1,721,001 research outputs found
Gram‐negative bacteria holding together in a biofilm. The acinetobacter baumannii way
Full text linkBacterial biofilms are a serious public‐health problem worldwide. In recent years, the rates of antibiotic‐resistant Gram‐negative bacteria associated with biofilm‐forming activity have increased worrisomely, particularly among healthcare‐associated pathogens. Acinetobacter baumannii is a critically opportunistic pathogen, due to the high rates of antibiotic resistant strains causing healthcare‐acquired infections (HAIs). The clinical isolates of A. baumannii can form biofilms on both biotic and abiotic surfaces; hospital settings and medical devices are the ideal environments for A. baumannii biofilms, thereby representing the main source of patient infections. However, the paucity of therapeutic options poses major concerns for human health infections caused by A. baumannii strains. The increasing number of multidrug‐resistant A. baumannii biofilmforming isolates in association with the limited number of biofilm‐eradicating treatments intensify the need for effective antibiofilm approaches. This review discusses the mechanisms used by this opportunistic pathogen to form biofilms, describes their clinical impact, and summarizes the current and emerging treatment options available, both to prevent their formation and to disrupt preformed A. baumannii biofilms
Repurposing the Veterinary Antibiotic Apramycin for Antibacterial and Antibiofilm Activity Against Pseudomonas aeruginosa From Cystic Fibrosis Patients
Full text linkObjectives: To evaluate the in vitro antibacterial, antibiofilm, and antivirulence activities of apramycin, comparatively to tobramycin, against a set of P. aeruginosa from chronically infected cystic fibrosis (CF) patients. Methods: The activity of antibiotics against planktonic cells was assessed by performing MIC, MBC, and time-kill assays. The activity against mature biofilms was evaluated, in a microtiter plate, both in terms of dispersion (crystal violet assay) and residual viability (viable cell count). The effect of drug exposure on selected P. aeruginosa virulence genes expression was assessed by real-time Reverse Transcription quantitative PCR (RT-qPCR). Results: Apramycin MIC90 and MBC90 values were found at least fourfold lower than those for tobramycin. A comparable trend was observed for mucoid strains. Only 4 out of 24 strains (16.6%) showed an apramycin MIC higher than the epidemiological cut-off value of 64 mg/L, whereas a higher resistance rate was observed for tobramycin (62.5%; p < 0.01 vs. apramycin). In time-kill analyses, both aminoglycosides were found bactericidal, although apramycin showed a more rapid effect and did not allow for regrowth. Apramycin generally stimulated biofilm biomass formation, whereas tobramycin showed opposite trends depending on the strain tested. Both drugs caused a highly significant, dose-dependent reduction of biofilm viability, regardless of strain and concentration tested. The exposure to apramycin and tobramycin caused increased expression of mexA and mexC (multidrug efflux pumps), whereas tobramycin specifically increased the expression of aprA (alkaline protease) and toxA (exotoxin A). Neither apramycin nor tobramycin showed cytotoxic potential toward IB3-1 bronchial epithelial CF cells. Conclusion: Our results warrant future pharmacokinetic and pharmacodynamic studies for supporting the rationale to repurpose apramycin, a veterinary aminoglycoside, for CF lung infections
Produzione di biofilm in ceppi di Lisyeria monocytogenes isolati da matrice ittica: correlazione con motilità e idrofobicità cellulare.
No full textInfluence of temperature on biofilm formation by Listeria monocytogenes on various food-contact surfaces, relationship with motility and cell surface hydrophobicity
No full textAims: To assess the ability of Listeria monocytogenes to form biofilm on differentfood-contact surfaces with regard to different temperatures, cellular hydrophobicityand motility.Methods and Results: Forty-four L. monocytogenes strains from food and foodenvironment were tested for biofilm formation by crystal violet staining. Biofilmlevels were significantly higher on glass at 4, 12 and 22C, as comparedwith polystyrene and stainless steel. At 37C, L. monocytogenes produced biofilmat significantly higher levels on glass and stainless steel, as compared withpolystyrene. Hydrophobicity was significantly (P < 0Æ05) higher at 37C than at4, 12 and 22C. Thirty (68Æ2%) of 44 strains tested showed swimming at 22Cand 4 (9Æ1%) of those were also motile at 12C. No correlation was observedbetween swimming and biofilm production.Conclusions: L. monocytogenes can adhere to and form biofilms on food-processingsurfaces. Biofilm formation is significantly influenced by temperature,probably modifying cell surface hydrophobicity.Significance and Impacts of the Study: Biofilm formation creates major problemsin the food industry because it may represent an important source of foodcontamination. Our results are therefore important in finding ways to preventcontamination because they contribute to a better understanding on howL. monocytogenes can establish biofilms in food industry and therefore survivein the processing environment.[...
Influence of temperature on biofilm formation by Listeria monocytogenes on various food-contact surfaces: relationship with motility and cell surface hydrophobicity.
No full textAims: To assess the ability of Listeria monocytogenes to form biofilm on different
food-contact surfaces with regard to different temperatures, cellular hydrophobicity
and motility.
Methods and Results: Forty-four L. monocytogenes strains from food and food
environment were tested for biofilm formation by crystal violet staining. Biofilm
levels were significantly higher on glass at 4, 12 and 22C, as compared
with polystyrene and stainless steel. At 37C, L. monocytogenes produced biofilm
at significantly higher levels on glass and stainless steel, as compared with
polystyrene. Hydrophobicity was significantly (P < 0Æ05) higher at 37C than at
4, 12 and 22C. Thirty (68Æ2%) of 44 strains tested showed swimming at 22C
and 4 (9Æ1%) of those were also motile at 12C. No correlation was observed
between swimming and biofilm production.
Conclusions: L. monocytogenes can adhere to and form biofilms on food-processing
surfaces. Biofilm formation is significantly influenced by temperature,
probably modifying cell surface hydrophobicity.
Significance and Impacts of the Study: Biofilm formation creates major problems
in the food industry because it may represent an important source of food
contamination. Our results are therefore important in finding ways to prevent
contamination because they contribute to a better understanding on how
L. monocytogenes can establish biofilms in food industry and therefore survive
in the processing environment
Produzione di biofilm in ceppi di Listeria monocytogenes isolati da matrice ittica: correlazione con motilità e idrofobicità cellulare
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Listeria monocytogenes from meat and meat-processing environments: biofilm formation, motility and hydrophobicity
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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