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Ação do ácido undecilênico liberado por material reembasador sobre os biofilmes de Candida albicans ou Candida glabrata; Effects of undecylenic acid released from denture liner on Candida albicans or Candida glabrata biofilms

Letícia Machado Gonçalves
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/05/2012 PT
Relevância na Pesquisa
26.06%
Os materiais reembasadores para próteses dentais removíveis, após a exposição à cavidade bucal, apresentam alterações estruturais que facilitam a colonização por espécies de Candida. Neste contexto, o ácido undecilênico (AUD) tem sido incorporado na formulação deste material na tentativa de reduzir o desenvolvimento de biofilmes fúngicos. No entanto, concentrações de AUD liberadas pelo material reembasador e os efeitos destas sobre o desenvolvimento dos biofilmes de Candida ainda não foram elucidados. Por isso, a proposta deste estudo foi investigar a cinética de liberação do AUD a partir do material reembasador e avaliar o efeito deste sobre o desenvolvimento de biofilmes de C. albicans ou C. glabrata. Inicialmente, simulou-se in vitro a liberação do AUD na cavidade bucal através da imersão de corpos de prova de material reembasador (10 mm x 2 mm) em saliva artificial, sendo o produto da liberação quantificado através de cromatografia gasosa. Em seguida, a suscetibilidade de um isolado de referência e dois isolados clínicos de C. albicans (ATCC 90028, P01 e P34) e C. glabrata (ATCC 2001, P11 e P31) ao AUD foi investigada através da concentração inibitória mínima (CIM), concentração fungicida mínima (CFM) e tempo de morte celular (time-kill). Para avaliar o efeito do AUD sobre os biofilmes de Candida...

Action of a cationic surfactant on the activity and removal of bacterial biofilms formed under different flow regimes

Simões, M.; Pereira, Maria Olívia; Vieira, M. J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /01/2005 ENG
Relevância na Pesquisa
26.09%
The action of the cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated to control biofilms (aged 7 d) formed by Pseudomonas fluorescens on stainless-steel slides, using flow cells reactors, under turbulent and laminar flow. The effect of CTAB was also investigated using planktonic cells in the presence and absence of BSA, by measuring the cellular respiratory activity and the ATP released. The action of CTAB on biofilms was assessed by means of cellular respiratory activity and variation of biofilm mass, immediately and 3, 7 and 12 h after the application of CTAB. The physical stability of the biofilm was also assessed using a rotating device, where the effect of the surfactant on the biofilm stability was evaluated through the variation of the mass remaining on the surface. CTAB significantly reduced the activity of the planktonic cells probably due to the rupture of the cells. This effect was significantly reduced in the presence of BSA. Planktonic cells were more easily inactivated than bacteria in biofilms. Biofilms formed under laminar flow were more susceptible than those formed under turbulent flow, but in both cases total inactivation was not achieved. Biofilm recovery was observed, in terms of respiratory activity...

Gene expression of Staphylococcus epidermidis biofilm and biofilm released cells exposed to farnesol

Cerca, Nuno; França, Ângela; Gomes, F. I.; Teixeira, P.; Vilanova, Manuel; Oliveira, Rosário
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 ENG
Relevância na Pesquisa
35.83%

A first new look into the interaction of Staphylococcus epidermidis biofilm-released cells with the host immune system

França, Ângela; Pérez-Cabezas, B.; Carvalhais, V.; Freitas, Ana Isabel Costa; Pier, G.; Vilanova, Manuel; Cerca, Nuno
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2013 ENG
Relevância na Pesquisa
96.4%
The widespread application of indwelling medical devices in the clinical setting, together with the remarkable ability of the commensal Staphylococcus epidermidis to adhere to these surfaces and form biofilms, has given to this bacterium the recognition of being a leading causative agent of nosocomial infections. Biofilms lifecycle is currently divided into 4 main steps: initial adhesion, accumulation, maturation and, disassembly. Biofilm disassembly, the release of the cells within the biofilm into the involving environment, is the less understood of all steps despite its involvement in the development of several serious acute infections such as endocarditis, bacteremia and pneumonia. Hence, due to its important consequences in human health and disease, the study of the cells released from S. epidermidis biofilms is crucial to create effective therapeutic strategies against these serious infections. For that reason, in order to better characterize S. epidermidis biofilm-released cells, we assessed their cell properties by determining 1) the expression of key genes involved in initial adhesion, biofilm regulation and disassembly, 2) the total protein profile, 3) the susceptibility to routinely used antibiotics for the treatment of staphylococcal infection...

Characterization of the molecular interactions between Staphylococcus epidermidis biofilm infections and the host immune system

França, Ângela
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Tese de Doutorado
Publicado em 16/12/2013 ENG
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46.3%
Tese de doutoramento em "Biomedical Engineering"; Staphylococcus epidermidis ranks first among the causative agents of nosocomial infections associated with indwelling medical devices. This association is due to the microorganism’s ability to colonize the surface of these devices and form biofilms. The biofilm lifecycle is divided into initial adhesion, accumulation and maturation, and biofilm disassembly. The major clinical complications of biofilm formation is their high resistance to antimicrobials and to the host immune system, resulting in the development of chronic infections. To uncover the mechanisms by which biofilms evade the host immune system and cause chronic infections, a transcriptomic analysis of S. epidermidis biofilms exposed to human blood was performed. Our results revealed extensive changes in the transcriptome, suggesting that a quick adaptation to the new environment was made. Genes involved in amino acids biosynthesis and iron utilization were strongly affected, indicating that these mechanisms are important factors in S. epidermidis biofilm survival in human blood. The biofilm disassembly stage has been associated with the development of acute infections, however, despite its importance in the clinical setting...

Biofilm Dispersal of Neisseria subflava and Other Phylogenetically Diverse Oral Bacteria

Kaplan, Jeffrey B.; Fine, Daniel H.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /10/2002 EN
Relevância na Pesquisa
36.24%
Polystyrene petri dishes containing liquid medium were inoculated with single-cell suspensions of a fresh clinical isolate of Neisseria subflava and were incubated under conditions of low vibration. N. subflava colonies grew firmly attached to the surface of the dish, while the broth remained clear. Growing colonies released cells into the medium, resulting in the appearance of 102 to 104 small satellite colonies attached to the surface of the dish in an area adjacent to each mature colony after 24 h. Satellite colonies grew in patterns of streamers shaped like jets and flares emanating from mature colonies and pointing toward the center of the dish. This dispersal pattern evidently resulted from the surface translocation of detached biofilm cells by buoyancy-driven convection currents that were generated due to slight temperature gradients in the medium. Streamers of satellite colonies ranged from 2 to >40 mm in length. Satellite colonies in very long streamers were relatively uniform in size regardless of their distance from the mature colony, suggesting that mature colonies released single cells or small clusters of cells into the medium and that the detachment, surface translocation, and subsequent surface reattachment of released cells were a transitory process. Incubation of N. subflava single cells in a perfused biofilm fermentor resulted in a large spike of the number of CFU in the perfusate after 9.5 h of growth...

Biofilm Growth and Detachment of Actinobacillus actinomycetemcomitans

Kaplan, Jeffrey B.; Meyenhofer, Markus F.; Fine, Daniel H.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /02/2003 EN
Relevância na Pesquisa
36.23%
The gram-negative, oral bacterium Actinobacillus actinomycetemcomitans has been implicated as the causative agent of several forms of periodontal disease in humans. When cultured in broth, fresh clinical isolates of A. actinomycetemcomitans form tenacious biofilms on surfaces such as glass, plastic, and saliva-coated hydroxyapatite, a property that probably plays an important role in the ability of this bacterium to colonize the oral cavity and cause disease. We examined the morphology of A. actinomycetemcomitans biofilm colonies grown on glass slides and in polystyrene petri dishes by using light microscopy and scanning and transmission electron microscopy. We found that A. actinomycetemcomitans developed asymmetric, lobed biofilm colonies that displayed complex architectural features, including a layer of densely packed cells on the outside of the colony and nonaggregated cells and large, transparent cavities on the inside of the colony. Mature biofilm colonies released single cells or small clusters of cells into the medium. These released cells adhered to the surface of the culture vessel and formed new colonies, enabling the biofilm to spread. We isolated three transposon insertion mutants which produced biofilm colonies that lacked internal...

Detachment of Actinobacillus actinomycetemcomitans Biofilm Cells by an Endogenous β-Hexosaminidase Activity

Kaplan, Jeffrey B.; Ragunath, Chandran; Ramasubbu, Narayanan; Fine, Daniel H.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2003 EN
Relevância na Pesquisa
36.12%
When cultured in broth, fresh clinical isolates of the gram-negative periodontal pathogen Actinobacillus actinomycetemcomitans form tenaciously adherent biofilm colonies on surfaces such as plastic and glass. These biofilm colonies release adherent cells into the medium, and the released cells can attach to the surface of the culture vessel and form new colonies, enabling the biofilm to spread. We mutagenized A. actinomycetemcomitans clinical strain CU1000 with transposon IS903φkan and isolated a transposon insertion mutant that formed biofilm colonies which were tightly adherent to surfaces but which lacked the ability to release cells into the medium and disperse. The transposon insertion in the mutant strain mapped to a gene, designated dspB, that was predicted to encode a secreted protein homologous to the catalytic domain of the family 20 glycosyl hydrolases. A plasmid carrying a wild-type dspB gene restored the ability of biofilm colonies of the mutant strain to disperse. We expressed A. actinomycetemcomitans DspB protein engineered to contain a hexahistidine metal-binding site at its C terminus in Escherichia coli and purified the protein by using Ni affinity chromatography. Substrate specificity studies performed with monosaccharides labeled with 4-nitrophenyl groups showed that DspB hydrolyzed the 1→4 glycosidic bond of β-substituted N-acetylglucosamine...

Poly(3-Hydroxybutyrate) Biosynthesis in the Biofilm of Alcaligenes eutrophus, Using Glucose Enzymatically Released from Pulp Fiber Sludge

Zhang, Songping; Norrlöw, Olof; Wawrzynczyk, Joanna; Dey, Estera Szwajcer
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /11/2004 EN
Relevância na Pesquisa
26.08%
Glucose, enzymatically released from pulp fiber sludge, was combined with inorganic salts and used as a growth medium for Alcaligenes eutrophus, a gram-negative strain producing poly(3-hydroxybutyrate) (PHB). By controlling the concentrations of the inorganic salts in the growth medium, almost 78% of the cell mass was converted to pure PHB. Efforts were made to find conditions for bacterial growth in the form of a biofilm on a cheap and reusable carrier. A number of positively charged carriers were tested, and the anion exchanger DEAE-Sephadex A-25 was chosen as a microcarrier for packed-bed biofilm cultures of A. eutrophus. Conditions for attachment, growth, and detachment were established. Biofilm formation on the microcarrier is strongly dependent on the ionic strength of the attachment medium. In order to achieve formation of the biofilm and its recovery from the microcarrier, the ionic strengths of the attachment and the detachment media were varied. Low ionic strength was tested for attachment, and high ionic strength was tested for detachment. Although biofilm formation in the packed-bed reactor is limited, the volumetric yield of cells based on the void volume of the packed bed is comparable with the batch culture yield.

Interaction of Candida albicans with Adherent Human Peripheral Blood Mononuclear Cells Increases C. albicans Biofilm Formation and Results in Differential Expression of Pro- and Anti-Inflammatory Cytokines▿ †

Chandra, Jyotsna; McCormick, Thomas S.; Imamura, Yoshifumi; Mukherjee, Pranab K.; Ghannoum, Mahmoud A.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.11%
Monocytes and macrophages are the cell types most commonly associated with the innate immune response against Candida albicans infection. Interactions between the host immune system and Candida organisms have been investigated for planktonic Candida cells, but no studies have addressed these interactions in a biofilm environment. In this study, for the first time, we evaluated the ability of C. albicans to form biofilms in the presence or absence of adherent peripheral blood mononuclear cells (PBMCs; enriched for monocytes and macrophages by adherence). Our analyses using scanning electron and confocal scanning laser microscopy showed that the presence of PBMCs enhanced the ability of C. albicans to form biofilms and that the majority of PBMCs were localized to the basal and middle layers of the biofilm. In contrast to the interactions of PBMCs with planktonic C. albicans, where PBMCs phagocytose fungal cells, PBMCs did not appear to phagocytose fungal cells in biofilms. Furthermore, time-lapse laser microscopy revealed dynamic interactions between C. albicans and PBMCs in a biofilm. Additionally, we found that (i) only viable PBMCs influence Candida biofilm formation, (ii) cell surface components of PBMCs did not contribute to the enhancement of C. albicans biofilm...

The cidA murein hydrolase regulator contributes to DNA release and biofilm development in Staphylococcus aureus

Rice, Kelly C.; Mann, Ethan E.; Endres, Jennifer L.; Weiss, Elizabeth C.; Cassat, James E.; Smeltzer, Mark S.; Bayles, Kenneth W.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.02%
The Staphylococcus aureus cidA and lrgA genes have been shown to affect cell lysis under a variety of conditions during planktonic growth. It is hypothesized that these genes encode holins and antiholins, respectively, and may serve as molecular control elements of bacterial cell lysis. To examine the biological role of cell death and lysis, we studied the impact of the cidA mutation on biofilm development. Interestingly, this mutation had a dramatic impact on biofilm morphology and adherence. The cidA mutant (KB1050) biofilm exhibited a rougher appearance compared with the parental strain (UAMS-1) and was less adherent. Propidium iodide staining revealed that KB1050 accumulated more dead cells within the biofilm population relative to UAMS-1, indicative of reduced cell lysis. In agreement with this finding, quantitative real-time PCR experiments demonstrated the presence of 5-fold less genomic DNA in the KB1050 biofilm relative to UAMS-1. Furthermore, treatment of the UAMS-1 biofilm with DNase I caused extensive cell detachment, whereas similar treatment of the KB1050 biofilm had only a modest effect. These results demonstrate that cidA-controlled cell lysis plays a significant role during biofilm development and that released genomic DNA is an important structural component of S. aureus biofilm.

CO2 Production as an Indicator of Biofilm Metabolism▿ †

Kroukamp, Otini; Wolfaardt, Gideon M.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.05%
Biofilms are important in aquatic nutrient cycling and microbial proliferation. In these structures, nutrients like carbon are channeled into the production of extracellular polymeric substances or cell division; both are vital for microbial survival and propagation. The aim of this study was to assess carbon channeling into cellular or noncellular fractions in biofilms. Growing in tubular reactors, biofilms of our model strain Pseudomonas sp. strain CT07 produced cells to the planktonic phase from the early stages of biofilm development, reaching pseudo steady state with a consistent yield of ∼107 cells·cm−2·h−1 within 72 h. Total direct counts and image analysis showed that most of the converted carbon occurred in the noncellular fraction, with the released and sessile cells accounting for <10% and <2% of inflowing carbon, respectively. A CO2 evolution measurement system (CEMS) that monitored CO2 in the gas phase was developed to perform a complete carbon balance across the biofilm. The measurement system was able to determine whole-biofilm CO2 production rates in real time and showed that gaseous CO2 production accounted for 25% of inflowing carbon. In addition, the CEMS made it possible to measure biofilm response to changing environmental conditions; changes in temperature or inflowing carbon concentration were followed by a rapid response in biofilm metabolism and the establishment of new steady-state conditions.

Application of a Bacteriophage Lysin To Disrupt Biofilms Formed by the Animal Pathogen Streptococcus suis ▿ †

Meng, Xiangpeng; Shi, Yibo; Ji, Wenhui; Meng, Xueling; Zhang, Jing; Wang, Hengan; Lu, Chengping; Sun, Jianhe; Yan, Yaxian
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2011 EN
Relevância na Pesquisa
26.02%
Bacterial biofilms are crucial to the pathogenesis of many important infections and are difficult to eradicate. Streptococcus suis is an important pathogen of pigs, and here the biofilm-forming ability of 32 strains of this species was determined. Significant biofilms were completely formed by 10 of the strains after 60 h of incubation, with exopolysaccharide production in the biofilm significantly higher than that in the corresponding planktonic cultures. S. suis strain SS2-4 formed a dense biofilm, as revealed by scanning electron microscopy, and in this state exhibited increased resistance to a number of antibiotics (ampicillin, amoxicillin, ciprofloxacin, kanamycin, and rifampin) compared to that of planktonic cultures. A bacteriophage lysin, designated LySMP, was used to attack biofilms alone and in combination with antibiotics and bacteriophage. The results demonstrated that the biofilms formed by S. suis, especially strains SS2-4 and SS2-H, could be dispersed by LySMP and with >80% removal compared to a biofilm reduction by treatment with either antibiotics or bacteriophage alone of less than 20%; in addition to disruption of the biofilm structure, the S. suis cells themselves were inactivated by LySMP. The efficacy of LySMP was not dose dependent...

The Immunomodulatory Activity of Staphylococcus aureus Products Derived from Biofilm and Planktonic Cultures

Sadowska, Beata; Więckowska-Szakiel, Marzena; Paszkiewicz, Małgorzata; Różalska, Barbara
Fonte: Springer Basel Publicador: Springer Basel
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.02%
Biofilms are probably one of the most common structures formed by microorganisms in various environments. The higher resistance of such microbial communities to stress conditions, including antibiotics and host immune response, is recently extensively studied. However, the weak activity of phagocytic cells against microbial biofilm is not yet fully understood and explained. The aim of this study was: (1) a qualitative and quantitative comparison of cell components/products released from Staphylococcus aureus biofilm or planktonic cultures, (2) evaluation of the influence of such cell components/products on murine leukocytes secretory function. For this, mouse peritoneal leukocytes were stimulated with biofilm or planktonic staphylococcal cultures or their acellular filtrates, and then the production of cytokines (TNF-α, IL-6, IL-10, MCP-1 and MIP-1α), hemolytic activity and staphylokinase (SAK) production was determined. It was found that similar staphylococcal components/products possessing the immunomodulatory properties, were present in both, biofilm and planktonic filtrates. Moreover, these compounds were similarly active in the stimulation of TNF-α and MCP-1 release from leukocytes. The hemolytic activity and SAK release by planktonic and biofilm cultures were also comparable. What is interesting...

Biofilm Matrix Exoproteins Induce a Protective Immune Response against Staphylococcus aureus Biofilm Infection

Gil, Carmen; Solano, Cristina; Burgui, Saioa; Latasa, Cristina; García, Begoña; Toledo-Arana, Alejandro; Lasa, Iñigo; Valle, Jaione
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/2014 EN
Relevância na Pesquisa
26.04%
The Staphylococcus aureus biofilm mode of growth is associated with several chronic infections that are very difficult to treat due to the recalcitrant nature of biofilms to clearance by antimicrobials. Accordingly, there is an increasing interest in preventing the formation of S. aureus biofilms and developing efficient antibiofilm vaccines. Given the fact that during a biofilm-associated infection, the first primary interface between the host and the bacteria is the self-produced extracellular matrix, in this study we analyzed the potential of extracellular proteins found in the biofilm matrix to induce a protective immune response against S. aureus infections. By using proteomic approaches, we characterized the exoproteomes of exopolysaccharide-based and protein-based biofilm matrices produced by two clinical S. aureus strains. Remarkably, results showed that independently of the nature of the biofilm matrix, a common core of secreted proteins is contained in both types of exoproteomes. Intradermal administration of an exoproteome extract of an exopolysaccharide-dependent biofilm induced a humoral immune response and elicited the production of interleukin 10 (IL-10) and IL-17 in mice. Antibodies against such an extract promoted opsonophagocytosis and killing of S. aureus. Immunization with the biofilm matrix exoproteome significantly reduced the number of bacterial cells inside a biofilm and on the surrounding tissue...

Surface-Mediated Release of a Small-Molecule Modulator of Bacterial Biofilm Formation: A Non-Bactericidal Approach to Inhibiting Biofilm Formation in Pseudomonas aeruginosa

Broderick, Adam H.; Breitbach, Anthony S.; Frei, Reto; Blackwell, Helen E.; Lynn, David M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.03%
We report an approach to preventing bacterial biofilm formation that is based on the surface-mediated release of 5,6-dimethyl-2-aminobenzimidazole (DMABI), a potent and non-bactericidal small-molecule inhibitor of bacterial biofilm growth. Our results demonstrate that DMABI can be encapsulated in thin films of a model biocompatible polymer [poly(lactide-co-glycolide), PLG] and be released in quantities that inhibit the formation of Pseudomonas aeruginosa biofilms by up to 75–90% on surfaces that otherwise support robust biofilm growth. This approach enables the release of this new anti-biofilm agent for over one month, and it can be used to inhibit biofilm growth on both film-coated surfaces and other adjacent surfaces (e.g., on other uncoated surfaces and at air/water interfaces). Our results demonstrate a non-bactericidal approach to the prevention of biofilm growth and provide proof of concept using a clinically relevant human pathogen. In contrast to coatings designed to kill bacteria on contact, this release-based approach should also permit the design of strategically placed depots that disseminate DMABI more broadly and exert inhibitory effects over larger areas, which could prove useful in applications where the design or function of a surface prohibits the application of a uniform coating. This approach could also be used to design new polymer-coated surfaces useful for fundamental studies of bacterial biofilm growth. In a broader context...

Osteocompatibility of Biofilm Inhibitors

Rawson, Monica; Haggard, Warren; Jennings, Jessica A
Fonte: Bentham Open Publicador: Bentham Open
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.07%
The demand for infection prevention therapies has led to the discovery of several biofilm inhibitors. These inhibiting signals are released by bacteria, fungi, or marine organisms to signal biofilm dispersal or disruption in Gram-positive, Gram-negative, and fungal microorganisms. The purpose of this study was to test the biocompatibility of five different naturally-produced biofilm chemical dispersal and inhibition signals with osteoblast-like cells: D-amino acids (D-AA), lysostaphin (LS), farnesol, cis-2-decenoic acid (C2DA), and desformyl flustrabromine (dFBr). In this preliminary study, compatibility of these anti-biofilm agents with differentiating osteoblasts was examined over a 21 days period at levels above and below concentrations active against bacterial biofilm. Anti-biofilm compounds listed above were serially diluted in osteogenic media and added to cultures of MC3T3 cells. Cell viability and cytotoxicity, after exposure to each anti-biofilm agent, were measured using a DNA assay. Differentiation characteristics of osteoblasts were determined qualitatively by observing staining of mineral deposits and quantitatively with an alkaline phosphatase assay. D-AA, LS, and C2DA were all biocompatible within the reported biofilm inhibitory concentration ranges and supported osteoblast differentiation. Farnesol and dFBr induced cytotoxic responses within the reported biofilm inhibitory concentration range and low doses of dFBr were found to inhibit osteoblast differentiation. At high concentrations...

Ciprofloxacin-Eluting Nanofibers Inhibits Biofilm Formation by Pseudomonas aeruginosa and a Methicillin-Resistant Staphylococcus aureus

Ahire, Jayesh J.; Neveling, Deon P.; Hattingh, Melanie; Dicks, Leon M. T.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 08/04/2015 EN
Relevância na Pesquisa
26.09%
Pseudomonas aeruginosa and Staphylococcus aureus are commonly associated with hospital-acquired infections and are known to form biofilms. Ciprofloxacin (CIP), which is normally used to treat these infections, is seldom effective in killing cells in a biofilm. This is mostly due to slow or weak penetration of CIP to the core of biofilms. The problem is accentuated by the release of CIP below MIC (minimal inhibitory concentration) levels following a rapid (burst) release. The aim of this study was to develop a drug carrier that would keep CIP above MIC levels for an extended period. Ciprofloxacin was suspended into poly(D,L-lactide) (PDLLA) and poly(ethylene oxide) (PEO), and electrospun into nanofibers (CIP-F). All of the CIP was released from the nanofibers within 2 h, which is typical of a burst release. However, 99% of P. aeruginosa PA01 cells and 91% of S. aureus Xen 30 cells (a methicillin-resistant strain) in biofilms were killed when exposed to CIP-F. CIP levels remained above MIC for 5 days, as shown by growth inhibition of the cells in vitro. The nanofibers were smooth in texture with no bead formation, as revealed by scanning electron and atomic force microscopy. A single vibration peak at 1632 cm-1, recorded with Fourier transform infrared spectroscopy...

The ΔF508-CFTR mutation results in increased biofilm formation by Pseudomonas aeruginosa by increasing iron availability

Moreau-Marquis, Sophie; Bomberger, Jennifer M.; Anderson, Gregory G.; Swiatecka-Urban, Agnieszka; Ye, Siying; O'Toole, George A.; Stanton, Bruce A.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.13%
Enhanced antibiotic resistance of Pseudomonas aeruginosa in the cystic fibrosis (CF) lung is thought to be due to the formation of biofilms. However, there is no information on the antibiotic resistance of P. aeruginosa biofilms grown on human airway epithelial cells or on the effects of airway cells on biofilm formation by P. aeruginosa. Thus we developed a coculture model and report that airway cells increase the resistance of P. aeruginosa to tobramycin (Tb) by >25-fold compared with P. aeruginosa grown on abiotic surfaces. Therefore, the concentration of Tb required to kill P. aeruginosa biofilms on airway cells is 10-fold higher than the concentration achievable in the lungs of CF patients. In addition, CF airway cells expressing ΔF508-CFTR significantly enhanced P. aeruginosa biofilm formation, and ΔF508 rescue with wild-type CFTR reduced biofilm formation. Iron (Fe) content of the airway in CF is elevated, and Fe is known to enhance P. aeruginosa growth. Thus we investigated whether enhanced biofilm formation on ΔF508-CFTR cells was due to increased Fe release by airway cells. We found that airway cells expressing ΔF508-CFTR released more Fe than cells rescued with WT-CFTR. Moreover, Fe chelation reduced biofilm formation on airway cells...

Role of Surface Protein SasG in Biofilm Formation by Staphylococcus aureus▿

Geoghegan, Joan A.; Corrigan, Rebecca M.; Gruszka, Dominika T.; Speziale, Pietro; O'Gara, James P.; Potts, Jennifer R.; Foster, Timothy J.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.06%
The SasG surface protein of Staphylococcus aureus has been shown to promote the formation of biofilm. SasG comprises an N-terminal A domain and repeated B domains. Here we demonstrate that SasG is involved in the accumulation phase of biofilm, a process that requires a physiological concentration of Zn2+. The B domains, but not the A domain, are required. Purified recombinant B domain protein can form dimers in vitro in a Zn2+-dependent fashion. Furthermore, the protein can bind to cells that have B domains anchored to their surface and block biofilm formation. The full-length SasG protein exposed on the cell surface is processed within the B domains to a limited degree, resulting in cleaved proteins of various lengths being released into the supernatant. Some of the released molecules associate with the surface-exposed B domains that remain attached to the cell. Studies using inhibitors and mutants failed to identify any protease that could cause the observed cleavage within the B domains. Extensively purified recombinant B domain protein is very labile, and we propose that cleavage occurs spontaneously at labile peptide bonds and that this is necessary for biofilm formation.