1,720,969 research outputs found
Microbiological quality control of single-walled carbon-nanotubes-coated surfaces experimentally contaminated
Full text linkThe 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
Lactoferrin and cystic fibrosis airway infection
No full textAirway infections in subjects with cystic fibrosis (CF)
are the most difficult diseases to treat and represent a
real challenge in the management of patients with CF,
affecting their quality of life.
Lactoferrin (Lf), a cationic glycoprotein able to chelate two Fe3+ ions per molecule with high affinity is one of
the most important glycoproteins of natural immunity present in airway secretions. Recently, Lf has
emerged as an important regulator of iron and inflammatory
homeostasis, exerting multiple functions both
dependent and independent on its iron-withholding
ability.
Herein, the role of iron and Lf in CF airway infection
is revised
Influence of sub-inhibitory antibiotics and flow condition on Staphylococcus aureus ATCC 6538 biofilm development and biofilm growth rate: BioTimer assay as a study model.
No full textStaphylococcus biofilm exhibits high antibiotic resistance and therapeutic doses of antibiotics are often sub-inhibitory. Whereas data are available on the effect of sub-inhibitory antibiotics on matrix formation, little is known on their influence on biofilm population. Here, using BioTimer Assay (BTA), a method developed to quantify biofilm population, the influence of sub-inhibitory gentamicin, ofloxacin and azithromycin on Staphylococcus aureus ATCC 6538 biofilm population in flow with respect to static condition was assessed. Antibiotics and flow condition increased biofilm population even if at different extent, depending on the antibiotic molecule. The greatest bacterial population was found in biofilm developed under flow condition in the presence of azithromycin. A significant increase in biofilm matrix was recorded for biofilm developed in the presence of antibiotics in flow with respect to static condition. The growth rates (GRs) of 24-h biofilm developed under the influence of antibiotics and flow condition were also evaluated using BTA and a specific mathematical model. Antibiotics and flow condition affected the GRs of 24-h biofilm even if at different extent. The lowest GR value was recorded for biofilm developed under flow condition in the presence of ofloxacin. Although further studies are needed, our data indicate that antibiotics and flow condition influenced biofilm development by increasing both bacterial population and matrix formation and affected the GRs of the developed biofilm. To the best of our knowledge, BTA is unique in allowing the calculation of the GRs of biofilm and it may be considered to be a useful study model to evaluate the activity of antibiofilm molecules.The Journal of Antibiotics advance online publication, 28 May 2014; doi:10.1038/ja.2014.66
LACTOFERRIN DECREASES INFLAMMATORY RESPONSE BY CYSTIC FIBROSIS BRONCHIAL CELLS INVADED WITH BURKHOLDERIA CENOCEPACIA IRON-MODULATED BIOFILM
No full textIn cystic fibrosis (CF) high iron concentration in airway secretion plays a pivotal role in bacterial multiplication and biofilm formation as well as in inflammatory response. Burkholderia cenocepacia, an opportunistic facultative pathogen responsible for chronic lung infections and cepacia syndrome, recurrently infects CF patients. Lactoferrin (Lf), an iron binding multifunctional glycoprotein synthesized by exocrine glands and neutrophils, has been found at higher concentration in the airway secretions of infected CF patients than in healthy subjects. Here the influence of milk derivative bovine lactoferrin (bLf), an emerging important regulator of iron and inflammatory homeostasis, on invasiveness of B. cenocepacia iron-modulated biofilm, as well as on inflammatory response by infected CF bronchial (IB3-1) cells, is reported. bLf did not significantly affect invasion efficacy by biofilm-forming B. cenocepacia clinical strains. Conversely, the addition of bLf to cell monolayers during infection significantly decreased the pro-inflammatory Interleukin (IL)-1 beta and increased the anti-inflammatory IL-11 expression compared to that observed in cells infected in the absence of bLf. The bLf ability to modulate genes expressed following B. cenocepacia infection seems related to its localization to the nucleus of infected IB3-1 cells. These results provide evidence for a role of bLf in the protection of infected CF cells from inflammation-related damage, thus extending the therapeutic potential of this multifunctional natural protein
“BIOTIMER ASSAY”: UN NUOVO METODO PER CONTARE STAPHYLOCCCUS IN BIOFILM SENZA MANIPOLAZIONE DEL CAMPIONE E PER VALUTARNE LA SENSIBILITÀ AGLI ANTIBIOTICI.
No full textBioTimer Assay, a new method for counting Staphylococcus spp. in biofilm without sample manipulation applied to evaluate antibiotic susceptibility of biofilm
No full textThe medical device-related infections are frequently a consequence of Staphylococcus biofilm, a lifestyle enhancing bacterial resistance to antibiotics. Antibiotic susceptibility tests are usually performed on planktonic forms of clinical isolates. Some methods have been developed to perform antibiotic susceptibility tests on biofilm. However, none of them counts bacterial inoculum. As antibiotic susceptibility is related to bacterial inoculum, the test results could be mistaken. Here, a new method, BidTimer Assay (BTA), able to count bacteria in biofilm without any manipulation of samples, is presented. Moreover, the BTA method is applied to analyze antibiotic susceptibility of six Staphylococcus strains in biofilm and to deter-mine the number of viable bacteria in the presence of sub-inhibitory doses of four different antibiotics. To validate BTA, the new method was compared to reference methods both for counting and antibiotic susceptibility tests. A high agreement between BTA and reference methods is found on planktonic forms. Therefore, BTA was employed to count bacteria in biofilm and to analyze biofilm antibiotic susceptibility. Results confirm the high resistance to antibiotics of Staphylococcus biofilm. Moreover, BTA counts the number of viable bacteria in the presence of sub-inhibitory doses of antibiotics. The results show that the number of viable bacteria depends on sub-inhibitory doses, age of biofilm and type of antibiotic. In particular, differently to gentamicin and ampicillin, sub-inhibitory doses of ofloxacin and azithromycin reduce the number of viable bacteria at lower extent in young than in old biofilm. In conclusion, BTA is a reliable, rapid, easy-to-perform, and versatile method, and it can be considered a useful tool to analyze antibiotic susceptibility of Staphylococcus spp. in biofilm. Published by Elsevier B.V
STREPTOCOCCUS MUTANS AND STREPTOCOCCUS SOBRINUS ARE ABLE TO ADHERE AND INVADE HUMAN GINGIVAL FIBROBLAST CELL LINE
No full textStreptococcus mutans and Streptococcus sobrinus, the principal etiologic agents of caries decay of teeth, are generally acquired in oral cavity at the moment of tooth eruption. However, as S. mutans has been detected in oral cavity of predentate children, the eruption of teeth seems not to be a necessary prerequisite, suggesting that this species may be not confined to dental plaque. Here, we evaluate the ability of S. mutans and S. sobrinus in planktonic and biofilm lifestyle to adhere, invade and survive within human gingival fibroblast (HGF-1) cells. Planktonic and biofilm streptococci adhered and invaded host cells to different extents, showing higher efficiencies of biofilm than planktonic counterparts. Moreover, planktonic and biofilm streptococci showed the same percentage of survival within host cells. Transmission electron and confocal microscopy observations confirmed intracellular localization of planktonic and biofilm bacteria. The adhesion, invasion and survival abilities within human oral cells may be considered S. mutans and S. sobrinus virulence mechanisms to colonize and persist in the oral cavity in the absence of tooth surface
Bovine lactoferrin inhibits the efficiency of invasion of respiratory A549 cells of different iron-regulated morphological forms of Pseudomonas aeruginosa and Burkholderia cenocepacia
No full textPseudomonas aeruginosa and Burkholderia cenocepacia are two important opportunistic respiratory pathogens of cystic fibrosis (CF) patients. Infections caused by these microorganisms are particularly difficult to eradicate because they are usually highly resistant to several currently available broad-spectrum antibiotics. Lactoferrin (Lf), a glycoprotein found in physiological fluids of mammals and present at high concentrations in infected and inflamed tissues, plays an important role in the natural defence mechanism against pathogens and in immune regulation. In the present study, we evaluate the ability of bovine lactoferrin (W) to influence P aeruginosa PAO1 and B. cenocepacia PV1 adhesiveness and invasiveness, using the A549 human bronchial cell line. Three different iron-induced morphological forms of bacteria (free-living, aggregates and biofilm) were assayed. The addition of bLf to cells just before infection had little influence on adhesion efficiency for all three of the morphological forms of B. cenocepacia PV1, while a slight increase in adhesion efficiency by R aeruginosa PAO1 was noticed. Conversely, invasion of all three morphological forms of both P aeruginosa and B. cenocepacia was strongly inhibited by the presence of bLf, independently of its degree of iron-binding activity. This is the first report demonstrating an anti-invasive property of bLf for strains of R aeruginosa and B. cenocepacia
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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