Reduction of bacterial adhesion to biocompatible polymer surfaces via plasma processing

Plasma processing of the surfaces of biomaterials is interesting because it enables modification of the characteristics of a surface without affecting bulk properties. In addition, the results are strongly influenced by the conditions of the treatment. Therefore, by adjusting the plasma parameters it is possible to tailor the surface properties to best fulfill the requirements of a given application. In this work, polyurethane substrates have been subjected to sulfur hexafluoride glow discharge plasmas. The influences of different SF 6 plasma exposure times and pressures on the adhesion of Staphylococcus aureus and Pseudomonas aeruginosa to the polymer have been investigated. The wettability and surface free energy have been evaluated via contact angle measurements. At low pressure (6.7 Pa) the contact angle decreases with increasing exposure time in the 180 s to 540 s interval, but at higher pressure (13.3 Pa) it increases as a function of the same variable. Bacterial adhesion has been quantified from in vitro experiments by determining the growth of colonies on Petri dishes treated with agar nutrient. It has been observed that the surface properties play an important role in microbe adhesion. For instance, the density of adhered P. aeruginosa decreased as the surface contact angle increased. S. aureus preferred to adhere to hydrophobic surfaces. © 2011 by Begell House, Inc.

Preparation and characterization of the bacterial cellulose/polyurethane nanocomposites

New nanocomposites based on bacterial cellulose nanofibers (BCN) and polyurethane (PU) prepolymer were prepared and characterized by SEM, FT-IR, XRD, and TG/DTG analyses. An improvement of the interface reaction between the BCN and the PU prepolymer was obtained by a solvent exchange process. FT-IR results showed the main urethane band at 2,270 cm-1 to PU prepolymer; however, in nanocomposites new bands appear as disubstituted urea at 1,650 and 1,550 cm-1. In addition, the observed decrease in the intensity of the hydroxyl band (3,500 cm-1) suggests an interaction between BCN hydroxyls and NCO-free groups. The nanocomposites presented a non-crystalline character, significant thermal stability (up to 230 °C) and low water absorption when compared to pristine BCN. © 2013 Akadémiai Kiadó, Budapest, Hungary.

Bacterial nanocellulose for medical implants

Bacterial cellulose (BC) has established to be a remarkably versatile biomaterial and can be used in wide variety of applied scientific endeavours, especially for medical devices. In fact, biomedical devices recently have gained a significant amount of attention because of an increased interest in tissue-engineered products for both wound care and the regeneration of damaged or diseased organs. Due to its unique nanostructure and properties, microbial cellulose is a natural candidate for numerous medical and tissue-engineered applications. Hydrophilic bacterial cellulose fibers of an average diameter of 50 nm are produced by the bacterium Acetobacter xylinum, using a fermentation process. The microbial cellulose fiber has a high degree of crystallinity. Using direct nanomechanical measurement, determined that these fibers are very strong and when used in combination with other biocompatible materials, produce nanocomposites particularly suitable for use in human and veterinary medicine. Moreover, the nanostructure and morphological similarities with collagen make BC attractive for cell immobilization and cell support. The architecture of BC materials can be engineered over length scales ranging from nano to macro by controlling the biofabrication process. The chapter describes the fundamentals, purification and morphological investigation of bacterial cellulose. This chapter deals with the modification of microbial cellulose and how to increase the compatibility between cellulosic surfaces and a variety of plastic materials. Furthermore, provides deep knowledge of fascinating current and future applications of bacterial cellulose and their nanocomposites especially in the medical field, materials with properties closely mimic that of biological organs and tissues were described. © Springer-Verlag Berlin Heidelberg 2013.

Do Atopobium vaginae, Megasphaera sp. and Leptotrichia sp. change the local innate immune response and sialidase activity in bacterial vaginosis?

Objectives: To investigate if the participation of Atopobium vaginae, Megasphaera sp. and Leptotrichia sp. in the bacterial community of bacterial vaginosis (BV) is associated with distinct patterns of this condition. Methods: In this cross-sectional controlled study, 205 women with BV and 205 women with normal flora were included. Vaginal rinsing samples were obtained for measuring the levels of pro-inflammatory cytokines and bacterial sialidases. Real-time PCR was used to quantify the BV-associated bacteria and to estimate the total bacterial load using the 16S rRNA. Principal component analysis (PCA) using the measured parameters was performed to compare the BV samples with lower and higher loads of the species of interest. Results: Higher bacterial load (p<0.001), levels of interleukin 1-β (p<0.001) and sialidase activity (p<0.001) were associated with BV. Women with BV and higher relative loads of A vaginae, Megasphaera sp. and Leptotrichia sp. presented increased sialidase activity, but unchanged cytokine levels. PCA analysis did not indicate a different pattern of BV according to the loads of A vaginae, Megasphaera sp. and Leptotrichia sp. Conclusions: Greater participation of A vaginae, Megasphaera sp. and Leptotrichia sp. in vaginal bacterial community did not indicate a less severe form of BV; moreover, it was associated with increased sialidase activity.

Qualitative analysis of preputial and vaginal bacterial microbiota in owl monkeys (Aotus azarai infulatus) raised in captivity

Background: The aim of this study was to identify the aerobic bacteria of the preputial and vaginal microbiota in owl monkeys that have been raised in captivity and to evaluate the antimicrobial susceptibility of these bacteria by gender and social organization. Methods: Thirty clinically healthy Aotus azarai infulatus were used. A total of 134 samples were collected, 60 from the preputial mucosa and 74 from the vaginal mucosa. An automated system of bacterial identification was used. Results and Conclusions: Staphylococcus intermedius and Proteus mirabilis were the microorganisms that were most frequently identified according to gender and social organization. The antimicrobial susceptibility of the isolated gram-positive bacteria was similar in both sexes. However, the gram-negative strains had some differences. The aerobic bacterial population of the vaginal and preputial microbiota is similar in owl monkeys, and there are no differences in the number and bacterial species according to sex and social organization. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

Optically transparent membrane based on bacterial cellulose/ polycaprolactone

Optically transparent membranes from bacterial cellulose (BC)/polycaprolactone (PCL) have been prepared by impregnation of PCL acetone solution into dried BC membranes. UV-Vis measurements showed an increase on transparency in BC/PCL membrane when compared with pristine BC. The good transparency of the BC/PCL can be related to the presence of BC nanofibers associated with deposit of PCL nano-sized spherulites which are smaller than the wavelength of visible light and practically free of light scattering. XRD results show that cellulose type I structure is preserved inside the BC/PCL membrane, while the mechanical properties suggested indicated that PCL acts as a plasticizer for the BC membrane. The novel BC/PCL membrane could be used for preparation of fully biocompatible flexible display and biodegradable food packaging.

Simple green approach to reinforce natural rubber with bacterial cellulose nanofibers

Natural rubber (NR) is a renewable polymer with a wide range of applications, which is constantly tailored, further increasing its utilizations. The tensile strength is one of its most important properties susceptible of being enhanced by the simple incorporation of nanofibers. The preparation and characterization of natural-rubber based nanocomposites reinforced with bacterial cellulose (BC) and bacterial cellulose coated with polystyrene (BCPS), yielded high performance materials. The nanocomposites were prepared by a simple and green process, and characterized by tensile tests, dynamical mechanical analysis (DMA), scanning electron microscopy (SEM), and swelling experiments. The effect of the nanofiber content on morphology, static, and dynamic mechanical properties was also investigated. The results showed an increase in the mechanical properties, such as Young's modulus and tensile strength, even with modest nanofiber loadings. © 2013 American Chemical Society.

Molecular epidemiology of methicillin-resistant Staphylococcus aureus in a burn unit from Brazil

Methicillin-resistant Staphylococcus aureus (MRSA) poses a threat for patients in burn units. Studies that mix epidemiological designs with molecular typing may contribute to the development of strategies for MRSA control. We conducted a study including: molecular characterization of Staphylococcal Chromosome Cassette mecA (SCCmec), strain typing with pulsed field gel electrophoresis (PFGE) and detection of virulence genes, altogether with a case-case-control study that assessed risk factors for MRSA and for methicillin-susceptible S. aureus (MSSA), using S. aureus negative patients as controls. Strains were collected from clinical and surveillance cultures from October 2006 through March 2009. MRSA was isolated from 96 patients. Most isolates (94.8%) harbored SCCmec type III. SCCmec type IV was identified in isolates from four patients. In only one case it could be epidemiologically characterized as community-associated. PFGE typing identified 36 coexisting MRSA clones. When compared to MSSA (38 isolates), MRSA isolates were more likely to harbor two virulence genes: tst and lukPV. Previous stay in other hospital and admission to Intensive Care Unit were independent risk factors for both MRSA and MSSA, while the number of burn wound excisions was significantly related with the former (OR = 6.80, 95%CI = 3.54-13.07). In conclusion, our study found polyclonal endemicity of MRSA in a burn unit, possibly related to importing of strains from other hospitals. Also, it pointed out to a role of surgical procedures in the dissemination of MRSA strains. © 2013 Elsevier Ltd and ISBI. All rights reserved.

ZnO nanostructures directly grown on paper and bacterial cellulose substrates without any surface modification layer

In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures. © 2013 The Royal Society of Chemistry.

Flexible magnetic membranes based on bacterial cellulose and its evaluation as electromagnetic interference shielding material

Flexible magnetic membranes with high proportion of magnetite were successfully prepared by previous impregnation of the never dried bacterial cellulose pellicles with ferric chloride followed by reduction with sodium bisulfite and alkaline treatment for magnetite precipitation. Membranes were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating magnetometer, field emission scanning electron microscopy (FEG-SEM) and impedance spectroscopy. Microwave properties of these membranes were investigated in the X-band (8.2 to 12.4 GHz). FEG-SEM micrographs show an effective coverage of the BC nanofibers by Fe 3O4 nanoparticles. Membranes with up to 75% in weight of particles have been prepared after 60 min of reaction. Magnetite nanoparticles in the form of aggregates well adhered to the BC fibers were observed by SEM. The average crystal sizes of the magnetic particles were in the range of 10 ± 1 to 13 ± 1 nm (estimated by XRD). The magnetic particles in the BC pellicles presented superparamagnetic behavior with a saturation magnetization in the range of 60 emu g- 1 and coercive force around 15 Oe. These magnetic pellicles also displayed high electrical permittivity and a potential application as microwave absorber materials. © 2013 Elsevier B.V.

Staphylococcus aureus: resistência de virulência e tipagem de MRSA pelas técnicas de MLST e spa typing

Pós-graduação em Doenças Tropicais - FMB

MOLECULAR TYPING OF Giardia duodenalis ISOLATES FROM NONHUMAN PRIMATES HOUSED IN A BRAZILIAN ZOO

A pesquisa de infecções por Giardia e a caracterização genotípica deste protozoário foi realizada em primatas não humanos (PNH) mantidos em Zoológico a fim de avaliar o seu potencial zoonótico. As amostras dos animais consistiram de fezes colhidas do piso de 22 baias onde eram mantidos 47 primatas de 18 diferentes espécies. Exames coproparasitológicos foram realizados pelos métodos de concentração por sedimentação e centrífugo-flutuação e revelaram a presença dos seguintes parasitas e suas respectivas frequências: Giardia (18%); Entamoeba spp. (18%); Endolimax nana (4.5%); Iodamoeba spp. (4.5%); oxiurídeos (4.5%) e estrongilídeos (4.5%). O DNA extraído de todas as amostras fecais foi submetido à técnica de PCR para a amplificação dos genes gdh e tpi de Giardia, porém, só foram obtidos amplicons das quatro amostras positivas provenientes de Ateles belzebuth, Alouatta caraya, Alouatta fusca and Alouatta seniculus. O seqüenciamento dos fragmentos amplificados foi possível apenas para as amostras oriundas de Ateles belzebuth (BA1), Alouatta fusca (BA2) e Alouatta caraya (BA3), cuja análise fenética de ambos os genes revelou pertencerem ao genótipo A. As análises das sequências de tpi revelaram que todas as amostras pertencem ao subgenótipo AII. No que se refere ao gene gdh as análises revelaram uma amostra pertencente ao subgenótipo AII (BA3) e duas ao subgenótipo A1 (BA1 e BA2). Considerando o potencial zoonótico do genótipo A e o fato de que os animais não apresentavam sintomas de infecção, os dados do presente trabalho salientam a importância de se realizar, periodicamente, exames coproparasitológicos dos animais de zoológico, para implementação de medidas preventivas para resguardar a saúde dos animais em cativeiro, a de seus tratadores e dos visitantes de parques zoológicos.

Detecção dos genes de virulência e identificação do perfil clonal de isolados de Staphylococcus aureus colonizantes de nasofaringe otbtidos em estudo de base populacional

Pós-graduação em Doenças Tropicais - FMB

Bacterial cellulose/triethanolamine based ion-conducting membranes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modular Hyperthermostable Bacterial Endo-beta-1, 4-Mannanase: Molecular Shape, Flexibility and Temperature-Dependent Conformational Changes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)