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1.
Int J Antimicrob Agents ; 57(5): 106319, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33716180

RESUMO

OBJECTIVES: A major problem for wound healing is contamination with bacteria, often resulting in biofilm formation and wound infection, which, in turn, needs immediate intervention such as surgical debridement and through irrigation. A topical treatment with cold atmospheric pressure plasma (CAP) for wound disinfection may present an alternative and less painful approach. METHODS: This study investigated the antibacterial effects of a cold atmospheric pressure argon plasma jet (kINPen® MED) as a CAP source, using the three-dimensional Staphylococcus aureus immunocompetent biofilm system hpBIOM in addition to a standard planktonic test. Furthermore, skin cell compatibility was evaluated using a keratinocyte (HaCat) model. RESULTS: CAP treatment (0-240 s) followed by incubation (15, 120 min) within the CAP-treated media showed slight bactericidal efficacy under planktonic conditions but no effect on biofilms. However, indirect CAP treatment of keratinocytes performed under the same conditions resulted in a significant decrease in metabolic activity. Short CAP treatment and exposure time (30 s; 15 min) induced a slight increase in the metabolic activity; however, longer treatments and/or exposure times led to pronounced reductions up to 100%. These effects could partially be reversed by addition of catalase, indicating a dominant role of CAP-generated hydrogen peroxide. CONCLUSIONS: These results indicate that plasma treatment does not lead to the desired disinfection or significant reduction in the bacterial burden of Staphylococcus aureus in a wet milieu or in biofilms. Thus, treatment with CAP could not be recommended as a single anti-bacterial therapy for wounds but could be used to support standard treatments.


Assuntos
Antibacterianos/farmacologia , Argônio/farmacologia , Queratinócitos/efeitos dos fármacos , Gases em Plasma/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Cicatrização/efeitos dos fármacos , Pressão Atmosférica , Biofilmes/efeitos dos fármacos , Células HaCaT , Humanos , Viabilidade Microbiana , Pele/efeitos dos fármacos , Staphylococcus aureus/citologia , Infecção dos Ferimentos/microbiologia , Infecção dos Ferimentos/terapia
2.
Anal Bioanal Chem ; 413(5): 1417-1428, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33388848

RESUMO

Surface-enhanced Raman scattering (SERS), based on the enhancement of the Raman signal of molecules positioned within a few nanometres from a structured metal surface, is ideally suited to provide bacterial-specific molecular fingerprints which can be used for analytical purposes. However, for some complex structures such as bacteria, the generation of reproducible SERS spectra is still a challenging task. Among the various factors influencing the SERS variability (such as the nature of SERS-active substrate, Raman parameters and bacterial specificity), we demonstrate in this study that the environment of Gram-positive and Gram-negative bacteria deposited on ultra-thin silver films also impacts the origin of the SERS spectra. In the case of densely packed bacteria, the obtained SERS signatures were either characteristic of the secretion of adenosine triphosphate for Staphylococcus aureus (S. aureus) or the cell wall and the pili/flagella for Escherichia coli (E. coli), allowing for an easy discrimination between the various strains. In the case of isolated bacteria, SERS mapping together with principal component analysis revealed some variabilities of the spectra as a function of the bacteria environment and the bactericidal effect of the silver. However, the variability does not preclude the SERS signatures of various E. coli strains to be discriminated.


Assuntos
Escherichia coli/química , Análise Espectral Raman/métodos , Staphylococcus aureus/química , Escherichia coli/citologia , Infecções por Escherichia coli/microbiologia , Humanos , Prata/química , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/citologia , Propriedades de Superfície
3.
J Appl Microbiol ; 130(2): 493-503, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32738017

RESUMO

AIMS: Diagnosis of Staphylococcus aureus is important in various diseases from hospital-acquired infections to foodborne diseases. This work reports two new luminescent affiprobes for specific detection of S. aureus. METHODS AND RESULTS: To develop advanced luminescent affiprobes, enhanced green fluorescent protein (EGFP) was flanked by single and double repeats of ZpA963 affibody using molecular biology studies. The recombinant proteins including fluorescent monomeric affibody (fA1 ) and fluorescent dimeric affibody (fA2 ) were expressed in the bacterial expression system, purified and used to identify the S. aureus. Fluorescence microscope and flow cytometry results demonstrated that the treated samples with fA1 and fA2 had relatively high fluorescent mean intensities in comparison to the untreated S. aureus cells. Moreover, it was revealed that 'fA2 ' affiprobe had lower dissociation constant value (about 25-fold) and was more effective for detection of S. aureus than the 'fA1 ' affiprobe. In addition, the binding of the affiprobes for some other pathogenic bacteria i.e. Escherichia coli, Bacillus cereus, Enterococcus faecalis and Staphylococcus saprophyticus was examined. Expectedly, no cross-reaction was observed for binding the constructed affiprobes to these bacteria, eliminating possibilities for false positive results. CONCLUSIONS: The results show that 'fA1 ' affiprobe and 'fA2 ' affiprobe are two new efficient luminescent affiprobes for detecting S. aureus. SIGNIFICANCE AND IMPACT OF THE STUDY: We developed a new approach for detection of Staphylococcus aureus in a simple one-step process and in low concentrations of probes. In the best of our knowledge, this is the first study to direct detection of bacterial cells by affiprobes and may be used to develop new diagnostic kits.


Assuntos
Técnicas Bacteriológicas/métodos , Citometria de Fluxo/métodos , Sondas Moleculares/metabolismo , Staphylococcus aureus/isolamento & purificação , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/isolamento & purificação , Proteínas de Fluorescência Verde/metabolismo , Humanos , Luminescência , Sondas Moleculares/genética , Sondas Moleculares/isolamento & purificação , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/metabolismo , Especificidade da Espécie , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/citologia , Staphylococcus aureus/metabolismo
4.
Int J Nanomedicine ; 15: 10321-10330, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33364759

RESUMO

Background: Vaccination provides a viable alternative to antibiotics for the treatment of drug-resistant bacterial infection. Bacterial protoplasts have gained much attention for a new generation vaccine due to depleting toxic outer wall components. Purpose: The objective of this study was to reveal the effects of bacterial protoplast-derived nanovesicles (PDNVs) size on antibacterial immunity. Methods: Herein, we prepared bacterial PDNVs with different sizes by removing the cell wall of Staphylococcus aureus (S. aureus) to generate multi-antigen nanovaccines. Furthermore, we investigated the ability of PDNVs in different sizes to activate dendritic cells (DCs) and trigger humoral and cellular immune responses in vivo. Results: We obtained particles of ∼200 nm, 400 nm, and 700 nm diameters and found that all the PDNVs readily induce efficient maturation of DCs in the draining lymph nodes of the vaccinated mice. Dramatically, the activation of DCs was increased with decreasing particle sizes. In addition, vaccination with PDNVs generated elevated expression levels of specific antibody and the production of INF-γ, especially the smaller ones, indicating the capability of inducing strong humoral immunity and Th1 biased cell responses against the source bacteria. Conclusion: These observed results provide evidence for size-dependent orchestration of immune responses of PDNVs and help to rationally design and develop effective antibacterial vaccines.


Assuntos
Vacinas Bacterianas/química , Vacinas Bacterianas/imunologia , Protoplastos/química , Staphylococcus aureus/citologia , Staphylococcus aureus/imunologia , Animais , Células Dendríticas/imunologia , Imunidade Celular/imunologia , Imunidade Humoral/imunologia , Camundongos , Nanoestruturas/química
5.
Adv Mater ; 32(52): e2005679, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33179362

RESUMO

It is commonly accepted that nanoparticles (NPs) can kill bacteria; however, the mechanism of antimicrobial action remains obscure for large NPs that cannot translocate the bacterial cell wall. It is demonstrated that the increase in membrane tension caused by the adsorption of NPs is responsible for mechanical deformation, leading to cell rupture and death. A biophysical model of the NP-membrane interactions is presented which suggests that adsorbed NPs cause membrane stretching and squeezing. This general phenomenon is demonstrated experimentally using both model membranes and Pseudomonas aeruginosa and Staphylococcus aureus, representing Gram-positive and Gram-negative bacteria. Hydrophilic and hydrophobic quasi-spherical and star-shaped gold (Au)NPs are synthesized to explore the antibacterial mechanism of non-translocating AuNPs. Direct observation of nanoparticle-induced membrane tension and squeezing is demonstrated using a custom-designed microfluidic device, which relieves contraction of the model membrane surface area and eventual lipid bilayer collapse. Quasi-spherical nanoparticles exhibit a greater bactericidal action due to a higher interactive affinity, resulting in greater membrane stretching and rupturing, corroborating the theoretical model. Electron microscopy techniques are used to characterize the NP-bacterial-membrane interactions. This combination of experimental and theoretical results confirm the proposed mechanism of membrane-tension-induced (mechanical) killing of bacterial cells by non-translocating NPs.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Membrana Celular/efeitos dos fármacos , Ouro/química , Ouro/farmacologia , Fenômenos Mecânicos/efeitos dos fármacos , Nanopartículas Metálicas , Fenômenos Biomecânicos/efeitos dos fármacos , Membrana Celular/metabolismo , Pseudomonas aeruginosa/citologia , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/citologia , Staphylococcus aureus/efeitos dos fármacos
6.
Biomolecules ; 10(11)2020 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-33233724

RESUMO

Neonatal sepsis is a life-threatening condition and Staphylococcus aureus is one of its major causes. However, to date, no rapid and sensitive diagnostic tool has been developed for its direct detection. Bioinformatics analyses identified a surface-exposed 112-amino acid polypeptide of the cell wall protein NWMN_1649, a surface protein involved in cell aggregation and biofilm formation, as being a species-specific and highly conserved moiety. The polypeptide was cloned, purified, and used to immunize mice to raise specific immunoglobulins. The purified antibodies were conjugated to gold nano-particles and used to assemble an immunochromatographic strip (ICS). The developed prototype ICS detected as low as 5 µg purified polypeptide and 102 CFU/mL S. aureus within 15 min. The strip showed superior ability to directly detect S. aureus in neonatal sepsis blood specimens without prior sample processing. Moreover, it showed no cross-reaction in specimens infected with two other major causes of neonatal sepsis; coagulase-negative staphylococci and Klebsiella pneumoniae. The selected NWMN_1649-derived polypeptide demonstrates success as a promising biomolecule upon which a prototype ICS has been developed. This ICS provides a rapid, direct, sensitive, and specific option for the detection of S. aureus causing neonatal sepsis. Such a tool is urgently needed especially in resources-limited countries.


Assuntos
Cromatografia de Afinidade/métodos , Sepse Neonatal/diagnóstico , Sepse Neonatal/imunologia , Peptídeos/química , Peptídeos/imunologia , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/imunologia , Animais , Antígenos de Bactérias/biossíntese , Antígenos de Bactérias/imunologia , Antígenos de Bactérias/isolamento & purificação , Biologia Computacional , Simulação por Computador , Feminino , Humanos , Recém-Nascido , Nanopartículas Metálicas/química , Camundongos Endogâmicos BALB C , Sepse Neonatal/sangue , Sepse Neonatal/microbiologia , Biossíntese Peptídica/imunologia , Peptídeos/isolamento & purificação , Sensibilidade e Especificidade , Infecções Estafilocócicas/sangue , Staphylococcus aureus/citologia , Staphylococcus aureus/imunologia
7.
Molecules ; 25(21)2020 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-33114746

RESUMO

Staphylococcus aureus (S. aureus) creates an array of challenges for the food industry and causes foodborne diseases in people, largely due to its strong antibiotic resistance. Mandarin (Citrus reticulata L.) essential oil (MEO) is recognized as a natural and safe preservative; however, the antibacterial effects and mechanism of MEO to combat S. aureus are not yet clearly understood. This study will examine the inhibitory effects of MEO against S. aureus and explore the antibacterial mechanism thereof from the perspective of membrane destruction. The antibacterial activity of MEO on planktonic S. aureus was examined to determine the minimal inhibitory concentration (MIC). Scanning electron microscope (SEM) images revealed the direct impacts of MEO treatment on the cell structure of S. aureus. The cell membrane was observed to be depolarized, the determination of extracellular nucleic acids, proteins and intracellular adenosine triphosphate (ATP) confirmed the increased permeability of the cell membrane, its integrity was destroyed and the cellular constituents had leaked. These results, thus, provided conclusive evidence that MEO constrains the growth of planktonic S. aureus by affecting the permeability and integrity of its cell membrane. Our study provides a basis for the further development and utilization of MEO as a natural antibacterial agent in the food industry.


Assuntos
Antibacterianos/farmacologia , Citrus/química , Óleos Voláteis/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Staphylococcus aureus/citologia
8.
Sci Rep ; 10(1): 16084, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32999342

RESUMO

Populations of genetically identical bacteria are phenotypically heterogeneous, giving rise to population functionalities that would not be possible in homogeneous populations. For instance, a proportion of non-dividing bacteria could persist through antibiotic challenges and secure population survival. This heterogeneity can be studied in complex environmental or clinical samples by spreading the bacteria on agar plates and monitoring time to growth resumption in order to infer their metabolic state distribution. We present ColTapp, the Colony Time-lapse application for bacterial colony growth quantification. Its intuitive graphical user interface allows users to analyze time-lapse images of agar plates to monitor size, color and morphology of colonies. Additionally, images at isolated timepoints can be used to estimate lag time. Using ColTapp, we analyze a dataset of Staphylococcus aureus time-lapse images including populations with heterogeneous lag time. Colonies on dense plates reach saturation early, leading to overestimation of lag time from isolated images. We show that this bias can be corrected by taking into account the area available to each colony on the plate. We envision that in clinical settings, improved analysis of colony growth dynamics may help treatment decisions oriented towards personalized antibiotic therapies.


Assuntos
Contagem de Colônia Microbiana/métodos , Processamento de Imagem Assistida por Computador/métodos , Software , Ágar , Algoritmos , Carga Bacteriana/métodos , Carga Bacteriana/estatística & dados numéricos , Contagem de Colônia Microbiana/estatística & dados numéricos , Humanos , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Staphylococcus aureus/citologia , Staphylococcus aureus/crescimento & desenvolvimento , Imagem com Lapso de Tempo , Interface Usuário-Computador
9.
Bioorg Chem ; 104: 104190, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32919130

RESUMO

Interactions of two newly synthesized and six previously reported benzoxanthene lignans (BXLs), analogues of rare natural products, with DNA/RNA, G-quadruplex and HSA were evaluated by a set of spectrophotometric methods. Presence/absence of methoxy and hydroxy groups on the benzoxanthene core and minor modifications at C-1/C-2 side pendants - presence/absence of phenyl ring and presence/absence of methoxy and hydroxy groups on phenyl ring - influenced the fluorescence changes and the binding strength to double-stranded (ds-) and G-quadruplex structures. In general, compounds without phenyl ring showed stronger fluorescence changes upon binding than phenyl-substituted BXLs. On the other hand, BXLs with an unsubstituted phenyl ring showed the best stabilization effects of G-quadruplex. Circular dichroism spectroscopy results suggest mixed binding mode, groove binding and partial intercalation, to ds-DNA/RNA and end-stacking to top or bottom G-tetrads as the main binding modes of BXLs to those targets. All compounds exhibited micromolar binding affinities toward HSA and an increased protein thermal stability. Moderate to strong antiradical scavenging activity was observed for all BXLs with hydroxy groups at C-6, C-9 and C-10 positions of the benzoxanthene core, except for derivative bearing methoxy groups at these positions. BXLs with unsubstituted or low-substituted phenyl ring and one derivative without phenyl ring showed strong growth inhibition of Gram-positive Staphylococcus aureus. All compounds showed moderate to strong tumor cell growth-inhibitory activity and cytotoxicity.


Assuntos
Antineoplásicos/farmacologia , DNA Tumoral Circulante/química , Lignanas/farmacologia , RNA Neoplásico/química , Albumina Sérica Humana/química , Xantenos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Escherichia coli K12/citologia , Escherichia coli K12/efeitos dos fármacos , Humanos , Lignanas/síntese química , Lignanas/química , Estrutura Molecular , Salmonella enterica/citologia , Salmonella enterica/efeitos dos fármacos , Staphylococcus aureus/citologia , Staphylococcus aureus/efeitos dos fármacos , Relação Estrutura-Atividade , Células Tumorais Cultivadas , Xantenos/síntese química , Xantenos/química
10.
Indian J Med Microbiol ; 38(2): 216-218, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32883937

RESUMO

Staphylococcus aureus and other Gram negative bacteria produce small colony variants (SCV) which usually emerge after exposure to antimicrobials. They cause repeated infections, treatment failures and often pass unnoticed during cultures due to unusual appearance and incomplete incubation. This infectious disease grand round highlights a similar clinical case with atypical history and appearance of a SCV of S. aureus and why prolonged incubation is necessary for aspirates from patients with recurrent infections like abscesses.


Assuntos
Abscesso/microbiologia , Infecções Comunitárias Adquiridas/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/isolamento & purificação , Abscesso/diagnóstico , Abscesso/tratamento farmacológico , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Infecções Comunitárias Adquiridas/diagnóstico , Infecções Comunitárias Adquiridas/tratamento farmacológico , Diagnóstico Diferencial , Humanos , Lactente , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/citologia , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento
11.
Anal Chem ; 92(18): 12451-12459, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32799451

RESUMO

Pathogen-associated infections represent one of the major threats to human health and require reliable methods for immediate and robust identification of pathogenic microorganisms. Here, an inexpensive cellulase-linked immunomagnetic methodology was developed for the specific and ultrasensitive analysis of bacteria at their single-cell levels within a 3 h procedure. Detection of a model bacterium, Escherichia coli, was performed in a sandwich reaction with E. coli-specific either aptamer or antibody (Ab)-modified magnetic beads (MBs) and Ab/aptamer reporter molecules linked to cellulase. The cellulase-labeled immuno-aptamer sandwich applied onto nitrocellulose-film-modified electrodes digested the film and changed its electrical conductivity. Electrode's chronocoulometric responses at 0.3 V, in the absence of any redox indicators, allowed a single E. coli cell detection and from 1 to 4 × 104 CFU mL-1 E. coli quantification. No interference/cross-reactivity from Salmonella enteritidis, Enterobacter agglomerans, Pseudomonas putida, Staphylococcus aureus, and Bacillus subtilis was observed when the assay was performed on Ab-modified MBs, and E. coli could be quantified in tap water and milk. This electrochemically label-free methodology is sufficiently fast, highly specific, and sensitive to be used in direct in-field applications. The assay can be adapted for specific detection of other bacterial strains of either the same or different species and offers new analytical tools for fast, specific, and reliable analysis of bacteria in the clinic, food, and environment.


Assuntos
Celulase/metabolismo , Escherichia coli/isolamento & purificação , Separação Imunomagnética , Bacillus subtilis/citologia , Bacillus subtilis/isolamento & purificação , Bacillus subtilis/metabolismo , Celulase/química , Eletrodos , Enterobacter/citologia , Enterobacter/isolamento & purificação , Enterobacter/metabolismo , Escherichia coli/citologia , Escherichia coli/metabolismo , Pseudomonas putida/citologia , Pseudomonas putida/isolamento & purificação , Pseudomonas putida/metabolismo , Salmonella enteritidis/citologia , Salmonella enteritidis/isolamento & purificação , Salmonella enteritidis/metabolismo , Análise de Célula Única , Staphylococcus aureus/citologia , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/metabolismo
12.
Nat Commun ; 11(1): 4097, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32796861

RESUMO

Staphylococcus aureus is generally thought to divide in three alternating orthogonal planes over three consecutive division cycles. Although this mode of division was proposed over four decades ago, the molecular mechanism that ensures this geometry of division has remained elusive. Here we show, for three different strains, that S. aureus cells do not regularly divide in three alternating perpendicular planes as previously thought. Imaging of the divisome shows that a plane of division is always perpendicular to the previous one, avoiding bisection of the nucleoid, which segregates along an axis parallel to the closing septum. However, one out of the multiple planes perpendicular to the septum which divide the cell in two identical halves can be used in daughter cells, irrespective of its orientation in relation to the penultimate division plane. Therefore, division in three orthogonal planes is not the rule in S. aureus.


Assuntos
Proteínas de Bactérias/metabolismo , Staphylococcus aureus/citologia , Staphylococcus aureus/metabolismo , Proteínas de Bactérias/genética , Microbiologia , Imagem com Lapso de Tempo
13.
Bioconjug Chem ; 31(9): 2201-2210, 2020 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-32786505

RESUMO

The tetrazine/trans-cyclooctene (TCO) inverse electron-demand Diels-Alder (IEDDA) reaction is the fastest bioorthogonal "click" ligation process reported to date. In this context, TCO reagents have found widespread applications; however, their availability and structural diversity is still somewhat limited due to challenges connected with their synthesis and structural modification. To address this issue, we developed a novel strategy for the conjugation of TCO derivatives to a biomolecule, which allows for the creation of greater structural diversity from a single precursor molecule, i.e., trans,trans-1,5-cyclooctadiene [(E,E)-COD] 1, whose preparation requires standard laboratory equipment and readily available reagents. This two-step strategy relies on the use of new bifunctional TCO linkers (5a-11a) for IEDDA reactions, which can be synthesized via 1,3-dipolar cycloaddition of (E,E)-COD 1 with different azido spacers (5-11) carrying an electrophilic function (NHS-ester, N-succinimidyl carbonate, p-nitrophenyl-carbonate, maleimide) in the ω-position. Following bioconjugation of these electrophilic linkers to the nucleophilic residue (cysteine or lysine) of a protein (step 1), the resulting TCO-decorated constructs can be subjected to a IEDDA reaction with tetrazines functionalized with fluorescent or near-infrared (NIR) tags (step 2). We successfully used this strategy to label bovine serum albumin with the TCO linker 8a and subsequently reacted it in a cell lysate with the fluorescein-isothiocyanate (FITC)-derived tetrazine 12. The same strategy was then used to label the bacterial wall of Gram-positive Staphylococcus aureus, showing the potential of these linkers for live-cell imaging. Finally, we determined the impact of structural differences of the linkers upon the stability of the bioorthogonal constructs. The compounds for stability studies were prepared by conjugation of TCO linkers 6a, 8a, and 10a to mAbs, such as Rituximab and Obinutuzumab, and subsequent labeling with a reactive Cy3-functionalized tetrazine.


Assuntos
Alcadienos/química , Corantes Fluorescentes/química , Alcadienos/síntese química , Animais , Bovinos , Química Click , Reação de Cicloadição , Ciclo-Octanos/síntese química , Ciclo-Octanos/química , Corantes Fluorescentes/síntese química , Soroalbumina Bovina/química , Staphylococcus aureus/citologia , Staphylococcus aureus/isolamento & purificação
14.
Carbohydr Polym ; 247: 116685, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829813

RESUMO

Quaternary ammonium chitooligosaccharides (QACOS) was incorporated onto the ZnO/palygorskite (ZnO/PAL) nanocomposite by a simple electrostatic self-assembly process to produce a new organic-inorganic nanocomposite (QACOS/ZnO/PAL) with excellent antibacterial activity. After loading QACOS, the Zeta potential of ZnO/PAL was changed from -26.7 to +30.3 mV, which facilitates to improve the targeting behavior of ZnO/PAL towards bacteria and its contact with bacteria, resulting in a significant improvement of antibacterial capability. The MIC values of QACOS/ZnO/PAL for inhibiting bacteria (0.5 mg/mL for E. coli and 1 mg/L for S. aureus) were superior to ZnO/PAL and QACOS, demonstrated an expected synergistic antibacterial effect between QACOS and ZnO/PAL. The improved contact and interface interaction between QACOS/ZnO/PAL and bacteria makes it easier to destroy the structural integrity of bacteria. As a whole, the incorporation of polysaccharide as regulators of surface charge opens up a new way to further enhance the antibacterial activity of inorganic antibacterial materials.


Assuntos
Compostos de Amônio/química , Antibacterianos/química , Quitina/análogos & derivados , Compostos de Magnésio/química , Nanocompostos/química , Compostos de Silício/química , Óxido de Zinco/química , Compostos de Amônio/farmacologia , Antibacterianos/farmacologia , Quitina/química , Quitina/farmacologia , Escherichia coli/citologia , Escherichia coli/efeitos dos fármacos , Compostos Inorgânicos/química , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Nanocompostos/ultraestrutura , Staphylococcus aureus/citologia , Staphylococcus aureus/efeitos dos fármacos , Eletricidade Estática , Propriedades de Superfície , Óxido de Zinco/farmacologia
15.
Carbohydr Polym ; 247: 116692, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829820

RESUMO

The development of minimally invasive surgery has created a demand for ideal medical adhesives exhibiting biocompatibility, biodegradability, antimicrobial activity, and strong adhesion to tissues in wet environments. However, as clinically approved surgical tissue glues suffer from poor adhesion activation, limited adhesion strength, and toxicity, novel tissue glues are highly sought after. Herein, a mussel-inspired injectable hydrogel was prepared from catechol- and methacrylate-modified chitosan/gelatin and shown to exhibit biocompatibility, inherent antimicrobial activity, and good adhesion to wet tissues. Moreover, as this gel could be applied onto tissue surfaces and cured in situ within seconds of body contact by a biocompatible and multifunctional redox initiator (H2O2-ascorbic acid), it was concluded to be a promising surgical sealant and wound dressing (even for infected wounds) accelerating wound healing.


Assuntos
Antibacterianos/química , Quitosana/química , Gelatina/química , Hidrogéis/química , Procedimentos Cirúrgicos sem Sutura/métodos , Adesivos Teciduais/química , Infecção dos Ferimentos/tratamento farmacológico , Animais , Antibacterianos/administração & dosagem , Antibacterianos/farmacologia , Ácido Ascórbico/administração & dosagem , Ácido Ascórbico/química , Ácido Ascórbico/farmacologia , Bivalves/química , Temperatura Corporal , Catecóis/química , Quitosana/administração & dosagem , Quitosana/farmacologia , Gelatina/administração & dosagem , Gelatina/farmacologia , Hidrogéis/administração & dosagem , Hidrogéis/farmacologia , Peróxido de Hidrogênio/administração & dosagem , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/farmacologia , Injeções , Metacrilatos/química , Camundongos , Células NIH 3T3 , Pseudomonas aeruginosa/efeitos dos fármacos , Ratos Sprague-Dawley , Staphylococcus aureus/citologia , Staphylococcus aureus/efeitos dos fármacos , Adesivos Teciduais/administração & dosagem , Adesivos Teciduais/farmacologia , Cicatrização/efeitos dos fármacos , Infecção dos Ferimentos/metabolismo , Infecção dos Ferimentos/patologia
16.
Arch Pharm Res ; 43(6): 630-638, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32627141

RESUMO

Staphylococcus aureus is a pathogen that causes critical diseases, such as pneumonia, endocarditis, and bacteremia, upon gaining access to the bloodstream of the host. Because host innate immunity alone cannot fight against this rapidly expanding pathogen, the use of antibiotic agents is necessary to clear out S. aureus. However, sub-populations of S. aureus fail to respond to the antibiotics resulting in ineffective clearance of the bacteria. One mechanism by which S. aureus does not respond to the antibiotics is by developing resistance through alterations in its genetic makeup, and genetic studies have revealed a major portion of mechanisms that are responsible for the rise of these antibiotic-resistant strains. Another sub-population that fails to respond to the antibiotics is called persister cells. There is a mounting clinical evidence that these persister cells significantly contribute to the antibiotic failure and persistent infection, but a clear mechanistic picture of the formation of the S. aureus persister cells is unavailable. This review focuses on drawing out a mechanistic map of factors that contribute to the formation of S. aureus persister cells. Understanding the mechanism will provide future direction for the development of novel antibiotic strategies to more efficiently tackle infections caused by S. aureus.


Assuntos
Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/citologia , Antibacterianos/farmacologia , Humanos , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/patologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética
17.
ACS Appl Mater Interfaces ; 12(31): 35626-35637, 2020 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-32657116

RESUMO

Pathogenic bacterial fouling in agriculture and food-associated products poses mounting food safety concerns today. Efficient integration of precise tracking and on-demand bacterial killing to achieve the source control of pathogenic bacteria at the single-cell level is one of the most valuable antifouling methods for safeguarding food safety but remains unexplored. Here, we report an all-in-one design strategy as a proof of concept to establish a stimuli-responsive nanoprobe PDANSs-FAM-Apt for the detection of Staphylococcus aureus (S. aureus) at the single-cell level, which could be capable of guiding the on-demand photothermal killing of bacteria upon near-infrared (NIR) light irradiation. By examining the size-dependent modulation of the fluorescence resonance energy transfer efficiency to polydopamine nanospheres (PDANSs), PDANSs-FAM-Apt was finally assembled by 6-carboxyfluorescein-terminated S. aureus, binding the aptamer (FAM-Apt) and PDANSs at ∼258 nm through π-π stacking interactions. As a result, PDANSs-FAM-Apt exhibits a remarkable fluorescence enhancement (∼261-fold) to S. aureus with a satisfactory detection limit of 1.0 cfu/mL, allowing for assay at the single-cell level and thus ultralow background fluorescence imaging of S. aureus as well as its biofilms. Moreover, PDANSs-FAM-Apt shows a high photothermal bactericidal property upon NIR light irradiation, endowing it with the strong capacity to efficiently produce heat for destroying S. aureus and its biofilms with the guidance of imaging results. This work emphasizes the versatility of using the combination of stimuli-responsive fluorescence imaging dependent on the PDANS size modulation and NIR light-activated photothermal antibacterial activity to design stimuli-responsive nanoprobes with an improved precision for pathogenic bacteria monitoring and source controlling, which opens a promising antifouling avenue to eliminate bacteria and disrupt bacterial biofilms in agriculture and food-related industries.


Assuntos
Antibacterianos/química , Aptâmeros de Nucleotídeos/química , Corantes Fluorescentes/química , Indóis/química , Nanosferas/química , Polímeros/química , Staphylococcus aureus/isolamento & purificação , Antibacterianos/farmacologia , Aptâmeros de Nucleotídeos/farmacologia , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/farmacologia , Indóis/farmacologia , Raios Infravermelhos , Imagem Óptica , Tamanho da Partícula , Polímeros/farmacologia , Análise de Célula Única , Staphylococcus aureus/citologia , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície
18.
Int J Mol Sci ; 21(11)2020 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-32545315

RESUMO

The study aimed to analyze morphological and functional changes of Staphylococcus aureus cells due to trans-anethole (a terpenoid and the major constituent of fennel, anise, or star anise essential oils) exposition, and their consequences for human neutrophils phagocytic activity as well as IL-8 production (recognized as the major chemoattractant). The investigation included the evaluation of changes occurring in S. aureus cultures, i.e., staphyloxanthin production, antioxidant activities, cell size distribution, and cells composition as a result of incubation with trans-anethole. It was found that the presence of trans-anethole in the culture medium reduced the level of staphyloxanthin production, as well as decreased antioxidant activities. Furthermore, trans-anethole-treated cells were characterized by larger size and a tendency to diffuse in comparison to the non-treated cells. Several cell components, such as phospholipids and peptidoglycan, were found remarkably elevated in the cultures treated with trans-anethole. As a result of the aforementioned cellular changes, the bacteria were phagocytized by neutrophils more efficiently (ingestion and parameters associated with killing activity were at a higher level as compared to the control system). Additionally, IL-8 production was at a higher level for trans-anethole modified bacteria. Our results suggest that trans-anethole represents a promising measure in combating severe staphylococcal infections, which has an important translational potential for clinical applications.


Assuntos
Anisóis/farmacologia , Antibacterianos/farmacologia , Imunidade Inata/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Adulto , Anisóis/administração & dosagem , Anisóis/imunologia , Antibacterianos/administração & dosagem , Antibacterianos/imunologia , Antioxidantes/metabolismo , Bacteriemia/tratamento farmacológico , Bacteriemia/imunologia , Bacteriemia/microbiologia , Contagem de Células Sanguíneas , Feminino , Humanos , Interleucina-8/metabolismo , Masculino , Nitroazul de Tetrazólio/metabolismo , Fagócitos/efeitos dos fármacos , Fagócitos/imunologia , Fagócitos/microbiologia , Fagocitose/efeitos dos fármacos , Fagocitose/imunologia , Espectroscopia de Infravermelho com Transformada de Fourier , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/imunologia , Staphylococcus aureus/citologia , Staphylococcus aureus/metabolismo , Xantofilas/metabolismo
19.
Nature ; 582(7811): 294-297, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32523118

RESUMO

The primary structural component of the bacterial cell wall is peptidoglycan, which is essential for viability and the synthesis of which is the target for crucial antibiotics1,2. Peptidoglycan is a single macromolecule made of glycan chains crosslinked by peptide side branches that surrounds the cell, acting as a constraint to internal turgor1,3. In Gram-positive bacteria, peptidoglycan is tens of nanometres thick, generally portrayed as a homogeneous structure that provides mechanical strength4-6. Here we applied atomic force microscopy7-12 to interrogate the morphologically distinct Staphylococcus aureus and Bacillus subtilis species, using live cells and purified peptidoglycan. The mature surface of live cells is characterized by a landscape of large (up to 60 nm in diameter), deep (up to 23 nm) pores constituting a disordered gel of peptidoglycan. The inner peptidoglycan surface, consisting of more nascent material, is much denser, with glycan strand spacing typically less than 7 nm. The inner surface architecture is location dependent; the cylinder of B. subtilis has dense circumferential orientation, while in S. aureus and division septa for both species, peptidoglycan is dense but randomly oriented. Revealing the molecular architecture of the cell envelope frames our understanding of its mechanical properties and role as the environmental interface13,14, providing information complementary to traditional structural biology approaches.


Assuntos
Bacillus subtilis/citologia , Bacillus subtilis/ultraestrutura , Parede Celular/química , Parede Celular/ultraestrutura , Microscopia de Força Atômica , Staphylococcus aureus/citologia , Staphylococcus aureus/ultraestrutura , Bacillus subtilis/química , Viabilidade Microbiana , Peptidoglicano/química , Peptidoglicano/isolamento & purificação , Peptidoglicano/ultraestrutura , Staphylococcus aureus/química
20.
Appl Opt ; 59(12): 3773-3783, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32400505

RESUMO

In this paper, a volume phase holographic optical element based digital holographic interferometer is designed and used for quantitative phase imaging of biological cells [white blood cells, red blood cells, platelets, and Staphylococcus aureus (S. aureus) bacteria cells]. The experimental results reveal that sharp images of the S. aureus bacteria cells of the order of ${\sim}{1}\;{\unicode{x00B5}{\rm m}}$∼1µm can be clearly seen. The volume phase holographic grating will remove the stray light from the system reaching toward the grating and will minimize the coherent noise (speckle noise). This will improve the sharpness in the image reconstructed from the recorded digital hologram.


Assuntos
Plaquetas/citologia , Diagnóstico por Imagem/instrumentação , Eritrócitos/citologia , Holografia/métodos , Interferometria/instrumentação , Leucócitos/citologia , Staphylococcus aureus/citologia , Algoritmos , Desenho de Equipamento , Humanos , Processamento de Imagem Assistida por Computador/instrumentação , Razão Sinal-Ruído
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