Готові списки джерел за темами / Staphylococcus aureus biofilms

Добірка наукової літератури з теми "Staphylococcus aureus biofilms"

Автор: Grafiati
Опубліковано: 10 грудня 2022
Оновлено: 28 січня 2023

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Статті в журналах з теми "Staphylococcus aureus biofilms"

1

Wu, Julie A., Caroline Kusuma, James J. Mond, and John F. Kokai-Kun. "Lysostaphin Disrupts Staphylococcus aureus and Staphylococcus epidermidis Biofilms on Artificial Surfaces." Antimicrobial Agents and Chemotherapy 47, no. 11 (November 2003): 3407–14. http://dx.doi.org/10.1128/aac.47.11.3407-3414.2003.

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ABSTRACT Staphylococci often form biofilms, sessile communities of microcolonies encased in an extracellular matrix that adhere to biomedical implants or damaged tissue. Infections associated with biofilms are difficult to treat, and it is estimated that sessile bacteria in biofilms are 1,000 to 1,500 times more resistant to antibiotics than their planktonic counterparts. This antibiotic resistance of biofilms often leads to the failure of conventional antibiotic therapy and necessitates the removal of infected devices. Lysostaphin is a glycylglycine endopeptidase which specifically cleaves the pentaglycine cross bridges found in the staphylococcal peptidoglycan. Lysostaphin kills Staphylococcus aureus within minutes (MIC at which 90% of the strains are inhibited [MIC90], 0.001 to 0.064 μg/ml) and is also effective against Staphylococcus epidermidis at higher concentrations (MIC90, 12.5 to 64 μg/ml). The activity of lysostaphin against staphylococci present in biofilms compared to those of other antibiotics was, however, never explored. Surprisingly, lysostaphin not only killed S. aureus in biofilms but also disrupted the extracellular matrix of S. aureus biofilms in vitro on plastic and glass surfaces at concentrations as low as 1 μg/ml. Scanning electron microscopy confirmed that lysostaphin eradicated both the sessile cells and the extracellular matrix of the biofilm. This disruption of S. aureus biofilms was specific for lysostaphin-sensitive S. aureus, as biofilms of lysostaphin-resistant S. aureus were not affected. High concentrations of oxacillin (400 μg/ml), vancomycin (800 μg/ml), and clindamycin (800 μg/ml) had no effect on the established S. aureus biofilms in this system, even after 24 h. Higher concentrations of lysostaphin also disrupted S. epidermidis biofilms.
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2

Izano, Era A., Matthew A. Amarante, William B. Kher, and Jeffrey B. Kaplan. "Differential Roles of Poly-N-Acetylglucosamine Surface Polysaccharide and Extracellular DNA in Staphylococcus aureus and Staphylococcus epidermidis Biofilms." Applied and Environmental Microbiology 74, no. 2 (November 26, 2007): 470–76. http://dx.doi.org/10.1128/aem.02073-07.

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ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis are major human pathogens of increasing importance due to the dissemination of antibiotic-resistant strains. Evidence suggests that the ability to form matrix-encased biofilms contributes to the pathogenesis of S. aureus and S. epidermidis. In this study, we investigated the functions of two staphylococcal biofilm matrix polymers: poly-N-acetylglucosamine surface polysaccharide (PNAG) and extracellular DNA (ecDNA). We measured the ability of a PNAG-degrading enzyme (dispersin B) and DNase I to inhibit biofilm formation, detach preformed biofilms, and sensitize biofilms to killing by the cationic detergent cetylpyridinium chloride (CPC) in a 96-well microtiter plate assay. When added to growth medium, both dispersin B and DNase I inhibited biofilm formation by both S. aureus and S. epidermidis. Dispersin B detached preformed S. epidermidis biofilms but not S. aureus biofilms, whereas DNase I detached S. aureus biofilms but not S. epidermidis biofilms. Similarly, dispersin B sensitized S. epidermidis biofilms to CPC killing, whereas DNase I sensitized S. aureus biofilms to CPC killing. We concluded that PNAG and ecDNA play fundamentally different structural roles in S. aureus and S. epidermidis biofilms.
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3

Saising, Jongkon, Linda Dube, Anne-Kathrin Ziebandt, Supayang Piyawan Voravuthikunchai, Mulugeta Nega, and Friedrich Götz. "Activity of Gallidermin on Staphylococcus aureus and Staphylococcus epidermidis Biofilms." Antimicrobial Agents and Chemotherapy 56, no. 11 (August 27, 2012): 5804–10. http://dx.doi.org/10.1128/aac.01296-12.

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ABSTRACTDue to their abilities to form strong biofilms,Staphylococcus aureusandStaphylococcus epidermidisare the most frequently isolated pathogens in persistent and chronic implant-associated infections. As biofilm-embedded bacteria are more resistant to antibiotics and the immune system, they are extremely difficult to treat. Therefore, biofilm-active antibiotics are a major challenge. Here we investigated the effect of the lantibiotic gallidermin on two representative biofilm-forming staphylococcal species. Gallidermin inhibits not only the growth of staphylococci in a dose-dependent manner but also efficiently prevents biofilm formation by both species. The effect on biofilm might be due to repression of biofilm-related targets, such asica(intercellular adhesin) andatl(major autolysin). However, gallidermin's killing activity on 24-h and 5-day-old biofilms was significantly decreased. A subpopulation of 0.1 to 1.0% of cells survived, comprising “persister” cells of an unknown genetic and physiological state. Like many other antibiotics, gallidermin showed only limited activity on cells within mature biofilms.
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4

Horiuk, Y. V., M. D. Kukhtyn, Y. S. Stravskyy, S. I. Klymnyuk, K. M. Vergeles, and V. V. Horiuk. "Influence of staphylococcal Phage SAvB14 on biofilms, formed by Staphylococcus aureus variant bovis." Regulatory Mechanisms in Biosystems 10, no. 3 (August 22, 2019): 314–18. http://dx.doi.org/10.15421/021948.

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The use of bacteriophages for the treatment of chronic inflammatory processes has proved to be relevant, especially during isolation of antibiotic-resistant pathogens formed in biofilms. The article presents the results of research on the influence of Phage SAvB14 on young and mature biofilms formed by Staphylococcus aureus variant bovis. In the experiments we used cultures of S. aureus and a specific Phage SAvB14 isolated from the secretion of the mammary gland of cows suffering from chronic mastitis. In the study of the influence of bacteriophage on formed biofilms we determined the optical density of the dye solution that was washed from the biofilm photometrically on a spectrophotometer PE-5400UV (Ecroskhim, Russia) and the number of staphylococcal cells in the biofilm after the action of the bacteriophage on 24-hour and 72-hour biofilms by a ten-fold dilution on beef-extract agar. It was determined that under the influence of the bacteriophage on young 24-hour biofilms of S. aureus var. bovis, the optical density of the dye solution from biofilm increased within 4 hours up to 10% and the number of microbial cells increased by 1.8 times. After 32 hours of bacteriophage action, the optical density of the dye solution decreased on average by 34% compared to the initial density and the number of S. aureus cells in the biofilm decreased by 30 times. This indicates that microbial cells of young biofilms are not subject to complete lysis during the action of even this specific bacteriophage. Degradation of 77.5% of biofilm under the influence of the bacteriophage was observed on mature 72-hour biofilm within 32 hours at 37 °C. At the same time, viable cells of S. aureus were not isolated from the biofilm. This indicates the high lytic activity of the bacteriophage against mature biofilm bacteria and the possibility of its use in chronic staphylococcal infections caused by S. aureus var. bovis. Thus, the obtained data indicate that when mature 72-hour biofilms are exposed to the researched bacteriophage, their degradation is more intense compared with the young 24-hour biofilms, and the amount of destroyed biofilm was on average 2 times higher. This suggests that the use of specific staphylococcal Phage SAvB14 isolated by us for the destruction of biofilm, formed by S. aureus var. bovis, is promising.
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5

Hrynchuk, N. I., N. O. Vrynchanu, T. A. Buchtyarova, D. M. Dudikova, Yu V. Korotkyi, and L. B. Bondarenko. "Antibiofilm Effect of Adamantane Derivative against Staphylococcus aureus." Mikrobiolohichnyi Zhurnal 83, no. 1 (February 17, 2021): 58–67. http://dx.doi.org/10.15407/microbiolj83.01.058.

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Currently, one of the most urgent problems in clinical practice is the antibiotic therapy ineffectiveness at chronic diseases treatment caused by biofilms-forming microorganisms. One of the ways to its solution is the search for new compounds with antibiofilm activity which can prevent the adhesion of microorganisms, disrupt the structure of the biofilm matrix and affect the Quorum sensing system. The aim of the study was to investigate adamantane derivative 1-[4-(1-adamantyl) phenoxy]-3-(N-benzyl,N-dimethylamino)-2-propanol chloride (KVM-97) antimicrobial activity mechanism against Staphylococcus aureus biofilms. Methods. The ability of the adamantane derivative KVM-97 to prevent S. aureus biofilm formation and to destroy previously formed biofilms has been tested on polystyrene plates by gentian violet sorption on these structures, followed by desorption with organic solvent and use of resazurin (redox indicator). The S. aureus cells viability in mature biofilms was evaluated with specific dyes for living (acridine orange) and dead (propidium iodide) cells. Lowry method was used to assess the effect of KVM-97 on the matrix components for the total protein contents determination, the polysaccharides were detected spectrophotometrically (using phenol and sulfuric acid), Bap-protein – by test with Congo red. Persisters’ subpopulation was detected by activation of the SOS response in bacteria when exposed to high concentrations of antimicrobial substances. Results. It was found that KVM-97 (the compound with the adamantyl radical) showed an antibiofilm effect against S. aureus, decreasing biofilm biomass: at the biofilm formation stage – by 22.5% and 75.0%, while in case of 2-day biofilms treatment – by 34.5% and 32.4% at 0.5 MIC and 5.0 MIC respectively. Compound KVM-97 was able to reduce the number of metabolically active S. aureus cells only at the stage of biofilm formation (reduction by 92.7 and 95.8% at 2.0 and 5.0 MIC). Obtained results indicated that this adamantane-containing compound did not affect the protein and polysaccharides contents of S. aureus biofilms matrix. The changes of Bap-protein level caused by KVM-97 were not statistically significant (p>0.05). It was shown that KVM-97 did not prevent the formation of metabolically inactive persister cells; their share was 0.71% of the control. Conclusions. Thus, adamantane-containing compound KVM-97 is able to prevent S. aureus biofilm formation, causing significant biofilms’ mass reduction, as well as lowering the viable cells number in them and destroying already formed biofilms. Its antibiofilm effects are not associated with matrix protein and polysaccharides synthesis impairments. Further thorough investigations are needed to establish the effect of this compound on eDNA synthesis, the Quorum sensing system, and the ica and arg genes expression of S. aureus responsible for biofilm formation.
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6

Yarwood, Jeremy M., Douglas J. Bartels, Esther M. Volper, and E. Peter Greenberg. "Quorum Sensing in Staphylococcus aureus Biofilms." Journal of Bacteriology 186, no. 6 (March 15, 2004): 1838–50. http://dx.doi.org/10.1128/jb.186.6.1838-1850.2004.

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ABSTRACT Several serious diseases are caused by biofilm-associated Staphylococcus aureus, infections in which the accessory gene regulator (agr) quorum-sensing system is thought to play an important role. We studied the contribution of agr to biofilm development, and we examined agr-dependent transcription in biofilms. Under some conditions, disruption of agr expression had no discernible influence on biofilm formation, while under others it either inhibited or enhanced biofilm formation. Under those conditions where agr expression enhanced biofilm formation, biofilms of an agr signaling mutant were particularly sensitive to rifampin but not to oxacillin. Time lapse confocal scanning laser microscopy showed that, similar to the expression of an agr-independent fluorescent reporter, biofilm expression of an agr-dependent reporter was in patches within cell clusters and oscillated with time. In some cases, loss of fluorescence appeared to coincide with detachment of cells from the biofilm. Our studies indicate that the role of agr expression in biofilm development and behavior depends on environmental conditions. We also suggest that detachment of cells expressing agr from biofilms may have important clinical implications.
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7

Singhal, Deepti, Andrew Foreman, Josh-Jervis Bardy, and Peter-John Wormald. "Staphylococcus aureus biofilms." Laryngoscope 121, no. 7 (June 6, 2011): 1578–83. http://dx.doi.org/10.1002/lary.21805.

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8

Tuon, Felipe Francisco, Paula Hansen Suss, Joao Paulo Telles, Leticia Ramos Dantas, Nícolas Henrique Borges, and Victoria Stadler Tasca Ribeiro. "Antimicrobial Treatment of Staphylococcus aureus Biofilms." Antibiotics 12, no. 1 (January 4, 2023): 87. http://dx.doi.org/10.3390/antibiotics12010087.

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Staphylococcus aureus is a microorganism frequently associated with implant-related infections, owing to its ability to produce biofilms. These infections are difficult to treat because antimicrobials must cross the biofilm to effectively inhibit bacterial growth. Although some antibiotics can penetrate the biofilm and reduce the bacterial load, it is important to understand that the results of routine sensitivity tests are not always valid for interpreting the activity of different drugs. In this review, a broad discussion on the genes involved in biofilm formation, quorum sensing, and antimicrobial activity in monotherapy and combination therapy is presented that should benefit researchers engaged in optimizing the treatment of infections associated with S. aureus biofilms.
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9

Achek, Rachid, Helmut Hotzel, Ibrahim Nabi, Souad Kechida, Djamila Mami, Nassima Didouh, Herbert Tomaso, et al. "Phenotypic and Molecular Detection of Biofilm Formation in Staphylococcus aureus Isolated from Different Sources in Algeria." Pathogens 9, no. 2 (February 24, 2020): 153. http://dx.doi.org/10.3390/pathogens9020153.

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Staphylococcus aureus is an opportunistic bacterium causing a wide variety of diseases. Biofilm formation of Staphylococcus aureus is of primary public and animal health concern. The purposes of the present study were to investigate the ability of Staphylococcus aureus isolated from animals, humans, and food samples to form biofilms and to screen for the presence of biofilm-associated and regulatory genes. In total, 55 Staphylococcus aureus isolated from sheep mastitis cases (n = 28), humans (n = 19), and from food matrices (n = 8) were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The ability of Staphylococcus aureus for slime production and biofilm formation was determined quantitatively. A DNA microarray examination was performed to detect adhesion genes (icaACD and biofilm-associated protein gene (bap)), genes encoding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs), regulatory genes (accessory gene regulator (agr) and staphylococcal accessory regulator (sarA)), and the staphylococcal cassette chromosome mec elements (SCCmec). Out of 55 Staphylococcus aureus isolates, 39 (71.0%) and 23 (41.8%) were producing slime and biofilm, respectively. All Staphylococcus aureus strains isolated from food showed biofilm formation ability. 52.6% of the Staphylococcus aureus strains isolated from sheep with mastitis, and 17.9% of isolates from humans, were able to form a biofilm. Microarray analysis typed the Staphylococcus aureus into 15 clonal complexes. Among all Staphylococcus aureus isolates, four of the human isolates (21.1%) harbored the mecA gene (SCCmec type IV) typed into 2 clonal complexes (CC22-MRSA-IV and CC80-MRSA-IV) and were considered as methicillin-resistant, while two of them were slime-producing. None of the isolates from sheep with mastitis harbored the cna gene which is associated with biofilm production. The fnbB gene was found in 100%, 60% and 40% of biofilm-producing Staphylococcus aureus isolated from food, humans, and sheep with mastitis, respectively. Three agr groups were present and agr group III was predominant with 43.6%, followed by agr group I (38.2%), and agr group II (18.2%). This study revealed the capacity of Staphylococcus aureus isolates to form biofilms and highlighted the genetic background displayed by Staphylococcus aureus isolates from different sources in Algeria.
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Sharma, Mrinalini, Livia Visai, Francesca Bragheri, Ilaria Cristiani, Pradeep Kumar Gupta, and Pietro Speziale. "Toluidine Blue-Mediated Photodynamic Effects on Staphylococcal Biofilms." Antimicrobial Agents and Chemotherapy 52, no. 1 (October 29, 2007): 299–305. http://dx.doi.org/10.1128/aac.00988-07.

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ABSTRACT Staphylococci are important causes of nosocomial and medical-device-related infections. Their virulence is attributed to the elaboration of biofilms that protect the organisms from immune system clearance and to increased resistance to phagocytosis and antibiotics. Photodynamic treatment (PDT) has been proposed as an alternative approach for the inactivation of bacteria in biofilms. In this study, we have investigated the effect of the photodynamic action of toluidine blue O (TBO) on the viability and structure of biofilms of Staphylococcus epidermidis and of a methicillin-resistant Staphylococcus aureus strain. Significant inactivation of cells was observed when staphylococcal biofilms were exposed to TBO and laser simultaneously. The effect was found to be light dose dependent. Confocal laser scanning microscopic study suggested damage to bacterial cell membranes in photodynamically treated biofilms. In addition, scanning electron microscopy provided direct evidence for the disruption of biofilm structure and a decrease in cell numbers in photodynamically treated biofilms. Furthermore, the treatment of biofilms with tetrasodium EDTA followed by PDT enhanced the photodynamic efficacy of TBO in S. epidermidis, but not in S. aureus, biofilms. The results suggest that photodynamic treatment may be a useful approach for the inactivation of staphylococcal biofilms adhering to solid surfaces of medical implants.
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Більше джерел

Дисертації з теми "Staphylococcus aureus biofilms"

1

Graziano, Talita Signoreti 1988. "Effects of statins in the bacterial viability and on biofilm of Staphylococcus aureus." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289491.

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Orientadores: Karina Cogo Müller, Francisco Carlos Groppo
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-25T11:18:29Z (GMT). No. of bitstreams: 1 Graziano_TalitaSignoreti_M.pdf: 1603562 bytes, checksum: 9522f75e1f8c1147c84c0fde100549ed (MD5) Previous issue date: 2014
Resumo: As estatinas são um grupo de fármacos que atuam como inibidores competitivos da enzima 3-Hidroxi-3-MetilGlutaril Coenzima-A Redutase (HMG-CoA redutase). Além de atuarem como importantes agentes hipolipemiantes, também apresentam outros efeitos, chamados de pleiotrópicos. Diversos estudos têm explorado um possível efeito protetor das estatinas atuando na redução na morbidade e mortalidade de várias doenças infecciosas. A atividade antimicrobiana das estatinas tem sido reportada por estudos in vivo e in vitro. O objetivo desse estudo foi avaliar os efeitos das estatinas sobre o crescimento e viabilidade de bactérias aeróbias patogênicas, e o efeito da sinvastatina sobre o biofilme de Staphylococcus aureus. Culturas das espécies de Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli e Enterococcus faecalis foram avaliadas na forma planctônica quanto à sensibilidade à atorvastatina, pravastatina e sinvastatina, através do teste de Concentração Inibitória Mínima (CIM). Além disso, diante da atividade apresentada pela sinvastatina contra S. aureus, foi determinada a ação dessa droga sobre a viabilidade celular através dos testes de Time-kill e Efeito pós-antibiótico (EPA). Também foi verificado um possível efeito sinérgico entre a sinvastatina e vancomicina. Por fim, a ação da sinvastatina foi avaliada contra biofilmes de S. aureus. Os valores de CIM da sinvastatina para o microrganismo S. aureus foram: 15,65 µg/ml (ATCC 29213) e 31,25 µg/ml (ATCC 33591, 43300, 14458 e 6538). A sinvastatina apresentou um perfil bacteriostático, e na concentração de 4xCIM seu EPA foi similar ao da vancomicina. Não foi encontrado nenhum tipo de interação entre a associação de sinvastatina e vancomicina. Entretanto, a sinvastatina foi capaz de reduzir a formação do biofilme nas concentrações entre 1/8CIM à 4xCIM. Além disso, na concentração 4xMIC foi capaz de diminuir a viabilidade, biomassa e a produção de polissacarídeos extracelulares e aumentar a produção de polissacarídeos intracelulares de biofilmes maduros de S. aureus. A produção de proteínas pelo biofilme não foi alterada. Em conclusão, os resultados encontrados mostram que a sinvastatina possui um grande potencial a ser explorado, principalmente em relação ao descobrimento de novos antimicrobianos
Abstract: Statins are drugs that competitively inhibit the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA). Besides their important lipid-lowering action, they also are pleiotropic agents. Several studies have explored a possible protective effect of statins to reduce the morbidity and mortality of various infectious diseases. The antimicrobial activity of statins has been reported by in vivo and in vitro studies. The aim of this study was to evaluate the effects of statins on the growth, viability and biofilm formation of pathogenic aerobic bacteria. The Minimum Inhibitory Concentrations (MIC) of atorvastatin, pravastatin and simvastatin against planktonic cells of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis strains were obtained. Since simvastatin showed activity against S. aureus, its effects on cell viability were evaluated in a time-kill and post-antibiotic effect (PAE) assays. A possible synergistic effect between simvastatin and vancomycin was also assessed. In addition, the effect of simvastatin against biofilms of S. aureus was tested. The MIC values of simvastatin for S. aureus were: 15.65 µg/ml (ATCC 29213) and 31.25 µg/ml (ATCC 33591, 43300, 14458 and 6538). Simvastatin showed a bacteriostatic profile, and in a 4x>MIC concentration the PAE was similar to vancomycin. No synergistic effect was found between simvastatin and vancomycin. Simvastatin was able to reduce the formation of biofilms in concentrations ranging from 1/8MIC to 4xMIC. In addition, the 4xMIC was able to decrease the viability, biomass and production of extracellular polysaccharides and increase the production of intracellular polysaccharides on mature biofilm of S. aureus. The protein production on biofilm was not altered in the presence of simvastatin . In conclusion, our results showed that simvastatin has a great potential to be explored, especially in relation to the development new antimicrobial agents
Mestrado
Farmacologia, Anestesiologia e Terapeutica
Mestra em Odontologia
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2

Marques, Claire. "Etude de l'impact d'antibiotiques sur des biofilms de Staphylococcus aureus." Thesis, Clermont-Ferrand 1, 2016. http://www.theses.fr/2016CLF1PP02.

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Анотація:
Les infections ostéo-articulaires requièrent souvent un acte chirurgical couplé à une antibiothérapie prolongée, en lien avec la capacité des bactéries en cause à former des biofilms sur les prothèses. La présence d’antibiotiques à des concentrations sub-inhibitrices (sub-CMI) peut stimuler la capacité des bactéries à former des biofilms, ce qui complexifie la problématique. Notre étude avait pour but de caractériser in vitro le comportement biofilm d’une souche clinique de Staphylococcus aureus issue d’une infection ostéo-articulaire en présence de 12 antibiotiques préconisés dans le traitement des infections à staphylocoques, à différentes concentrations (dont des concentrations sub-CMI).Un dénombrement des bactéries viables a été effectué à partir de biofilms formés en présence de chacun des 12 antibiotiques à différentes concentrations (incluant des concentrations sub-CMI), ainsi que dans les suspensions présentes autour de ces mêmes biofilms. La présence de 7 d'entre eux (ceftaroline, daptomycine, gentamicine, fosfomycine, ofloxacine, rifampicine et vancomycine) entraînait une inhibition de la formation de biofilm à des concentrations inférieures ou égales aux concentrations critiques. L'action de la fosfomycine s'étendait même à des concentrations sub-CMI. Seules la daptomycine et la gentamicine étaient capables d’agir à la fois sur les bactéries sessiles et sur les bactéries non-adhérentes en suspension.Quant aux biofilms mâtures de cette même souche préalablement formés en absence d'antibiotiques, seules des concentrations 800 à 51200 fois supérieures à la CMI -concentrations largement incompatibles avec une utilisation thérapeutique - entraînaient leur éradication.Dans la deuxième partie de ce travail, nous avons concentré nos efforts sur l'action de la fosfomycine, choisie en fonction de son effet sur la formation de biofilm et de son intérêt thérapeutique. Une analyse transcriptomique des cellules présentes dans les biofilms formés en présence de fosfomycine et de cellules issues de biofilms matures traités ultérieurement à la fosfomycine a montré que la présence de cet antibiotique induisait majoritairement une sous expression de gènes codant des protéines impliquées dans le métabolisme et le transport des nucléotides, des acides aminés et des carbohydrates. Des gènes codant des adhésines et des protéines impliquées dans la synthèse de la capsule (ScdA) étaient également sous-exprimés. De manière moins importante, l'expression de gènes codant des molécules impliquées dans la synthèse du peptidoglycane (MGT et MurA) et des autolysines était également diminuée. Le ralentissement métabolique et les modifications induites au niveau des membranes par la présence de l'antibiotique seraient responsables du changement des capacités d'adhésion de la bactérie.L'impact de la fosfomycine à une concentration sub-CMI sur les caractéristiques des bactéries viables isolées dans la suspension autour des biofilms a également été déterminé. De façon surprenante, ces bactéries montrent une capacité accrue à former du biofilm par rapport à celles issues de l'environnement d'un biofilm non soumis à l'action de l'antibiotique, en lien probablement avec un accroissement d'épaisseur de leur couche de peptidoglycane.En conclusion, ces données obtenues in vitro devront être confirmées dans des modèles d'infections expérimentales in vivo. Malgré tout, elles soulignent la pertinence de l’utilisation de la fosfomycine dans la prévention des infections ostéo-articulaires liées à S. aureus, à condition d'éradiquer en parallèle les formes non adhérentes
Osteoarticular infections (OAI) often require a surgical procedure with prosthesis removal followed by long-term complex antibiotherapy. The ability of Staphylococcus aureus to adhere and produce biofilm on the surface of implanted material contributes to treatment failures and microbiological relapses. In addition, biofilm formation can be induced by some antibiotics at sub-minimal inhibitory concentrations (sub-MICs). The present study characterizes in vitro the effects of 12 antibiotics on biofilm formed by a strain of methicillin-susceptible Staphylococcus aureus isolated from an osteo-articular infection.The influence of these antibiotics was assessed on biofilm formation at concentrations including the breakpoints, by numbering viable cells in the biofilm biomass and in the suspensions (unattached cells) surrounding the biofilm. Biofilm formation was prevented in presence of ceftarolin, daptomycin, fosfomycin, gentamicin, ofloxacin, rifampicin and vancomycin at the highest concentrations tested. Only fosfomycin showed inhibition properties also at sub-MICs. Unattached and sessile viable bacteria were undetectable to daptomycin and gentamicin at the highest concentrations tested.Determination of the minimum biofilm eradication concentrations (MBECs) indicated that in vitro eradication of 24h-old biofilms required concentrations at least 800 times higher than the planktonic MIC, concentrations obviously not compatibles with classical therapeutic doses.In the second part of this work, we focused our study on the action of fosfomycin, because of its effect on biofilm formation and its therapeutic interest. A transcriptome analysis was performed with sessile cells from both biofilm formed in the presence of sub-MIC of fosfomycin and cells from pre-formed 24h-old biofilm treated by fosfomycin at sub-MBEC. Fosfomycin induced mostly down regulation of genes assigned to nucleotide, amino acid and carbohydrate transport and metabolism. Adhesins and capsular biosynthesis proteins (ScdA) encoding genes were also down regulated. To a lesser extent, peptidoglycan biosynthesis proteins (MGT and MurA) and autolysins encoding genes were found down regulated. Metabolic slowdown and cell membrane modifications induced by fosfomycin are likely to be responsible for the impairment of bacterial adhesion capacity.The action of fosfomycin at sub-MIC on unattached cells surrounding biofilm was also analyzed. Surprisingly, they displayed higher capacity to form new biofilm than their counterparts obtained without fosfomycin, probably associated with their large peptidoglycan layer.In conclusion, these data underline the relevance of the use of fosfomycine in preventing osteo-articular infections due to S. aureus and should be assessed in in vivo experiments. However, simultaneous eradication of unattached cells should also be considered due to the high capacities of these cells to disseminate and establish new biofilm, a real risk of treatment failure
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Pinto, Geraldo Camilo de Souza [UNESP]. "Eficácia da terapia fotodinâmica antimicrobiana em biofilmes de Staphylococcus Aureus suscetível e resistente á meticilina." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/97310.

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A necessidade de superar o desafio criado pelos biofilmes resistentes aos tratamentos antimicrobianos convencionais tem levado à busca por tratamentos alternativos, como terapia fotodinâmica antimicrobiana (aPDT). Este estudo avaliou in vitro a eficácia da aPDT na inativação de biofilmes de Staphylococcus aureus suscetíveis e resistentes à meticilina (MRSA e MSSA), mediado pelos fotossensibilizadores (PSs) Curcumina (Cur) e Photodithazine® (PDZ). Biofilmes foram formados e tratados com diferentes concentrações de Cur (0, 20, 40 e 80 μM) e PDZ (0, 50 e 75 mg/L), e iluminados ou não por fonte de luz LED (Cur 455 ± 3 nm/ 5,28 J/cm2; PDZ 660 ± 3 nm/ 5,28 J/cm2 ou 50 J/cm²). Os grupos Controle Positivo (CP) não receberam nenhum PS e também não foram iluminados. A viabilidade dos micro-organismos após a aPDT foi avaliado pelo número de colônias viáveis, pelo ensaio de XTT e pela utilização do kit LIVE/DEAD® na Microscopia Confocal de Varredura à Laser (MCVL). Os resultados foram avaliados por análises de variância de dois fatores de efeitos fixos (ANOVA) e complementados por comparações múltiplas de médias pelo teste de Tukey. Para ambas as cepas, todas as concentrações de Cur e PDZ testadas reduziram significativamente a atividade metabólica e o UFC/mL para ambos micro-organismos quando comparado com os grupos CN (p0,05). Os resultados foram otimizados para a Cur quando utilizou-se a maior concentração (80 μM), para a PDZ, a maior redução nos micro-organismos foi observada quando associou-se a maior concentração de PDZ (75 mg/L) com a maior dose de luz (50 J/cm²). Os biofilmes submetidos a aPDT demostraram pela MCVL um maior número de células coradas em vermelho, indicando que a aPDT foi eficaz para promover danos ou morte às células bacterianas. Assim, a aPDT pode ser considerada promissora para atuar de forma sinérgica no tratamento de infecções bacterianas
The need to overcome the challenge created by biofilms regarding conventional antimicrobial approaches has lead to search of alternative treatments such as Antimicrobial Photodynamic Therapy (aPDT). This in vitro study evaluated the efficacy of aPDT using the photosensitizer (PS) Curcumin (Cur) and Photodithazine® (PDZ) in the inactivation of biofilms of methicillin susceptible and resistant S. aureus (MSSA and MRSA). Biofilms were treated with different Cur (0, 20, 40 or 80 μM of Cur) and PDZ concentrations (0, 50 or 75 mg/L) and illuminated or not with LED source (Cur 455 ± 3 nm/ 5.28 J/cm2; PDZ 660 ± 3 nm/ 5.28 J/cm2 or 50 J/cm²). Positive control samples were not exposed to PS or light. The microorganisms viability after aPDT were evaluated by counting the number of colonies, the XTT assay and LIVE/DEAD® staining using confocal laser scanning microscopy (CLSM). The results were evaluated by analysis of variance, two-factor fixed effects (ANOVA) and complemented by multiple comparisons by Tukey test. For both strains, all the tested Cur and PDZ concentrations reduced significantly both biofilm metabolic activity and CFU/mL compared to the negative control (p0.05). Moreover, the results were optimized for Cur when the higher concentration was used (80 μM); For PDZ, the best results were obtained when it was associated a higher concentration of PDZ (75 mg/L) with the higher dose of light (50 J/cm²). Biofilms submitted to aPDT showed a large number of red-stained colonies, indicating that this therapy was efficient in disrupting the bacterial membrane. It can be concluded that PS was efficient in reducing viable colonies of both S. aureus strains by damaging cell membrane and causing cell death. Thus, the aPDT is can be considered promising to act synergistically in the treatment of bacterial infections
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4

Pinto, Geraldo Camilo de Souza. "Eficácia da terapia fotodinâmica antimicrobiana em biofilmes de Staphylococcus Aureus suscetível e resistente á meticilina /." Araraquara, 2013. http://hdl.handle.net/11449/97310.

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Анотація:
Orientador: Ana Claúdia Pavarina
Banca: Eunice Teresinha Giampaolo
Banca: Ana Paula Dias Ribeiro
Resumo: A necessidade de superar o desafio criado pelos biofilmes resistentes aos tratamentos antimicrobianos convencionais tem levado à busca por tratamentos alternativos, como terapia fotodinâmica antimicrobiana (aPDT). Este estudo avaliou in vitro a eficácia da aPDT na inativação de biofilmes de Staphylococcus aureus suscetíveis e resistentes à meticilina (MRSA e MSSA), mediado pelos fotossensibilizadores (PSs) Curcumina (Cur) e Photodithazine® (PDZ). Biofilmes foram formados e tratados com diferentes concentrações de Cur (0, 20, 40 e 80 μM) e PDZ (0, 50 e 75 mg/L), e iluminados ou não por fonte de luz LED (Cur 455 ± 3 nm/ 5,28 J/cm2; PDZ 660 ± 3 nm/ 5,28 J/cm2 ou 50 J/cm²). Os grupos Controle Positivo (CP) não receberam nenhum PS e também não foram iluminados. A viabilidade dos micro-organismos após a aPDT foi avaliado pelo número de colônias viáveis, pelo ensaio de XTT e pela utilização do kit LIVE/DEAD® na Microscopia Confocal de Varredura à Laser (MCVL). Os resultados foram avaliados por análises de variância de dois fatores de efeitos fixos (ANOVA) e complementados por comparações múltiplas de médias pelo teste de Tukey. Para ambas as cepas, todas as concentrações de Cur e PDZ testadas reduziram significativamente a atividade metabólica e o UFC/mL para ambos micro-organismos quando comparado com os grupos CN (p0,05). Os resultados foram otimizados para a Cur quando utilizou-se a maior concentração (80 μM), para a PDZ, a maior redução nos micro-organismos foi observada quando associou-se a maior concentração de PDZ (75 mg/L) com a maior dose de luz (50 J/cm²). Os biofilmes submetidos a aPDT demostraram pela MCVL um maior número de células coradas em vermelho, indicando que a aPDT foi eficaz para promover danos ou morte às células bacterianas. Assim, a aPDT pode ser considerada promissora para atuar de forma sinérgica no tratamento de infecções bacterianas
Abstract: The need to overcome the challenge created by biofilms regarding conventional antimicrobial approaches has lead to search of alternative treatments such as Antimicrobial Photodynamic Therapy (aPDT). This in vitro study evaluated the efficacy of aPDT using the photosensitizer (PS) Curcumin (Cur) and Photodithazine® (PDZ) in the inactivation of biofilms of methicillin susceptible and resistant S. aureus (MSSA and MRSA). Biofilms were treated with different Cur (0, 20, 40 or 80 μM of Cur) and PDZ concentrations (0, 50 or 75 mg/L) and illuminated or not with LED source (Cur 455 ± 3 nm/ 5.28 J/cm2; PDZ 660 ± 3 nm/ 5.28 J/cm2 or 50 J/cm²). Positive control samples were not exposed to PS or light. The microorganisms viability after aPDT were evaluated by counting the number of colonies, the XTT assay and LIVE/DEAD® staining using confocal laser scanning microscopy (CLSM). The results were evaluated by analysis of variance, two-factor fixed effects (ANOVA) and complemented by multiple comparisons by Tukey test. For both strains, all the tested Cur and PDZ concentrations reduced significantly both biofilm metabolic activity and CFU/mL compared to the negative control (p0.05). Moreover, the results were optimized for Cur when the higher concentration was used (80 μM); For PDZ, the best results were obtained when it was associated a higher concentration of PDZ (75 mg/L) with the higher dose of light (50 J/cm²). Biofilms submitted to aPDT showed a large number of red-stained colonies, indicating that this therapy was efficient in disrupting the bacterial membrane. It can be concluded that PS was efficient in reducing viable colonies of both S. aureus strains by damaging cell membrane and causing cell death. Thus, the aPDT is can be considered promising to act synergistically in the treatment of bacterial infections
Mestre
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5

Blanchard, Alex Paul. "Peroxygen disinfection of Pseudomonas aeruginosa and Staphylococcus aureus biofilms." Thesis, University of Bath, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342075.

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Chapman, Jenelle. "BIOFILMS: A DEVELOPMENTAL NICHE FOR VANCOMYCIN-INTERMEDIATE RESISTANT STAPHYLOCOCCUS AUREUS." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2204.

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The glycopeptide vancomycin is commonly used to treat a variety of bacterial infections, especially multi-drug resistant species of bacteria such as Staphylococcus aureus. While vancomycin remains an effective treatment for Staphylococcal infections, strains of vancomycin-intermediate Staphylococcus aureus (VISA) and vancomycin-resistant Staphylococcus aureus (VRSA) strains have emerged. One mechanism for the increased antibiotic (vancomycin-intermediate) resistance is due to acquisition of various mutations within different genes that alter the cell wall physiology making vancomycin ineffective. Biofilm development is a bacterial mode of growth that can lead to mutations within the bacterial genome and allow for advantageous traits such as increased antibiotic resistance. The biofilm environment can be harsh, having niches that are often nutrient and oxygen deficient, leading to damaged DNA. This DNA damage induces the SOS response to repair double-stranded breaks in DNA, and enables bacterial survival. However, DNA repair via the SOS response is an error-prone system that often results in mutations within the genome. We hypothesize that the acquisition of vancomycin intermediate resistance is an unintended consequence within the S. aureus biofilm environment. To assess the hypothesis, both wildtype and RecA/LexA deficient biofilms were grown in microtiter assays with and without the addition of sub-inhibitory concentrations of vancomycin. Efficiency of plating techniques were used to quantify the subpopulation of biofilm-derived S. aureus cells that developed vancomycin intermediate resistance. Microtiter assays and efficiency of plating techniques were repeated using multiple strains of S. aureus. Experimentation was repeated by comparing the subpopulation of biofilm-derived and planktonic culture cells that grew in intermediate-concentrations of vancomycin with three additional strains of S. aureus. Mutagenesis that occurs within the biofilm environment was further assessed by plating both biofilm-derived and planktonic culture cells on sheep blood agar and tryptic soy agar supplemented with streptomycin, novobiocin, or rifampicin, and quantifying the non-hemolytic variants that grew on blood agar, or the number of colonies that grew in the presence of an antibiotic, respectively. The biofilm results were then compared to the results from wildtype and RecA/LexA deficient planktonic cultures and used to determine the impact of the S. aureus biofilm environment in the acquisition of vancomycin intermediate resistance. The results indicate that a larger subpopulation of cells derived from wildtype biofilms grew in increased concentrations of vancomycin (4 µg/ml) as compared to the planktonic counterpart. The subpopulation of cells derived from wildtype biofilms was also higher than all subpopulations of RecA/LexA deficient biofilm and planktonic cultures. Further experimentation indicates that this phenomenon may not be specific to all strain backgrounds of S. aureus. Additionally, growth with sub-inhibitory concentrations of vancomycin did not exhibit an exaggerated subpopulation of cells in biofilm environments or planktonic cultures that could grow in intermediate-concentrations of vancomycin, however standard antibiotic testing suggests that the mechanism by which point mutations occur in planktonic conditions may be mediated by the RecA and SOS response system. Bacteria that live in a biofilm community are often subjected to harsh environments. In order to survive, the SOS response system will be activated to repair damaged DNA. This error prone process will result in mutational changes and increased genetic diversity. The VISA phenotype may be a result of the diversity that occurs within the biofilm environment. While the VISA phenotype would be an unintended consequence of genetic diversity and gene transfer in the biofilm setting, it demonstrates that mutations that occur within the biofilm environment allow for S. aureus to better adapt to new environments, including the presence of widely used antibiotics such as vancomycin.
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Fernandes, Renan Aparecido. "Fitossíntese de nanopartículas de prata a partir de extrato de cascas de romã e desenvolvimento de formulação para tratamento de feridas : avaliação antimicrobiana, citotóxica e potencial cicatrizante em um modelo in vivo /." Araçatuba, 2017. http://hdl.handle.net/11449/151982.

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Анотація:
Orientador: Debora de Barros Barbosa
Coorientadora: Andresa Aparecida Berretta e Silva
Banca: Alberto Carlos Botazzo Delbem
Banca: Denise Pedrini Ostini
Banca: Luiz Fernando Gorup
Banca: Elaine Cristina Guerbach Conti
Resumo: O objetivo deste estudo foi avaliar a capacidade de produção de nanopartículas de prata através do extrato da casca de romã, e produzir formulações contendo estas nanopartículas para uso em feridas. Elas foram testadas quanto à ação antimicrobiana, citotóxica e potencial cicatrizante. Para a produção das nanopartículas de prata propôs-se uma síntese utilizando-se como base duas metodologias já estabelecidas na literatura, utilizando-se para reação carboximetilcelulose, propilenoglicol, nitrato de prata, água e extrato da casca de romã como agente redutor. O extrato da casca de romã foi caracterizado em parâmetros como pH, massa seca e quantidade de taninos bioativos (ácido elágico e totais fenólicos expressos em ácido gálico). Os totais fenólicos do extrato foram também dosados após seu aquecimento nas diferentes condições de tempo e temperatura propostos para as sínteses das nanopartículas de prata (12 minutos, 1 hora e 2 horas, à 50ºC e 100ºC). As nanopartículas de prata produzidas foram, então, adicionadas a uma solução contendo compostos para produção de formulações para serem utilizadas no tratamento de feridas. Elas foram caracterizadas através de espectroscopia UV-Visível, microscopia eletrônica de varredura (MEV), potencial zeta e dosagem de íons remanescentes após as reações. A atividade antimicrobiana tanto das nanopartículas como de suas formulações contra Candida albicans SC 5314 e Staphylococcus aureus ATCC 25923 foi avaliada por meio do método da microdiluição. ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The aim of this study was to investigate the production of silver nanoparticles through peel extract of pomegranate, and produce formulations containing these particles to be used in wound healings. Its antimicrobial action, cytotoxicity and healing potential were tested. The synthesis of silver nanoparticles were based on two methods proposed in the literature with some modifications, which were used carboxymethylcellulose, propylene glycol, silver nitrate, water and peel extract of pomegranate as reducing agent. The peel extract was characterized by pH, dry mass and bioactive tannins (elagic acid and total phenols expressed as galic acid). The total phenols were also quantified after being heated at 50ºC and 100ºC for 12 minutes, 1 hour and 2 hours. Then, silver nanoparticles were added in a solution containing products to develop a formulation to be tested in wound healing. They were characterized by UV-Vis spectroscopy, scanning electron microscopy (SEM), zeta potential and the quantification of remaining silver ions after the synthesis reaction. The antimicrobial activity of the nanoparticles and formulations were tested against Candida albicans (SC 5314) e Staphylococcus aureus (ATCC 25923) by microdilution method. After submitting the peel extract to different conditions of temperature and times (50ºC and 100ºC for 12 minutes, 1 hour and 2 hours), it was noted that the values of the minimum inhibitory concentration was not affected and were 391 μg/ml and 781 μg/ml for S. aureus and C. albicans. The formation of silver nanoparticles was confirmed through the formation of characteristic peaks in the UV-Vis spectroscopy and SEM images, and it was observed that the reaction at 50ºC for 12 min produced silver nanoparticles with regular forms and better dispersed in the formulation. The synthesis proposed promoted...
Doutor
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8

Liesse, Iyamba Jean-Marie. "Etude de l'interaction des souches cliniques de Staphylococcus aureus avec une surface abiotique." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209630.

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Анотація:
Staphylococcus aureus est l’une des causes majeures des infections communautaires et nosocomiales. Ce germe est responsable des infections aiguës et chroniques dont la plupart sont dues à sa capacité à adhérer sur les implants médicaux et à former un biofilm. D’après le Center for Disease Control and Prevention (CDC), 65% des infections bactériennes sont dues à la présence des biofilms. En outre, les infections associées aux biofilms constituent un problème majeur en clinique et sont la cause de l’augmentation de la mortalité et du coût de traitement.

Chez S. aureus, la formation du biofilm se déroule en deux phases principales: la première phase est l’attachement initial des cellules sur une surface, et la seconde est la multiplication et la formation d’une communauté structurée, mature et multicouche des cellules bactériennes. A l’intérieur du biofilm, les bactéries développent plusieurs types d’interactions et accroissent leur résistance aux agents antimicrobiens et aux défenses immunitaires de l’hôte, ce qui constitue un véritable problème de santé publique.

Les objectifs de ce travail étaient: (1) de caractériser des souches cliniques de S. aureus sensibles et résistantes à la méticilline (SASM et SARM) par une analyse phénotypique et génotypique; (2) d’étudier la répercussion des propriétés de membranes sur l’adhésion et la formation du biofilm; (3) de rechercher un moyen pour la prévention de l’adhésion et de la formation d’un biofilm sur une surface abiotique.

Deux souches de référence et 12 souches cliniques de S. aureus (4 SARM et 8 SASM) collectées à Kinshasa ont été caractérisées par la résistance aux antibiotiques, par le typage d’une région X du gène spa codant pour la protéine A de S. aureus et par la détermination des propriétés de la surface cellulaire. L’adhésion à une surface et la formation du biofilm ont été respectivement étudiées par la méthode de Biofilm Ring Test® (BFRT®) et par celle de coloration au cristal violet. Ces deux méthodes ont été utilisées pour l’évaluation de l’activité de l’acide éthylèneglycol tétraacétique (EGTA) sur l’adhésion et la formation du biofilm.

L’amplification par PCR (Polymerase Chain Reaction) d’un fragment du gène mecA a confirmé l’appartenance des souches étudiées au phénotype SARM ou SASM. L’analyse par PCR des répétitions présentes dans la séquence codante de la protéine A de S. aureus (spa typing) a permis d’identifier 7 types spa pour toutes les souches SARM et SASM2 dont un nouveau type spa t10715.

Les résultats du test MATS (Microbial Adhesion to Solvents) ont montré que les souches de S. aureus sensibles et résistantes à la méticilline possédaient des propriétés membranaires différentes susceptibles de modifier l’adhésion ou la formation d’un biofilm. Les souches sensibles à la méticilline avaient une paroi plus hydrophobe que celle de souches résistantes dont la paroi était acide, acceptrice d’électrons.

Les études sur l’interaction entre des souches cliniques de S. aureus et des surfaces abiotiques ont montré que les souches SARM adhéraient moins vite à une surface et formaient moins de biofilms que les souches SASM.

Les études de l’activité de l’EGTA, un chélateur des cations divalents, ont montré que ce dernier inhibait l’adhésion de souches SARM à une surface abiotique comme un tube de cathéter et empêchait la formation d’un biofilm par toutes les souches sensibles et résistantes à la méticilline. Cette action inhibitrice sur la formation du biofilm était réversible en présence d’un cation divalent (magnésium, calcium ou manganèse).

L’ensemble des données obtenues sur l’adhésion et la formation du biofilm par la méthode de BFRT® et par celle de coloration au cristal violet ont montré que le BFRT® était la méthode de choix dans les études de l’adhésion initiale des souches de S. aureus sur une surface abiotique. Le BFRT® pourrait être utilisée dans le screening rapide de produits contre l’adhésion bactérienne à la surface des implants médicaux à base de polystyrène ou de silicone.


Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished

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Vance, Lindsey. "The Inhibitory Effects of a Novel Gel on Staphylococcus aureus Biofilms." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/honors/435.

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Анотація:
Antibiotic resistance is an ever-growing topic of concern within the medical field causing researchers to examine the mechanisms of resistance to develop new antimicrobials. Bacteria’s ability to form biofilms is one mechanism which aids in antimicrobial resistance. Staphylococcus aureus is of special interest as it is one of the most frequent biofilm-forming bacteria found on medical devices causing infections and posing dangerous threats in a clinical setting. A recently developed antimicrobial gel has been shown to have profound effects on treating bacterial infections and wound healing. This research is centered upon examining the antimicrobial effects of this gel on the three different stages of biofilm formation in clinical and laboratory strains of S. aureus. Through a series of experiments examining the effects this gel has on S. aureus at the stages of biofilm attachment, maturation, and dispersion, the gel has shown significant levels of inhibition. These findings indicate that the novel gel disrupts biofilm forming processes of S. aureus, which provides useful information for fighting infections in the medical field. Further research on the uses and effects of this new gel could lead possibility using the antimicrobial compound for a variety of clinical purposes.
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10

Vieira, Estevão Alan. "Ação antimicrobiana de ramnolipídeos sobre células sésseis e planctônicas de Staphylococcus aureus: efeito do pH." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-13032019-163150/.

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Intoxicações alimentares são uma das causas mais significativas de mortalidade em países desenvolvidos e em desenvolvimento, sendo as contaminações bacterianas as responsáveis pela maioria dos casos. Dentre elas destacam-se as causadas por espécies de Staphylococcus, que são nocivas tanto pela infecção do organismo hospedeiro, quanto pela intoxicação por enterotoxinas termoestáveis presentes em alimentos contaminados e mal acondicionados. Além disso, a capacidade de S. aureus formarem biofilmes confere maior proteção contra agentes de controle. Neste contexto, torna-se importante desenvolver novos métodos visando inibir estes agentes patogênicos. Uma alternativa ao emprego de conservantes sintéticos é a utilização de biossurfatantes, como os ramnolipídeos (RL) que, além de apresentarem alta estabilidade a temperatura, pH e concentração salina, apresentam baixa toxicidade e são biodegradáveis. O objetivo deste trabalho foi avaliar o efeito do pH na atividade antimicrobiana dos RL sobre células planctônicas e sésseis de Staphylococcus aureus (ATCC 8095) e comparar seu efeito ao do dodecil sulfato de sódio (SDS). Os resultados mostraram que o pH exerce grande influência na ação dos surfatantes, sendo mais efetiva em valores de pH menores. Em pH 5, os RL apresentaram ação bactericida (CBM=19,5 mg L-1) superior ao SDS (CBM=39,1 mg L-1), sendo capazes de inibir e remover 80% dos biofilmes em concentrações de 156,2 mg L-1 e reduzir em cerca de 40 % a hidrofobicidade da superfície celular de S. aureus. Em valores de pH maiores a ação dos RL não superou a do SDS, porém estes ainda mostraram resultados promissores, principalmente na remoção de biofilmes evidenciado pela microscopia confocal. A espectroscopia FTIR revelou que quando em pH 6, 7 e 8 S. aureus, possivelmente, induz alterações em sua membrana celular a fim de diminuir a sensibilidade aos surfatantes. As imagens de MEV mostraram que os RL promovem deformações nas células, podendo levá-las a ruptura. O aumento da força iônica, promovido pela adição de NaCl no meio, favoreceu a ação antimicrobiana dos RL, o que torna a aplicação dos RL em alimentos bastante promissora.
Food poisoning can be considered one of the most significant causes of mortality in developed and developing countries with bacterial contamination being responsible for the majority of cases. Among them are those caused by Staphylococcus species that can beharmful, both from the infection of the host organism as the intoxication by thermostable enterotoxins present in contaminated and poorly conditioned food. In addition, the ability to form biofilms gives S. aureus greater protection against control agents. Under this context, it becomes important to develop new methods to inhibit those pathogens. An alternative to the use of synthetic preservatives are biosurfactants such as rhamnolipids (RL), which shows high stability to temperature, pH and salt concentration along with the fact that they have low toxicity and are biodegradable. The aim of this study was to evaluate the effect of pH on the antimicrobial activity of RL on planktonic and sessile Staphylococcus aureus cells (ATCC 8095) and compare its effect to that of the sodium dodecyl sulfate (SDS). The results showed that pH exerts a great influence on the action of surfactants, with greater effectiveness at lower pH. At pH 5, RL presented higher bactericidal action (CBM = 19.5 mg L-1) than SDS (CBM = 39.1 mg L-1), also being able to inhibit and remove 80% of biofilms at concentrations of 156. 2 mg L- 1 and reduce the hydrophobicity of S. aureus cell surface by about 40%. At higher pH values, the action of RL did not exceed that of SDS, neverthelessthey showed promising results, mainly on the removal of biofilms evidenced by confocal microscopy. FTIR spectroscopy revealed that at pH 6, 7 and 8,S. aureus possibly induces changes in its cell membrane in order to decrease the sensitivity to surfactants. The MEV images showed that the RL cause deformations in the cells, which can lead to rupture. The increase in ionic strength, promoted by the addition of NaCl in the medium, favored the antimicrobial action of RL, which makes the application of RL in foods very promising.
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Книги з теми "Staphylococcus aureus biofilms"

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Hodgson, Anne Elizabeth. Biofilm-specific physiologies of staphylococcus aureus. Manchester: Universityof Manchester, 1994.

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Частини книг з теми "Staphylococcus aureus biofilms"

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Rosenthal, Carolyn B., Joe M. Mootz, and Alexander R. Horswill. "Staphylococcus aureus Biofilm Formation and Inhibition." In Springer Series on Biofilms, 233–55. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-53833-9_11.

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Musini, Anjaneyulu, Sai Pavan Chilumoju, and Archana Giri. "Biofilm Formation in Drug-Resistant Pathogen Staphylococcus aureus." In Microbial Biofilms, 23–46. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003184942-3.

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Archer, Nathan K., J. William Costerton, Jeff G. Leid, and Mark E. Shirtliff. "Immunological Methods for Staphylococcus aureus Infection Diagnosis and Prevention." In Springer Series on Biofilms, 61–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29554-6_5.

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Silva, Vanessa, José L. Capelo, Gilberto Igrejas, and Patrícia Poeta. "Molecular Mechanisms of Antimicrobial Resistance in Staphylococcus aureus Biofilms." In Emerging Modalities in Mitigation of Antimicrobial Resistance, 291–314. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-84126-3_12.

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Kalia, Vipin Chandra, Shikha Koul, Subhasree Ray, and Jyotsana Prakash. "Targeting Quorum Sensing Mediated Staphylococcus aureus Biofilms: A Proteolytic Approach." In Biotechnological Applications of Quorum Sensing Inhibitors, 23–32. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-9026-4_2.

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Riool, Martijn, and Sebastian A. J. Zaat. "Biomaterial-Associated Infection: Pathogenesis and Prevention." In Urinary Stents, 245–57. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04484-7_20.

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AbstractThe use of medical devices, such as urinary stents, catheters, artificial heart valves, prosthetic joints and other implants, collectively often referred to as “biomaterials” has increased dramatically over the past century, and has become a major part of modern medicine and our daily life. With the aging society, the higher demand on these devices to restore function and quality of life, combined with the ever improving technology within the medical field, the problem of biomaterial-associated infection (BAI) is expected to increase.The most common causative microorganisms in BAI are Staphylococcus aureus, a major pathogen in wound infections, and Staphylococcus epidermidis, the harmless skin commensal. Depending on the type of device and location of application, other pathogens such as coagulase-negative staphylococci, enterococci, streptococci, Propionibacterium acnes and yeast can also cause BAI.Prevention of BAI is a challenging problem, in particular due to the increased risk of resistance development associated with current antibiotic-based strategies. Here we showed the evidence of biofilms as a source for peri-implant tissue colonization, clearly showing the importance of preventive measures to be able to act both against implant and tissue colonization. Subsequently, we described different strategies to prevent BAI and other difficult-to-treat biofilm infections. We conclude that future research should focus on the development of combination devices with both anti-fouling or contact-killing capacities—to protect the implant—and controlled release of an antimicrobial agent to protect the surrounding tissue.
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Kumar, Sanjay, Simranjeet Singh, Vijay Kumar, Shivika Datta, Daljeet Singh Dhanjal, Priyanka Sharma, and Joginder Singh. "Pathogenesis and Antibiotic Resistance of Staphylococcus aureus." In Model Organisms for Microbial Pathogenesis, Biofilm Formation and Antimicrobial Drug Discovery, 99–115. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-1695-5_7.

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Cassat, James E., Chia Y. Lee, and Mark S. Smeltzer. "Investigation of Biofilm Formation in Clinical Isolates of Staphylococcus aureus." In Methods in Molecular Biology, 127–44. Totowa, NJ: Humana Press, 2007. http://dx.doi.org/10.1007/978-1-59745-468-1_10.

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Cassat, James E., Mark S. Smeltzer, and Chia Y. Lee. "Investigation of Biofilm Formation in Clinical Isolates of Staphylococcus aureus." In Methods in Molecular Biology, 195–211. Totowa, NJ: Humana Press, 2013. http://dx.doi.org/10.1007/978-1-62703-664-1_12.

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Noguera, M., O. Franquesa, D. Herrera, C. Cifuentes, R. Guix, T. Prenafeta, and R. March. "Efficacy of a Staphylococcus aureus biofilm-embedded bacterin against coagulase-negative staphylococci intramammary infections in dairy cows." In Udder Health and Communication, 381. Wageningen: Wageningen Academic Publishers, 2011. http://dx.doi.org/10.3920/978-90-8686-742-4_72.

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Тези доповідей конференцій з теми "Staphylococcus aureus biofilms"

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Bigelow, Timothy A., Clayton Thomas, Huaiqing Wu, and Kamal Itani. "Impact of step size on histotripsy treatment of staphylococcus aureus biofilms on surgical mesh." In 2017 IEEE International Ultrasonics Symposium (IUS). IEEE, 2017. http://dx.doi.org/10.1109/ultsym.2017.8091780.

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Bigelow, Timothy, Clayton Thomas, Huaiqing Wu, and Kamal Itani. "Impact of step size on histotripsy treatment of Staphylococcus aureus biofilms on surgical mesh." In 2017 IEEE International Ultrasonics Symposium (IUS). IEEE, 2017. http://dx.doi.org/10.1109/ultsym.2017.8092540.

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Pradhana, A. A. S., S. D. Astuti, M. Khasanah, and R. K. D. Ardianti. "Detection of gas concentrations based on age on Staphylococcus aureus biofilms with gas array sensors." In THE 2ND INTERNATIONAL CONFERENCE ON PHYSICAL INSTRUMENTATION AND ADVANCED MATERIALS 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0034112.

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Oubekka, S. Daddi, R. Briandet, F. Waharte, M. P. Fontaine-Aupart, and K. Steenkeste. "Image-based Fluorescence Recovery After Photobleaching (FRAP) to dissect vancomycin diffusion-reaction processes in Staphylococcus aureus biofilms." In European Conference on Biomedical Optics. Washington, D.C.: OSA, 2011. http://dx.doi.org/10.1364/ecbo.2011.80871i.

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Daddi Oubekka, S., R. Briandet, F. Waharte, M. P. Fontaine-Aupart, and K. Steenkeste. "Image-based fluorescence recovery after photobleaching (FRAP) to dissect vancomycin diffusion-reaction processes in Staphylococcus aureus biofilms." In European Conferences on Biomedical Optics, edited by Nirmala Ramanujam and Jürgen Popp. SPIE, 2011. http://dx.doi.org/10.1117/12.889461.

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Ferreira, Maria Gabriela, DENISE VON DOLINGER DE BRITO RÖDER, MÁRIO PAULO AMANTE PENATTI, PRISCILA GUERINO VILELA ALVES, and RALCIANE DE PAULA MENEZES. "O QUE HÁ DE NOVO SOBRE A AÇÃO DE PRODUTOS NATURAIS NA INIBIÇÃO DA FORMAÇÃO DE BIOFILME POR ISOLADOS DE STAPHYLOCOCCUS AUREUS?" In II Congresso Nacional de Microbiologia Clínica On-line. Revista Multidisciplinar em Saúde, 2022. http://dx.doi.org/10.51161/ii-conamic/34.

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Introdução: Staphylococcus aureus é um patógeno oportunista responsável por diversos tipos de infecções, tais como: osteomielite, artrite séptica, endocardite, pneumonia, bacteremia e infecções relacionadas a implantes, impactando nas taxas de morbimortalidade. Além disso, esse microrganismo possui mecanismos de virulência que dificultam a ação dos antimicrobianos, dentre esses mecanismos destaca-se a formação de biofilme, definido como uma comunidade de microrganismos aderidos a uma superfície envoltos por uma matriz extracelular polimérica. Diante disso, estudos que avaliam o potencial anti virulência de compostos naturais tem aumentado ao longo dos anos, com destaque para aquelas substâncias com propriedades terapêuticas já conhecidas. Objetivo: Essa revisão integrativa teve como objetivo elencar os estudos publicados em 2021, que avaliaram a ação de extratos naturais na inibição da formação de biofilme por S. aureus. Material e Métodos: O levantamento bibliográfico foi feito no período de setembro a novembro de 2021, nas bases de dados Pubmed e Portal de Periódicos CAPES utilizando Descritores em Ciências e Saúde: biofilm and extracts, anti biofilm activity of natural extracts, biofilm and S. aureus and natural extracts, biofilm and Gram positive and natural extracts, anti biofilm and Gram positive and natural extracts. Foram selecionados para análise artigos disponíveis na íntegra, publicados entre janeiro e novembro de 2021. Resultados: A busca resultou em 336 artigos, dos quais 11 estavam de acordo com os critérios de inclusão, as plantas utilizadas nos estudos foram: Allium spp., Krameria lappacea, Macrozamia communis, Montrichardia linifera, Zygophyllum coccineum L, Eucalyptus sideroxylon, Illicium verum, Punica granatum L, Sapindus mukorossi, Anthriscus cerefolium e Apis mellifera L. Dentre os extratos vegetais utilizados nos estudos, Allium spp (62,5 µg/mL)., Zygophyllum coccineum L. (3,9 μg/mL) e Eucalyptus sideroxylon (50 µg/mL), foram considerados promissores, pois foram capazes de inibir mais de 66,8% da formação de biofilme por S. aureus em baixas concentrações. Conclusão: A partir dos estudos elencados, extratos naturais possuem ação contra o biofilme de S. aureus. Portanto, esta revisão servirá como um ponto de partida para elaboração de novos estudos, para que esses materiais vegetais possam ser utilizados no tratamento de infecções relacionadas à formação de biofilme.
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Brum, Natália Franco, éverton Patric Dos Santos Amaral, Leonardo Quintana Soares Lopes, and Patrícia Kolling Marquezan. "ATIVIDADE ANTIMICROBIANA E ANTIBIOFILME DO ÓLEO ESSENCIAL DE SALVIA ROSMARINUS FRENTE À BACTÉRIA STAPHYLOCOCCUS AUREUS." In III Congresso Brasileiro de Ciências Farmacêuticas On-line. Revista Multidisciplinar em Saúde, 2022. http://dx.doi.org/10.51161/conbracif/62.

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Introdução: Os biofilmes são comunidades complexas de microrganismos aderidos a uma superfície. Essa capacidade torna o microrganismo até 1.000x mais resistente aos antibióticos e ao sistema imunológico. O Staphylococcus aureus é uma das principais causas de infecções nosocomiais e causadora de doenças relacionadas a biofilme, como fibrose cística. A Salvia romarinus popularmente conhecida por alecrim, é uma planta aromática cultivada pelo mundo inteiro com diversas propriedades terapêuticas. Objetivos: O objetivo do estudo foi verificar o potencial antimicrobiano e antibiofilme do óleo essencial de S. rosmarinus contra S. aureus. Material e métodos: A determinação da concentração inibitória (CIM) mínima foi realizada pela técnica de microdiluição em placa de 96 poços. Realizou-se, uma diluição seriada do óleo essencial (100 – 1,56 mg/mL) e após foi adicionado o microrganismos (S. aureus ATCC 25923). Para a concentração bactericida mínima (CBM), uma alíquota (1 µL) de cada poço foi semeada em ágar Nutriente. A menor concentração que não demonstrou crescimento de colônias foi considerada a CBM. A formação do biofilme foi feita em placa de 96 poços em caldo TSB suplementado com 2% de glicose. O biofilme foi tratado com o óleo essencial nas concentrações de 25 e 50 mg/mL. A quantificação do biofilme tratado foi feita pela técnica de cristal violeta (1%) e a absorbância foi lida em 570 nm utilizando um leitor de microplacas. Para verificar a capacidade de inibir a formação do biofilme, o microrganismo foi adicionado ao caldo na placa de 96 poços juntamente com 2 concentrações sub-inibitórias do óleo essencial (12,5 e 6,25 mg/mL). A técnica de microdiluição mostrou CIM e CBM de 25 mg/ml. Resultados: O óleo essencial mostrou que em 24 horas foi capaz de diminuir o biofilme em aproximadamente 29% na concentração de 50 mg/mL. Além disso, na concentração de 6,25 mg/mL, o óleo foi capaz de inibir a formação do biofilme em 86%. Conclusão: Os resultados mostraram que o óleo essencial de Salvia Rosimarinus pode vir a ser uma alternativa a formação do biofilme de S. aureus, entretanto, mais estudos devem ser realizados para verificar o perfil de segurança e o mecanismo de ação deste produto.
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Viana, Marcelino Gevilbergue, João Pedro Reinaldo De Araújo, and Louise Duarte Matias de Amorim. "Inibição do crescimento de Staphylococcus aureus em biofilme por ação do extrato bruto do metabólito de Fusarium sp." In I Congresso Nacional de Microbiologia Clínica On-Line. Revista Multidisciplinar em Saúde, 2021. http://dx.doi.org/10.51161/rems/1159.

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Introdução: Biofilmes bacterianos são responsáveis por infecções oportunistas e sistêmicas, sendo considerada a comunidade microbiana mais resistente a antibióticos. Objetivo: Avaliar in vitro a ação antimicrobiana do extrato bruto do metabólito de Fusarium sp. sobre biofilmes de S. aureus e P. aeruginosa. Material e métodos: Fusarium sp foi obtido como endófito das folhas de Ziziphus joazeiro a partir do tratamento de desinfecção e sua identificação morfológica realizada a partir da coloração de esporos e comparação. A planta foi coletada no município de Rafael Fernandes, Rio Grande do Norte, feita sua identificação taxonômica e depositadas em exsicatas no laboratório de Biologia do Instituto Federal de Educação, Ciência e Tecnologia (IFRN) em Pau dos Ferros – RN. Fusarium sp. foi mantido em meio BDA, contendo antibiótico, e armazenado a 35º C por 48 horas. Após esse período foram retirados discos miceliais e adicionados em meio líquido BD por oito dias, sob agitação a 50 rpm, para a obtenção do metabólito. Para a obtenção dos biofilmes cepas ATCC de S. aureus e P. aeruginosa foram colocadas em meio líquido e em contato com biocupons por sete dias em agitação à 28ºC. Os tratamentos utilizados foram: 100, 150 e 200 µL do extrato bruto do metabólito de Fusarium sp., sendo adicionados a 300 mL de água destilada por duas horas de contato. Como controle negativo foi utilizada água destilada. A taxa de inibição foi calculada pela relação de absorbância. Não foi realizada a identificação molecular do metabólito. Resultados: A melhor taxa de inibição foi obtida para o tratamento de 200 µL sobre biofilmes de S. aureus, chegando a média de 70,5%. Não houve diferença estatística entre o controle e os demais tratamentos sobre biofilmes de P. aeruginosa. Conclusão: O extrato bruto do metabólito de Fusarium sp. demonstrou eficácia sobre o crescimento de S. aureus em biofilme no tempo avaliado.
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A. Rashid, Sirwan, Sawsan Muhammed Sorchee, Mustafa D. Yonus, and Omar F. Bahjat. "Identification Biofilm Producers s. Aureus Isolates and Detect their Biofilm Genes from Gingivitis Cases." In 4th International Conference on Biological & Health Sciences (CIC-BIOHS’2022). Cihan University, 2022. http://dx.doi.org/10.24086/biohs2022/paper.586.

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Gingivitis is one of the most common oral disorders and is caused by the accumulation of plaque in people with poor oral hygiene. The purpose of this study is to detect Staphylococcus aureus biofilm producers in cases of gingivitis and detect their biofilm genes. During the months of November 2018 and February 2019, a sample of fifty patients diagnosed clinically with gingivitis were collected from the laboratory of the Faculty of Dentistry at Hawler Medical University. Using the traditional culture method and vitek 2, eleven S. aureus bacteria isolates were identified. Using the Congo red agar method, biofilm detection was performed to test the ability to form biofilm. The S. aureus isolates were put through a series of tests to see if the genes responsible for the biofilm could be found (PCR). Biofilm formation method of detection using Congo red agar showed that 10 (90.1%) of S. aureus were biofilm positive and one 1 (9.1%) were biofilm negative. As well as the results of molecular analysis by using PCR showed that isolated S. aureus were carried biofilm genes icaC (100%), icaD (100%), cna (90.9%) and fnba (100%). Gingivitis is one of the most common oral diseases in our area, and this research found that the majority of S. aureus isolates carry the icaC, icaD, cna, and fnba Biofilm genes.
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Lins, Nathalia Alexandre Eloy, Maria Carolina Oliveira Lins, Renan Lennon Silva Henrique, Pettely Thaíse De Souza Santos Palmeira, Maria Helena Chaves de Vasconcelos Catão, Sérgio de Lemos Campello, Anderson Stevens Leônidas Gomes, Patrícia Lins Azevedo do Nascimento, and Cláudia Cristina Brainer de Oliveira Mota. "Analysis of biofilm growth over bulk fill composite resins through optical coherence tomography." In Latin America Optics and Photonics Conference. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.tu1b.4.

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OCT evaluated the biofilm adhesion over dental enamel and bulk fill composite resins. Samples were exposed to Staphylococcus aureus and Candida albicans and scanned by OCT. Resins showed higher Candida colonization, compared to enamel group.
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Звіти організацій з теми "Staphylococcus aureus biofilms"

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Rahimipour, Shai, and David Donovan. Renewable, long-term, antimicrobial surface treatments through dopamine-mediated binding of peptidoglycan hydrolases. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597930.bard.

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There is a need for renewable antimicrobial surface treatments that are semi- permanent, can eradicate both biofilms and planktonic pathogens over long periods of time and that do not select for resistant strains. This proposal describes a dopamine binding technology that is inexpensive, bio-friendly, non-toxic, and uses straight-forward commercially available products. The antimicrobial agents are peptidoglycanhydrolase enzymes that are non-toxic and highly refractory to resistance development. The goal of this project is to create a treatment that will be applicable to a wide variety of surfaces and will convey long-lasting antimicrobial activity. Although the immediate goal is to create staphylolytic surfaces, the technology should be applicable to any pathogen and will thus contribute to no less than 3 BARD priorities: 1) increased animal production by protecting animals from invasive and emerging diseases, 2) Antimicrobial food packaging will improve food safety and security and 3) sustainable bio- energy systems will be supported by coating fermentation vats with antimicrobials that could protect ethanolic fermentations from Lactobacillus contamination that reduces ethanol yields. The dopamine-based modification of surfaces is inspired by the strong adhesion of mussel adhesion proteins to virtually all types of surfaces, including metals, polymers, and inorganic materials. Peptidoglycanhydrolases (PGHs) meet the criteria of a surface bound antimicrobial with their site of action being extracellular peptidoglycan (the structural basis of the bacterial cell wall) that when breached causes osmotic lysis. As a proof of principle, we will develop technology using peptidoglycanhydrolase enzymes that target Staphylococcus aureus, a notoriously contagious and antimicrobial-resistant pathogen. We will test for susceptibility of the coating to a variety of environmental stresses including UV light, abrasive cleaning and dessication. In order to avoid resistance development, we intend to use three unique, synergistic, simultaneous staphylococcal enzyme activities. The hydrolases are modular such that we have created fusion proteins with three lytic activities that are highly refractory to resistance development. It is essential to use multiple simultaneous activities to avoid selecting for antimicrobial resistant strains. This strategy is applicable to both Gram positive and negative pathogens. We anticipate that upon completion of this award the technology will be available for commercialization within the time required to achieve a suitable high volume production scheme for the required enzymes (~1-2 years). We expect the modified surface will remain antimicrobial for several days, and when necessary, the protocol for renewal of the surface will be easily applied in a diverse array of environments, from food processing plants to barnyards.
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