in vitro bactericidal activity against a broad spectrum of clinically relevant gram-positive pathogens. Here we demonstrate that telavancin's antibacterial activity derives from at least two mechanisms. As observed with vancomycin, telavancin inhibited late-stage peptidoglycan biosynthesis in a substrate-dependent fashion and bound the cell wall, as it did the lipid II surrogate tripeptideN,N′-diacetyl-l-lysinyl-d-alanyl-d-alanine, with high affinity. Telavancin also perturbed bacterial cell membrane potential and permeability. In methicillin-resistantStaphylococcus aureus, telavancin caused rapid, concentration-dependent depolarization of the plasma membrane, increases in permeability, and leakage of cellular ATP and K+. The timing of these changes correlated with rapid , concentration-dependent loss of bacterial viability, suggesting that the early bactericidal activity of telavancin results from dissipation of cell membrane potential and an increase in membrane permeability. Binding and cell fractionation studies provided direct evidence for an interaction of telavancin with the bacterial cell membrane; stronger binding interactions were observed with the bacterial cell wall and cell membrane relative to vancomycin. We suggest that this multifunctional mechanism of action confers advantageous antibacterial properties.

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Altering the Proclivity towards Daptomycin Resistance in Methicillin-Resistant Staphylococcus aureus Using Combinations with Other Antibiotics

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00502-12 ◽

2012 ◽

Vol 56 (10) ◽

pp. 5046-5053 ◽

Cited By ~ 40

Author(s):

Andrew D. Berti ◽

Justine E. Wergin ◽

Gary G. Girdaukas ◽

Scott J. Hetzel ◽

George Sakoulas ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Cell Membrane ◽

Membrane Integrity ◽

Wall Thickening ◽

Methicillin Resistant ◽

Content Type ◽

Cell Membrane Integrity ◽

Cell Membrane Fluidity

ABSTRACTDaptomycin (DAP) is increasingly used as a part of combination therapy, particularly in complex methicillin-resistantStaphylococcus aureus(MRSA) infections. While multiple studies have reported the potential for synergy between DAP and adjunctive anti-infectives, few have examined the influence of adjunctive therapy on the emergence of DAP resistance. This study examined eight adjunctive antimicrobial combinations with DAPin vitroand the emergence of DAP resistance over time (up to 4 weeks) using clinical isolates of DAP-susceptible MRSA (MIC, 0.5 μg/ml) in which DAP resistance subsequently developed during patient therapy (MIC, 3 μg/ml). In addition to DAP susceptibility testing, selected strains were examined for phenotypic changes associated with DAP resistance, including changes to cell wall thickness (CWT) and cell membrane alterations. The addition of either oxacillin or clarithromycin in medium containing DAP significantly inhibited the development of DAP resistance through the entirety of the 4-week exposure (10- to 32-fold MIC reduction from that of DAP alone). Combinations with rifampin or fosfomycin were effective in delaying the emergence of DAP resistance through the end of week one only (week one MIC, 0.5 μg/ml; week four MIC, 24 μg/ml). Cell wall thickening was observed for all antibiotic combinations regardless of their effect on the DAP MIC (14 to 70% increase in CWT), while changes in cell membrane fluidity were variable and treatment dependent. DAP showed reduced activity against strains with DAP MICs of 1 to 12 μg/ml, but cell membrane integrity was still disrupted at concentrations achieved with doses greater than 10 mg/kg of body weight. The emergence of DAP resistance in MRSA is strongly influenced by the presence of subinhibitory concentrations of adjunctive antimicrobials. These data suggest that combining DAP with oxacillin or clarithromycin may delay the development of DAP resistance in cases requiring prolonged antibiotic therapy.

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In VitroCross-Resistance to Daptomycin and Host Defense Cationic Antimicrobial Peptides in Clinical Methicillin-Resistant Staphylococcus aureus Isolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00223-11 ◽

2011 ◽

Vol 55 (9) ◽

pp. 4012-4018 ◽

Cited By ~ 86

Author(s):

Nagendra N. Mishra ◽

James McKinnell ◽

Michael R. Yeaman ◽

Aileen Rubio ◽

Cynthia C. Nast ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Cell Membrane ◽

Antimicrobial Peptides ◽

Surface Charge ◽

Host Defense ◽

Cationic Antimicrobial Peptides ◽

Methicillin Resistant ◽

Membrane Order

ABSTRACTWe investigated the hypothesis that methicillin-resistantStaphylococcus aureus(MRSA) isolates developing reduced susceptibilities to daptomycin (DAP; a calcium-dependent molecule acting as a cationic antimicrobial peptide [CAP]) may also coevolve reducedin vitrosusceptibilities to host defense cationic antimicrobial peptides (HDPs). Ten isogenic pairs of clinical MRSA DAP-susceptible/DAP-resistant (DAPs/DAPr) strains were tested against two distinct HDPs differing in structure, mechanism of action, and origin (thrombin-induced platelet microbicidal proteins [tPMPs] and human neutrophil peptide-1 [hNP-1]) and one bacterium-derived CAP, polymyxin B (PMB). Seven of 10 DAPrstrains had point mutations in themprFlocus (with or withoutyycoperon mutations), while three DAPrstrains had neither mutation. Several phenotypic parameters previously associated with DAPrwere also examined: cell membrane order (fluidity), surface charge, and cell wall thickness profiles. Compared to the 10 DAPsparental strains, their respective DAPrstrains exhibited (i) significantly reduced susceptibility to killing by all three peptides (P< 0.05), (ii) increased cell membrane fluidity, and (iii) significantly thicker cell walls (P< 0.0001). There was no consistent pattern of surface charge profiles distinguishing DAPsand DAPrstrain pairs. Reducedin vitrosusceptibility to two HDPs and one bacterium-derived CAP tracked closely with DAPrin these 10 recent MRSA clinical isolates. These results suggest that adaptive mechanisms involved in the evolution of DAPralso provide MRSA with enhanced survivability against HDPs. Such adaptations appear to correlate with MRSA variations in cell membrane order and cell wall structure. DAPrstrains with or without mutations in themprFlocus demonstrated significant cross-resistance profiles to these unrelated CAPs.

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VraSR and Virulence Trait Modulation during Daptomycin Resistance in Methicillin-Resistant Staphylococcus aureus Infection

mSphere ◽

10.1128/msphere.00557-18 ◽

2019 ◽

Vol 4 (1) ◽

Cited By ~ 9

Author(s):

Agustina Taglialegna ◽

Maria C. Varela ◽

Roberto R. Rosato ◽

Adriana E. Rosato

Keyword(s):

Staphylococcus Aureus ◽

Cell Wall ◽

Cell Membrane ◽

Virulence Factors ◽

Bacterial Resistance ◽

Methicillin Resistant ◽

Content Type ◽

Bacterial Physiology ◽

Two Component ◽

Mrsa Infection

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) threatens human health in hospital and community settings. The lipopeptide antibiotic daptomycin (DAP) is a frequently used treatment option for MRSA infection. DAP exposure can cause bacterial resistance because mutations are induced in genes implicated in cell membrane and cell wall metabolism. Adaptations aimed at surviving antimicrobial pressure can affect bacterial physiology and modify in vivo aptitude and pathogenesis. In this study, clinical DAP-susceptible (DAPs) and DAP-resistant (DAPr) MRSA isolates were used to investigate associations between DAP resistance and staphylococcal virulence. We previously found that VraSR is a critical sensor of cell membrane/wall homeostasis associated with DAP acquisition during MRSA infection. The present study found that DAPr CB1634 and CB5014 MRSA strains with vraSR upregulation were less virulent than their susceptible counterparts, CB1631 and CB5013. Differential gene-transcription profile analysis revealed that DAPr CB1634 had decreased agr two-component system expression, virulence factors, and highly suppressed hemolysis activity. Functional genetic analysis performed in DAPr CB1634 strains using vraSR inactivation followed by gene complementation found that vraSR acted as a transcriptional agrA regulator. These results indicated that VraSR has a broad range of regulatory functions. VraSR also appeared to affect DAPr adherence to epithelial cells, which would affect DAPr strain colonization and survival in the host. The correlation between DAP resistance and decreased virulence was also found in the CB5013 (DAPs) and CB5014 (DAPr) pair. Taken together, these findings are the first evidence that DAP resistance and MRSA virulence are tightly connected and involve compromised expression of regulatory and virulence determinants. IMPORTANCE Methicillin-resistant S. aureus continues to develop resistance to antimicrobials, including those in current clinical use as daptomycin (DAP). Resistance to DAP arises by mutations in cell membrane and cell wall genes and/or upregulation of the two-component VraSR system. However, less is known about the connection between the pathogen and virulence traits during DAP resistance development. We provide new insights into VraSR and its regulatory role for virulence factors during DAP resistance, highlighting coordinated interactions that favor the higher persistence of MRSA DAP-resistant strains in the infected host.

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Antibacterial Mechanism of Dihydrotanshinone I

Natural Product Communications ◽

10.1177/1934578x21996158 ◽

2021 ◽

Vol 16 (2) ◽

pp. 1934578X2199615

Author(s):

Lin Zhao ◽

Yingying Zhao ◽

Jinfeng Wei ◽

Zhenhua Liu ◽

Changqin Li ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Activity ◽

Cell Membrane ◽

Protein Content ◽

Methicillin Resistant Staphylococcus Aureus ◽

Methicillin Resistant ◽

Beta Lactamases ◽

Extended Spectrum ◽

Sds Page ◽

Extended Spectrum Beta Lactamases

The antimicrobial activity and the underlying action mechanisms of dihydrotanshinone I against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases Staphylococcus aureus were investigated with Kleihauer-Betke (K-B) test. The antibacterial mechanisms of dihydrotanshinone I were investigated by monitoring the changes in electric conductivity, concentration of AKP, protein content, and patterns of protein electrophoretic bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The antibacterial rings showed that antimicrobial activity of dihydrotanshinone I at 18 mM was stronger to Staphylococcus aureus than to methicillin-resistant Staphylococcus aureus and extended-spectrum beta-lactamases Staphylococcus aureus. The minimum inhibitory concentration (MIC) and IC50 values showed that dihydrotanshinone I had the strongest inhibitory activity against S. aureus (MIC = 280 µM, IC50 = 874 ± 0.01 µM, respectively). Dihydrotanshinone I could increase the electric conductivity, concentration of alkaline phosphatase (AKP) and protein content. The patterns of protein bands in SDS-PAGE were changed obviously. Dihydrotanshinone I also significantly inhibited S. aureus, methicillin-resistant S. aureus, and extended-spectrum beta-lactamases S. aureus, indicating that dihydrotanshinone I can damage the structures of cell wall and cell membrane to increase permeability of cell membrane and release of cell components. Dihydrotanshinone I could influence the synthesis of bacterial protein, destroy the protein, or reject the anabolism or expression of the protein, and finally lead to the loss of normal physiological function of bacteria.

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Mechanism of Azalomycin F5a against Methicillin-Resistant Staphylococcus aureus

BioMed Research International ◽

10.1155/2018/6942452 ◽

2018 ◽

Vol 2018 ◽

pp. 1-5 ◽

Cited By ~ 2

Author(s):

Li Xu ◽

Xuejie Xu ◽

Ganjun Yuan ◽

Yimin Wang ◽

Yunqiu Qu ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cell Membrane ◽

Adenylate Kinase ◽

Kinase Activity ◽

Methicillin Resistant Staphylococcus Aureus ◽

Membrane Lipids ◽

Molecular Targets ◽

Phospholipid Bilayer ◽

Cell Membrane Permeability ◽

Methicillin Resistant

To investigate the mechanism of azalomycin F5a against methicillin-resistant Staphylococcus aureus (MRSA), the conductivity of MRSA suspension and the adenylate kinase activity of MRSA culture were determined with the intervention of azalomycin F5a, which were significantly increased compared to those of blank controls. This inferred that azalomycin F5a could lead to the leakage of cellular substances possibly by increasing permeability to kill MRSA. As phospholipid bilayer was mainly responsible for cell-membrane permeability, the interaction between azalomycin F5a and cell-membrane lipids was further researched by determining the anti-MRSA activities of azalomycin F5a combined with cell-membrane lipids extracted from test MRSA or with 1,2-dipalmitoyl-sn-glycero-3-phospho-glycerol (DPPG) for possible molecular targets lying in MRSA cell-membrane. The results indicated that the anti-MRSA activity of azalomycin F5a remarkably decreased when it combined with membrane lipids or DPPG. This indicated that cell-membrane lipids especially DPPG might be important targets of azalomycin F5a against MRSA.

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Analysis of Cell Membrane Characteristics of In Vitro-Selected Daptomycin-Resistant Strains of Methicillin-Resistant Staphylococcus aureus

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01682-08 ◽

2009 ◽

Vol 53 (6) ◽

pp. 2312-2318 ◽

Cited By ~ 146

Author(s):

Nagendra N. Mishra ◽

Soo-Jin Yang ◽

Ayumi Sawa ◽

Aileen Rubio ◽

Cynthia C. Nast ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Cell Membrane ◽

Surface Charge ◽

Parental Strain ◽

Phospholipid Content ◽

Surface Binding ◽

Methicillin Resistant ◽

Positive Surface Charge ◽

Vancomycin Mics

ABSTRACT Our previous studies of clinical daptomycin-resistant (Dapr) Staphylococcus aureus strains suggested that resistance is linked to the perturbations of several key cell membrane (CM) characteristics, including the CM order (fluidity), phospholipid content and asymmetry, and relative surface charge. In the present study, we examined the CM profiles of a well-known methicillin-resistant Staphylococcus aureus (MRSA) strain (MW2) after in vitro selection for DAP resistance by a 20-day serial passage in sublethal concentrations of DAP. Compared to levels for the parental strain, Dapr strains exhibited (i) decreased CM fluidity, (ii) the increased synthesis of total lysyl-phosphatidylglycerol (LPG), (iii) the increased flipping of LPG to the CM outer bilayer, and (iv) the increased expression of mprF, the gene responsible for the latter two phenotypes. In addition, we found that the expression of the dlt operon, which also increases positive surface charge, was enhanced in the Dapr mutants. These phenotypic and genotypic changes correlated with reduced DAP surface binding, mirroring observations made in clinical Dapr isolates. In this strain, serial exposure to DAP induced an increase in vancomycin MICs into the vancomycin-intermediate S. aureus (VISA) range (4 μg/ml) in parallel with increasing DAP MICs. Also, this Dapr strain exhibited significantly thicker cell walls than the parental strain, potentially correlating with the coevolution of the VISA phenotype and implicating cell wall structure and/or function in the Dapr phenotype. Importantly, despite the overexpression of mprF and dlt, the relative net positive surface charge was decreased in the Dapr mutants, suggesting that other factors contribute to the surface charge alterations and that a simple charge repulsion mechanism could not entirely explain the Dapr phenotype in these strains.

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