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1.
J Med Microbiol ; 68(10): 1438-1444, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31385784

RESUMO

Introduction. Combretum leprosum (Combretaceae) is commonly found in the Northeast Region of Brazil and is known for several bioactivities, including antimicrobial ones. Because of increasing bacterial antibiotic resistance, natural products from several plants have been studied as putative adjuvants to antibiotic activity, including products from C. leprosum. Aims. This study was carried out to investigate the structural properties, bactericidal activity and antibiotic modifying action of the lupane triterpene 3ß,6ß,16ß-trihydroxylup-20(29)-ene (CLF1) isolated from C. leprosum Mart. leaves.Methods. The CLF1 was evaluated by the Fourier transform infrared spectroscopy method and the antibacterial activity of this compound was assayed alone and in association with antibiotics by microdilution assay.Results. Spectroscopic studies confirmed the molecular structure of the CLF1 and permitted assignment of the main infrared bands of this natural product. Microbiological assays showed that this lupane triterpene possesses antibacterial action with clinical relevance against Staphylococcus aureus. The CLF1 triterpene increased antimicrobial activity against the multidrug-resistant Escherichia coli 06 strain when associated with the antibiotics gentamicin and amikacin. Synergistic effects were observed against the S. aureus 10 strain in the presence of the CLF1 triterpene with the antibiotic gentamicin.Conclusion. In conclusion, the CLF1 compound may be useful in the development of antibacterial drugs against the aforementioned bacteria.


Assuntos
Antibacterianos/farmacologia , Combretum/química , Extratos Vegetais/farmacologia , Triterpenos/farmacologia , Antibacterianos/química , Antibacterianos/isolamento & purificação , Brasil , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Gentamicinas/farmacologia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Triterpenos/química , Triterpenos/isolamento & purificação
2.
APMIS ; 127(11): 717-726, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31407405

RESUMO

This study aims to determine the prevalence of Staphylococcus aureus colonizing patients and ICU environment of a teaching hospital, the virulence and antimicrobial susceptibility profile of the isolates, and to evaluate the genetic relationship among them. A total of 536 swabs (134 of patients and 402 of ICU environment) were collected and analyzed to detect S. aureus. The antimicrobial susceptibility of the isolates was determined by disk diffusion test, and the detection of the mecA and virulence factors genes was performed by PCR, in addition to SCCmec typing. The genetic similarity of the isolates was determined by PFGE. Staphylococcus aureus was isolated in 12.7% of the swabs. The prevalence of colonization was 13.4% in patients and 12.4% in the environmental samples. The multidrug resistance was determined in 82.4% of the isolates. The prevalence of methicillin-resistant S. aureus was 20.6%, with 50.0% classified as SCCmec IV. The intermediate resistance to vancomycin was detected in 5.9% and 4.4% of the isolates obtained from patients and environment, respectively. Identical isolates obtained from different patients and sources were grouped into several clusters. The results showed dissemination of multidrug-resistant strains between patients and fomites and the persistence of MRSA and VISA isolates in the ICU environment.


Assuntos
Antibacterianos/farmacologia , Resistência a Meticilina , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidade , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana , Feminino , Variação Genética , Humanos , Unidades de Terapia Intensiva/estatística & dados numéricos , Masculino , Meticilina/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Filogenia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Vancomicina/farmacologia , Virulência , Fatores de Virulência/genética
3.
J Agric Food Chem ; 67(35): 9749-9756, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31415718

RESUMO

Bovine lactoferrin N-lobe plays an important key in the nonimmunological defense system. In this work, the most suitable promoter Pveg was selected and the fragment coding bovine lactoferrin N-lobe was optimized according to codon bias of Bacillus. The recombinant plasmid pMA0911-Pveg-mBLF-N was introduced into Baicillus subtilis 168 to create B. subtilis/pMA0911-Pveg-mBLF-N. The bovine lactoferrin N-lobe was highly expressed at 28 °C for 15 h. Its purified protein was obtained with 16.5 mg/L and a purity of 93.6% using ammonium sulfate precipitation, Ni-NTA, and molecular exclusion. About 200 ng/mL purified bovine lactoferrin N-lobe completely inhibited cell-growth of Escherichia coli JM109 (DE3), 70.3% of Pseudomonas aeruginosa CGMCC 1.6740, and 41.5% of Staphylococcus aureus CGMCC 1.282. To our knowledge, this is the first report about active expression, purification, and characterization of bovine lactoferrin N-lobe in safe bacterium B. subtilis, which opens an available application way in the biomedical and food industries.


Assuntos
Antibacterianos/farmacologia , Bacillus subtilis/genética , Códon/genética , Lactoferrina/genética , Regiões Promotoras Genéticas , Animais , Antibacterianos/metabolismo , Bacillus subtilis/metabolismo , Clonagem Molecular , Códon/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Expressão Gênica , Engenharia Genética , Lactoferrina/metabolismo , Lactoferrina/farmacologia , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
4.
J Agric Food Chem ; 67(29): 8191-8196, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31282662

RESUMO

Conversion of free fatty acids into monoacylglycerol gives rise to new structural properties, particularly amphipathic property. Therefore, monoacylglycerols are widely used in pharmaceutical and food industries and are also reported to facilitate better absorption into the human body. A functional fatty acid when transformed into a monoacylglycerol will possibly conserve both the original functionality and amphipathic property. The compound 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) was generated from oleic acid by Pseudomonas aeruginosa PR3 and was known to contain antimicrobial activities against a broad range of food-borne and plant pathogenic bacteria. Here, we attempted to convert DOD into its monoacylglycerol form using lipase for producing an amphipathic antibacterial agent. Consequently, the monoacylglycerol of DOD (DOD-MAG) was successfully produced by coincubating DOD, glycerol, and lipase at 30 °C. The maximum conversion yield reached 70% after 12 h of incubation. Antibacterial activity of DOD-MAG was enhanced by 8 times from the original activity of DOD against food-borne bacteria.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Monoglicerídeos/química , Ácidos Oleicos/química , Ácidos Oleicos/farmacologia , Pseudomonas aeruginosa/química , Antibacterianos/metabolismo , Microbiologia de Alimentos , Ácidos Oleicos/metabolismo , Pseudomonas aeruginosa/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
5.
J Sci Food Agric ; 99(13): 6049-6059, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31342530

RESUMO

BACKGROUND: The scarcity of irrigation water is severely affecting global crop production. In this context, biostimulants are increasingly used as alternatives means against abiotic stress conditions. In this study, phenolic compounds composition and bioactive properties of common bean (Phaseolus vulgaris L.) plants grown under water stress conditions and biostimulants application were investigated. RESULTS: Sixteen individual phenolic compounds were detected in both pods and seeds with a notable difference in their compositional profile. A significant effect on phenolic compounds content and composition was also observed for the biostimulants tested. Regarding the antibacterial activity, pods of the second harvest and seed extracts showed significant efficacy against Bacillus cereus, especially in water-stressed plants, where all biostimulant treatments were more effective than positive controls. Moreover, all biostimulant treatments for seed extracts of water-stressed plants were more effective against Staphylococcus aureus compared with ampicillin, whereas streptomycin showed the best results. Extracts from pods of the second harvest from normally irrigated plants showed the best results against the fungi tested, except for Penicillium verrucosum var. cyclopium. Finally, no significant cytotoxic effects were detected. CONCLUSION: In conclusion, the biostimulants tested increased total phenolic compounds content compared with control treatment, especially in pods of the first harvest and seeds of water-stressed plants. Moreover, bioactive properties showed a varied response in regard to irrigation and biostimulant treatment. Therefore, biostimulants can be considered as a useful means towards increasing phenolic compounds content, and they may also affect the antimicrobial properties of pods and seeds extracts. © 2019 Society of Chemical Industry.


Assuntos
Desidratação , Phaseolus/química , Phaseolus/fisiologia , Fenóis/farmacologia , Extratos Vegetais/farmacologia , Água/metabolismo , Bacillus cereus/efeitos dos fármacos , Bacillus cereus/crescimento & desenvolvimento , Phaseolus/crescimento & desenvolvimento , Phaseolus/microbiologia , Fenóis/química , Fenóis/metabolismo , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Sementes/química , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Sementes/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Estresse Fisiológico , Água/análise
6.
Int J Food Microbiol ; 305: 108254, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31238194

RESUMO

Pathogens in viable but nonculturable (VBNC) state can escape traditional detection methods based on culturable ability, thus bringing risks to food safety and human health. Considering Staphylococcus aureus as a kind of primary foodborne pathogen, this study attempted to investigate whether citric acid, a food additive commonly used, can force S. aureus into VBNC state along with low temperature. Treated with citric acid solution (pH 4.0) at 4 °C, S. aureus was confirmed to enter into VBNC state after induction for 18 days. Meanwhile, resuscitation was achieved in culture medium rather than in nutrition-free saline solution. In VBNC cells, ATP concentration still maintained at a high level, as about two-thirds of exponential-phase cells. For survival, intracellular structure of VBNC cells changed remarkably, including irregular cell shape, denser cytoplasm, space between cell wall and cell membrane, and decreased density of nuclear region. Notably, resistance of VBNC cells to simulated gastric fluid improved when compared with exponential-phase cells. What are noted above suggests that VBNC state adopted by S. aureus might be a survival strategy to the adverse environment (acidity stress and low temperature). In conclusion, our study sounds an alarm for the safety of citric acid-containing foods.


Assuntos
Ácido Cítrico/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Temperatura Baixa , Meios de Cultura/química , Meios de Cultura/metabolismo , Staphylococcus aureus/crescimento & desenvolvimento
7.
Chemotherapy ; 64(1): 22-27, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31167192

RESUMO

BACKGROUND: Pantothenate, the fundamental precursor to coenzyme A, is required for optimal growth and virulence of microbial pathogens. It is synthesized by the enzyme-catalyzed condensation of ß-alanine and pantoate, which has shown susceptibility to inhibition by analogs of its molecular constituents. Accordingly, analogs of ß-alanine are gaining inquiry as potential antimicrobial chemotherapeutics. METHODS: We synthesized and evaluated 35 derivatives of ß-alanine, substituted at the α, ß, amine, and carboxyl sites, derived from in silico, dynamic molecular modeling to be potential competitive inhibitors of pantothenate synthetase. Employing the Clinical Laboratory Standards M7-A6 broth microdilution method, we tested these for inhibition of growth in Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. RESULTS: All compounds proved entirely ineffective in all species tested, with no inhibition of growth being observed up to 200 µM/mL. CONCLUSIONS: Upon revision of the literature, we conclude that high enzyme selectivity or external salvage mechanisms may render this strategy futile against most bacteria.


Assuntos
Proteínas de Bactérias/metabolismo , Peptídeo Sintases/metabolismo , beta-Alanina/metabolismo , Proteínas de Bactérias/antagonistas & inibidores , Sítios de Ligação , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Escherichia coli/crescimento & desenvolvimento , Simulação de Acoplamento Molecular , Peptídeo Sintases/antagonistas & inibidores , Estrutura Terciária de Proteína , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , beta-Alanina/análogos & derivados , beta-Alanina/farmacologia
8.
Environ Pollut ; 249: 1106-1114, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31146316

RESUMO

Graphene oxide (GO) has been demonstrated to be key component for diverse applications. However, their potential environmental reactivity, fate and risk have not been fully evaluated to date. In this study, we investigated the photochemical reactivity of four types of GO with different oxidation degrees in aqueous environment, and their related toxicity to two bacterial models Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was further compared. After UV-irradiation, a large amount of oxygen functional groups on GO were reduced and the electronic conjugations within GO were restored as indicated by UV-visible absorption spectra, X-ray photoelectron spectroscopy and Raman spectroscopy analysis. Moreover, the higher the oxidation degree of the pristine GO was, the more obvious of the photo-transformation changes were. In order to further reveal the photochemical reactivity mechanisms, the reactive oxygen species (ROS) generation of GO was monitored. The quantity of ROS including singlet oxygen (1O2), superoxide anions (O2·-), and hydroxyl radicals (·OH) increased with increasing oxidation degree of GO, which was in accordance with the previous characterization results. Scanning electron microscopy and cell growth analyses of E. coli and S. aureus showed that the photochemical transformation enhanced the toxicity of GO, which might be due to an increase in functional group density. The higher conductivity of the reduced graphene oxide (RGO) was responsible for its stronger toxicity than GO through membrane damage and oxidative stress to bacteria. This study revealed that the oxidation degrees play important roles in photochemical transformation and the resulting toxicity of GO, which is helpful for understanding the environmental behaviors and risks of GO in aquatic environments.


Assuntos
Escherichia coli/efeitos dos fármacos , Grafite/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Escherichia coli/crescimento & desenvolvimento , Grafite/efeitos da radiação , Oxirredução , Processos Fotoquímicos , Espécies Reativas de Oxigênio/metabolismo , Staphylococcus aureus/crescimento & desenvolvimento , Poluentes Químicos da Água/efeitos da radiação
9.
J Sci Food Agric ; 99(13): 6032-6041, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31226218

RESUMO

BACKGROUND: In order to inhibit microorganisms and improve storage quality of fresh-cut cucumber, fresh-cut cucumber was treated by carbon dots (CDs) from kelp/chitosan (CH) coating solution with CD concentrations of 0%, 1.5%, 3% and 4.5% and then packaged as well as stored at 4 °C for 15 days. The effect of CDs/CH coating on microorganisms and the quality of modified-atmosphere-packaged fresh-cut cucumber during storage were investigated. RESULTS: The CDs was monodispersed spherical morphology with size distribution of 0.54-0.83 nm. Interaction of CDs and CH had the generation of strong hydrogen bond. Inhibition zone diameters of CDs/CH coating against Staphylococcus aureus and Escherichia coli were enhanced with the increase of CD concentrations. Moreover, CDs/CH coating inhibited the growth of total number of colonies, mold, and yeast in modified-atmosphere-packaged fresh-cut cucumber during storage. A coating of 4.5% CDs/CH effectively reduced the losses of weight, firmness, and total soluble solids, the degradation of ascorbic acid content and flavor, and inhibited peroxidases activity, as well as decreased water mobility in fresh-cut cucumber during storage. CONCLUSION: The results indicated that a CDs/CH coating was helpful for inhibiting microorganisms and improving storage quality, and could be an effective method to prolong shelf life of fresh-cut cucumber. © 2019 Society of Chemical Industry.


Assuntos
Carbono/farmacologia , Quitosana/farmacologia , Cucumis sativus/efeitos dos fármacos , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Carbono/química , Quitosana/química , Cucumis sativus/microbiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Embalagem de Alimentos , Conservação de Alimentos/instrumentação , Conservantes de Alimentos/química , Armazenamento de Alimentos , Fungos/efeitos dos fármacos , Fungos/crescimento & desenvolvimento , Humanos , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Paladar
10.
Int J Nanomedicine ; 14: 2773-2780, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31118610

RESUMO

Purpose: An important application of silver nanoparticles (Ag NPs) is their use as an antimicrobial and wound dressing material. The aim of this study is to investigate the morphological dependence on the antimicrobial activity and cellular response of Ag NPs. Materials and methods: Ag NPs of various shapes were synthesized in an aqueous solution using a simple method. The morphology of the synthesized Ag NPs was observed via TEM imaging. The antimicrobial activity of the Ag NPs with different morphologies was evaluated against various microorganisms (Escherichia coli [E. coli], Staphylococcus aureus [S. aureus], Pseudomonas aeruginosa [P. aeruginosa]). The antimicrobial activity of the Ag NPs was also examined according to the concentration in terms of the growth rate of E. coli. Results: The TEM images indicated that the Ag NPs with different morphologies (sphere, disk and triangular plate) had been successfully synthesized. The antimicrobial activity obtained from the inhibition zone was in the order of spherical Ag NPs > disk Ag NPs > triangular plate Ag NPs. In contrast, fibroblast cells grew well in all types of Ag NPs when the cell viability was evaluated via an MTT assay. An inductively coupled plasma mass assay showed that the difference in the antimicrobial activities of the Ag NPs was closely associated with the difference in the release rate of the Ag ions due to the difference in the surface area of the Ag NPs. Conclusion: The morphological dependence of the antimicrobial activity of the Ag NPs can be explained by the difference in the Ag ion release depending on the shape. Therefore, it will be possible to control the antimicrobial activity by controlling the shape and size of the Ag NPs.


Assuntos
Anti-Infecciosos/farmacologia , Nanopartículas Metálicas/química , Prata/química , Prata/farmacologia , Animais , Antibacterianos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Íons , Nanopartículas Metálicas/ultraestrutura , Camundongos , Testes de Sensibilidade Microbiana , Células NIH 3T3 , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
11.
MBio ; 10(2)2019 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-31040245

RESUMO

Staphylococcus aureus has the ability to cause infections in multiple organ systems, suggesting an ability to rapidly adapt to changing carbon and nitrogen sources. Although there is little information about the nutrients available at specific sites of infection, a mature skin abscess has been characterized as glucose depleted, indicating that peptides and free amino acids are an important source of nutrients for the bacteria. Our studies have found that mutations in enzymes necessary for growth on amino acids, including pyruvate carboxykinase (ΔpckA) and glutamate dehydrogenase (ΔgudB), reduced the ability of the bacteria to proliferate within a skin abscess, suggesting that peptides and free amino acids are important for S. aureus growth. Furthermore, we found that collagen, an abundant host protein that is present throughout a skin abscess, serves as a reservoir of peptides. To liberate peptides from the collagen, we identified that the host protease, MMP-9, as well as the staphylococcal proteases aureolysin and staphopain B function to cleave collagen into peptide fragments that can support S. aureus growth under nutrient-limited conditions. Moreover, the oligopeptide transporter Opp3 is the primary staphylococcal transporter responsible for peptide acquisition. Lastly, we observed that the presence of peptides (3-mer to 7-mer) induces the expression of aureolysin, suggesting that S. aureus has the ability to detect peptides in the environment.IMPORTANCE Staphylococcus aureus has the ability to cause infections in a variety of niches, suggesting a robust metabolic capacity facilitating proliferation under various nutrient conditions. The mature skin abscess is glucose depleted, indicating that peptides and free amino acids are important sources of nutrients for S. aureus Our studies have found that mutations in both pyruvate carboxykinase and glutamate dehydrogenase, enzymes that function in essential gluconeogenesis reactions when amino acids serve as the major carbon source, reduce bacterial burden in a murine skin abscess model. Moreover, peptides liberated from collagen by host protease MMP-9 as well as the staphylococcal protease aureolysin support S. aureus growth in an Opp3-dependent manner under nutrient-limited conditions. Additionally, the presence of peptides induces aureolysin expression. Overall, these studies define one pathway by which S. aureus senses a nutrient-limiting environment and induces factors that function to acquire and utilize carbon from host-derived sources.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Peptídeo Hidrolases/metabolismo , Proteínas/metabolismo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/metabolismo , Animais , Análise Mutacional de DNA , Elementos de DNA Transponíveis , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL
12.
Microbiol Immunol ; 63(3-4): 147-150, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31037765

RESUMO

It is not known how Leptospira react to wound or a cut infected with microbes, such as pathogenic Staphylococcus, or their common habitat on oral or nasal mucosal membranes. In the present study, Staphylococcus aureus MTCC-737 showed strong co-aggregation with leptospiral strains (>75%, visual score of + 4) in vitro. All tested strains of Leptospira were able to form biofilm with S. aureus. Scanning electron microscopy analysis revealed intertwined networks of attached cells of L. interrogans and S. aureus, thus providing evidence of a matrix-like structure. This phenomenon may have implications in Leptospira infection, which occurs via cuts and wounds of the skin.


Assuntos
Biofilmes/crescimento & desenvolvimento , Leptospira interrogans/crescimento & desenvolvimento , Interações Microbianas/fisiologia , Dermatopatias Bacterianas/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Coinfecção/microbiologia , Coinfecção/patologia , Leptospirose/microbiologia , Leptospirose/patologia , Microscopia Eletrônica de Varredura , Dermatopatias Bacterianas/patologia , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/patologia
13.
Curr Microbiol ; 76(7): 842-847, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31053906

RESUMO

Diabetic foot ulcer infections are frequently polymicrobial in nature and exhibit increased morbidity and mortality, as well as, treatment failures. Interactions between Acinetobacter baumannii and Staphylococcus aureus were studied, which showed strain-dependent changes in growth and antibiotic susceptibility. This study examined the interactions between two clinical strains of A. baumannii (1929) and S. aureus (1928) that were recovered from skin and soft tissues of a diabetic patient. When S. aureus 1928 and A. baumannii 1929 were co-cultured together, there was no significant decrease in growth in either clinical strains, indicating that both strains can co-exist in the same site of infection. Additionally, neither strains experienced statistically significant changes in susceptibility. These findings highlight that these two pathogens can be found in the same niche of infection, which may lead to more aggressive outcome of the infection.


Assuntos
Infecções por Acinetobacter/microbiologia , Coinfecção/microbiologia , Pé Diabético/microbiologia , Interações Microbianas , Infecções dos Tecidos Moles/microbiologia , Infecções Estafilocócicas/microbiologia , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/crescimento & desenvolvimento , Acinetobacter baumannii/isolamento & purificação , Acinetobacter baumannii/fisiologia , Antibacterianos/farmacologia , Complicações do Diabetes/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/fisiologia
14.
Biosens Bioelectron ; 135: 200-207, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-31026774

RESUMO

This paper describes an integrated microfluidic SlipChip device for rapid antimicrobial susceptibility testing (AST) of bloodstream pathogens in positive blood cultures. Unlike conventional AST methods, which rely on an overnight subculture of positive blood cultures to obtain isolated colonies, this device enables direct extraction and enrichment of the bacteria from positive blood cultures by dielectrophoresis. SlipChip technology enables parallel inoculation of the extracted bacteria into nanoliter-scale broth droplets to perform multiplexed ASTs simultaneously. The nanoliter confinement in the droplets increases the effective inoculation amount of the bacteria, shortens the diffusion distance of nutrient elements and gases, and allows faster growth and proliferation rates. Entropy-based image analysis used for the characterization of bacterial susceptibility patterns eliminates the requirement for single-cell morphological analysis and fluorescence labeling. As a proof-of-concept, the susceptibility patterns of Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538p, and a positive blood culture containing Escherichia coli against several broad-spectrum antibiotics were determined by the SlipChip device. The on-chip AST results were well matched with those respectively reported by the broth microdilution method and a BD Phoenix Automated Microbiology System. Reliable AST results can be reported to clinicians within 3-8 h using this simple device after positive blood culture, allowing earlier proper administration of antimicrobial therapy.


Assuntos
Antibacterianos/farmacologia , Dispositivos Lab-On-A-Chip , Testes de Sensibilidade Microbiana/instrumentação , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Infecções por Escherichia coli/sangue , Infecções por Escherichia coli/tratamento farmacológico , Humanos , Infecções Estafilocócicas/sangue , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
15.
Infect Immun ; 87(7)2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31010815

RESUMO

Using an affinity column retention assay, we showed that the purified Tet38 membrane transporter of Staphylococcus aureus bound specifically to host cell CD36 and to the complex CD36-Toll-like receptor 2 (TLR-2), but not to TLR-2 alone or TLR-2 and S. aureus lipoteichoic acid (LTA). We tested the effect of LTA on the internalization of S. aureus tet38 mutant QT7 versus RN6390 by A549 epithelial cells. Addition of anti-LTA antibody to the bacteria prior to adding to A549 cells reduced internalization of QT7 2-fold compared to that with nonspecific antibody treatment. QT7 internalized 4- to 6-fold less than RN6390 with or without anti-LTA antibody. These data suggested that Tet38 and LTA were independently involved in the invasion process. The wall teichoic acid (WTA) inhibitor tunicamycin had an 8-fold decrease in activity with overexpression of tet38 and a 2-fold increase in activity in QT7 (tet38). Reserpine (an inhibitor of efflux pumps) reduced the effect of tet38 overexpression on tunicamycin resistance 4-fold. In addition, tet38 affected growth in the presence of LTA inhibitor Congo red, with overexpression increasing growth and deletion of tet38 reducing growth. In conclusion, Tet38 contributes to S. aureus invasion of A549 via direct binding to CD36 of the complex CD36-TLR-2, and LTA independently bound to TLR-2. The reduction of tunicamycin resistance in the presence of reserpine and the survival ability of the tet38 overexpressor in the presence of Congo red suggest that Tet38 can also protect the synthesis of LTA and WTA in S. aureus against their inhibitors, possibly functioning as an efflux pump.


Assuntos
Proteínas de Bactérias/metabolismo , Antígenos CD36/metabolismo , Vermelho Congo/farmacologia , Infecções Estafilocócicas/metabolismo , Staphylococcus aureus/metabolismo , Ácidos Teicoicos/biossíntese , Receptor 2 Toll-Like/metabolismo , Tunicamicina/farmacologia , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Antígenos CD36/genética , Humanos , Lipopolissacarídeos/metabolismo , Ligação Proteica , Infecções Estafilocócicas/genética , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento , Ácidos Teicoicos/metabolismo , Receptor 2 Toll-Like/genética
16.
Nat Microbiol ; 4(7): 1114-1119, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30936487

RESUMO

Social interactions play an increasingly recognized key role in bacterial physiology1. One of the best studied is quorum sensing (QS), a mechanism by which bacteria sense and respond to the status of cell density2. While QS is generally deemed crucial for bacterial survival, QS-dysfunctional mutants frequently arise in in vitro culture. This has been explained by the fitness cost an individual mutant, a 'quorum cheater', saves at the expense of the community3. QS mutants are also often isolated from biofilm-associated infections, including cystic fibrosis lung infection4, as well as medical device infection and associated bacteraemia5-7. However, despite the frequently proposed use of QS blockers to control virulence8, the mechanisms underlying QS dysfunctionality during infection have remained poorly understood. Here, we show that in the major human pathogen Staphylococcus aureus, quorum cheaters arise exclusively in biofilm infection, while in non-biofilm-associated infection there is a high selective pressure to maintain QS control. We demonstrate that this infection-type dependence is due to QS-dysfunctional bacteria having a significant survival advantage in biofilm infection because they form dense and enlarged biofilms that provide resistance to phagocyte attacks. Our results link the benefit of QS-dysfunctional mutants in vivo to biofilm-mediated immune evasion, thus to mechanisms that are specific to the in vivo setting. Our findings explain why QS mutants are frequently isolated from biofilm-associated infections and provide guidance for the therapeutic application of QS blockers.


Assuntos
Biofilmes/crescimento & desenvolvimento , Infecções Relacionadas a Cateter/microbiologia , Evasão da Resposta Imune , Leucócitos/imunologia , Percepção de Quorum/fisiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/imunologia , Animais , Proteínas de Bactérias/genética , Infecções Relacionadas a Cateter/imunologia , Células Cultivadas , Modelos Animais de Doenças , Feminino , Humanos , Camundongos Endogâmicos C57BL , Viabilidade Microbiana , Mutação , Percepção de Quorum/genética , Infecções Estafilocócicas/imunologia , Infecções Cutâneas Estafilocócicas/imunologia , Infecções Cutâneas Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/fisiologia , Transativadores/genética
17.
Microb Pathog ; 132: 117-123, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31009656

RESUMO

In this study, we isolated four Weissella confusa strains from the healthy horse feces to test their potential as equine probiotics. The identification and characteristics of these isolates were determined as per standard methods. Resistance and susceptibility of the isolated strains were tested to low pHs, different heat treatments, commonly used antibiotics and against the pathogenic strains of Salmonella, Pasteurella, Staphylococcus aureus, and Escherichia coli. After 3 h cultural in different pH medium, the 4 strains still had a certain amount of survival above pH 3.0. WH2 and WH4 were still viable at pH2.5. All the isolated strains showed proper growth at 60 °C while no strain survived at 80 °C. The inhibition of α-amylase, the scavenging ability of free radical DPPH· and hydroxyl free radical HO·were also investigated. The results showed that WH4 had highest inhibition rate of α-amylase activity and DPPH· free radical scavenging rate, and the inhibition rate of α-amylase activity was 24.09% and the DPPH· free radical scavenging rate was 35.78%. The inhibition rate ofα-amylase activity and DPPH· scavenging rate of free radicals in the other three strains were about 10%. The clearance rate of hydroxyl radical (HO·) in 4 strains was between 12% and 15%. The antibiotic susceptibilities varied for these four Weisella strains but all of them showed resistance against the frequently used equine antibiotics. All the four strains successfully suppressed the growth of standard strains in in vitro bacteriostasis experiment, which included Salmonella enteritidis (NTNC13349), Escherichia coli (C83902) and Staphylococcus aureus (BNCC186335). they also successfully suppressed the growth of state key laboratory isolating pathogens, which are Pasterurella multocida and Salmonella. Our findings suggest that the isolated strains of Weissella confusa can act as potential equine probiotics and should be explored further.


Assuntos
Fezes/microbiologia , Probióticos/isolamento & purificação , Weissella/isolamento & purificação , Weissella/fisiologia , Animais , Antibacterianos/farmacologia , Compostos de Bifenilo , Escherichia coli/crescimento & desenvolvimento , Cavalos , Concentração de Íons de Hidrogênio , Radical Hidroxila , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Pasteurella/crescimento & desenvolvimento , Filogenia , Picratos , Salmonella/crescimento & desenvolvimento , Análise de Sequência de DNA , Staphylococcus aureus/crescimento & desenvolvimento , Estresse Fisiológico , Weissella/efeitos dos fármacos , Weissella/crescimento & desenvolvimento , alfa-Amilases/metabolismo
18.
Mater Sci Eng C Mater Biol Appl ; 101: 53-63, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31029348

RESUMO

Endotracheal tubes (ETTs) are a common source of bacterial colonization, leading to ventilator-associated pneumonia (VAP). This research developed a biofilm-resistant ETT, following the principles of green chemistry. Using an aqueous layer-by-layer (LbL) technique, a thick polyelectrolyte multilayered film was deposited on a ventilation tube. The polyelectrolyte multilayered film accommodated silver nanoparticles (AgNPs) formed in situ by reducing Ag+ ions with Eucalyptus citriodora leaf extract. The multilayered film coating conformed to the curved surfaces of the ETT. Film thickness and silver content increased exponentially with the number of polyelectrolyte bilayer pairs, and a sufficiently high AgNPs content of 10-30%w/w was obtained at 75 to 125 bilayer films. Adhesion of the Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was prevented by 99.9 and 99.99%, respectively, without cytotoxic effects against human lung epithelial cells (p < 0.05).


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Química Verde/métodos , Intubação Intratraqueal , Nanopartículas Metálicas/química , Polieletrólitos/farmacologia , Prata/farmacologia , Células A549 , Morte Celular/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Humanos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Gases em Plasma/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/fisiologia , Molhabilidade
19.
J Basic Microbiol ; 59(7): 701-712, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31032943

RESUMO

Silver nanoparticles (AgNPs) are at the forefront of the swiftly developing scope of nanotechnology. In the current study, we investigated the green synthesis of AgNPs using Artemisia scoporia as a reducing and capping agent. The biosynthesized AgNPs were characterized using ultraviolet-visible spectroscopy, X-ray diffraction, Fourier-Transform infrared spectroscopy, dispersive absorption spectroscopy, scanning electron microscopy, and transmission electron microscopy. The efficacy of the nanoparticle synthesis was assessed by comparing the antibiofilm activity with commercial AgNPs. The effect of sub-minimum inhibitory concentrations (MICs) of AgNPs on biofilm formation was determined by microtiter plate assay. The expression level of the icaA and icaR genes was assessed by real-time polymerase chain reaction assay. The structural and functional aspects of AgNPs were confirmed. The expression levels of icaA and icaR in the isolates exposed to sub-MIC of both commercial and biosynthetic AgNPs were lower and higher than in the control group, respectively. Our results also indicated that greater reduction and induction in icaA and icaR gene expression were noticed with the sub-MIC doses of biosynthetic AgNP versus commercial AgNP, respectively. This study suggested the application of AgNPs as a significant therapeutic and clinical option in the future and usage for fabricating medical implants. Nevertheless, further investigation is required for examining the pharmaceutical and medicinal properties of AgNPs.


Assuntos
Artemisia/química , Biofilmes/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Nanopartículas Metálicas/química , Prata/química , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Biofilmes/crescimento & desenvolvimento , Farmacorresistência Bacteriana Múltipla , Química Verde , Humanos , Testes de Sensibilidade Microbiana , Nanomedicina , Extratos Vegetais/química , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/isolamento & purificação
20.
Microb Pathog ; 131: 150-157, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30965089

RESUMO

In this study, essential oil extracted from Syagrus coronata seeds (SCEO) was evaluated for antibacterial and antibiofilm activities against Staphylococcus aureus; in addition, Galleria mellonella model was used as an in vivo infection model. SCEO was mainly composed by fatty acids (89.79%) and sesquiterpenes (8.5%). The major components were octanoic acid, dodecanoic acid, decanoic acid and γ-eudesmol. SCEO showed bactericidal activity (minimal bactericidal concentration from 312 to 1250 µg/mL) against all tested S. aureus clinical isolates, which showed distinct biofilm-forming and multiple drug resistance phenotypes. SCEO weakly reduced biomass but remarkably decreased cell viability in pre-formed biofilms of S. aureus isolate UFPEDA-02 (ATCC-6538). Electron microscopy analysis showed that SCEO treatments decreased the number of bacterial cells (causing structural alterations) and lead to loss of the roughness in the multiple layers of the three-dimensional biofilm structure. In addition, overproduction of exopolymeric matrix was observed. SCEO at 31.2 mg/kg improved the survival of G. mellonela larvae inoculated with UFPEDA-02 isolate and reduced the bacterial load in hemolymph and melanization. In conclusion, SCEO is an antibacterial agent against S. aureus strains with different resistance phenotypes and able to disturb biofilm architecture. Our results show SCEO as a potential candidate to drug development.


Assuntos
Antibacterianos/farmacologia , Arecaceae/química , Biofilmes/efeitos dos fármacos , Lepidópteros/microbiologia , Óleos Voláteis/farmacologia , Extratos Vegetais/farmacologia , Staphylococcus/efeitos dos fármacos , Animais , Antibacterianos/química , Biofilmes/crescimento & desenvolvimento , Brasil , Modelos Animais de Doenças , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Óleos Voláteis/química , Extratos Vegetais/química , Sementes/química , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
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