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2.
Adv Exp Med Biol ; 1145: 181-195, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31364079

RESUMO

Biofilm is an adaptive bacterial strategy whereby microorganisms become encased in a complex glycoproteic matrix. The low concentration of oxygen and nutrients in this environment leads to heterogeneous phenotypic changes in the bacteria, with antimicrobial tolerance being of paramount importance. As with other antibiotics, the activity of colistin is impaired by biofilm-embedded bacteria. Therefore, the recommendation for administering high doses in combination with a second drug, indicated for planktonic infections, remains valid in this setting. Notably, colistin has activity against metabolically inactive biofilm-embedded cells located in the inner layers of the biofilm structure. This is opposite and complementary to the activity of other antimicrobials that are able to kill metabolically active cells in the outer layers of the biofilm. Several experimental models have shown a higher activity of colistin when used in combination with other agents, and have reported that this can avoid the emergence of colistin-resistant subpopulations. Most experience of colistin in biofilm-associated infections comes from patients with cystic fibrosis, where the use of nebulized colistin allows high concentrations to reach the site of the infection. However, limited clinical experience is available in other scenarios, such as osteoarticular infections or device-related central nervous system infections caused by multi-drug resistant microorganisms. In the latter scenario, the use of intraventricular or intrathecal colistin also permits high local concentrations and good clinical results. Overall, the efficacy of intravenous colistin seems to be poor, but its association with a second antimicrobial significantly increases the response rate. Given its activity against inner bioflm-embedded cells, its possible role in combination with other antibiotics, beyond last-line therapy situations, should be further explored.


Assuntos
Antibacterianos/uso terapêutico , Biofilmes/efeitos dos fármacos , Colistina/uso terapêutico , Doenças Ósseas Infecciosas/tratamento farmacológico , Infecções do Sistema Nervoso Central/tratamento farmacológico , Fibrose Cística/microbiologia , Farmacorresistência Bacteriana Múltipla , Humanos , Testes de Sensibilidade Microbiana
3.
World J Microbiol Biotechnol ; 35(9): 133, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31432254

RESUMO

There is a significant increase in the discovery of new antimicrobial compounds in recent past to combat drug resistant pathogens. Members of the genus Bacillus and related genera have been screened extensively due to their ability to produce wide range of antimicrobial compounds. In this study, we have isolated and characterized a new antimicrobial peptide from a marine bacterium identified as Virgibacillus species. The low molecular mass and stability of the antimicrobial substance pointed towards the bacteriocinogenic nature of the compound. The RAST analysis of genome sequence showed presence of a putative bacteriocin biosynthetic cluster containing genes necessary for synthesis of a lanthipeptide. Translated amino acid sequence of mature C-terminal propeptide showed identity with salivaricin A (52.2%) and lacticin A (33.3%). Accordingly, the mass (2417 Da) obtained by MALDI analysis was in agreement with posttranslational modifications of the leader peptide to yield three methyl lanthionine rings and a disulfide bond between two free cysteine residues. The lanthipeptide was named as virgicin, which selectively inhibited the growth of Gram-positive bacteria and biofilm formation by Enterococcus faecalis. Inhibition of biofilm formation by E. faecalis was also observed in in vitro model experiments using hydroxyapatite discs. Thus, virgicin appears to be a promising new bacteriocin to control oral biofilm formation by selective pathogens.


Assuntos
Bacteriocinas/isolamento & purificação , Bacteriocinas/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/crescimento & desenvolvimento , Peptídeos/isolamento & purificação , Peptídeos/farmacologia , Virgibacillus/metabolismo , Bacteriocinas/química , Bacteriocinas/genética , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Vias Biossintéticas/genética , Genoma Bacteriano , Peso Molecular , Família Multigênica , Peptídeos/química , Peptídeos/genética , Água do Mar/microbiologia , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Virgibacillus/classificação , Virgibacillus/isolamento & purificação
4.
J Appl Oral Sci ; 27: e20180699, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31411265

RESUMO

OBJECTIVE: This study investigated the role of extracellular deoxyribonucleic acid (eDNA) on Enterococcus faecalis ( E. faecalis ) biofilm and the susceptibility of E. faecalis to sodium hypochlorite (NaOCl). METHODOLOGY: E. faecalis biofilm was formed in bovine tooth specimens and the biofilm was cultured with or without deoxyribonuclease (DNase), an inhibitor of eDNA. Then, the role of eDNA in E. faecalis growth and biofilm formation was investigated using colony forming unit (CFUs) counting, eDNA level assay, crystal violet staining, confocal laser scanning microscopy, and scanning electron microscopy. The susceptibility of E. faecalis biofilm to low (0.5%) or high (5%) NaOCl concentrations was also analyzed by CFU counting. RESULTS: CFUs and biofilm formation decreased significantly with DNase treatment (p<0.05). The microstructure of DNase-treated biofilms exhibited less structured features when compared to the control. The volume of exopolysaccharides in the DNase-treated biofilm was significantly lower than that of control (p<0.05). Moreover, the CFUs, eDNA level, biofilm formation, and exopolysaccharides volume were lower when the biofilm was treated with DNase de novo when compared to when DNase was applied to matured biofilm (p<0.05). E. faecalis in the biofilm was more susceptible to NaOCl when it was cultured with DNase (p<0.05). Furthermore, 0.5% NaOCl combined with DNase treatment was as efficient as 5% NaOCl alone regarding susceptibility (p>0.05). CONCLUSIONS: Inhibition of eDNA leads to decrease of E. faecalis biofilm formation and increase of susceptibility of E. faecalis to NaOCl even at low concentrations. Therefore, our results suggest that inhibition of eDNA would be beneficial in facilitating the efficacy of NaOCl and reducing its concentration.


Assuntos
Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , DNA Bacteriano/farmacologia , Desoxirribonucleases/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/crescimento & desenvolvimento , Hipoclorito de Sódio/farmacologia , Animais , Bovinos , Contagem de Colônia Microbiana , Cavidade Pulpar/microbiologia , Testes de Sensibilidade Microbiana , Microscopia Confocal , Microscopia Eletrônica de Varredura , Polissacarídeos Bacterianos/isolamento & purificação , Reprodutibilidade dos Testes , Fatores de Tempo
5.
Dokl Biochem Biophys ; 486(1): 206-208, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31367822

RESUMO

The aim of this work was to study the fine structure of bacterial films grown on the inner tube surface of a flow reactor. Using the scanning electron microscopy (SEM) approaches, the detailed biofilm relief was visualized. The action of electrochemically reduced water (ERW) on the biofilm ultrastructure generated by the plankton form of E. coli and/or lacto bacteria was investigated. The treatment with an ERW solution destroyed the biofilm organic polymer matrix and bacterial cells embedded in the matrix.


Assuntos
Biofilmes/efeitos dos fármacos , Água/química , Água/farmacologia , Biofilmes/crescimento & desenvolvimento , Eletroquímica , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia
6.
Bol. latinoam. Caribe plantas med. aromát ; 18(4): 411-424, jul. 2019. tab, ilus
Artigo em Inglês | LILACS | ID: biblio-1008180

RESUMO

Thymol (2-isopropyl-5-methylphenol) is an aromatic monoterpene found in essential oils extracted from plants belonging to the Lamiaceae family, such as Thymus, Ocimum, Origanum, Satureja, Thymbra and Monarda genera. Growth and biofilm formation by Listeria monocytogenes CLIP 74902 were evaluate using three carbon sources in the presence of thymol. Specific growth rate (h-1) values at 37o with glucose, trehalose and cellobiose with the addition of thymol (µg/mL) 0 (control) and 750, were respectively: 0.22, 0.07; 0.14, 0.04; 0.11, 0.04. Lag periods obtained under the same conditions were (h): 8.19, 13.2; 22.5, 27.5; 23.1, 28.1. A marked antibiofilm activity was observed against the exposure with 750 µg/mL of thymol, showing a high percentage of inhibition: glucose (99 %), trehalose (97 %) and cellobiose (98%), compared to the control. The results suggest that thymol could be used to inhibit the growth and production of biofilms by L. monocytogenes in the food industry.


Timol (2-isopropil-5-metilfenol) es un monoterpeno aromático presente en los aceites esenciales extraídos de plantas pertenecientes a la familia Lamiaceae, como los géneros Thymus, Ocimum, Origanum, Satureja, Thymbra y Monarda. El crecimiento y formación de biopelícula por Listeria monocytogenes CLIP 74902 fueron evaluados utilizando tres fuentes de carbono en presencia de timol. La velocidad específica de crecimiento (h-1) a 37o con glucosa, trehalosa y celobiosa con la adición de timol (µg/mL) 0 (control) y 750, fueron respectivamente: 0.22, 0.07; 0.14, 0.04, 0.11, 0,04. Los períodos lag obtenidos en las mismas condiciones fueron (h): 8.19, 13.2; 22.5, 27.5; 23.1, 28.1. Una marcada actividad antibiofilm fue obtenida con 750 µg/mL de timol, mostrando un alto porcentaje de inhibición con glucosa (99%), trehalosa (97%) y celobiosa (98%), respecto al control. Los resultados sugieren que timol podría ser usado para inhibir el crecimiento y producción de biopelículas por L. monocytogenes en la industria alimentaria.


Assuntos
Timol/farmacologia , Biofilmes/efeitos dos fármacos , Listeria monocytogenes/efeitos dos fármacos , Terpenos/farmacologia , Cinética , Biofilmes/crescimento & desenvolvimento , Meio Ambiente , Fermentação , Microbiologia de Alimentos , Listeria monocytogenes/crescimento & desenvolvimento
7.
J Med Microbiol ; 68(9): 1353-1358, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31271350

RESUMO

Introduction. Candida auris is a pathogenic yeast that mainly affects immunosuppressed patients and those with implanted medical devices. This pathogen also displays elevated resistance to common antifungals and high survival and spreading capacities. Since no antifungal breakpoints have yet been defined for this pathogen, the data obtained here can be useful for further research concerning treatment or implementation of a prevention and disinfection protocol. Our aim was to study the antifungal resistance of C. auris to current antifungals in planktonic and sessile states. Using confocal laser scanning microscopy and viable biomass production, we demonstrated the ability of C. auris to develop a mature biofilm. We compared the minimal inhibitory concentration (MIC) and the minimal biofilm eradication concentration (MBEC) for the C. auris DSM 21092 strain plus two clinical isolates, and the results were compared with those obtained for Candida albicans and Candida parapsilosis, two species strongly linked to bloodstream infections and infections associated with biomaterials. We found that the clinical isolates of C. auris were resistant to fluconazole and sensitive to echinocandins and polyenes. The C. auris biofilms did not show susceptibility to any antifungal agent, showing MBECs that were up to 512-fold higher than the MICs. These findings highlight the importance of biofilm formation as a key factor underlying the resistance of this species to antifungals and suggest that the presence of implantable medical devices is one of the major risk factors in immunocompromised patients.


Assuntos
Antifúngicos/farmacologia , Biofilmes/efeitos dos fármacos , Candida/efeitos dos fármacos , Candida/isolamento & purificação , Candida albicans/efeitos dos fármacos , Candida parapsilosis/efeitos dos fármacos , Candidíase/microbiologia , Contagem de Colônia Microbiana , Farmacorresistência Fúngica , Equinocandinas/farmacologia , Fluconazol/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Microscopia Confocal , Polienos/farmacologia
8.
Chem Commun (Camb) ; 55(66): 9765-9768, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31355394

RESUMO

Bacterial quorum sensing has been implicated in a number of pathogenic bacterial processes, such as biofilm formation, making it a crucial target for developing materials with a novel antibiotic mode of action. This paper describes poly(N-isopropyl acrylamide) that has been covalently linked, at multiple chain ends, to homoserine lactone to give a highly branched polymer functionalized with a key messenger molecule implicated in QS. This novel functional material has shown promising anti-QS activity in a Chromobacterium violaceum assay.


Assuntos
Acrilamidas/farmacologia , Chromobacterium/efeitos dos fármacos , Percepção de Quorum/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Chromobacterium/fisiologia
9.
Int J Nanomedicine ; 14: 4613-4624, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31308651

RESUMO

Background: Bacterial infection is a common and serious complication in orthopedic implants following traumatic injury, which is often associated with extensive soft tissue damage and contaminated wounds. Multidrug-resistant bacteria have been found in these infected wounds, especially in patients who have multi trauma and prolonged stay in intensive care units.Purpose: The objective of this study was to develop a coating on orthopedic implants that is effective against drug-resistant bacteria. Methods and results: We applied nanoparticles (30-70nm) of the trace element selenium (Se) as a coating through surface-induced nucleation-deposition on titanium implants and investigated the antimicrobial activity against drug resistant bacteria including Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-resistant Staphylococcus epidermidis (MRSE) in vitro and in an infected femur model in rats.The nanoparticles were shown in vitro to have antimicrobial activity at concentrations as low as 0.5ppm. The nanoparticle coatings strongly inhibited biofilm formation on the implants and reduced the number of viable bacteria in the surrounding tissue following inoculation of implants with biofilm forming doses of bacteria. Conclusion: This study shows a proof of concept for a selenium nanoparticle coatings as a potential anti-infective barrier for orthopedic medical devices in the setting of contamination with multi-resistant bacteria. It also represents one of the few (if only) in vivo assessment of selenium nanoparticle coatings on reducing antibiotic-resistant orthopedic implant infections.


Assuntos
Anti-Infecciosos/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Nanopartículas/química , Ortopedia , Próteses e Implantes , Selênio/farmacologia , Staphylococcus epidermidis/efeitos dos fármacos , Animais , Biofilmes/efeitos dos fármacos , Placas Ósseas , Parafusos Ósseos , Células Cultivadas , Contagem de Colônia Microbiana , Humanos , Masculino , Nanopartículas/ultraestrutura , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Ratos Sprague-Dawley , Titânio/farmacologia
10.
Int J Nanomedicine ; 14: 4667-4679, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31308652

RESUMO

Purpose: The pathogenicity in Candida spp was attributed by several virulence factors such as production of tissue damaging extracellular enzymes, germ tube formation, hyphal morphogenesis and establishment of drug resistant biofilm. The objective of present study was to investigate the effects of silver nanoparticles (AgNPs) on growth, cell morphology and key virulence attributes of Candida species. Methods: AgNPs were synthesized by the using seed extract of Syzygium cumini (Sc), and were characterized by UV-Vis spectrophotometer, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). ScAgNPs were used to evaluate their antifungal and antibacterial activity as well as their potent inhibitory effects on germ tube and biofilm formation and extracellular enzymes viz. phospholipases, proteinases, lipases and hemolysin secreted by Candida spp. Results: The MICs values of ScAgNPs were ranged from 0.125-0.250 mg/ml, whereas the MBCs and MFCs were 0.250 and 0.500 mg/ml, respectively. ScAgNPs significantly inhibit the production of phospholipases by 82.2, 75.7, 78.7, 62.5, and 65.8%; proteinases by 82.0, 72.0, 77.5, 67.0, and 83.7%; lipase by 69.4, 58.8, 60.0, 42.9, and 65.0%; and hemolysin by 62.8, 69.7, 67.2, 73.1, and 70.2% in C. albicans, C. tropicalis, C. dubliniensis, C. parapsilosis and C. krusei, respectively, at 500 µg/ml. ScAgNPs inhibit germ tube formation in C. albicans up to 97.1% at 0.25 mg/ml. LIVE/DEAD staining results showed that ScAgNPs almost completely inhibit biofilm formation in C. albicans. TEM analysis shows that ScAgNPs not only anchored onto the cell surface but also penetrated and accumulated in the cytoplasm that causes severe damage to the cell wall and cytoplasmic membrane. Conclusion: To summarize, the biosynthesized ScAgNPs strongly suppressed the multiplication, germ tube and biofilm formation and most importantly secretion of hydrolytic enzymes (viz. phospholipases, proteinases, lipases and hemolysin) by Candia spp. The present research work open several avenues of further study, such as to explore the molecular mechanism of inhibition of germ tubes and biofilm formation and suppression of production of various hydrolytic enzymes by Candida spp.


Assuntos
Antifúngicos/farmacologia , Candida/crescimento & desenvolvimento , Candida/patogenicidade , Nanopartículas Metálicas/química , Prata/farmacologia , Antifúngicos/química , Biofilmes/efeitos dos fármacos , Candida/citologia , Candida/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Proteínas Hemolisinas/metabolismo , Humanos , Hidrólise , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Syzygium/química , Virulência/efeitos dos fármacos , Fatores de Virulência
11.
Pol J Microbiol ; 68(2): 263-268, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31257792

RESUMO

Polyphosphate (polyP) is a food additive with antimicrobial activity. Here we evaluated the effects of sodium tripolyphosphate (polyP3, Na5P3O10) on four major oral bacterial species, in both single- and mixed-culture. PolyP3 inhibited three opportunistic pathogenic species: Fusobacterium nucleatum, Prevotella intermedia, and Porphyromonas gingivalis. On the contrary, a commensal bacterium Streptococcus gordonii was relatively less susceptible to polyP3 than the pathogens. When all bacterial species were co-cultured, polyP3 (≥ 0.09%) significantly reduced their total growth and biofilm formation, among which the three pathogenic bacteria were selectively inhibited. Collectively, polyP3 may be an alternative antibacterial agent to control oral pathogenic bacteria.Polyphosphate (polyP) is a food additive with antimicrobial activity. Here we evaluated the effects of sodium tripolyphosphate (polyP3, Na5P3O10) on four major oral bacterial species, in both single- and mixed-culture. PolyP3 inhibited three opportunistic pathogenic species: Fusobacterium nucleatum, Prevotella intermedia, and Porphyromonas gingivalis. On the contrary, a commensal bacterium Streptococcus gordonii was relatively less susceptible to polyP3 than the pathogens. When all bacterial species were co-cultured, polyP3 (≥ 0.09%) significantly reduced their total growth and biofilm formation, among which the three pathogenic bacteria were selectively inhibited. Collectively, polyP3 may be an alternative antibacterial agent to control oral pathogenic bacteria.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Placa Dentária/tratamento farmacológico , Fusobacterium nucleatum/efeitos dos fármacos , Periodontite/tratamento farmacológico , Polifosfatos/farmacologia , Porphyromonas gingivalis/efeitos dos fármacos , Prevotella intermedia/efeitos dos fármacos , Placa Dentária/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Boca/microbiologia , Periodontite/microbiologia , Periodontite/prevenção & controle , Streptococcus gordonii/efeitos dos fármacos
12.
J Photochem Photobiol B ; 197: 111541, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31272033

RESUMO

Here, we report the novel fabrication of ZnO nanoparticles using the Costus igneus leaf extract. Gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy to determine the bioactive components present in the plant extract. The synthesis of Ci-ZnO NPs (C. igneus- coated zinc oxide nanoparticles) was accomplished using a cost-effective and simple technique. Ci-ZnO NPs were specified using UV-visible spectroscopy, FTIR, XRD, and TEM. Ci-ZnO NPs was authenticated by UV-Vis and exhibited a peak at 365 nm. The XRD spectra proved the crystalline character of the Ci-ZnO NPs synthesized as hexagonal wurtzite. The FTIR spectrum illustrated the presence of possible functional groups present in Ci-ZnO NPs. The TEM micrograph showed evidence of the presence of a hexagonal organization with a size of 26.55 nm typical of Ci-ZnO NPs. The α-amylase and α-glucosidase inhibition assays demonstrated antidiabetic activity of Ci-ZnO NPs (74 % and 82 %, respectively), and the DPPH [2,2-diphenyl-1-picrylhydrazyl hydrate] assay demonstrated the antioxidant activity of the nanoparticles (75%) at a concentration of 100 µg/ml. The Ci-ZnO NPs exhibited promising antibacterial and biofilm inhibition activity against the pathogenic bacteria Streptococcus mutans, Lysinibacillus fusiformis, Proteus vulgaris, and Vibrio parahaemolyticus. Additionally, the Ci-ZnO NPs showed biocompatibility with mammalian RBCs with minimum hemolytic activity (0.633 % ±â€¯0.005 %) at a concentration of 200 µg/ml.


Assuntos
Antibacterianos/farmacologia , Antioxidantes/química , Biofilmes/efeitos dos fármacos , Nanopartículas Metálicas/química , Extratos Vegetais/química , Óxido de Zinco/química , Antibacterianos/síntese química , Antibacterianos/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Costus/química , Costus/metabolismo , Eritrócitos/citologia , Eritrócitos/efeitos dos fármacos , Eritrócitos/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/fisiologia , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/fisiologia , Química Verde , Hemólise/efeitos dos fármacos , Humanos , Insulina/química , Nanopartículas Metálicas/toxicidade , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Extratos Vegetais/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , alfa-Amilases/antagonistas & inibidores , alfa-Amilases/metabolismo
13.
Microbiol Res ; 226: 19-26, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31284940

RESUMO

Pseudomonas aeruginosa is one of the most common pathogens associated with nosocomial infections and a great concern to immunocompromised individuals especially in the cases of cystic fibrosis, AIDS and burn wounds. The pathogenicity of P. aeruginosa is largely directed by the quorum sensing (QS) system. Hence, QS may be considered an important therapeutic target to combat P. aeruginosa infections. The anti-quorum sensing and anti-biofilm efficacy of aromatic aldehyde, 5-hydroxymethylfurfural (5-HMF) against P. aeruginosa PAO1 were assessed. At the sub-inhibitory concentration, 5-HMF suppressed the production of QS-controlled virulence phenotypes and biofilm formation in P. aeruginosa. It was also able to significantly enhance the survival rate of C. elegans infected with P. aeruginosa. The in silico studies revealed that 5-HMF could serve as a competitive inhibitor for the auto-inducer molecules as it exhibited a strong affinity for the regulatory proteins of the QS-circuits i.e. LasR and RhlR. In addition, a significant down-regulation in the expression of QS-related genes was observed suggesting the ability of 5-HMF in mitigating the pathogenicity of P. aeruginosa.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Furaldeído/análogos & derivados , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/patogenicidade , Percepção de Quorum/efeitos dos fármacos , Animais , Proteínas de Bactérias , Caenorhabditis elegans , Simulação por Computador , Modelos Animais de Doenças , Furaldeído/farmacologia , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Percepção de Quorum/genética , Taxa de Sobrevida , Transativadores , Virulência/efeitos dos fármacos , Fatores de Virulência
14.
Expert Opin Investig Drugs ; 28(8): 687-694, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31269823

RESUMO

Introduction: Acute otitis media (AOM) is a common disease, particularly in infants and young children. Almost all children experience at least one episode of AOM in the first 3 years of age, and approximately 50% experience recurrent episodes in the same period of time. Areas covered: Some new potentially effective preventive or therapeutic approaches to AOM have been identified and are not discussed even in the most updated guidelines. The main aim of this narrative review is to detail what has been recently suggested. Expert opinion: Several new measures have been suggested to reduce systemic antibiotic abuse in AOM therapy and prophylaxis. For therapy, the administration of preparations containing antibiotics, bacteriophages or peptides can allow trans-tympanic passage of effective anti-otopathogen measures and the use of vaccines or immunoglobulins can disrupt biofilm. For AOM prophylaxis, new vaccines and the use of probiotics by nasal spray are in development. However, further advances in the selection of children for whom antimicrobial therapy and/or prophylaxis measures are truly needed could be derived from studies that analyse the association between genetic characteristics of the host and development of AOM with specific characteristics of aetiology or tendency to recur.


Assuntos
Desenvolvimento de Medicamentos/métodos , Drogas em Investigação/uso terapêutico , Otite Média/tratamento farmacológico , Doença Aguda , Animais , Antibacterianos/administração & dosagem , Biofilmes/efeitos dos fármacos , Pré-Escolar , Humanos , Lactente , Otite Média/microbiologia , Seleção de Pacientes , Recidiva
15.
Biochemistry (Mosc) ; 84(5): 509-519, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31234765

RESUMO

Microorganisms residing within a biofilm become more tolerant to antibiotics and other types of adverse impact, and biofilm formation by pathogenic bacteria is an important problem of current medicine. Polysaccharides that prevent biofilm formation are among the promising candidates to help tackle this problem. Earlier we demonstrated the ability of a potato polysaccharide galactan to inhibit biofilm formation by a Pseudomonas aeruginosa clinical isolate. Here we investigate the effect of potato galactan on P. aeruginosa biofilms in more detail. Microscopic analysis indicated that the galactan did not interfere with the adhesion of bacterial cells to the substrate but prevented the build-up of bacterial biomass. Moreover, the galactan not only inhibited biofilm formation, but partially destroyed pre-formed biofilms. Presumably, this activity of the galactan was due to the excessive aggregation of bacterial cells, which prohibited the formation and maintenance of proper biofilm architecture, or due to some other mechanisms of biofilm structure remodeling. This led to an unexpected effect, i.e., P. aeruginosa biofilms treated with an antibiotic and the galactan retained more viable bacterial cells compared to biofilms treated with the antibiotic alone. Galactan is the first polysaccharide demonstrated to exert such effect on bacterial biofilms.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Galactanos/farmacologia , Pseudomonas aeruginosa/fisiologia , Aderência Bacteriana/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Microscopia de Fluorescência , Pseudomonas aeruginosa/crescimento & desenvolvimento , Solanum tuberosum/metabolismo
16.
World J Microbiol Biotechnol ; 35(7): 96, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31218558

RESUMO

The biofilm-forming ability of Listeria spp. is a concern to the food industry and health sectors. The aim of this study was to verify the inhibitory activity of bacteriocins produced by enterococci (Enterococcus faecium 20, 22 and 24 and Enterococcus faecalis 27) on developing biofilm and preformed biofilm of Listeria species. Bacteriocins were partially purified from cell free supernatant (CFS). L. monocytogenes 2032, L. innocua 2050 and L. ivanovii 2056 were selected to analyse the inhibitory effect of bacteriocins on biofilm biomass (crystal violet staining) and biofilm viability (XTT-reduction). The biomass of the developing and preformed biofilms of Listeria species were reduced (p < 0.05) in the presence of all bacteriocins tested. Overall, the reduction in biofilm biomass of developing biofilms was up to 87.4% for bacteriocin produced by E. faecium 22 (CFS22) against L. ivanovii and up to 87.1% for CFS22 against L. monocytogenes. These findings are in accordance with those observed in confocal microscopy analysis. Most of the CFS-containing bacteriocin (CFS22, CFS24, CFS27) were effective at decreasing the viability of biofilm cells from all Listeria species. The highest reduction in viability was observed for L. monocytogenes preformed biofilm cells (up to 98.7%), evidenced by fluorescence microscopy of propidium iodide-labelled cells. Scanning electron microscopy showed that cells of biofilm-treated bacteriocins displayed degenerative changes that may be indicative of cellular leakages. This study suggests that bacteriocins produced by enterococci have prospective applications to prevent biofilm formation and/or to reduce cell viability of formed biofilms of distinct Listeria species.


Assuntos
Bacteriocinas/farmacologia , Biofilmes/efeitos dos fármacos , Enterococcus/metabolismo , Listeria monocytogenes/efeitos dos fármacos , Listeria/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Biomassa , Enterococcus faecalis/metabolismo , Enterococcus faecium/metabolismo , Indústria de Processamento de Alimentos , Viabilidade Microbiana/efeitos dos fármacos
17.
Int J Nanomedicine ; 14: 3861-3874, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31213806

RESUMO

Purpose: Infections associated with medical devices that are caused by biofilms remain a considerable challenge for health care systems owing to their multidrug resistance patterns. Biofilms of Pseudomonas aeruginosa and Staphylococcus aureus can result in life-threatening situations which are tough to eliminate by traditional methods. Antimicrobial photodynamic inactivation (aPDT) constitutes an alternative method of killing deadly pathogens and their biofilms using reactive oxygen species (ROS). This study investigated the efficacy of enhanced in vitro aPDT of P. aeruginosa and S. aureus using malachite green conjugated to carboxyl-functionalized multi-walled carbon nanotubes (MGCNT). Both the planktonic cells and biofilms of test bacteria were demonstrated to be susceptible to the MGCNT conjugate. These MGCNT conjugates may thus be employed as a facile strategy for designing antibacterial and anti-biofilm coatings to prevent the infections associated with medical devices. Methods: Conjugation of the cationic dye malachite green to carbon nanotube was studied by UV-visible spectroscopy, high-resolution transmission electron microscopy, and Fourier transform infrared spectrometry. P. aeruginosa and S. aureus photodestruction were studied using MGCNT conjugate irradiated for 3 mins with a red laser of wavelength 660 nm and radiant exposure of 58.49 J cm-2. Results: Upon MGCNT treatment, S. aureus and P. aeruginosa were reduced by 5.16 and 5.55 log10 , respectively. Compared to free dye, treatment with MGCNT afforded improved phototoxicity against test bacteria, concomitant with greater ROS production. The results revealed improved biofilm inhibition, exopolysaccharide inhibition, and reduced cell viability in test bacteria treated with MGCNT conjugate. P. aeruginosa and S. aureus biofilms were considerably reduced to 60.20±2.48% and 67.59±3.53%, respectively. Enhanced relative MGCNT phototoxicity in test bacteria was confirmed using confocal laser scanning microscopy. Conclusion: The findings indicated that MGCNT conjugate could be useful to eliminate the biofilms formed on medical devices by S. aureus and P. aeruginosa.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Nanotubos de Carbono/química , Fotoquimioterapia , Plâncton/citologia , Plâncton/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Corantes de Rosanilina/farmacologia , Staphylococcus aureus/fisiologia , Cinética , Peroxidação de Lipídeos/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Nanotubos de Carbono/ultraestrutura , Pseudomonas aeruginosa/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Staphylococcus aureus/efeitos dos fármacos
18.
Int J Nanomedicine ; 14: 3983-3993, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31213810

RESUMO

Background: Infections caused by drug resistant bacteria are a major health concern worldwide and have prompted scientists to carry out efforts to overcome this challenge. Researchers and pharmaceutical companies are trying to develop new kinds of antimicrobial agents by using different physical and chemical methods to overcome these problems. Materials and methods: In the present study, rifampicin conjugated silver (Rif-Ag) nanoparticles have successfully been synthesized using a chemical method. Characterization of the nanoparticles was performed using a UV-Vis spectrophotometer, FTIR, SEM, TEM, and AFM. Results: The AFM, SEM, and TEM results showed that the average particle size of Rif-Ag nanoparticles was about 15-18±4 nm. The FTIR spectra revealed the conjugation of -NH2 and -OH functional moiety with silver nanoparticles surface. Considering the penetrating power of rifampicin, the free drug is compared with synthesized nanoparticle for antimicrobial, biofilm inhibition, and eradication potential. Synthesized nanoparticles were found to be significantly active as compared to drug alone. Conclusion: This study has shown greater biofilm inhibitory and eradicating potential against methicillin resistant Staphylococcus aureus and Klebsiella pneumoniae, as evident by crystal violet, MTT staining, and microscopic analysis. So, it will be further modified, and studies for the mechanism of action are needed.


Assuntos
Biofilmes/efeitos dos fármacos , Klebsiella pneumoniae/fisiologia , Nanopartículas Metálicas/química , Staphylococcus aureus Resistente à Meticilina/fisiologia , Rifampina/farmacologia , Prata/farmacologia , Antibacterianos/farmacologia , Temperatura Alta , Humanos , Concentração de Íons de Hidrogênio , Klebsiella pneumoniae/efeitos dos fármacos , Nanopartículas Metálicas/ultraestrutura , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Rifampina/química , Sais , Prata/química , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Microbiol Immunol ; 63(7): 251-260, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31166029

RESUMO

Streptococcus mutans is a cariogenic bacterium that localizes in the oral cavity. Glycyrrhetinic acid (GRA) is a major component of licorice extract. GRA and several derivatives, including disodium succinoyl glycyrrhetinate (GR-SU), are known to have anti-inflammatory effects in humans. In this study, the antimicrobial effect of GRA and its derivatives against the S. mutans UA159 strain were investigated. Minimum inhibitory concentrations (MICs) of GRA and GR-SU showed antibacterial activity against the S. mutans strain, whereas other tested derivatives did not. Because GR-SU is more soluble than GRA, GR-SU was used for further experiments. The antibacterial activity of GR-SU against 100 S. mutans strains was evaluated and it was found that all strains are susceptible to GR-SU, with MIC values below 256 µg/mL. A cell viability assay showed that GR-SU has a bacteriostatic effect on S. mutans cells. As to growth kinetics, sub-MICs of GR-SU inhibited growth. The effect of GR-SU on S. mutans virulence was then investigated. GR-SU at sub-MICs suppresses biofilm formation. Additionally, GR-SU greatly suppresses the pH drop caused by the addition of glucose and glucose-induced expression of the genes responsible for acid production (ldh and pykF) and tolerance (aguD and atpD). Additionally, expression of enolase, which is responsible for the carbohydrate phosphotransferase system, was not increased in the presence of GR-SU, indicating that GR-SU suppresses incorporation of sugars into S. mutans. In conclusion, GR-SU has antibacterial activity against S. mutans and also decreases S. mutans virulence.


Assuntos
Antibacterianos/farmacologia , Ácido Glicirretínico/farmacologia , Glycyrrhiza/química , Extratos Vegetais/farmacologia , Streptococcus mutans/efeitos dos fármacos , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos/genética , Glucose/metabolismo , Ácido Glicirretínico/química , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Extratos Vegetais/química , Streptococcus mutans/genética , Streptococcus mutans/crescimento & desenvolvimento , Virulência , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
20.
Phytochemistry ; 164: 192-205, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31174083

RESUMO

The chemical composition of five marine microalgae (Dunaliella sp., Dunaliella salina, Chaetoceros calcitrans, Chaetoceros gracilis and Tisochrysis lutea) was investigated through nuclear magnetic resonance (NMR) spectroscopic study of the soluble material obtained by sequential extraction with hexane, ethyl acetate (AcOEt) and methanol of biomass from stationary phase cultures. Hexane extracted the major lipids present in the microalgae during the stationary phase of growth, which correspond to storage lipids. Triacylglycerols (TGs) were the only storage lipids produced by Dunaliella and Chaetoceros. In contrast, T. lutea predominantly stored polyunsaturated long-chain alkenones, with sterols also detected as minor components of the hexane extract. The molecular structure of brassicasterol was determined in T. lutea and the presence of squalene in this sample was also unequivocally detected. Monogalactosyldiacylglycerols (MGDGs) and pigments were concentrated in the AcOEt extracts. C. calcitrans and D. salina constituted an exception due to the high amount of TGs and glycerol produced, respectively, by these two strains. Chlorophylls a and b and ß-carotene were the major pigments synthesized by Dunaliella and chlorophyll a and fucoxanthin were the only pigments detected in Chaetoceros and T. lutea. Information concerning the acyl chains present in TGs and MGDGs as well as the positional distribution of acyl chains on the glycerol moiety was obtained by NMR analysis of hexane and AcOEt extracts, with results consistent with those expected for the genera studied. Fatty acid composition of TGs in the two Dunaliella strains was different, with polyunsaturated acyl chains almost absent in the storage lipids produced by D. salina. Except in C. calcitrans, the polar nature of soluble compounds was inferred through the relative extraction yield using methanol as the extraction solvent. Glycerol was the major component of this fraction for the Dunaliella strains. In T. lutea 1,4/2,5-cyclohexanetetrol (CHT) and dimethylsulfoniopropionate (DMSP) preponderated. CHT was also the major polyol present in the Chaetoceros strains in which DMSP was not detected, but prominent signals of 2,3-dihydroxypropane-1-sulfonate (DHSP) were observed in the 1H NMR spectra of methanolic extracts. The presence of DHSP confirms the production of this metabolite by diatoms. In addition, several other minor compounds (digalactosyldiacyglycerols (DGDGs), sulphoquinovosyldiacylglycerols (SQDGs), amino acids, carbohydrates, scyllo-inositol, mannitol, lactic acid and homarine) were also identified in the methanolic extracts. The antibacterial and antibiofilm activities of the extracts were tested. The AcOEt extract from C. gracilis showed a moderate antibiofilm activity.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Biofilmes/efeitos dos fármacos , Microalgas/química , Ressonância Magnética Nuclear Biomolecular , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antifúngicos/química , Antifúngicos/isolamento & purificação , Fungos/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Microalgas/metabolismo , Testes de Sensibilidade Microbiana , Conformação Molecular
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