86,558 research outputs found
The potential human exposure to antibiotic resistant-Escherichia coli through recreational water
No full textIt is important that bathing water sites are free as possible from antibiotic resistant bacteria (ARB) to prevent the spread of difficult to treat infections throughout the population. This study examines the possible human exposure to antibiotic resistant Escherichia coli (AR-E. coli) through recreational activities at two different bathing water sites located near wastewater treatment plants (WWTPs). A quantitative risk assessment model was created to model the pathway of the AR-E. coli from the WWTPs effluent water through to the bathing water sites. Both sampling data and data from scientific literature were used. The main steps considered for the model were: the dilution and decay of the AR-E. coli from the WWTPs effluent water into the river; the dilution of the river into the bathing water sites and the human exposure to AR-E. coli through recreational activities at the bathing water sites (as a result of water ingestion). The results show the mean predicted human exposure levels ranged between 0.45 and 345.09 cfu/100 ml. A back calculation method determined that in accordance with the European Bathing Water Directive (2006/7/EC) (BWD) to be considered “poor” water quality, the concentration of AR-E. coli in WWTP effluent water would need to exceed 2.45 log cfu/ml at site 1 and exceed 2.71 log cfu/ml at site 2. This study provides valuable information for regulatory bodies and policy makers on the possible human exposure levels to AR-E. coli and the maximum permissible concentrations in WWTP effluent water to ensure compliance with relevant bathing water legislation
Multifactorial aspects of antimicrobial activity of propolis
No full textWe investigated the antibacterial activity of sub-inhibitory concentrations of ethanolic extract of propolis (EEP), and its effect on the antibacterial activity of some antibiotics. Some clinically isolated Gram-positive strains were used. Moreover, sub-inhibitory concentrations of EEP were used to value its action on some important virulence factors like lipase and coagulase enzymes, and on biofilm formation in Staphylococcus aureus. Our results indicated that EEP had a significant antimicrobial activity towards all tested clinical strains. Adding EEP to antibacterial tested drugs, it drastically increased the antimicrobial effect of ampicillin, gentamycin and streptomycin, moderately the one of chloramphenicol, ceftriaxon and vancomycin, while there was no effect with erithromycin. Moreover, our results pointed out an inhibitory action of EEP on tipase activity of 18 Staphytococcus spp. strains and an inhibitory effect on coagulase of 11 S. aureus tested strains. The same EEP concentrations showed a negative interaction with adhesion and consequent biofilm formation in S. aureus ATCC 6538P. (c) 2006 Elsevier GmbH. All rights reserved
Microbiological quality control of single-walled carbon-nanotubes-coated surfaces experimentally contaminated
No full textThe emergence of new nanotechnologies involves the spreading of nanoparticles in various fields of human life. Nanoparticles in general and, more specifically, carbon nanotubes have been adopted for many practical approaches i.e.: coatings for medical devices, food process industry and drug delivery. Humans will be increasingly exposed to nanoparticles but the susceptibility of nanostructured materials to microbial colonization in process of manufacturing and storage has not been thoroughly considered. Therefore, the microbiological quality control of nanoparticles plays a pivotal role. Different analytical methods have been attempted for detecting bacterial population contaminating a surface, but no one can be considered fully appropriate. Here, BioTimer Assay (BTA) and conventional sonication followed by colony forming units method (S-CFU) were applied for microbiological quality control of single-walled carbon nanotubes (SWCNTs)-coated surfaces experimentally contaminated with Streptococcus mutans and Pseudomonas aeruginosa. Our results demonstrated that S-CFU is unreliable to actually determine the number of bacteria, contaminating abiotic surfaces, as it does not detach all adherent bacteria and kills part of the bacterial population. Instead, BTA is a reliable method to enumerate bacteria colonizing SWCNTs-coated surfaces and can be considered a useful tool for microbiological quality control of nanomaterials for human use. © Società Italiana di Fisica
Production of bacteriolytic enzymes as a tool for characterizing enterococci
No full textBacteriolytic enzymes secreted by log-phase cultures of enterococci (Enterococcus faecalis, Ent. faecium, Ent. durans, Ent. hirae, Ent. casseliflavus, Ent. avium, Ent. mundtii) were analysed by means of a zymogram technique to resolve activities according to the size of their polypeptide component and their specificities towards different substrates. Heterogeneous patterns of lytic activity were observed with different species. For each test substrate, homogeneous patterns of lytic activities were observed with strains of the same species, except for Ent. faecalis strains, which showed heterogeneous lytic patterns even towards the same substrate, and could be divided into at least four different groups according to their lytic pattern. No lytic activity was common to all strains tested. Results of zymogram analysis of Enterococcus bacteriolytic enzymes were consistent with current knowledge on enterococcal taxonomy, indicating that this analytical approach may be a useful tool for fine-tuned characterization of different enterococcal strains
The optimal exercise to rest ratios in repeated sprint ability training in youth soccer players.
No full textHuman exposure to antibiotic resistant-Escherichia coli through irrigated lettuce
No full textAntibiotic resistant bacteria (ARB) have been found on fresh fruit and vegetables globally. These types of ARB infections are spreading rapidly and are a major human health threat. A quantitative human exposure assessment model was created using scenario analysis to investigate the potential human exposure to antibiotic resistant Escherichia coli (AR-E. coli) through the consumption of lettuce irrigated with surface water. Scientific literature and site specific data were collected to model each process from farm to fork to calculate the concentration of AR-E. coli on the lettuce at the point of human consumption. The processes examined were the adhesion, colonisation and viability of bacteria on the lettuce; the effect of different post-harvest cleaning processes; the effect of consuming the lettuce before, on or after the expiry date; and the effect of the consumer washing the lettuce. The results show the mean human exposure levels ranged between 1.00 × 10−2 and 1.35 × 106 colony forming units (CFU) of AR-E. coli per 100 g of surface water irrigated lettuce for the different scenarios investigated. The mean probability of illness from consuming 100 g of lettuce contaminated with potential pathogenic antibiotic-sensitive E. coli was between 1.46 × 10−9 to 1.88 × 10−2. A back calculation revealed that in order for the EC No 1441/2007 regulation to be exceeded (≥1000 CFU/g of E. coli on lettuce at the manufacturing stage), the mean contamination levels required in the irrigation water would need to be 2.7, 3.1 or 4.8 log CFU/ml using the post-harvest treatments of washing with water, rapid cooling with water and washing with a chlorine solution respectively. The information generated from this model could help to set guidelines for producers on maximum permissible AR-E. coli contamination levels in irrigation water and provides recommendations on the best post-harvest treatment to use
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Thickness measurement of soft thin films on periodically patterned magnetic substrates by phase difference magnetic force microscopy
No full textThe need for accurate measurement of the thickness of soft thin films is continuously encouraging the development of techniques suitable for this purpose. We propose a method through which the thickness of the film is deduced from the quantitative measurement of the contrast in the phase images of the sample surface acquired by magnetic force microscopy, provided that the film is deposited on a periodically patterned magnetic substrate. The technique is demonstrated by means of magnetic substrates obtained from standard floppy disks. Colonies of Staphylococcus aureus adherent to such substrates were used to obtain soft layers with limited lateral (a few microns) and vertical (hundreds of nanometers) size. The technique is described and its specific merits, limitations and potentialities in terms of accuracy and measurable thickness range are discussed. These parameters depend on the characteristics of the sensing tip/cantilever as well as of the substrates, the latter in terms of spatial period and homogeneity of the magnetic domains. In particular, with the substrates used in this work we evaluated an uncertainty of about 10%, a limit of detection of 50-100. nm and an upper detection limit (maximum measurable thickness) of 1 μm, all obtained with standard lift height values (50-100. nm). Nonetheless, these parameters can be easily optimized by selecting/realizing substrates with suitable spacing and homogeneity of the magnetic domains. For example, the upper detection limit can be increased up to 25 - 50 μm while the limit of detection can be reduced to a few tens of nanometers or a few nanometers. © 2013 Elsevier B.V
Exercise-to-rest ratios in repeated sprint ability training in women's soccer
No full textBACKGROUND: The aim of this study was to investigate the applicability of three different exercise-to-rest ratios in repeated sprint ability (RSA) training in women's soccer players, applying those which are usually adopted in male adult and young players, when performing three different sprinting modes (straight, shuttle, and sprinting with changing of direction). METHODS: Fifteen trained female soccer players (height: 1.65±0.06 m; weight: 59.3±9.0 kg; BMI 21.6±2.7 kg/m2; age: 23.3±5.9 years) participated to the study. In order to compare the different values of the time recorded, an index of fatigue (IF%) was used. Recovery times among trials in the sets were administered according to the 1:5, 1:3, 1:2 exercise-to-rest ratio, respectively. Blood lactate concentrations at the end of each set were analyzed. RESULTS: Significant differences among trials within each set (repeated measures ANOVA; P<0.05) were found, as evidence of fatigue over time, with an average decay of performance of about 5% but no significant differences were found in IF%, among the three different sprinting modalities when applying the investigated exercise-to-rest ratios (factorial ANOVA; P>0.05). Significant differences were found in blood lactate concentrations (P<0.05). CONCLUSIONS: The results of this study confirm that the exercise-to-rest ratios considered in this study might be suitable to design effective testing protocols and training sessions aimed at the development of the RSA in women's soccer players, keeping the performances in the speed domain (IF% <7-8%) but inducing the fatigue processes sought with this kind of training method
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