The antibacterial effect of potassium-sodium niobate ceramics based on controlling piezoelectric properties.

The implant infection is one of the most serious postsurgical complications of medical device implantation. Therefore, the development of biocompatible materials with improved antibacterial properties is of great importance. It might be a new insight to apply the intrinsic electrical properties of biomaterials to solve this problem. Here, potassium-sodium niobate piezoceramics (K0.5Na0.5NbO3, KNN) with different piezoelectric constants were prepared, and the microstructures and piezoelectric properties of these piezoceramics were evaluated. Moreover, the antibacterial effect and biocompatibility of these piezoceramics were assayed. Results showed that these piezoceramics were able to decrease the colonies of bacteria staphylococcus aureus (S. aureus), favor the rat bone marrow mesenchymal stem cells (rBMSCs) proliferation and promote the cell adhesion and spreading. The above effects were found closely related to the surface positive charges of the piezoceramics, and the sample bearing the most positive charges on its surface (sample 80KNN) had the best performance in both antibacterial effect and biocompatibility. Based on our work, it is feasible to develop biocompatible antibacterial materials by controlling piezoelectric properties.

Antimicrobial Activity of Mesenchymal Stem Cells: Current Status and New Perspectives of Antimicrobial Peptide-Based Therapies.

While mesenchymal stem cells (MSCs)-based therapy appears to be promising, there are concerns regarding possible side effects related to the unwanted suppression of antimicrobial immunity leading to an increased risk of infection. Conversely, recent data show that MSCs exert strong antimicrobial effects through indirect and direct mechanisms, partially mediated by the secretion of antimicrobial peptides and proteins (AMPs). In fact, MSCs have been reported to increase bacterial clearance in preclinical models of sepsis, acute respiratory distress syndrome, and cystic fibrosis-related infections. This article reviews the current evidence regarding the direct antimicrobial effector function of MSCs, focusing mainly on the role of MSCs-derived AMPs. The strategies that might modulate the expression and secretion of these AMPs, leading to enhanced antimicrobial effect, are highlighted. Furthermore, studies evaluating the presence of AMPs in the cargo of extracellular vesicles (EVs) are underlined as perspective opportunities to develop new drug delivery tools. The antimicrobial potential of MSCs-derived EVs can also be heightened through cell conditioning and/or drug loading. Finally, improving the pharmacokinetics and delivery, in addition to deciphering the multi-target drug status of AMPs, should synergistically lead to key advances against infections caused by drug-resistant strains.

Atividade antimicrobiana e qualidade físico-química do mel de Apis mellifera e Tetragonisca angustula (jataí) produzidas no estado de Mato Grosso / Antimicrobial activity and physicochemical quality Apis mellifera honey and Tetragonisca angustula (jataí) produced in the state of Mato Grosso

Mato Grosso presents a variety of factors influencing antimicrobial activity and physico-chemical quality of honey, altering its therapeutic properties. The aim of this study was to determine the in vitro antimicrobial activity of honeys, from nine municipalities in the state of Mato Grosso, compared with isolates of Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 and assess their physical and chemical quality. Antimicrobial activity was made by the cylinder plate method, as described by Esmerino et. al (2004) and physico-chemical analyzes were performed according to the methodologies of the Instituto Adolfo Lutz: All samples showed antimicrobial activity proportional to the concentration of honey used. There was greater inhibition of growth of Staphylococcus aureus than for E. coli, with larger inhibition zones for honey Tetragonisca angustula. In physicochemical analysis, two samples of honey were not within the limits established by Brazilian legislation. (AU)

Mato Grosso apresenta uma diversidade de fatores que influenciam na atividade antimicrobiana e na qualidade físico-química do mel, alterando suas propriedades terapêuticas. O objetivo deste trabalho foi verificar in vitro a atividade antimicrobiana de méis, provenientes de nove municípios do Estado de Mato Grosso, frente aos isolados de Staphylococ- cus aureus ATCC 25923 e Escherichia coli ATCC 25922 e avaliar sua qualidade físico-química. A atividade antimicrobiana foi feita pelo método , de cilindro em placa, conforme descrito por Esmerino et. al (2004) e as análises físico-químicas foram feitas segundo as metodologias do Instituto Adolfo Lutz. Todas as amostras apresentaram atividade antimicrobiana proporcional à concentração de mel utilizada. Houve maior inibição do crescimento do Staphylococcus aureus do que para Escherichia coli, com maiores halos de inibição para o mel de Tetragonisca angustula. Nas análises físico-químicas, duas amostras não tiveram resultados dentro do limite estabelecido pela legislação brasileira. (AU)

Antimicrobial activity and mineral composition of shiitake mushrooms cultivated on agricultural waste

The antimicrobial activity and mineral composition of shiitake mushrooms were evaluated in four isolates of Lentinula edodes. Mushrooms were cultivated on artificial logs, based on eucalyptus sawdust enriched with 20 percent rice, wheat, or soybean bran, or combination of 10 percent of two of these supplements. The substrates were humidified with a 0.1 percent mate tea extract or water. Logs of Eucalyptus grandis were also used to cultivate the shiitake mushrooms. The antimicrobial activity of an aqueous extract, corresponding to 40 mg of mushroom dry matter, was in some cases, depending on the isolate, able to inhibit both Bacillus subtilis and Escherichia coli K-12, independent of substrate composition or the growth stage of the mushrooms. Nitrogen, phosphorus, potassium, magnesium and calcium concentrations varied according to the substrate on which the mushrooms were cultivated, being, generally, higher with cultivation on artificial rather than natural eucalyptus logs. It could be concluded that, in addition to the fungal isolate, substrate composition and, processing methods must be considered during the production of antimicrobial substance(s) as well as in the mushroom nutritional composition.