Página 1 dos resultados de 8802 itens digitais encontrados em 0.015 segundos

Avaliação da eficácia da limpeza e desinfecção de alto nível na remoção do biofilme em canais de endoscópios; Evaluation of cleaning efficacy and high level disinfection whem removing biofilm from endoscopes channels

Balsamo, Ana Cristina
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/02/2009 PT
Relevância na Pesquisa
36.98%
Os endoscópios são equipamentos aprovados para serem reutilizados, apesar de apresentarem estrutura interna complexa, composta por canais longos com lúmens estreitos, o que permite a aderência de matéria orgânica e microrganismos, favorecendo assim a formação de biofilmes. Estes dificultam o processamento eficaz, representando um desafio no reuso desses equipamentos. A formação do biofilme é inevitável ao longo do processamento dos endoscópios e há grande dificuldade em removê-lo completamente. Em razão disso, pesquisas atuais apontam-no como possível responsável pela transmissão de infecções exógenas e efeitos adversos que se manifestam em pacientes submetidos a endoscopias gastrointestinais. Essa realidade tem trazido à tona a preocupação em erradicá-lo. Assim, este estudo teve como objetivos avaliar a ação da desinfecção de alto nível na remoção de biofilme após limpeza prévia com escovação em corpos amostrais, simulando os canais de endoscópios flexíveis e comparar os produtos comercialmente disponíveis no mercado nacional para a remoção do biofilme dos endoscópios. Trata-se de uma pesquisa experimental, laboratorial e comparativa. Foram utilizados tubos de revestimento interno de politetrafluoretileno (Teflon®) e a Pseudomonas aeruginosa como microrganismo teste...

Influência de moléculas autoindutoras produzidas por Escherichia coli na formação de biofilme por Listeria monocytogenes; Influence of autoinducers produced by Escherichia coli on biofilm formation by Listeria monocytogenes.

Grandi, Aline Zago de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/06/2015 PT
Relevância na Pesquisa
36.99%
Listeria monocytogenes é um micro-organismo Gram-positivo que está comumente associado a doenças de origem alimentar. Possui a capacidade de sobreviver a condições adversas e de formar biofilme em diferentes superfícies abióticas, tornando-se um problema constante para a indústria de alimentos, pois pode comprometer a sanitização e aumentar o risco de contaminação pós-processamento. A formação de biofilme pode ser regulada por um mecanismo denominado quorum sensing, no qual ocorre intensa comunicação célula-célula, mediada por moléculas químicas, chamadas de autoindutoras. Pouco se sabe sobre a ocorrência de interação entre bactérias Gram- positivas e negativas na formação de biofilmes, sendo mais frequentes estudos entre bactérias do mesmo grupo. A fim de avaliar a ocorrência de interação entre Escherichia coli e L. monocytogenes (Lm), desenvolveu-se esta pesquisa com os seguintes objetivos: i) verificar a capacidade de Lm sorotipo 1/2a selvagem e sua mutante isogênica (ΔprfA ΔsigB) formar biofilme em presença de Escherichia coli, avaliando-se a importância dos reguladores de virulência, prfA e sigB, no processo; e ii) verificar a produção e interferência de moléculas autoindutoras de E. coli E2348/69 na formação de biofilme por Lm. Os ensaios de formação de biofilme foram realizados utilizando-se lâminas de aço-inoxidável AISI 304 #4 imersas em caldo infusão de cérebro e coração (BHI) e em meio pré-condicionado (MPC) por E. coli...

Avaliação da hidrofobicidade e da formação de biofilme em poliestireno por Salmonella Heidelberg isoladas de abatedouro avícola; Hydrophobicity and biofilm formation on polystyrene by Salmonella Heidelberg isolated from a poultry slaughterhouse

Rodrigues, Laura Beatriz; Santos, Luciana Ruschel dos; Rizzo, Natalie N.; Tagliari, Vinícius Z.; Oliveira, Amauri Picollo de; Trenhago, Graciela; Rodegheri, Silvio C.; Taglietti, Ricardo Manuel; Dickel, Elci L.; Nascimento, Vladimir Pinheiro do
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
36.95%
Bactérias do gênero Salmonella são consideradas a principal causa de infecções alimentares em humanos associadas a produtos avícolas, na maioria dos países. São capazes de formar biofilmes em diferentes superfícies, dificultando sua eliminação por procedimentos de limpeza e sanificação na indústria de alimentos. Estudos demonstram uma melhor adesão microbiana com o aumento da hidrofobicidade, tanto da superfície celular como do substrato de adesão. Neste trabalho, avaliou-se a formação de biofilme em placas de poliestireno por S. Heidelberg isoladas de abatedouros avícolas, cultivadas em caldo TSB com diferentes concentrações de glicose e a hidrofobicidade destas cepas na fase logarítmica (4h) e na fase estacionária (24h) do crescimento bacteriano. No caldo TSB sem suplementação de glicose, todas as amostras foram capazes de formar biofilme, sendo duas amostras fortemente formadoras de biofilme, e a maioria fracamente formadora. Nos caldos TSB com 0,5, 1,0 e 1,5% de glicose, todas as amostras foram fracamente formadoras. Nos caldos TSB com 2,0 a 4,0% de glicose, várias amostras apresentaram-se não formadoras e as demais fracamente formadoras. Após a incubação a 36ºC por 4 horas, o índice de hidrofobicidade foi inferior a 10%...

Candida species biofilm and Candida albicans ALS3 polymorphisms in clinical isolates

Bruder-nascimento, Ariane; Camargo, Carlos Henrique; Mondelli, Alessandro Lia; Sugizaki, Maria Fátima; Sadatsune, Terue; Bagagli, Eduardo
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: 1371-1377
ENG
Relevância na Pesquisa
36.93%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 2007/01946-4; Processo FAPESP: 2008/10835-4; Processo FAPESP: 2008/09231-7; Over the last decades, there have been important changes in the epidemiology of Candida infections. In recent years, Candida species have emerged as important causes of invasive infections mainly among immunocompromised patients. This study analyzed Candida spp. isolates and compared the frequency and biofilm production of different species among the different sources of isolation: blood, urine, vulvovaginal secretions and peritoneal dialysis fluid. Biofilm production was quantified in 327 Candida isolates obtained from patients attended at a Brazilian tertiary public hospital (Botucatu, Sao Paulo). C. albicans ALS3 gene polymorphism was also evaluated by determining the number of repeated motifs in the central domain. Of the 198 total biofilm-positive isolates, 72 and 126 were considered as low and high biofilm producers, respectively. Biofilm production by C. albicans was significantly lower than that by non-albicans isolates and was most frequently observed in C. tropicalis. Biofilm production was more frequent among bloodstream isolates than other clinical sources,in urine...

Composição microbiologica e bioquimica do biofilme dental formado em diferentes tempos e sua relação com a desmineralização do esmalte; Microbiological and biochemical composition of dental biofilm formed at different periods and its relationship with enamel demineralization

Glauber Campos Vale
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/02/2006 PT
Relevância na Pesquisa
36.95%
O biofilme dental exposto a sacarose in situ por 13 dias ou mais apresenta altas concentrações de polissacarídeos extra-celulares (PEC), altas contagens da lactobacilos e baixa concentração inorgânica. Entretanto, essas mudanças e suas conseqüências em estágios inferiores de formação de biofilme são desconhecidas. Assim, o objetivo deste estudo foi avaliar a composição microbiológica e bioquímica do biofilme dental formado na presença de sacarose ou glicose + frutose em diferentes tempos, com a finalidade de observar a dinâmica de maturação do biofilme e sua relação com a desmineralização do esmalte. Doze voluntários adultos utilizaram em 3 fases cruzadas de 14 dias, um dispositivo intra-oral palatino contendo 6 blocos de esmalte dental humano, os quais foram expostos 8 vezes ao dia aos seguintes tratamentos: água destilada e deionizada (T1), solução de glicose 10% + frutose a 10% (T2) ou solução de sacarose a 20% (T3). O biofilme foi coletado após 3, 7 e 14 dias de formação e avaliado quanto à composição microbiológica e bioquímica. A análise microbiológica consistiu nas contagens de microrganismos totais (MT), estreptococos totais (ET), estreptococos do grupo mutans (EM), lactobacilos (LB)...

The relationship between inhibition of bacterial adhesion to a solid surface by sub-MICs of antibiotics and subsequent development of a biofilm

Cerca, Nuno; Martins, Silvia; Pier, Gerald B.; Oliveira, Rosário; Azeredo, Joana
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2005 ENG
Relevância na Pesquisa
36.95%
Many studies have demonstrated that subminimal inhibitory concentrations (sub-MICs) of antibiotics can inhibit initial microbial adherence to medical device surfaces. It has been suggested that, by inhibiting initial adhesion, biofilm formation might be prevented. However, since initial adherence and subsequent biofilm formation may be two distinct phenomena, conclusions regarding the effects of sub-MIC antibiotics on initial adhesion cannot be extrapolated to biofilm formation. In this study, we evaluated the adherence of several clinical isolates of coagulase-negative staphylococci (CoNS) to acrylic and the effect of sub-MICs of vancomycin, cefazolin, dicloxacillin and combinations of these antibiotics on adherence and biofilm formation. Most of the antibiotics used resulted in effective reduction of bacterial adherence to acrylic, in some cases reaching over 70% inhibition of adherence. When strains with a high biofilm-forming capacity were grown in sub-MICs of those antibiotics, there existed combinations of the drugs that significantly inhibited biofilm formation. However, most of the antibiotic combinations that inhibited adherence did not have a profound effect on biofilm formation. When comparing the results of the effect of sub-MIC amounts of antibiotics in inhibiting adherence with their effect on the inhibition of biofilm formation...

Effect of cationic surfactants on biofilm removal and mechanical stability

Simões, M.; Pereira, Maria Olívia; Vieira, M. J.
Fonte: IWA publishing Publicador: IWA publishing
Tipo: Conferência ou Objeto de Conferência
Publicado em //2004 ENG
Relevância na Pesquisa
36.93%
In this study, a methodology is proposed to evaluate the mechanical stability of biofilms, by using a stainless steel rotating device where biofilms formed by Pseudomonas fluorescens were allowed to grow for 7 days at 300 rmp. Those biofilms were afterwards submitted to the joined action of chemical agents and mechanical cleaning. Two cationic surfactants (cetyltrimethyl ammonium bromide - CTAB and benzalkonium chloride - BC) were the agents tested. Mechanical cleaning was performed by the variation of the rotation speeds of the rotating device. The following conclusions can be drawn: the biofilm has an inherent mechanical stability; the increase in the rotation speed increased the biofilm removal, but total biofilm removal was not found for the surfactants. BC promoted the increase in the biofilm mechanical stability while CTAB promoted the weakening in the biofilm mechanical stability. From this study, it can be stated that the chemical treatment is far from being a tool that induces massive biofilm detachment and even the synergistic chemical and mechanical treatment did not promoted total biofilm removal.

Characterization of biofilm formation on a humic material

Rodrigues, A. L.; Brito, A. G.; Janknecht, P.; Silva, J.; Machado, A. V.; Nogueira, R.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em /11/2008 ENG
Relevância na Pesquisa
36.93%
Biofilms are major sites of carbon cycling in streams. Therefore, it is crucial to improve knowledge about biofilms’ structure and microbial composition to understand their contribution in the self-purification of surface water. The present work intends to study biofilm formation in the presence of humic substances (HSs) as a carbon source. Two biofilm flowcells were operated in parallel; one with synthetic stream water, displaying a background carbon concentration of 1.26 ± 0.84 mg L−1, the other with added HSs and an overall carbon concentration of 9.68 ± 1.00 mg L−1. From the biofilms’ results of culturable and total countable cells, it can be concluded that the presence of HSs did not significantly enhance the biofilm cell density. However, the biofilm formed in the presence of HSs presented slightly higher values of volatile suspended solids (VSS) and protein. One possible explanation for this result is that HSs adsorbed to the polymeric matrix of the biofilm and were included in the quantification of VSS and protein. The microbial composition of the biofilm with addition of HSs was characterized by the presence of bacteria belonging to beta-Proteobacteria, Cupriavidus metallidurans and several species of the genus Ralstonia were identified...

Adhesion and biofilm formation on polystyrene by drinking water-isolated bacteria

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: Springer Science+Business Media Publicador: Springer Science+Business Media
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
Relevância na Pesquisa
36.93%
This study was performed in order to characterize the relationship between adhesion and biofilm formation abilities of drinking water-isolated bacteria (Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.). Adhesion was assessed by two distinct methods: thermodynamic prediction of adhesion potential by quantifying hydrophobicity and the free energy of adhesion; and by microtiter plate assays. Biofilms were developed in microtiter plates for 24, 48 and 72 h. Polystyrene (PS) was used as adhesion substratum. The tested bacteria had negative surface charge and were hydrophilic. PS had negative surface charge and was hydrophobic. The free energy of adhesion between the bacteria and PS was[0 mJ/m2 (thermodynamic unfavorable adhesion). The thermodynamic approach was inappropriate for modelling adhesion of the tested drinking water bacteria, underestimating adhesion to PS. Only three (B. cepacia, Sph. capsulata and Staphylococcus sp.) of the six bacteria were non-adherent to PS. A. calcoaceticus, Methylobacterium sp. and M. mucogenicum were weakly adherent. This adhesion ability was correlated with the biofilm formation ability when comparing with the results of 24 h aged biofilms. Methylobacterium sp. and M. mucogenicum formed large biofilm amounts...

Presence of extracellular DNA in the Candida albicans biofilm matrix and its contribution to biofilms

Martins, M.; Uppuluri, Priya; Thomas, Derek P.; Cleary, Ian A.; Henriques, Mariana; Lopez-Ribot, José L.; Oliveira, Rosário
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
Relevância na Pesquisa
36.95%
DNA has been described as a structural component of the extracellular matrix (ECM) in bacterial biofilms. In Candida albicans, there is a scarce knowledge concerning the contribution of extracellular DNA (eDNA) to biofilm matrix and overall structure. This work examined the presence and quantified the amount of eDNA in C. albicans biofilm ECM and the effect of DNase treatment and the addition of exogenous DNA on C. albicans biofilm development as indicators of a role for eDNA in biofilm development. We were able to detect the accumulation of eDNA in biofilm ECM extracted from C. albicans biofilms formed under conditions of flow, although the quantity of eDNA detected differed according to growth conditions, in particular with regards to the medium used to grow the biofilms. Experiments with C. albicans biofilms formed statically using a microtiter plate model indicated that the addition of exogenous DNA (>160 ng/ml) increases biofilm biomass and, conversely, DNase treatment (>0.03 mg/ml) decreases biofilm biomass at later time points of biofilm development. We present evidence for the role of eDNA in C. albicans biofilm structure and formation, consistent with eDNA being a key element of the ECM in mature C. albicans biofilms and playing a predominant role in biofilm structural integrity and maintenance.; National Institute of Dental & Craniofacial Research; Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/28222/2006; National Institute of Allergy and Infectious Diseases

Colistin surface conditioning impairs Pseudomonas aeruginosa biofilm formationand enhances ciprofloxacin antimicrobial activity

Machado, Idalina; Lopes, H.; Mendes, D.; Pereira, Maria Olívia
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 ENG
Relevância na Pesquisa
36.98%
Bacterial biofilms on medical devices (MD) are commonly associated with persistent infections. Biofilm formation is central to pathogenesis due to the ability of the biofilm-entrapped bacteria to evade the host immune responses and the increased antimicrobial resistance phenotype often shown by sessile microorganisms. In order to control the infections related with MD, antimicrobial peptide conditioning of MD surfaces can be an attractive answer. Colistin (COL), an important cationic antimicrobial peptide (AMP) produced by Bacillus polymyxa strains, was used to coat polystyrene (PS) surfaces. This work aims at characterizing the antimicrobial effect of COL surface coating to impair Pseudomonas aeruginosa adhesion and subsequent biofilm formation. The response of P. aeruginosa 24 h biofilms treatment with Ciprofloxacin (CIP) in non-conditoned and COL conditioned surfaces was also assessed P. aeruginosa from collection (ATCC 10145) (PAC) and P. aeruginosa isolated (PAI) from a medical device (endoscope) were used as biofilm producers. PS surfaces were pre-conditioned with 64 mg/L of COL during 30 min. Biofilms were then developed in unconditioned and COL-conditioned surfaces, being after treated with Ciprofloxacin (CIP) at 0.75 mg/L. Biofilms were phenotypically characterized in terms of biomass...

Comparison of methods to assess biofilm disinfection and recovery by drinking water-isolated bacteria

Simões, Lúcia C.; Simões, M.; Vieira, M. J.
Fonte: ICAR 2012 Publicador: ICAR 2012
Tipo: Conferência ou Objeto de Conferência
Publicado em //2012 ENG
Relevância na Pesquisa
36.95%
Drinking water (DW) distribution systems are known to harbour biofilms even in the presence of disinfectants. DW biofilms are constituted by microbial communities adapted to low nutrient concentrations and high chlorine levels. Biofilm formation and resistance to disinfection have been recognized as important factors that contribute to the survival and persistence of microbial contamination in DW. The purpose of this work was the comparison of diverse methods to assess the disinfection of biofilms formed by six DW-isolated opportunistic bacteria (Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.) by sodium hypochlorite (SHC). Single and multi-species biofilms (composed of combinations of 6 and 5 bacteria) were developed in 96- wells microtiter plates for 3 days, afterwards, were exposed to several independent SHC concentrations (0.1, 0.5, 1 and 10 mg/L) during 1 h. The potential of biofilms to recover was assessed 24 h after disinfection. The disinfection efficacy and recovery were assessed in terms of variation in: biofilm mass (crystal violet staining); metabolic activity (XTT staining); cultivability (CFUs) and viability (Live/Dead staining). The results indicated that biomass removal increased with increasing SHC concentration...

Relationship between biofilm formation and antibiotic resistance in commensal isolates of Staphylococcus epidermidis

Oliveira, Fernando; Melo, Luís D. R.; Cerca, Nuno
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2013 ENG
Relevância na Pesquisa
37.03%
Staphylococcus epidermidis is a common bacterial coloniser of the normal human microflora and usually have a benign relationship with the host. For several years, S. epidermidis was regarded as a harmless commensal microorganism. However, this bacterium is now recognised as an opportunistic pathogen, representing a leading cause of healthcare-associated infections. The major recognised determinants in the pathogenesis of S. epidermidis infections are its ability to form thick and multilayered biofilms along with high resistance to several classes of antibiotics. Biofilms are defined as structured communities of microorganisms embedded in a self-produced matrix of extracellular polymeric. It is well established that bacteria exhibiting a biofilm phenotype are more recalcitrant to antibiotic therapy. Hence, these two pathogenic features stated above appear to be intimately related. The present study aimed to evaluate the pathogenic potential of commensal S. epidermidis isolates through the assessment of their biofilm formation ability and antibiotic susceptibility profiles, as well as to analyse the relationship between biofilm formation and antibiotic resistance. To achieve that, thirty-one S. epidermidis isolates from Portuguese healthy volunteers (obtained from September 2012 to April 2013) were tested for biofilm formation ability...

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
36.95%
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...

Importance of biofilm as food source for shrimp (Farfantepenaeus paulensis) evaluated by stable isotopes (??13C and ??15N)

Abreu, Paulo Cesar Oliveira Vergne de; Ballester, Eduardo Luis Cupertino; Odebrecht, Clarisse; Wasielesky Junior, Wilson Francisco Britto; Cavalli, Ronaldo Oliveira; Gran??li, Wilhelm; Anesio, Alexandre
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.95%
The contribution of biofilm and artificial feeds for the growth of the pink shrimp Farfantepenaeus paulensis reared in tanks and net cages were evaluated by using stable isotope (??13C and ??15N) analysis. In the net cage experiment, mass balance and mixing equations showed that the biofilm contribution to shrimp growth was over 49% of carbon and 70% of nitrogen. These data suggest that the artificial feed offered in this experiment, although ingested, was not properly incorporated in the shrimp tissue. In contrast, biofilm growing in tanks contributed little to the nitrogen incorporated by the shrimp (maximum of 29%). In this experiment, shrimp presented an unusually large isotope fractionation. These results imply that the shrimp are selectively ingesting some items from the biofilm, or differentially assimilate specific items of the artificial feed, due to differential digestibility. The hypothesis of selective feeding of biofilm microorganisms was corroborated in the experiment with net cages, where shrimp preferentially consumed centric diatoms. This study also demonstrated that shrimp biofilm consumption and the presence of artificial feed largely influenced biofilm formation. The consumption of centric diatoms by shrimp seem to stimulate biofilm chlorophyll-a...

There is a specific response to pH by isolates of Haemophilus influenzae and this has a direct influence on biofilm formation

Ishak, N.; Tikhomirova, A.; Bent, S.J.; Ehrlich, G.D.; Hu, F.Z.; Kidd, S.P.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2014 ENGLISH
Relevância na Pesquisa
36.96%
BACKGROUND: Haemophilus influenzae colonizes the nasopharynx as a commensal. Strain-specific factors allow some strains to migrate to particular anatomical niches, such as the middle ear, bronchi or blood, and induce disease by surviving within the conditions present at these sites in the body. It is established that H. influenzae colonization and in some cases survival is highly dependent on their ability to form a biofilm. Biofilm formation is a key trait in the development of chronic infection by certain isolates. This is exemplified by the contrast between the biofilm-forming strains found in middle ear infections and those isolates that survive within the blood and are rarely associated with biofilm development. RESULTS: Screening a group of H. influenzae strains revealed only slight variations in their growth across a range of pH conditions. However, some isolates responded to a pH of 8.0 by the formation of a biofilm. While the type b capsular blood isolate Eagan did not form a biofilm and grew at the same rate regardless of pH 6.8-8.0, transcriptomic analyses demonstrated that at pH 8.0 it uniquely induced a gluconate-uptake and metabolism pathway, which concurrently imports H+. A non-typeable H. influenzae, isolated from the middle ear...

Wirksamkeit ausgewählter Antibiotika auf bakterielle Erreger von Lungeninfektionen bei Patienten mit Mukoviszidose unter aeroben und anaeroben Wachstumsbedingungen sowie unter Biofilmwachstum; Efficiency of selected antibiotics onto bacterial germs of lung infections at patients of cystic fibrosis under aerobic and anaerobic conditions as well as under biofilm growth

Zanker, Falk
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
37%
In den mit Schleim verstopften Luftwegen von Patienten mit cystischer Fibrose (CF) herrschen anaerobe Verhältnisse vor. Unter diesen Bedingungen kann Pseudomonas aeruginosa, der häufigste Erreger von chronischen, zum Tode führenden CF-Lungeninfektionen, verstärkt Biofilme bilden. Es ist bekannt, daß unter anaeroben Verhältnissen Antibiotika sich in ihrer Wirksamkeit verschlechtern können und daß Biofilm die Bakterien vor Antibiotika schützt. In der vorliegenden Arbeit wurde der Einfluß dieser Umweltfaktoren auf die Wirkung der Antibiotika Meropenem und Ciprofloxacin, welche zur Therapie von CF-Lungeninfektionen eingesetzt werden, gegen P. aeruginosa untersucht. Außerdem wurde getestet, ob durch die Substanzen Azithromycin und DNase die Biofilmbildung von P. aeruginosa inhibiert werden konnte. Die Antibiotikatests unter anaeroben Bedingungen wurden mit Hilfe einer Anaerobenkammer durchgeführt, dabei wurden noch weitere Bakterien und Antibiotika zu Vergleichszwecken getestet. Um die Wirksamkeit der Antibiotika in Biofilm zu prüfen wurde ein Biofilmtest etabliert. Meropenem reduzierte P. aeruginosa unter aeroben Bedingungen gut (minimale bakterizide Konzentration (MBK) = 1 µg/ml), im Biofilm schlechter (MBK = 8 µg/ml) und unter anaeroben Bedingungen zeigte sich keine signifikante Wirkung (MBK > 1024 µg/ml)...

Étude sur le biofilm et les mécanismes de résistance à la bacitracine chez Clostridium perfringens

Charlebois, Audrey
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
37.04%
Clostridium perfringens est ubiquitaire dans l’environnement. Ce microorganisme peut être retrouvé dans la flore normale du tractus gastro-intestinal des mammifères et peut également causer une variété d’infections intestinales. Le phénotype de résistance à la bacitracine a déjà été rapporté chez C. perfringens mais les gènes associés n’ont pas été caractérisés. Dans cette étude, 24 des 99 isolats de C. perfringens aviaires testés ont démontré une résistance à la bacitracine. Les analyses ont révélé la présence d’un transporteur ABC ainsi que d’une undécaprénol kinase surproduite. Ces deux mécanismes semblent être codés par l’opéron bcrABDR. En amont et en aval des gènes bcr, un élément IS1216-like a été identifié, celui-ci pouvant jouer un rôle dans la dissémination de la résistance à la bacitracine. Des analyses d’hybridation sur ADN ont révélé que les gènes bcrABDR étaient localisés sur le chromosome. De plus, il a été démontré que les gènes bcr étaient exprimés en présence de bacitracine. Plusieurs études ont associé la tolérance aux antibiotiques et aux désinfectants à la formation de biofilm. Dans la littérature, peu d’informations sont disponibles sur le biofilm de C. perfringens. La majorité des isolats testés dans cette étude ont démontré la formation d’un biofilm. L’analyse de la matrice a démontré que celle-ci contenait des protéines...

Zinc as an agent for the prevention of biofilm formation by pathogenic bacteria

Wu, Chan
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
Relevância na Pesquisa
37.01%
Les biofilms sont des communautés structurées de micro-organismes enrobées dans une matrice extracellulaire. Les biofilms sont impliqués dans la persistance de plusieurs maladies infectieuses et la matrice extracellulaire du biofilm protège les bactéries contre les cellules du système immunitaire de l'hôte, les antibiotiques et les désinfectants. Récemment notre laboratoire a démontré que le zinc inhibe la formation de biofilm chez Actinobacillus pleuropneumoniae, une bactérie pathogène du porc. Le but de cette étude est d'évaluer l'effet du zinc sur la croissance et la formation du biofilm chez différentes bactéries pathogènes du porc, telles que Bordetella bronchiseptica, Escherichia coli, Haemophilus parasuis, Salmonella, Staphylococcus aureus et Streptococcus suis. Les bactéries ont été cultivées dans des plaques de 96 puits sous condition optimale de formation de biofilm et les biofilms ont été colorés au cristal violet. La présence du biofilm a été confirmée par microscopie confocale à balayage laser à l’aide du marqueur fluorescent FilmTracerTM FM ® 1-43. À des concentrations micromolaires, le zinc inhibe faiblement la croissance bactérienne et bloque d'une manière dose-dépendante la formation de biofilm d’A. pleuropneumoniae...

Effect of chloramine concentration on biofilm maintenance on pipe surfaces exposed to nutrient-limited drinking water

Park,Se-Keun; Kim,Yeong-Kwan
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2008 EN
Relevância na Pesquisa
36.96%
This study addresses the effect of specific monochloramine concentration on biofilm density and bacterial functional potential in nutrient-limited water. The efficacy of monochloramine residual maintenance on biofilm density was studied at a range of 0.5 to 2.0 mg/ℓ, using a 3:1 (w/w) dosing ratio of chlorine to ammonia, with the provision of low-nutrient water (0.18 mg/ℓ as total organic carbon, 0.055 mg/l as biodegradable dissolved organic carbon, and 10.5 µg/ℓ as assimilable organic carbon) using a granular activated carbon (GAC) filter. Biofilm density was monitored using biofilm bacteria counts and analysis of the physiological substrate utilisation profiles in Biolog gram-negative (GN) micro-plates. The monochloramine residuals were maintained stable in the low-nutrient water pipes, which contributed to the inhibition of biofilm density. Increasing the monochloramine residual from 0.5 to 2.0 mg/ℓ suppressed the total cells and heterotrophic plate count (HPC) bacteria in the biofilms by about 1 and 2 log units, respectively. The biofilm HPC densities were more sensitive to monochloramine residual, and the reduction in biofilm HPC densities expressed as log CFU/cm² showed an exponential relationship with the increase in monochloramine residual. The Biolog micro-plate-based community-level assay showed that the biofilm communities occurring at 3 levels of chloramination were distinguished by the differences in their substrate utilisation potentials. The functional/metabolic potential of the biofilm community's ability to utilise specific substrates was much lower at higher monochloramine concentration. Results suggest that the maintenance of a consistently high-level monochloramine residual in the low-nutrient water system led not only to a reduction in biofilm density on pipe surfaces but also depressed potential functional/metabolic ability of the biofilm community.