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1.
J Med Microbiol ; 69(9): 1132-1144, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32812863

RESUMO

Introduction. While colonization by Staphylococcus aureus in haemodialysis patients has been assessed, knowledge about colonization by beta-lactam-resistant Gram-negative bacilli is still limited.Aim. To describe clinical and molecular characteristics in haemodialysis patients colonized by S. aureus (MSSA-MRSA) and beta-lactam-resistant Gram-negative bacilli in an ambulatory renal unit.Methodology. The study included patients with central venous catheters in an outpatient haemodialysis facility in Medellín, Colombia (October 2017-October 2018). Swab specimens were collected from the nostrils and skin around vascular access to assess colonization by S. aureus (MSSA-MRSA). Stool samples were collected from each patient to evaluate beta-lactam-resistant Gram-negative bacilli colonization. Molecular typing included PFGE, multilocus sequence typing (MLST), spa typing and enterobacterial repetitive intergenic consensus-PCR (ERIC). Clinical information was obtained from medical records and personal interview.Results. A total of 210 patients were included in the study. S. aureus colonization was observed in 33.8 % (n=71) of the patients, 4.8 % (n=10) of which were colonized by methicillin-resistant S. aureus. Stool samples were collected from 165 patients and of these 41.2 % (n=68) and 11.5 % (n=19) were colonized by extended-spectrum-beta-lactamase-producing (ESBL) and carbapenem-resistant bacilli, respectively. Typing methods revealed high genetic diversity among S. aureus and ESBL-producing Gram-negative bacilli (ESBL-GNB). Antibiotic use and hospitalization in the previous 6 months were observed in more than half of the studied population.Conclusion. The high colonization by ESBL-GNB in haemodialysis patients shows evidence for the need for stronger surveillance, not only for S. aureus but also for multidrug-resistant bacilli in order to avoid their spread. Additionally, the high genetic diversity suggests other sources of transmission outside the renal unit instead of horizontal transmission between patients.


Assuntos
Antibacterianos/farmacologia , Infecção Hospitalar/microbiologia , Bactérias Gram-Negativas/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/microbiologia , Lactamas/farmacologia , Resistência beta-Lactâmica , Idoso , Fezes/microbiologia , Feminino , Bactérias Gram-Negativas/classificação , Bactérias Gram-Negativas/genética , Bactérias Gram-Negativas/isolamento & purificação , Humanos , Masculino , Pessoa de Meia-Idade , Diálise Renal , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/isolamento & purificação
2.
Int J Nanomedicine ; 15: 4325-4331, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32606680

RESUMO

Purpose: The purpose of this study was to investigate the effect of different commercially used dental materials (RelyX Luting Plus and Dyract Extra) mixed with either a metallic ionic solution or a colloidal suspension of metallic nanoparticles. Both the solution and the suspension contained a mixture of silver, copper, and lithium ions. Methods: The metal/ion-incorporated dental materials were prepared into disk-shaped samples and tested against the growth of Staphylococcus aureus. The susceptibility of bacteria against the antibacterial dental disks was tested using two methods: counting the colony-forming units per milliliter and disk diffusion (Kirby-Bauer). The incorporated materials (Dyract and Rely cement) were tested for ion release using flame atomic absorption spectroscopy. Results: Assessment showed efficient antibacterial activity of metal ion-incorporated Rely luting cement, exhibited by the formation of inhibition zones larger than those formed by the standard antibiotic, as well as a reduction in bacterial number of sevenfold after incubation for 24 hours. Dyract material incorporated with nanoparticles showed no significant clear zones and had no inhibiting effect on bacterial colony numbers after incubation for 24 hours. The release of silver, copper, and lithium metal ions depended on the type of both dental material and the incorporated nanoagents. The metal ion-incorporated Rely Plus cement released the highest levels of metal ions, which was attributed to its antibacterial efficiency. Conclusion: Rely Plus cement incorporated with the nanoparticle suspension demonstrated high antibacterial potency, due to the release of the highest concentrations of silver, copper, and lithium metal ions. This work is the first direct comparative study of dental materials with different forms of nanomixtures (metallic nanoparticles and soluble metallic ions) and their antibacterial effects after incubation with bacterial culture for 24 hours.


Assuntos
Materiais Dentários/farmacologia , Nanopartículas/química , Staphylococcus aureus/crescimento & desenvolvimento , Antibacterianos/farmacologia , Contagem de Colônia Microbiana , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacos
3.
PLoS One ; 15(7): e0235740, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32678859

RESUMO

This study evaluated the larvicidal activity of Origanum majorana Linnaeus essential oil, identified the chemical composition, evaluated the antimicrobial, cytotoxic and antioxidant potential. The larvicidal activity was evaluated against larvae of the third stage of Aedes aegypti Linaeus, whereas the chemical composition was identified by gas chromatography coupled to mass spectrometer, the antimicrobial activity was carried out against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus auereus, the antioxidant activity was evaluated from of 2.2-diphenyl-1-picryl-hydrazila sequestration and Artemia salina Leach cytotoxicity. Regarding to the results, the larvicidal activity showed that O. majorana L. essential oil caused high mortality in A. aegypti L. larvae. In the chromatographic analysis, the main component found in O. majorana L. essential oil was pulegone (57.05%), followed by the other components verbenone (16.92%), trans-p-menthan-2-one (8.57%), iso-menthone (5.58%), piperitone (2.83%), 3-octanol (2.35%) and isopulegol (1.47%). The antimicrobial activity showed that E. coli and P. aeruginosa bacteria were more sensitive to oil than S. aureus, which was resistant at all concentrations. Essential oil did not present antioxidant activity, but it has high cytotoxic activity against A. salina L.


Assuntos
Aedes/efeitos dos fármacos , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Óleos Voláteis/farmacologia , Origanum/química , Animais , Antibacterianos/química , Antioxidantes/farmacologia , Bactérias/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Folhas de Planta/química , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
4.
PLoS One ; 15(5): e0233485, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32470050

RESUMO

Antimicrobial resistance is a growing global health and economic concern. Current antimicrobial agents are becoming less effective against common bacterial infections. We previously identified pyrrolocins A and C, which showed activity against a variety of Gram-positive bacteria. Structurally similar compounds, known as pyrrolidinediones (e.g., TA-289, equisetin), also display antibacterial activity. However, the mechanism of action of these compounds against bacteria was undetermined. Here, we show that pyrrolocin C and equisetin inhibit bacterial acetyl-CoA carboxylase (ACC), the first step in fatty acid synthesis. We used transcriptomic data, metabolomic analysis, fatty acid rescue and acetate incorporation experiments to show that a major mechanism of action of the pyrrolidinediones is inhibition of fatty acid biosynthesis, identifying ACC as the probable molecular target. This hypothesis was further supported using purified proteins, demonstrating that biotin carboxylase is the inhibited component of ACC. There are few known antibiotics that target this pathway and, therefore, we believe that these compounds may provide the basis for alternatives to current antimicrobial therapy.


Assuntos
Acetil-CoA Carboxilase/antagonistas & inibidores , Proteínas de Bactérias/antagonistas & inibidores , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/metabolismo , Pirrolidinonas/farmacologia , Tetra-Hidronaftalenos/farmacologia , Acetil-CoA Carboxilase/química , Antibacterianos/farmacologia , Proteínas de Bactérias/química , Domínio Catalítico/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Ácidos Graxos/biossíntese , Perfilação da Expressão Gênica , Bactérias Gram-Positivas/crescimento & desenvolvimento , Humanos , Metabolômica , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/metabolismo
5.
Int J Food Microbiol ; 326: 108650, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32402916

RESUMO

Use of carbon dots (CDs) in combination with aqueous chitosan solution to extend shelf life and improve stability of soy milk was investigated. Soy milk samples with chitosan solution (0.00%, 0.08%, 0.12%, 0.16% and 0.20%) and banana-based CDs (4%, 6% and 8%) were prepared and stored at room temperature (25-30 °C) for shelf life evaluation. Soy milk with 0.16% chitosan solution exhibited improved stability as evident by increased viscosity, stability coefficient, zeta potential and decreased centrifugation rate compared with soy milk without chitosan. The suitable amount of carbon dots could effectively inhibit the growth of Escherichia coli, Staphylococcus aureus and Bacillus subtilis. Soy milk with 0.16% chitosan and 8% CDs exhibited longer shelf life and significantly lower total bacterial count after storage at room temperature for up to 4 days. Electronic nose-based flavor characteristics of all treated soy milk samples were not far from that of the control sample.


Assuntos
Bacillus subtilis/crescimento & desenvolvimento , Quitosana/farmacologia , Escherichia coli/crescimento & desenvolvimento , Armazenamento de Alimentos/estatística & dados numéricos , Leite de Soja/metabolismo , Staphylococcus aureus/crescimento & desenvolvimento , Bacillus subtilis/efeitos dos fármacos , Carbono/farmacologia , Escherichia coli/efeitos dos fármacos , Contaminação de Alimentos/análise , Pontos Quânticos , Staphylococcus aureus/efeitos dos fármacos , Paladar , Água/farmacologia
6.
J Food Sci ; 85(4): 947-955, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32237089

RESUMO

Edible packaging films have been widely studied because of its safety, green, and effective characteristics. In this paper, chitosan (CH) edible films containing hexahydro-ß-acids (HBA) were prepared, and its physical and mechanical properties, bioactivity, and their impact on the shelf life of pork were investigated. The infrared spectra indicated that the molecular interaction between CH and HBA was observed. Scanning electron microscopy was used to analyze the surface morphology of the film, and light transmittance analysis displayed that the addition of HBA enhanced the film's UV blocking performance. Compared to the CH film, the tensile strength of CH-HBA film increased to 29.19 ± 0.45 MPa, and the scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) reached 1.40 ± 0.01 mg rutin/cm2 of the film. The antibacterial activity of the CH-HBA film on Escherichia coli (44825) and Staphylococcus aureus (26001) showed that the CH-HBA film is a feasible antibacterial package. Furthermore, compared to pork packaged in CH and polyethylene films, fresh pork packaged with CH-HBA films displayed prolongation of shelf life due to reduction in microbial proliferation, thiobarbituric values, pH, and total volatile base nitrogen contents during storage at 4 °C for 16 days. The freshness of pork was prolonged by 7-8 days when the dosage of HBA was increased to 0.3% from 0.1% (w/v). These results revealed that the CH-HBA film can effectively extend the shelf life of pork. PRACTICAL APPLICATION: This study effectively prolonged the shelf life of pork. A chitosan-edible film combined with hexahydro-ß-acids has a potential application value in replacing traditional packaged fresh meat.


Assuntos
Antibacterianos/farmacologia , Quitosana/farmacologia , Embalagem de Alimentos/instrumentação , Carne Vermelha/análise , Ácidos/análise , Ácidos/farmacologia , Animais , Antibacterianos/análise , Quitosana/análise , Filmes Comestíveis , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Embalagem de Alimentos/métodos , Armazenamento de Alimentos , Carne Vermelha/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Suínos , Resistência à Tração
7.
PLoS One ; 15(4): e0231397, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32302332

RESUMO

The increasing challenge of antibiotic resistance requires not only the discovery of new antibiotics, but also the development of new alternative approaches. Therefore, in the present study, we investigated for the first time the antibacterial potential of phytic acid (myo-inositol hexakisphosphate, IP6), a natural molecule that is 'generally recognized as safe' (FDA classification), against the proliferation of common foodborne bacterial pathogens such as Listeria monocytogenes, Staphylococcus aureus and Salmonella Typhimurium. Interestingly, compared to citric acid, IP6 was found to exhibit significantly greater inhibitory activity (P<0.05) against these pathogenic bacteria. The minimum inhibitory concentration of IP6 varied from 0.488 to 0.97 mg/ml for the Gram-positive bacteria that were tested, and was 0.244 mg/ml for the Gram-negative bacteria. Linear and general models were used to further explore the antibacterial effects of IP6. The developed models were validated using experimental growth data for L. monocytogenes, S. aureus and S. Typhimurium. Overall, the models were able to accurately predict the growth of L. monocytogenes, S. aureus, and S. Typhimuriumin Polymyxin acriflavine lithium chloride ceftazidime aesculin mannitol (PALCAM), Chapman broth, and xylose lysine xeoxycholate (XLD) broth, respectively. Remarkably, the early logarithmic growth phase of S. Typhimurium showed a rapid and severe decrease in a period of less than one hour, illustrating the bactericidal effect of IP6. These results suggest that IP6 is an efficient antibacterial agent and can be used to control the proliferation of foodborne pathogens. It has promising potential for environmentally friendly applications in the food industry, such as for food preservation, food safety, and for prolonging shelf life.


Assuntos
Antibacterianos/farmacologia , Microbiologia de Alimentos , Listeria monocytogenes/efeitos dos fármacos , Ácido Fítico/farmacologia , Salmonella typhimurium/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Ácido Cítrico/farmacologia , Modelos Lineares , Listeria monocytogenes/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Salmonella typhimurium/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento
8.
J Food Sci ; 85(5): 1523-1535, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32282078

RESUMO

Bacteriocins are defined as ribosomally synthesized antibacterial peptides/proteins that either kill or inhibit the growth of other bacteria. In the present study, the physicochemical properties, mode of action, and potential use in food preservation of a novel bacteriocin BM1122 from Lactobacillus crustorum MN047 were studied. It exhibited a broad inhibitory spectrum against selected Gram-positive and Gram-negative bacteria. Kinetic curves revealed efficient time-dependent bactericidal activity. Moreover, BM1122 possessed low hemolytic activity and good thermal stability between 60 and 120 °C. It was resistant to a wide range of pH (2 to 11) and proteinases. The scanning and transmission electron microscopy showed that BM1122 led to plasmolysis of Staphylococcus aureus and pore formation in Escherichia coli. Flow cytometric analysis demonstrated that BM1122 destroyed cell membrane integrity. Additionally, BM1122 could also inhibit biofilm formation and disturb the normal cell cycles of S. aureus and E. coli. Finally, BM1122 may enhance the inhibition of S. aureus and E. coli on beef meat stored at 4 °C for a duration of 10 days. These findings indicated that BM1122 had the potential for use as a natural preservative in the food industry. PRACTICAL APPLICATION: Fresh raw meats are highly perishable products. Bacteriocin BM1122 with a broad antibacterial spectrum can inhibit the growth of microorganisms in beef meat during refrigerated storage.


Assuntos
Antibacterianos/farmacologia , Bacteriocinas/farmacologia , Lactobacillus/química , Animais , Antibacterianos/química , Antibacterianos/metabolismo , Bacteriocinas/química , Bacteriocinas/metabolismo , Bovinos , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Conservação de Alimentos , Lactobacillus/metabolismo , Carne Vermelha/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
9.
J Food Sci ; 85(5): 1513-1522, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32243587

RESUMO

The objective of this study was to evaluate the antibacterial effect of Chinese wild blueberry extract and its fractions against Listeria monocytogenes, Staphylococcus aureus, Salmonella Enteritidis, and Vibrio parahaemolyticus. Chinese wild blueberry (Vaccinium uliginosum) crude extract (BBE) was obtained using methanol extraction, and sugars plus organic acids (F1), phenolics fraction (F2), and anthocyanins plus proanthocyanidins (F3) fractions were separated using C-18 Sep-Pak columns. The minimal inhibitory concentration and minimal bactericidal concentration of each fractional component were determined using a two-fold-serial dilution method. Nucleic acid leakage (OD260 nm ) and protein release (Bradford protein assay) were determined by spectrophotometry, to evaluate the permeability of the cell membrane. F3 was found to exhibit the greatest antimicrobial activity against the four tested strains, followed by F2, F1, and BBE. V. parahaemolyticus was the most sensitive to the all fractions, followed by S. Enteritidis, L. monocytogenes, and S. aureus. Survival curve analysis showed that the number of bacteria decreased from six log colony-forming units (CFU) to less than 10 CFU after bacteria were treated with fractions for 12 hr, which demonstrated the bactericidal effect of blueberry fractions. Furthermore, when the pathogens were treated with fractions for 2 hr, the OD260 nm and OD595 nm values increased significantly (P < 0.01), which indicated the significant release of nucleic acid and protein. The results from this study indicated that blueberry fractions, especially F3, inhibited the growth of foodborne pathogens by damaging their cell membrane, and may be developed as a natural preservative to prevent and control foodborne pathogens. PRACTICAL APPLICATION: A blueberry crude extract and its sugars plus organic acids, phenolics, and anthocyanins plus proanthocyanidins fractions, inhibited the growth of foodborne pathogens by destroying their cell membrane. Therefore, Chinese wild blueberries have potential as a natural preservative to prevent and control foodborne pathogens.


Assuntos
Antibacterianos/farmacologia , Mirtilos Azuis (Planta)/química , Extratos Vegetais/farmacologia , Antocianinas/análise , Antocianinas/farmacologia , Antibacterianos/química , Microbiologia de Alimentos , Conservantes de Alimentos/química , Conservantes de Alimentos/farmacologia , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Fenóis/análise , Fenóis/farmacologia , Extratos Vegetais/química , Proantocianidinas/análise , Proantocianidinas/farmacologia , Salmonella enteritidis/efeitos dos fármacos , Salmonella enteritidis/crescimento & desenvolvimento , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
10.
J Food Sci ; 85(4): 1193-1202, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32144762

RESUMO

In this study, starch-based films incorporating metal oxide (MO2 ) nanoparticles (NPs) of TiO2 and SiO2 (at a concentration of 1 to 4 wt. %) were produced by solution casting method. In order to exhibit antimicrobial properties, MO2 NPs were modified by synthesizing silver (Ag) ions over the NPs using cationic adsorption method. Ag ions were then reduced to metallic Ag by sodium borohydride solution. Scanning electron microscopy showed a smooth surface for the pure starch film. Incorporating MO2 @Ag NPs in the films increased surface roughness with agglomerated NPs within starch matrix. Energy dispersive X-ray analysis exhibited a uniform dispersion of Ag-loaded MO2 NPs, which increases surface contact between these NPs and the biopolymer matrix leading to improved physical and mechanical properties of the resulting films. With increasing in the NPs concentrations, the tensile strength and elongation at break % of the films increased and decreased, respectively. Incorporating MO2 @Ag NPs into starch matrix decreased solubility in water and water vapor permeability of the obtained films, and significantly inhibited the growth of Escherichia coli and Staphylococcus aureus. The most antibacterial effect was obtained for the films containing higher weight concentrations of Ag-loaded SiO2 -NPs.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Dióxido de Silício/química , Prata/química , Prata/farmacologia , Titânio/química , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Nanocompostos/química , Nanopartículas/química , Permeabilidade , Solubilidade , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Resistência à Tração
11.
J Dairy Sci ; 103(5): 4100-4108, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32197850

RESUMO

Staphylococcus aureus is one of the main causative agents of food poisoning. This bacterium is an important component of cheese microbiota and plays an important role in foodborne diseases. Another important component of the microbiota is the lactic acid bacterium, which actively participates in processes that define the physicochemical, sensorial, and microbiological features of cheese. Of the various microbiological interactions in cheese, the interaction between lactic acid bacteria and Staph. aureus is most relevant. To this end, we evaluated the viability of Staph. aureus strains and the expression of their enterotoxins in cheeses produced experimentally, using Weissella paramesenteroides GIR16L4 or Lactobacillus rhamnosus D1 or both as starter cultures. Over 7 d, we observed that the presence of lactic acid bacteria did not impair Staph. aureus growth. However, via qPCR we observed a change in the gene expression of staphylococcal enterotoxins, suggesting that molecular communication exists between Staph. aureus strains and lactic acid bacteria in cheese.


Assuntos
Toxinas Bacterianas/metabolismo , Queijo/microbiologia , Enterotoxinas/metabolismo , Lactobacillus rhamnosus/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento , Superantígenos/metabolismo , Weissella/crescimento & desenvolvimento , Animais , Toxinas Bacterianas/genética , Queijo/análise , Enterotoxinas/genética , Microbiologia de Alimentos , Lactobacillales/metabolismo , Lactobacillus rhamnosus/metabolismo , Leite , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Superantígenos/genética , Transcriptoma , Weissella/metabolismo
12.
Food Microbiol ; 89: 103374, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32138980

RESUMO

Cooked rice with pork floss (CRPF) wrapped in dried seaweed is one of the most popular ready-to-eat (RTE) foods in many Asian countries, particularly in Taiwan. The products are susceptible to Staphylococcus aureus contamination and temperature abuse during manufacturing, distribution, and storage. The objective of this study was to examine the effect of temperature on its growth in RTE CRPF for use in risk assessment and prevention of staphylococcal food poisoning (SFP). Inoculated CRPF samples were stored at 4, 12, 18, 25, and 35°C, and the change in the populations of S. aureus during storage were analyzed using three primary models to determine specific growth rate (µmax), lag-phase duration (λ), and maximum population density (ymax). The Ratkowsky square-root and Huang square-root (HSR) models were used as the secondary models to describe the effect of temperature on µmax, and a linear and an exponential regression models were used to describe the effect of temperature on λ and ymax, respectively. The model performance was evaluated by the root mean square error (RMSE), bias factor (Bf), and accuracy factor (Af) when appropriate. Results showed that three primary models were suitable for describing the growth curves, with RMSE ≤ 0.3 (log MPN/g). Using µmax obtained from the Huang model, the minimum growth temperature (Tmin) estimated by the HSR model was 7.0°C, well in agreement with the reported Tmin. The combination of primary and secondary models for predicting S. aureus growth was validated by additional growth curves at 30°C, which showed that the RMSE was 0.6 (log MPN/g). Therefore, the developed models were acceptable for predicting the growth of S. aureus in CRPF under likely temperature abuse conditions and can be applied to assess the risk of S. aureus in CRPF and design temperature controls to reduce the risk of SFP.


Assuntos
Inocuidade dos Alimentos , Produtos da Carne/análise , Staphylococcus aureus/crescimento & desenvolvimento , Temperatura , Animais , Manipulação de Alimentos , Modelos Biológicos , Oryza , Suínos
13.
Food Microbiol ; 89: 103450, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32138997

RESUMO

This study was conducted to address the dearth in works that simultaneously compare the growth and inactivation behaviors of selected pathogens in different milk products. In worst-case scenarios where hygienic practices are absent and heavy microbiological contaminations occur, Salmonella enterica, Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus multiplied in all samples at room temperature (27 °C). Most organisms readily proliferated with growth lag (tlag) values ranging from 0.00 to 5.95 h. Growth rates (KG) ranged from 0.16 to 0.67 log CFU/h. Sanitary risk times (SRTs) for a 1-log population increase ranged from 1.85 to 6.27 h, while 3.69-12.55 h were the SRTs determined for 2-log population increase. Final populations (Popfin) ranged from 7.11 to 9.36 log CFU/mL. Inactivation in heavily contaminated milk during Holder pasteurization revealed biphasic inactivation behavior with total log reduction (TLR) after exposure to 62.5 °C for 30 min ranging from 1.91 (90.8%) to 6.00 (99.9999%). These results emphasize the importance food safety systems in the handling of milk and milk products during manufacture and preparation.


Assuntos
Bactérias/crescimento & desenvolvimento , Inocuidade dos Alimentos , Fórmulas Infantis/microbiologia , Leite Humano/microbiologia , Leite/microbiologia , Animais , Bovinos , Escherichia coli O157/crescimento & desenvolvimento , Feminino , Microbiologia de Alimentos , Humanos , Lactente , Listeria monocytogenes/crescimento & desenvolvimento , Pasteurização , Salmonella enterica/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento , Temperatura
14.
Int J Food Microbiol ; 321: 108560, 2020 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-32078866

RESUMO

Foodborne illnesses affect the health of consumers worldwide, and thus searching for potential antimicrobial agents against foodborne pathogens is given an increased focus. This research evaluated the influence of sodium lactate (SL), encapsulated (e) and unencapsulated (u) polyphosphates (PP; sodium tripolyphosphate, STP; sodium acid pyrophosphate, SPP), and their combinations on Salmonella Typhimurium, Escherichia coli O157:H7 and Staphylococcus aureus growth in cooked ground beef during 30 day storage at 4 or 10 °C. pH, water activity (aw), oxidation-reduction potential (ORP) and S. Typhimurium, E. coli O157:H7 and S. aureus counts were determined. S. Typhimurium was not found in SPP-SL combination groups after 30 day storage at 4 °C (P <0.05). Lower S. Typhimurium levels were determined in only SL containing groups stored at 10 °C than group with only tested microorganism (MO, P < 0.05). Although there was no change in S. Typhimurium load in all SL incorporated groups during 10 °C storage, S. Typhimurium count increased in other groups (P < 0.05). E. coli O157:H7 in MO and STP groups showed an increase at 4 °C, whereas it decreased in SPP-SL combination groups (P < 0.05). A gradual increase in E. coli O157:H7 at 10 °C was determined in MO and only PP incorporated groups, whereas there was a decrease in STP-SL or SPP-SL combination groups (P < 0.05). E. coli O157:H7 count was stable in SL containing groups during 10 °C storage. A gradual decrease in S. aureus was determined in all treatments at 4 °C, whereas S. aureus count increased in MO and uSTP groups during 10 °C storage (P < 0.05). There was no change in S. aureus level in only eSTP or uSPP or ueSTP containing groups at 10 °C, meantime it decreased in other groups (P < 0.05). The lowest S. aureus load was achieved by uSPP-SL or eSPP-SL or ueSPP-SL combinations after 30 days at both storage temperatures (P < 0.05). In general, pH was higher in samples with STP than those with SPP and control (P < 0.05). The lowest aw was generally obtained in all SL containing groups at both storage temperatures (P < 0.05). Lower ORP was determined in all PP incorporated groups during storage at both temperatures compared to others (P < 0.05). ORP in all treatments generally increased (P < 0.05) during storage at both storage temperatures. This study showed that encapsulation is not a factor affecting antimicrobial efficiency of PP and using PP-SL combinations have synergistic effect on reducing the viability of S. Typhimurium, E. coli O157:H7 and S. aureus and their subsequent growth ability in cooked ground beef.


Assuntos
Escherichia coli O157/efeitos dos fármacos , Polifosfatos/farmacologia , Carne Vermelha/microbiologia , Salmonella typhimurium/efeitos dos fármacos , Lactato de Sódio/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Animais , Cápsulas , Bovinos , Contagem de Colônia Microbiana , Sinergismo Farmacológico , Escherichia coli O157/crescimento & desenvolvimento , Manipulação de Alimentos , Microbiologia de Alimentos , Polifosfatos/química , Carne Vermelha/análise , Salmonella typhimurium/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento , Temperatura
15.
Colloids Surf B Biointerfaces ; 188: 110783, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32004907

RESUMO

The failure of dental implants is usually caused by bacteria infection, poor bioactivity and biocompatibility. It is a common phenomenon clinically. Statherin, a salivary protein, plays a crucial role of mediator between materials and cells/bacteria. However, the conformation of statherin might be changed by the implants in vivo. In this study, we investigated the effects of statherin on the bioactivities, antibacterial abilities and biocompatibilities of the titanium metals and the reaction mechanism. We found that the conformation of statherin was mainly influenced by surface composition, surface structure, surface roughness, surface hydrophilia and Ti-OH groups of materials. Statherin could decrease the cell biocompatibility of the titanium metals including pure titanium (PT), anodic oxidation (AO), sandblasting and etching (SLA) and plasma spraying hydroxyapatite (HA) coating in HGF cell experiments, regulate the bio-mineralization ability of HA coating in SBF, and enhance the antibacterial properties of PT and HA coating. This study revealed that surface properties of materials could change the conformation of statherin, which influenced the bioactivities, antibacterial properties and biocompatibilities of the materials in return.


Assuntos
Antibacterianos/metabolismo , Materiais Revestidos Biocompatíveis/metabolismo , Proteínas e Peptídeos Salivares/metabolismo , Titânio/metabolismo , Adsorção , Antibacterianos/química , Antibacterianos/farmacologia , Linhagem Celular , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Implantes Dentários , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Humanos , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Conformação Proteica , Proteínas e Peptídeos Salivares/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Propriedades de Superfície , Titânio/química , Titânio/farmacologia
16.
Biofouling ; 36(2): 126-137, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32093497

RESUMO

Microbial biofilms are associated with persistent infections because of their high tolerance to antimicrobial agents and host defenses. The effects of centipede oil from Scolopendra subspinipes mutilans and its main components were investigated to identify non-toxic biofilm inhibitors. Centipede oil and linoleic acid at 20 µg ml-1 markedly inhibited biofilm formation by two fluconazole-resistant Candida albicans strains and three Staphylococcus aureus strains without affecting their planktonic cell growth. Also, both centipede oil and linoleic acid inhibited hyphal growth and cell aggregation by C. albicans. In addition, centipede oil and linoleic acid showed anti-biofilm activities against mixed C. albicans and S. aureus biofilms. Transcriptomic analysis showed that centipede oil and linoleic acid downregulated the expressions of several hypha/biofilm-related genes in C. albicans and α-hemolysin in S. aureus. Furthermore, both compounds effectively reduced C. albicans virulence in a nematode infection model with minimal toxicity.


Assuntos
Anti-Infecciosos/farmacologia , Biofilmes/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Ácido Linoleico/farmacologia , Óleos Voláteis/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Animais , Anti-Infecciosos/toxicidade , Artrópodes/química , Biofilmes/crescimento & desenvolvimento , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/microbiologia , Candida albicans/crescimento & desenvolvimento , Candida albicans/patogenicidade , Hifas/crescimento & desenvolvimento , Ácido Linoleico/toxicidade , Testes de Sensibilidade Microbiana , Óleos Voláteis/toxicidade , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/patogenicidade , Virulência/efeitos dos fármacos
17.
Infect Immun ; 88(5)2020 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-32094249

RESUMO

Staphylococcus aureus is a noted human and animal pathogen. Despite decades of research on this important bacterium, there are still many unanswered questions regarding the pathogenic mechanisms it uses to infect the mammalian host. This can be attributed to it possessing a plethora of virulence factors and complex virulence factor and metabolic regulation. PurR, the purine biosynthesis regulator, was recently also shown to regulate virulence factors in S. aureus, and mutations in purR result in derepression of fibronectin binding proteins (FnBPs) and extracellular toxins, required for a so-called hypervirulent phenotype. Here, we show that hypervirulent strains containing purR mutations can be attenuated with the addition of purine biosynthesis mutations, implicating the necessity for de novo purine biosynthesis in this phenotype and indicating that S. aureus in the mammalian host experiences purine limitation. Using cell culture, we showed that while purR mutants are not altered in epithelial cell binding, compared to that of wild-type (WT) S. aureus, purR mutants have enhanced invasion of these nonprofessional phagocytes, consistent with the requirement of FnBPs for invasion of these cells. This correlates with purR mutants having increased transcription of fnb genes, resulting in higher levels of surface-exposed FnBPs to promote invasion. These data provide important contributions to our understanding of how the pathogenesis of S. aureus is affected by sensing of purine levels during infection of the mammalian host.


Assuntos
Mutação/genética , Purinas/biossíntese , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/genética , Fatores de Virulência/genética , Células A549 , Animais , Proteínas de Bactérias/genética , Proteínas de Transporte/genética , Linhagem Celular , Citoplasma/genética , Células Epiteliais/fisiologia , Feminino , Fibronectinas/genética , Regulação Bacteriana da Expressão Gênica/genética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Fagócitos/fisiologia , Células RAW 264.7 , Infecções Estafilocócicas/microbiologia , Transcrição Genética/genética
18.
J Agric Food Chem ; 68(4): 1101-1109, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31904947

RESUMO

ε-Poly-l-lysine (ε-PL) consists of 25-35 lysine residues which are linked by an isopeptide bond formed by dehydration condensation of α-carboxyl and ε-amino groups and has good antibacterial activity and broad-spectrum inhibition range. However, there is no clear conclusion about the structure and antibacterial mechanism of ε-PL in aqueous solution. Herein, a high purity of ε-PL was prepared using Amberlite IRC-50 ion-exchange resin. Membrane filtration and dynamic light scattering were used to study the variations of ε-PL aggregation in aqueous solution with pH value. The conformational changes and antibacterial activities of ε-PL and carbamoylated ε-PL in different water environments were studied with circular dichroism (CD) and inhibition zone. The structural changes during the spray-drying process were determined by Fourier transform infrared spectroscopy. The results indicated that the side chain amino charge played a decisive role in the ε-PL conformation and aggregation. ε-PL exhibited the properties of a ß-sheet during spray drying from acidic liquids to solids. The cation enhanced the antibacterial activity of ε-PL but did not play a key role. Instead, the backbone of ε-PL might determine the mechanism of ε-PL antibacterial.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Polilisina/química , Polilisina/farmacologia , Antibacterianos/metabolismo , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Transição de Fase , Polilisina/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Streptomyces/química , Streptomyces/metabolismo
19.
J Agric Food Chem ; 68(8): 2357-2365, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-31967810

RESUMO

Here, we investigated the effect of cold plasma (CP) on the biological activities of phloroglucinol. Phloroglucinol (7.92 and 15.84 mM in methanol) was treated with air dielectric barrier discharge plasma at 250 W. In vitro, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and ferrous-reducing antioxidant power (FRAP) values of phloroglucinol increased in plasma treatment in a time-dependent manner. CP treatment of phloroglucinol decreased the lipid oxidation of oil emulsion during storage and increased the antimicrobial activity against Bacillus cereus, Escherichia coli O157:H7, and Staphylococcus aureus. Angiotensin-converting enzyme (ACE) inhibitory activity of phloroglucinol increased and total phenolic content decreased based on CP treatment. The CP-induced polymerization of phloroglocinol to phlorotannin derivatives was identified using high-performance liquid chromatography with UV detector and electrospray ionization/mass spectrometry (HPLC-UV-ESI/MS) method. Consequently, the polymer structure of phloroglucinol was found in the CP-treated phloroglucinol. In addition, CP enhances the biological activity of phloroglucinol and could be applied to bioactive materials in food and related industries.


Assuntos
Floroglucinol/química , Floroglucinol/farmacologia , Gases em Plasma/química , Antibacterianos/química , Antibacterianos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Bacillus cereus/efeitos dos fármacos , Bacillus cereus/crescimento & desenvolvimento , Escherichia coli O157/efeitos dos fármacos , Escherichia coli O157/crescimento & desenvolvimento , Polimerização , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
20.
Mater Sci Eng C Mater Biol Appl ; 108: 110430, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923959

RESUMO

Functionalization of porous metals with antibacterial coatings is hotly pursued in recent decade. Here we fabricated a highly porous stainless steel component by selective laser melting and then coated with silver incorporated zeolite by in situ hydrothermal crystallization method. The morphology of their surface was investigated by scanning electron microscopy. The inhibition of Escherichia coli and Staphylococcus aureus were identified by bacterial viability studies after 24 h of incubation. More importantly, the obtained coatings show better osteointegration by spreading bone marrow stromal cells (BMSCs) after cultured with different scaffold extract solutions for 1, 3, and 5 days. These results suggest that silver incorporated zeolite coatings on 3D printed porous stainless steels exhibit better antibacterial activity and biocompatibility, showing potential application in the field of medical implant materials.


Assuntos
Antibacterianos , Materiais Revestidos Biocompatíveis , Escherichia coli/crescimento & desenvolvimento , Impressão Tridimensional , Prata , Aço Inoxidável , Staphylococcus aureus/crescimento & desenvolvimento , Zeolitas , Antibacterianos/química , Antibacterianos/farmacologia , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Porosidade , Prata/química , Prata/farmacologia , Aço Inoxidável/química , Aço Inoxidável/farmacologia , Zeolitas/química , Zeolitas/farmacologia
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