Investigation of the antimicrobial activity of the essential oil of Cymbopogon martini on S. aureus and E. coli biofilms

Biofilms are sessile communities of microbial cells embedded in an exopolymeric secreted matrix that can adhere both to abiotic and living surfaces, serving as a permanent source of contamination. Essential oils (EOs) have different characteristics depending on the plant due to a large number of compounds (eugenol, citral, carvacrol, among others). It has been noticed that EOs have promising antibacterial activity that can be explored as an effective alternative to control biofilms. The aim of this study was to assess the antimicrobial activity of the essential oil of Cymbopogon martini against pre-established single biofilms developed by Staphylococcus aureus and Escherichia coli. Biofilms were developed in 96-well microtiter plates for 24 h at 37 ºC, in an orbital shaker at 120 rpm, being afterwards submitted to EOs aggression for 15, 30 e 60 minutes. The essential oil were dissolved in DMSO (2.0 %) and saline water (0.85 %) with tween 80 (0.5 %) in order to obtain final concentrations of 0,12, 0,48, 0,96 and 1,92 %. Biofilms were characterized, before and after EO treatment, by total biomass, through crystal violet (CV), and number of cultivable bacterial cells, expressed as Log CFU per cm2. The C. martini essential oil did not have any effective antimicrobial action against S. aureus biofilms, since there was no significant reduction of the biofilm cultivable cells and biomass. Conversely, this essential oil showed a promising antimicrobial activity against E.coli biofilms as it was observed a significant reduction of the cultivable biofilm-growing cells, in general, for all the concentrations tested and exposure time periods. Similarly to S.aureus biofilms, the C. martinii essential oil was not effective in reducing the biomass of E. coli. From the data, it can be concluded that under the conditions tested, the C. martinii essential oil was more effective in the inhibition of the bacterial cells entrapped in E. coli biofilms than in the removal of biofilm mass. This inability to remove biofilm s from surfaces can be a drawback since the viable cells remaining within the biofilms after EOs treatment are protected by the exopolysaccharides matrix, allowing its multiplication. To overcome this situation, it would be interesting to assess the anti-biofilm potential of the C. martinii essential oil, as well as its synergistic activity with an antimicrobial agent with biofilm disrupting properties

Antibiofilm effect of some main components of essentials oils on E. coli biofilm

Fundação para a Ciência e Tecnologia (FCT)European Community - fund FEDER, through Program COMPETE, Project PTDC/SAUESA/6460912006 /FCOMP-01-0124-FEDER-00748

Effect of essential oils on the planktonic of S. aureus and E. coli cells

The essential oils of aromatic plants and their components have a wide range of applications in ethno-medicine, preservation, food flavoring and fragrances and in the perfume industries. Some essential oils derived from plants have revealed promising antimicrobial activity against a wide range of bacteria, including antibiotic resistant species. The aim of this study was to examine the antimicrobial effect of essential oils of Cinnamomum zeylanicum and Cymbopogon martini against planktonic Staphylococcus aureus and Escherichia coli growth. The antimicrobial activity of the essential oils was checked by bacterial growth, at 37 ºC and 120 rpm, in the presence of increasing concentrations of each essential oil for 24 h. Essential oils were dissolved in DMSO (2.0 %) and saline water (0.85 %) with tween 80 (0.5 %) in order to obtain final concentrations of 0.06 %, 0.09 % and 0.12%, for E. coli, and 0.09 %, 0, 12 %, 0.36 % and 0.48 %, for S. aureus. Bacterial planktonic growth over time was followed by the quantification of the number of viable through cultivation of aliquots in TSA. Data showed that E. coli was more sensitive to the action of both essential oils, since complete planktonic growth inhibition was attained with a concentration of 0.09 % of the essential oil of C. zeylanicum oil and 0.06 % of the essential oil of C. Martini. Conversely, S. aureus was less sensitive to the antimicrobial action of the essential oils. C. zeylanicum essential oil inhibited S. aureus growth only at concentrations of 0.36 % and 0.48 %, after 4 and 2 hours of growth. However, unexpectedly after 24 hours those S. aureus cells recovered gradually their planktonic growth. The data pointed out that it is crucial to check the bacterial behavior in the presence of antimicrobial products in different concentrations and over time due to the possible development of bacterial tolerance towards the mechanisms of action of those products. In fact, antimicrobials may have a positive effect in the early hours of application, as demonstrated by some results of this experiment. However, for longer times, the inhibitory effect of antimicrobials can be reverted by bacteria making ineffective their use as disinfectants in food industries. Addiotionally, the continuous exposure of bacteria to antimicrobials can influence the process of microbial resistance de development and increase. These preliminary results demonstrated the possibility of using essential oils of C. zeylanicum and C. martini against two bacteria that are responsible for foodborne illnesses at low concentrations but only for slightly prolonged periods of exposure

Susceptibility of monospecies and dual-species biofilms of Staphylococcus aureus and Escherichia coli to essential oils

The aim of this study was to investigate the susceptibility of Staphylococcus aureus and Escherichia coli biofilms formed on the polypropylene surface. The cultures were developed for 240 h, planktonic growth was characterized by colony-forming unit (cfu)/mL and biofilms was characterized by quantifying biomass and cfu/cm2. Essential oils (EOs) of citronella and lemon were extracted by hydrodistillation and characterized by gas chromatography. Biofilm formation occured after 3 h of contact. In dual-species biofilms, there was competition; S. aureus was the number of viable cells damaged by E. coli (P < 0.05). The EOs disinfectant action was similar in biofilms monospecies, viable cells and biomass decreased significantly. Dual-species biofilms were more resistant to EOs. The action EOs on biofilm suggest promising alternatives to sanitize industrial polypropylene surfaces.The authors thank the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) for the first author's scholarship, the Fundacao de Amparo a Pesquisa do estado de Minas Gerais (FAPEMIG) for the financial support, the Foundation for Science and Technology and European Community fund European Regional Development Fund (FEDER), in the ambit of the Project PTDC/SAUESA/6460912006/FCOMP-01-0124-FEDER-007480

The association of hydration status with physical signs, symptoms and survival in advanced cancer-The use of Bioelectrical Impedance Vector Analysis (BIVA) technology to evaluate fluid volume in palliative care: An observational study

Background Hydration in advanced cancer is a controversial area; however, current hydration assessments methods are poorly developed. Bioelectrical impedance vector analysis (BIVA) is an accurate hydration tool; however its application in advanced cancer has not been explored. This study used BIVA to evaluate hydration status in advanced cancer to examine the association of fluid status with symptoms, physical signs, renal biochemical measures and survival. Materials and methods An observational study of 90 adults with advanced cancer receiving care in a UK specialist palliative care inpatient unit was conducted. Hydration status was assessed using BIVA in addition to assessments of symptoms, physical signs, performance status, renal biochemical measures, oral fluid intake and medications. The association of clinical variables with hydration was evaluated using regression analysis. A survival analysis was conducted to examine the influence of hydration status and renal failure. Results The hydration status of participants was normal in 43 (47.8%), 'more hydrated' in 37 (41.1%) and 'less hydrated' in 10 (11.1%). Lower hydration was associated with increased symptom intensity (Beta = -0.29, p = 0.04) and higher scores for physical signs associated with dehydration (Beta = 10.94, p = 0.02). Higher hydration was associated with oedema (Beta = 2.55, p<0.001). Median survival was statistically significantly shorter in 'less hydrated' patients (44 vs. 68 days; p = 0.049) and in pre-renal failure (44 vs. 100 days; p = 0.003). Conclusions In advanced cancer, hydration status was associated with clinical signs and symptoms. Hydration status and pre-renal failure were independent predictors of survival. Further studies can establish the utility of BIVA as a standardised hydration assessment tool and explore its potential research application, in order to inform the clinical management of fluid balance in patients with advanced cancer

The Three Dimensions of Archaeology - Introduction

This volume brings together presentations from two sessions organized for the XVII World UISPP Conference that was held from 1-7 September 2014 in Burgos (Spain). The sessions are: The scientific value of 3D archaeology, organised by Hans Kamermans, Chiara Piccoli and Roberto Scopigno, and Detecting the Landscape(s) – Remote Sensing Techniques from Research to Heritage Management, organised by Axel Posluschny and Wieke de Neef. The common thread amongst the papers presented here is the application of digital recording techniques to enhance the documentation and analysis of the spatial component intrinsically present in archaeological data. For a long time the capturing of the third dimension, the depth, the height or z-coordinate, was problematic. Traditionally, excavation plans and sections were documented in two dimensions. Objects were also recorded in two dimensions, often from different angles. Remote sensing images like aerial photographs were represented as flat surfaces. Although depth could be visualized with techniques such as stereoscopes, analysis of relief was troublesome. All this changed at the end of the last century with the introduction of computer based digitization technologies, 3D software, and digital near-surface sampling devices. The spatial properties of the multi-scale archaeological dataset can now be accurately recorded, analysed and presented. Relationships between artefacts can be clarified by visualizing the records in a three dimensional space, computer-based simulations can be made to test hypotheses on the past use of space, remote sensing techniques help in detecting previously hidden features of landscapes, thus shedding light on bygone land uses.  Digital Archaeolog

OCORRÊNCIA DE CEPAS DE ESTAFILOCOCOS COAGULASE POSITIVA FORMADORAS DE COLÔNIAS ATÍPICAS EM ÁGAR BAIRD-PARKER EM QUEIJOS MATURADOS

Avaliou-se a presença de cepas de estafilococos coagulase positiva formadoras de colônias atípicas em 16 queijos maturados de vários tipos comercializados na cidade de Lavras, MG (Brasil). Diluições apropriadas foram semeadas em ágar Baird-Parker e as colônias isoladas foram submetidas à coloração de Gram e às provas de catalase, de oxidase, de coagulase, de termonuclease, de crescimento em aerobiose, em anaerobiose e em presença de NaCl 15%. Das 43 colônias atípicas avaliadas, 28 (65,1%) foram confirmadas como estafilococos produtores de coagulase e 10 (23,3%) identificadas como S. aureus. Colônias atípicas em ágar Baird-Parker obtidas de queijos maturados devem ser submetidas a testes para identificação, pois podem corresponder a cepas produtoras de toxinas. OCURRENCE OF COAGULASE POSITIVE STAPHYLOCOCCUS STRAINS FORMING ATYPICAL COLONIES IN BAIRD-PARKER AGAR ON RIPENED CHEESE Abstract The presence of coagulase positive staphylococcus strains forming atypical colonies were evaluated in 16 ripened cheeses of various sorts marketed in the city of Lavras. Adequate dilutions were plated on Baird-Parker agar and the isolate colonies were subjected to the Gram staining and tests of catalase, oxidase, coagulase, thermonuclease, growth in aerobiosis, in anaerobiosis and in the presence of 15% NaCl. Out of the 43 atypical colonies evaluated, 28 (65.1%) were confirmed as coagulase positive Staphylococcus strains and 10 (23.35%) were identified as S. aureus. Atypical colonies in Baird-Parker agar originated from ripened cheeses must be subjected to tests for identification, since they may correspond to enterotoxin-producing strain

Effects of anisotropic interactions on the structure of animal groups

This paper proposes an agent-based model which reproduces different structures of animal groups. The shape and structure of the group is the effect of simple interaction rules among individuals: each animal deploys itself depending on the position of a limited number of close group mates. The proposed model is shown to produce clustered formations, as well as lines and V-like formations. The key factors which trigger the onset of different patterns are argued to be the relative strength of attraction and repulsion forces and, most important, the anisotropy in their application.Comment: 22 pages, 9 figures. Submitted. v1-v4: revised presentation; extended simulations; included technical results. v5: added a few clarification

Predição da resistência genética ao carrapato de bovinos Braford e Hereford a partir de um painel denso de marcadores moleculares.

O problema do carrapato bovino; A alternativa da seleção genômica; Resultados experimentais; Procedimentos para aplicação prática; Considerações finais.bitstream/item/77131/1/CT41.pd

Pedestrians moving in dark: Balancing measures and playing games on lattices

We present two conceptually new modeling approaches aimed at describing the motion of pedestrians in obscured corridors: * a Becker-D\"{o}ring-type dynamics * a probabilistic cellular automaton model. In both models the group formation is affected by a threshold. The pedestrians are supposed to have very limited knowledge about their current position and their neighborhood; they can form groups up to a certain size and they can leave them. Their main goal is to find the exit of the corridor. Although being of mathematically different character, the discussion of both models shows that it seems to be a disadvantage for the individual to adhere to larger groups. We illustrate this effect numerically by solving both model systems. Finally we list some of our main open questions and conjectures