Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 40.942
Filtrar
1.
Ethiop J Health Sci ; 31(3): 663-672, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34483624

RESUMO

Background: This cross-sectional study was performed on isolates of Klebsiella pneumoniae, and E.coli from clinical specimens of patients admitted to Sayyad Shirazi Hospital by census sampling method in 2019. Antibiogram testing was performed using the disk diffusion method as defined by the Clinical and Laboratory Standards Organization for performing this test. Finally, the abundance of genes was evaluated by PCR using specific primers. Frequency, percentage, mean±SD were used to describe the data. Chi-square and Fisher's exact tests were used to compare the presence and absence of the studied genes alone and in the presence of each other. Result: This study was performed on 130 positive samples, isolated from 32 (24.6%) males and 98 (65.4%) females with a mean age of 43.78 ± 21.72. From the total number of 130 isolates, 84 (64.6%) consisted of E.coli, and 46 (35.4%) were Klebsiella. Most of the cultures were urine and vaginal (61.5%). The highest antibiotic resistance in isolates was cephalexin and cefazolin (67.9% in E.coli & 63% in Klebsiella). Colistin was identified as the most effective antibiotic (100%) in both. AMPC extendedspectrum ß-lactamase genes were present in 40 (30.8%) isolates. The highest frequency about the gene pattern of AMPC positive ß-lactamase bacteria was correlated to DHA, FOX, and CIT genes, while none of the samples contained the MOX ß-lactamase gene. E.coli and Klebsiella beta-lactamase-producing AMPC isolates were also significantly correlated with antibiotic resistance to the cephalosporin class (P <0.05). Conclusion: This study indicated a high percentage of resistance to third and fourth generation cephalosporins. Hence, careful antibiogram tests and prevention of antibiotic overuse in infections caused by AMPC-producing organisms and screening of clinical samples for the resistance mentioned above genes and providing effective strategies to help diagnose and apply appropriate treatments and change antibiotic usage strategies can partially prevent the transmission of this resistance.


Assuntos
Farmacorresistência Bacteriana/genética , Escherichia coli , Klebsiella pneumoniae , Antibacterianos/farmacologia , Estudos Transversais , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Infecções por Escherichia coli/tratamento farmacológico , Feminino , Humanos , Infecções por Klebsiella/tratamento farmacológico , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Masculino , Testes de Sensibilidade Microbiana , beta-Lactamases/genética
2.
Int J Mol Sci ; 22(16)2021 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-34445592

RESUMO

The Hfq protein is a bacterial RNA chaperone, involved in many molecular interactions, including control of actions of various small RNA regulatory molecules. We found that the presence of Hfq was required for survival of plasmid-containing Escherichia coli cells against high concentrations of chloramphenicol (plasmid p27cmr), tetracycline (pSC101, pBR322) and ampicillin (pBR322), as hfq+ strains were more resistant to these antibiotics than the hfq-null mutant. In striking contrast, production of Hfq resulted in low resistance to high concentrations of kanamycin when the antibiotic-resistance marker was chromosome-borne, with deletion of hfq resulting in increasing bacterial survival. These results were observed both in solid and liquid medium, suggesting that antibiotic resistance is an intrinsic feature of these strains rather than a consequence of adaptation. Despite its major role as RNA chaperone, which also affects mRNA stability, Hfq was not found to significantly affect kan and tet mRNAs turnover. Nevertheless, kan mRNA steady-state levels were higher in the hfq-null mutant compared to the hfq+ strain, suggesting that Hfq can act as a repressor of kan expression.This observation does correlate with the enhanced resistance to high levels of kanamycin observed in the hfq-null mutant. Furthermore, dependency on Hfq for resistance to high doses of tetracycline was found to depend on plasmid copy number, which was only observed when the resistance marker was expressed from a low copy plasmid (pSC101) but not from a medium copy plasmid (pBR322). This suggests that Hfq may influence survival against high doses of antibiotics through mechanisms that remain to be determined. Studies with pBR322Δrom may also suggest an interplay between Hfq and Rom in the regulation of ColE1-like plasmid replication. Results of experiments with a mutant devoid of the part of the hfq gene coding for the C-terminal region of Hfq suggested that this region, as well as the N-terminal region, may be involved in the regulation of expression of antibiotic resistance in E. coli independently.


Assuntos
Antibacterianos/farmacologia , Cromossomos Bacterianos/genética , Resistência Microbiana a Medicamentos/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Fator Proteico 1 do Hospedeiro/genética , Mutação , Plasmídeos/genética , Escherichia coli/efeitos dos fármacos
3.
Int J Mol Sci ; 22(16)2021 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-34445410

RESUMO

Development of novel therapeutics to treat antibiotic-resistant infections, especially those caused by ESKAPE pathogens, is urgent. One of the most critical pathogens is P. aeruginosa, which is able to develop a large number of factors associated with antibiotic resistance, including high level of impermeability. Gram-negative bacteria are protected from the environment by an asymmetric Outer Membrane primarily composed of lipopolysaccharides (LPS) at the outer leaflet and phospholipids in the inner leaflet. Based on a large hemi-synthesis program focusing on amphiphilic aminoglycoside derivatives, we extend the antimicrobial activity of 3',6-dinonyl neamine and its branched isomer, 3',6-di(dimethyloctyl) neamine on clinical P. aeruginosa, ESBL, and carbapenemase strains. We also investigated the capacity of 3',6-homodialkyl neamine derivatives carrying different alkyl chains (C7-C11) to interact with LPS and alter membrane permeability. 3',6-Dinonyl neamine and its branched isomer, 3',6-di(dimethyloctyl) neamine showed low MICs on clinical P. aeruginosa, ESBL, and carbapenemase strains with no MIC increase for long-duration incubation. In contrast from what was observed for membrane permeability, length of alkyl chains was critical for the capacity of 3',6-homodialkyl neamine derivatives to bind to LPS. We demonstrated the high antibacterial potential of the amphiphilic neamine derivatives in the fight against ESKAPE pathogens and pointed out some particular characteristics making the 3',6-dinonyl- and 3',6-di(dimethyloctyl)-neamine derivatives the best candidates for further development.


Assuntos
Compostos Alílicos/farmacologia , Antibacterianos/farmacologia , Framicetina/química , Bactérias Gram-Negativas/crescimento & desenvolvimento , Lipopolissacarídeos/metabolismo , Compostos Alílicos/síntese química , Compostos Alílicos/química , Antibacterianos/síntese química , Antibacterianos/química , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Permeabilidade da Membrana Celular/efeitos dos fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/metabolismo , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/metabolismo , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/metabolismo
4.
Malawi Med J ; 33(1): 59-64, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-34422235

RESUMO

Background: Non-susceptibility of bacteria to antiseptic agents used for preoperative skin preparations threaten the effectiveness of prevention of surgical site infections. Data concerning susceptibility of multidrug resistant bacteria strains to antiseptic agents was limited at our setting. This study presents the susceptibility of extended spectrum ß-lactamases producing Klebsiella pneumoniae and Escherichia coli (with and without biofilm formation) to antiseptic agents used for preoperative skin preparations at zonal referral hospital in Mwanza, Tanzania. Methods: This cross-sectional descriptive study was conducted through July 2020. Presumptive extended spectrum beta-lactamase producing Klebsiella pneumoniae and Escherichia coli were recovered for this study. Disc combination method was used to confirm production of ESBL while tube method was used to detect biofilms formation. Then, isolates were tested for susceptibility towards 10% povidone iodine, 70% methylated spirit, 50% hydrogen peroxide (6% of industrial H2O2 diluted in equal volume with sterile distilled water) and 2% chlorhexidine. STATA software version 13.0 was used for data analysis. Results: A total of 31 presumptive ESBL producers were recovered and phenotypically confirmed, whereas 54.8% (n=17) were K. pneumoniae and 45.2% (n=14) were E. coli. Five (35.7%) E. coli and seven (41.2%) K. pneumoniae had positive biofilms test results. Four (12.9%) bacteria were non-susceptible to antiseptic agents used for preoperative skin preparations. However, none exhibited resistance towards 10% PVP-I. Conclusion: In this study we highlight the existence of multidrug resistant Gram-negative bacteria with resistance to antiseptic agents used for preoperative skin preparation at a zonal referral hospital in Mwanza, Tanzania.


Assuntos
Anti-Infecciosos Locais/farmacologia , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Anti-Infecciosos Locais/uso terapêutico , Bactérias/classificação , Bactérias/efeitos dos fármacos , Bactérias/genética , Bactérias/isolamento & purificação , Biofilmes , Estudos Transversais , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/microbiologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/isolamento & purificação , Humanos , Infecções por Klebsiella/tratamento farmacológico , Klebsiella pneumoniae/isolamento & purificação , Testes de Sensibilidade Microbiana , Tanzânia
5.
Molecules ; 26(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34361717

RESUMO

The development of bio-based nanocomposites is of high scientific and industrial interest, since they offer excellent advantages in creating functional materials. However, dispersion and distribution of the nanomaterials inside the polymer matrix is a key challenge to achieve high-performance functional nanocomposites. In this context, for better dispersion, biobased triethyl citrate (TEC) as a dispersing agent in a liquid-assisted extrusion process was used to prepare the nanocomposites of poly (lactic acid) (PLA) and chitin nanocrystals (ChNCs). The aim was to identify the effect of the TEC content on the dispersion of ChNCs in the PLA matrix and the manufacturing of a functional nanocomposite. The nanocomposite film's optical properties; microstructure; migration of the additive and nanocomposites' thermal, mechanical and rheological properties, all influenced by the ChNC dispersion, were studied. The microscopy study confirmed that the dispersion of the ChNCs was improved with the increasing TEC content, and the best dispersion was found in the nanocomposite prepared with 15 wt% TEC. Additionally, the nanocomposite with the highest TEC content (15 wt%) resembled the mechanical properties of commonly used polymers like polyethylene and polypropylene. The addition of ChNCs in PLA-TEC15 enhanced the melt viscosity, as well as melt strength, of the polymer and demonstrated antibacterial activity.


Assuntos
Antibacterianos/síntese química , Quitina/química , Citratos/química , Nanocompostos/química , Nanopartículas/química , Poliésteres/química , Antibacterianos/farmacologia , Módulo de Elasticidade , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Nanocompostos/ultraestrutura , Nanopartículas/ultraestrutura , Reologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Resistência à Tração , Viscosidade
6.
Pan Afr Med J ; 39: 50, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34422173

RESUMO

Introduction: Suya, a form of barbecued meat widely consumed in Nigeria is a rising source of concern for the dissemination of pathogens and antibiotic resistance. Methods: this study was carried out to determine the antibiotic resistance profile of Escherichia coli (E. coli) isolated from Suya sold in Karu Local Government Area, Nasarawa State, Nigeria. A total of three hundred (300) Suya samples were collected and screened for the presence of E. coli. An antibiotic susceptibility study was carried out on the isolated bacteria to determine their resistance profiles. Results: the overall isolation and occurrence of E. coli was 13.3%. The isolated organisms were most resistant to Ampicillin (100%) followed by Amoxicillin/Clavulanic acid (95%), Ciprofloxacin (92.5%), Nitrofurantoin, Imipenem and Ceftriaxone (85%), Cefixime (80%), Streptomycin (77.5%), and Cotrimoxazole (77%), with a low level of resistance recorded against Gentamycin (5%). Most of the E. coli isolates had multiple resistance (MAR) to at least five antibiotics (MAR Index of = 0.5) and the most frequent MAR Index was 0.8 with 37.5% occurrence. The most frequently encountered resistance phenotype was Nitrofurantoin-Imipenem-Streptomycin-Ciprofloxacin-Ceftriaxone-Amoxicillin/clavulanic acid-Cefixime-Ampicillin. The E. coli isolates categorised based on drug resistance classes were Multi-Drug Resistance, MDR (97.5%), Pan Drug Resistance, PDR (2.5%), Non-Multi-Drug Resistance, NMDR (0.0%) and Extensive Drug Resistance, XDR (0.0%). Conclusion: these findings indicate a potential danger of multidrug resistant organisms in circulation. Antibiotics stewardship and drug resistance surveillance is strongly recommended for all stakeholders.


Assuntos
Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Carne Vermelha/microbiologia , Animais , Bovinos , Farmacorresistência Bacteriana Múltipla , Escherichia coli/isolamento & purificação , Testes de Sensibilidade Microbiana , Nigéria
7.
Molecules ; 26(15)2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34361759

RESUMO

Croton ferrugineus Kunth is an endemic species of Ecuador used in traditional medicine both for wound healing and as an antiseptic. In this study, fresh Croton ferrugineus leaves were collected and subjected to hydrodistillation for extraction of the essential oil. The chemical composition of the essential oil was determined by gas chromatography equipped with a flame ionization detector and gas chromatography coupled to a mass spectrometer using a non-polar and a polar chromatographic column. The antibacterial activity was assayed against three Gram-positive bacteria, one Gram-negative bacterium and one dermatophyte fungus. The radical scavenging properties of the essential oil was evaluated by means of DPPH and ABTS assays. The chemical analysis allowed us to identify thirty-five compounds representing more than 99.95% of the total composition. Aliphatic sesquiterpene hydrocarbon trans-caryophyllene was the main constituent with 20.47 ± 1.25%. Other main compounds were myrcene (11.47 ± 1.56%), ß-phellandrene (10.55 ± 0.02%), germacrene D (7.60 ± 0.60%), and α-humulene (5.49 ± 0.38%). The essential oil from Croton ferrugineus presented moderate activity against Candida albicans (ATCC 10231) with an MIC of 1000 µg/mL, a scavenging capacity SC50 of 901 ± 20 µg/mL with the ABTS method, and very strong antiglucosidase activity with an IC50 of 146 ± 20 µg/mL.


Assuntos
Anti-Infecciosos/química , Antioxidantes/química , Croton/química , Inibidores Enzimáticos/química , Óleos Voláteis/química , Folhas de Planta/química , Monoterpenos Acíclicos/química , Monoterpenos Acíclicos/isolamento & purificação , Alcenos/química , Alcenos/isolamento & purificação , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/farmacologia , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Benzotiazóis/antagonistas & inibidores , Compostos de Bifenilo/antagonistas & inibidores , Candida albicans/efeitos dos fármacos , Candida albicans/crescimento & desenvolvimento , Monoterpenos Cicloexânicos/química , Monoterpenos Cicloexânicos/isolamento & purificação , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Sesquiterpenos Monocíclicos/química , Sesquiterpenos Monocíclicos/isolamento & purificação , Picratos/antagonistas & inibidores , Sesquiterpenos Policíclicos/química , Sesquiterpenos Policíclicos/isolamento & purificação , Sesquiterpenos de Germacrano/química , Sesquiterpenos de Germacrano/isolamento & purificação , Ácidos Sulfônicos/antagonistas & inibidores , alfa-Glucosidases/química
8.
Molecules ; 26(16)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34443699

RESUMO

Three α,α-difluorophosphonate derivatives of fosmidomycin were synthesized from diethyl 1,1-difluorobut-3-enylphosphonate and were evaluated on Escherichia coli. Two of them are among the best 1-deoxy-d-xylulose 5-phosphate reductoisomerase inhibitors, with IC50 in the nM range, much better than fosmidomycin, the reference compound. They also showed an enhanced antimicrobial activity against E. coli on Petri dishes in comparison with the corresponding phosphates and the non-fluorinated phosphonate.


Assuntos
Antibacterianos/farmacologia , Fosfomicina/análogos & derivados , Ácidos Hidroxâmicos/farmacologia , Aldose-Cetose Isomerases/antagonistas & inibidores , Aldose-Cetose Isomerases/metabolismo , Farmacorresistência Bacteriana/efeitos dos fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Fosfomicina/síntese química , Fosfomicina/química , Fosfomicina/farmacologia , Testes de Sensibilidade Microbiana
9.
ACS Appl Mater Interfaces ; 13(33): 39446-39457, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34387085

RESUMO

Step-scheme (S-scheme) photocatalysts have been proposed for highly efficient charge separation and strong redox activity in the photocatalysis field. Here, we reported a facile strategy to obtain the S-scheme heterojunction composite TiO2/chlorophyll (Chl). The S-scheme heterojunction enables the significant improvement of electron transfer efficiency at the interfacial heterojunction of TiO2/Chl. Also, the lifted conduction band and valence band of TiO2/Chl resulted in more than 1.61 times generation of reactive oxidizing species, compared to that of bare TiO2. In addition, TiO2/Chl was applied as a photocatalytic bactericidal material to fabricate commercial masks for prolonged life span of the mask. The TiO2/Chl-coated mask filter exhibited excellent bactericidal effect on Escherichia coli under light illumination (2.94 × 107 cfu E. coli were killed by 1 cm-2 coated mask filters within illumination of 3 h), while commercial mask filters showed no bactericidal effect. After three circulation-sterilization tests, the TiO2/Chl-made mask filter maintained the initial bactericidal effect, which greatly extended the life span of the mask that presents a promising strategy to alleviate the supply stress of masks.


Assuntos
Antibacterianos/química , Clorofila/química , Nanocompostos/química , Titânio/química , Antibacterianos/farmacologia , Catálise , Escherichia coli/efeitos dos fármacos , Humanos , Luz , Máscaras , Oxirredução , Processos Fotoquímicos , Esterilização/métodos , Nanomedicina Teranóstica
10.
ACS Appl Mater Interfaces ; 13(33): 39806-39818, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34387459

RESUMO

Silver nanomaterials have attracted a great deal of interest due to their broad-spectrum antimicrobial activity. However, it is still challenging to balance the high antibacterial efficiency with low damage to biological cells of silver nanostructures, especially when the diameter decreases to less than 10 nm. Here, we developed a new type of Ag nanohybrid material via a unimolecular micelle template method, which presents amazing antibacterial activities and almost noncytotoxicity. First, water-soluble multiarm star-shaped brushlike copolymer α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 was precisely synthesized and its micelle behavior in different solvents was revealed. Then, nanocrystal clusters assembled by Ag grains (Ag@Template NCs) were prepared through an in situ redox route using the unimolecular micelle of α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 as the soft template, AgNO3 as a precursor, and tetrabutylammonium borohydride (TBAB) as the reducing agent. The overall size of the achieved Ag@Template NCs is controlled by the template structure at around 40 nm (Dh in DMF), and the size of the Ag grain can be easily regulated from ∼1 to ∼5 nm by adjusting the feeding ratio of AgNO3/acrylic acid (AA) units in the template from 1:10 to 1:1. Benefitting from the structural design of the template, all Ag@Template NCs prepared here exhibit excellent dispersibility and chemical stability in different aqueous environments (neutral, pH = 5.5, and 0.9% NaCl physiological saline solution), which play a crucial role in the long-term storage and potential application in a complex physiological environment. The antibacterial and cytotoxicity tests indicate that Ag@Template NCs display much better performance than Ag nanoparticles (Ag NPs), which have a comparable overall size of ∼25 nm. The inhibitory capability of Ag@Template NCs to bacteria strongly depends on the grain size. Specifically, the Ag@Template-1 NC assembled by the smallest grains (1.6 ± 0.3 nm) presents the best antibacterial activity. For E. coli (-), the MIC value is as low as 5 µg/mL (0.36 µg/mL of Ag), while for S. aureus (+), the value is around 10 µg/mL (0.72 µg/mL of Ag). The survival rate of L02 cells and lactate dehydrogenase assay together illustrate the low cytotoxicity possessed by the prepared Ag@Template NCs. Therefore, the proposed Ag@Template NC structure successfully resolves the high reactivity, instability, and fast oxidation issues of the ultrasmall Ag nanoparticles, and integrates high antibacterial efficiency and nontoxicity to biological cells into one platform, which implies its broad potential application in biomedicine.


Assuntos
Antibacterianos/efeitos adversos , Antibacterianos/química , Nanopartículas Metálicas/química , Prata/química , Antibacterianos/metabolismo , Boroidretos/química , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Polímeros/química , Compostos de Amônio Quaternário/química , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície , Nanomedicina Teranóstica
11.
Int J Mol Sci ; 22(14)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34299005

RESUMO

Nanoparticles can interact with the complement system and modulate the inflammatory response. The effect of these interactions on the complement activity strongly depends on physicochemical properties of nanoparticles. The interactions of silver nanoparticles with serum proteins (particularly with the complement system components) have the potential to significantly affect the antibacterial activity of serum, with serious implications for human health. The aim of the study was to assess the influence of graphite oxide (GO) nanocomposites (GO, GO-PcZr(Lys)2-Ag, GO-Ag, GO-PcZr(Lys)2) on the antibacterial activity of normal human serum (NHS), serum activity against bacteria isolated from alveoli treated with nanocomposites, and nanocomposite sensitivity of bacteria exposed to serum in vitro (using normal human serum). Additionally, the in vivo cytotoxic effect of the GO compounds was determined with application of a Galleria mellonella larvae model. GO-PcZr(Lys)2, without IR irradiation enhance the antimicrobial efficacy of the human serum. IR irradiation enhances bactericidal activity of serum in the case of the GO-PcZr(Lys)2-Ag sample. Bacteria exposed to nanocomposites become more sensitive to the action of serum. Bacteria exposed to serum become more sensitive to the GO-Ag sample. None of the tested GO nanocomposites displayed a cytotoxicity towards larvae.


Assuntos
Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Grafite/química , Nanopartículas Metálicas/química , Nanocompostos/química , Óxidos/química , Soro/efeitos dos fármacos , Animais , Antibacterianos/química , Anti-Infecciosos/química , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/efeitos da radiação , Humanos , Raios Infravermelhos , Larva/efeitos dos fármacos , Larva/efeitos da radiação , Lepidópteros/efeitos dos fármacos , Lepidópteros/efeitos da radiação , Nanopartículas Metálicas/administração & dosagem , Nanocompostos/administração & dosagem , Soro/microbiologia , Prata/química
12.
J Enzyme Inhib Med Chem ; 36(1): 1509-1520, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34238110

RESUMO

In the present study, a series of azo derivatives (TR-1 to TR-9) have been synthesised via the diazo-coupling approach between substituted aromatic amines with phenol or naphthol derivatives. The compounds were evaluated for their therapeutic applications against alpha-glucosidase (anti-diabetic) and pathogenic bacterial strains E. coli (gram-negative), S. aureus (gram-positive), S. aureus (gram-positive) drug-resistant strain, P. aeruginosa (gram-negative), P. aeruginosa (gram-negative) drug-resistant strain and P. vulgaris (gram-negative). The IC50 (µg/mL) of TR-1 was found to be most effective (15.70 ± 1.3 µg/mL) compared to the reference drug acarbose (21.59 ± 1.5 µg/mL), hence, it was further selected for the kinetic studies in order to illustrate the mechanism of inhibition. The enzyme inhibitory kinetics and mode of binding for the most active inhibitor (TR-1) was performed which showed that the compound is a non-competitive inhibitor and effectively inhibits the target enzyme by binding to its binuclear active site reversibly.


Assuntos
Antibacterianos/farmacologia , Compostos Azo/farmacologia , Inibidores Enzimáticos/farmacologia , Hipoglicemiantes/farmacologia , Simulação de Acoplamento Molecular , alfa-Glucosidases/metabolismo , Antibacterianos/síntese química , Antibacterianos/química , Compostos Azo/síntese química , Compostos Azo/química , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Escherichia coli/efeitos dos fármacos , Hipoglicemiantes/síntese química , Hipoglicemiantes/química , Cinética , Testes de Sensibilidade Microbiana , Estrutura Molecular , Pseudomonas aeruginosa/efeitos dos fármacos , Saccharomyces cerevisiae/enzimologia , Staphylococcus aureus/efeitos dos fármacos
13.
J Photochem Photobiol B ; 221: 112249, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34237541

RESUMO

Increasing interests in photodynamic treatment (PDT) for food preservation require a holistic method to evaluate and compare different photosensitizer (PS)-light treatments. In this report, the absorbed photons were used as the basis to assess the antimicrobial photodynamic efficacy of two PSs, chlorophyllin sodium magnesium salt (Chl-Mg) and chlorophyllin sodium copper salt (Chl-Cu), under blue and white light against two typical foodborne pathogens, Gram-negative Escherichia coli, and Gram-positive Staphylococcus aureus. The results showed that the phototoxicity of a PS was predominantly decided by the absorbed photons rather than the characteristics of light sources. Photosensitized Chl-Mg exhibited superior antimicrobial activity as compared to that of ChlCu. The applied treatments were found to be more effective against S. aureus than E. coli. Bacterial inactivation kinetics as a function of the number of absorbed photons could be described by Weibull model with R2 from 0.947-0.962, and kinetics constants D in the range of 0.202 × 1017 photons/cm2-2.409 × 1018 photons/cm2. The kinetics models may find promising applications in the design, assessment, and optimization of PDT processes.


Assuntos
Escherichia coli/efeitos dos fármacos , Luz , Fármacos Fotossensibilizantes/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Clorofilídeos/química , Cobre/química , Escherichia coli/efeitos da radiação , Microbiologia de Alimentos , Magnésio/química , Oxigênio Singlete/química , Oxigênio Singlete/metabolismo , Sódio/química , Staphylococcus aureus/efeitos da radiação
14.
Ultrason Sonochem ; 77: 105676, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34315058

RESUMO

In recent years, foodborne diseases caused by Escherichia coli are a major threat to the food industry and consumers. Antimicrobial peptides (AMPs) and ultrasound both have good inhibitory effects on E. coli. In this work, the mechanism of action and synergistic effect of an in silico predicted AMP, designated as TGH2 (AEFLREKLGDKCTDRHV), from the C-terminal sequence of Tegillarca granosa hemoglobin, combined with low-intensity ultrasound was explored. The minimal inhibitory concentration (MIC) of TGH2 on E. coli decreased by 4-fold to 31.25 µg/mL under 0.3 W/cm2 ultrasound treatment, while the time kill curve analysis showed that low-intensity ultrasound combined with peptide TGH2 had an enhanced synergistic bactericidal effect after 0.5 h. The permeability on E. coli cell membrane increased progressively during combined treatment with peptide TGH2 and low-intensity ultrasound, resulting in the leakage of intracellular solutes, as shown by transmission electron microscopy (TEM). Structural analysis using circular dichroism (CD) revealed that peptide TGH2 has an α-helical structure, showing a slight untwisting effect under 0.3 W/cm2 ultrasound treatment for 0.5 h. The findings here provide new insight into the potential application of ultrasound and AMPs combination in food preservation.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Peptídeos/química , Peptídeos/farmacologia , Ondas Ultrassônicas , Sequência de Aminoácidos , Cinética , Testes de Sensibilidade Microbiana
15.
Molecules ; 26(13)2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34279383

RESUMO

Silver has a long history of antibacterial effectiveness. The combination of atomically precise metal nanoclusters with the field of nucleic acid nanotechnology has given rise to DNA-templated silver nanoclusters (DNA-AgNCs) which can be engineered with reproducible and unique fluorescent properties and antibacterial activity. Furthermore, cytosine-rich single-stranded DNA oligonucleotides designed to fold into hairpin structures improve the stability of AgNCs and additionally modulate their antibacterial properties and the quality of observed fluorescent signals. In this work, we characterize the sequence-specific fluorescence and composition of four representative DNA-AgNCs, compare their corresponding antibacterial effectiveness at different pH, and assess cytotoxicity to several mammalian cell lines.


Assuntos
Antibacterianos/química , DNA de Cadeia Simples/química , Nanopartículas Metálicas/química , Prata/química , Antibacterianos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Fluorescência , Humanos , Nanopartículas Metálicas/toxicidade , Células THP-1
16.
Molecules ; 26(13)2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34279398

RESUMO

The aim of this study was to compare the influence of the extraction method, chemical composition, antimicrobial effects, antioxidant activity, and cytotoxicity on human cells of the non-polar extracts of grape (Vitis labrusca) and blackberry (Rubus fruticosus) seeds. The Soxhlet (Sox), Bligh-Dyer (BD), and ultrasound (US) methods were used for extractions. For blackberry non-polar seed extract, extraction via the BD method showed the highest mean values of total phenolic content (TPC), expressed in milligrams of gallic acid equivalent per 100 mL of non-polar seed extracts (102.37 mg GAE/100 mL), and higher antioxidant activity in relation to the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, expressed in milligrams of gallic acid equivalent per 100 mL of non-polar seed extracts (11.50 mg AAE/100 mL), if compared with the Sox and US extractions. Similar results were obtained for the non-polar grape seed extracts, where BD extraction obtained the highest values for TPC (28.61 mg GAE/100 mL) and DPPH (35.36 mg AAE/100 mL). The type of extraction method had an impact on the composition of fatty acids. Only the non-polar blackberry and grape seed extracts obtained via the Sox method showed some in vitro inhibitory effect against Escherichia coli (IAL 2064) and Staphylococcus aureus (ATCC 13565). Regardless of the extraction method used, the non-polar blackberry and grape seed extracts did not decrease the cell viability (IC50 >1000 µg/mL) of cancer and normal cell lines, thus indicating the relative safety of the extracts. All the seed extracts decreased the generation of reactive oxygen species in the cell lines. Blackberry and grape seed lipid fractions can be utilized as antioxidants, and the extraction methods used cause significant changes in relation to their bioactivity and chemical composition.


Assuntos
Anti-Infecciosos/química , Antioxidantes/química , Extrato de Sementes de Uva/química , Rubus/química , Anti-Infecciosos/farmacologia , Anti-Infecciosos/toxicidade , Antioxidantes/farmacologia , Antioxidantes/toxicidade , Escherichia coli/efeitos dos fármacos , Ácidos Graxos/análise , Flavonoides/análise , Extrato de Sementes de Uva/farmacologia , Staphylococcus aureus/efeitos dos fármacos
17.
Int J Mol Sci ; 22(11)2021 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-34199768

RESUMO

Single mutations can confer resistance to antibiotics. Identifying such mutations can help to develop and improve drugs. Here, we systematically screen for candidate quinolone resistance-conferring mutations. We sequenced highly diverse wastewater E. coli and performed a genome-wide association study (GWAS) to determine associations between over 200,000 mutations and quinolone resistance phenotypes. We uncovered 13 statistically significant mutations including 1 located at the active site of the biofilm dispersal gene bdcA and 6 silent mutations in the aminoacyl-tRNA synthetase valS. The study also recovered the known mutations in the topoisomerases gyrase (gyrA) and topoisomerase IV (parC). In summary, we demonstrate that GWAS effectively and comprehensively identifies resistance mutations without a priori knowledge of targets and mode of action. The results suggest that mutations in the bdcA and valS genes, which are involved in biofilm dispersal and translation, may lead to novel resistance mechanisms.


Assuntos
Farmacorresistência Bacteriana/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Mutação/genética , Quinolonas/farmacologia , Valina-tRNA Ligase/genética , Águas Residuárias/microbiologia , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Loci Gênicos , Estudo de Associação Genômica Ampla , Desequilíbrio de Ligação/genética , Modelos Moleculares , Fenótipo , Filogenia
18.
Int J Biol Macromol ; 185: 513-524, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34214575

RESUMO

It remains a great challenge to prepare polylactic acid (PLA) composites with excellent mechanical properties, superior anti-bacteria, and highly effective electromagnetic interference (EMI) shielding using ultralow loading of functional fillers. Herein, lignin particles were uniformly nano-sized as the matrix reinforcement and the fillers carrier via green mechanochemistry for improved thermal properties of polymer matrix. Through one-pot approach to a multitasking engineered agent, hybridized ZnO/Ag particles were synthesized for multi-functionalities. Inspired by mussels, the bio-derived dopamine cross-linker was introduced to in-situ synthesize the polypyrrole (PPy-PDa) glutinous nanofibrils as an interfacial modifier and a particles dispersant to regulate surface free energy of nanoparticles and improve filler-matrix interactions. With effective constructed 3D conductive networks by glutinous nanofibrils and hybridized particles, the dramatic improvement in EMI shielding and electrical conductivity was accomplished using an ultralow content of the conductive particles modifier (0.29 vol% Ag). The resulted biobased composites presented outstanding anti-dripping properties, mechanical properties, electrical conductivity (104.2 S/cm), anti-bacteria, joule heating, photothermal conversion ability and EMI shielding effectiveness (48.6 dB at X-band), which are superior to those reported. This work will broaden the application prospects of PLA composites in the fields of wearable electronics, food packaging and medical devices.


Assuntos
Antibacterianos/farmacologia , Lignina/química , Poliésteres/química , Prata/farmacologia , Óxido de Zinco/farmacologia , Animais , Antibacterianos/química , Bivalves , Condutividade Elétrica , Escherichia coli/efeitos dos fármacos , Química Verde , Nanopartículas Metálicas , Prata/química , Staphylococcus aureus/efeitos dos fármacos , Dispositivos Eletrônicos Vestíveis , Óxido de Zinco/química
19.
Int J Biol Macromol ; 185: 535-542, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34216656

RESUMO

Antimicrobial films based on polylactic acid (PLA) were developed by incorporating Thymus vulgaris essential oil (TV-EOs) with different concentrations of ethanolic extract of Mediterranean propolis (EEP) (5 wt% and 10 wt% based on PLA). The antimicrobial activities of EEP were performed by the agar disc diffusion method. The EEP exhibited high antimicrobial properties with inhibition zone diameter of 12.1 and 11.58 mm against Staphylococcus aureus and Penicillium sp., respectively. The addition of TV-EOs to films containing 5 and 10 wt% of EEP decrease the elastic modulus from 1292 MPa to 1084 MPa and 911.1 MPa to 794 MPa compared with films containing 5 and 10% of EEP alone, respectively. However, the elongation at break increased by 64% after the addition of TV-EOs to the film containing 10 wt% of EEP. Thermal stability of films improvement by the addition of TV-EOs and EEP. Antimicrobial activity of the films showed that films containing 10 wt% EEP inhibited the growth of Candida albicans and the combination of EEP and TV-EOs in the PLA matrix showed a synergistic effect against Escherichia coli. The developed PLA-based films with antimicrobial activity have a potential application in food packaging to increase the shelf life of packaged food.


Assuntos
Antibacterianos/farmacologia , Etanol/farmacologia , Óleos Voláteis/farmacologia , Poliésteres/química , Própole/química , Thymus (Planta)/química , Antibacterianos/química , Candida albicans/efeitos dos fármacos , Sinergismo Farmacológico , Escherichia coli/efeitos dos fármacos , Etanol/química , Embalagem de Alimentos , Armazenamento de Alimentos , Óleos Voláteis/química , Óleos Vegetais/química , Óleos Vegetais/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier
20.
Int J Biol Macromol ; 185: 620-628, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34216663

RESUMO

Mandarin (Citrus reticulata L.) essential oil (MEO) reportedly displays excellent antimicrobial properties. In this study, MEO was loaded into chitosan nanoparticles (CSNPs). The characteristics, antibacterial properties and benefit in pork preservation of MEO-CSNPs were evaluated. The MEO-CSNPs displayed an excellent encapsulation efficiency (EE) (67.32%-82.35%), the particle size values of 131.3 nm-161.9 nm, and the absolute zeta potential values above 30 mV. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, and thermogravimetric analysis (TGA) revealed that the MEO was incorporated into CSNPs without requiring a chemical reaction, the antibacterial activity of the MEO remained. Furthermore, the damage of MEO-chitosan nanoemulsions (MEO-CSs) to the cell membranes of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was confirmed by the change of bacterial cell morphology. The anti-biofilm assays verified that the MEO-CSs substantially inhibited biofilm formation and destroyed the mature biofilms. MEO-CSs were also applied to pork, proving a great potential for pork preservation. This study provides a potential approach for developing and utilizing MEO-CSs as natural antimicrobial agents in the food industry.


Assuntos
Quitosana/química , Citrus/química , Conservação de Alimentos/métodos , Óleos Voláteis/farmacologia , Carne de Porco , Animais , Membrana Externa Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Nanopartículas , Óleos Voláteis/química , Tamanho da Partícula , Óleos Vegetais/química , Óleos Vegetais/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/efeitos dos fármacos , Suínos , Termogravimetria , Difração de Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...