Papers by Alessandra Ferreira
Brazilian Archives of Biology and Technology, 2007
The aim of this study was to characterize bacteriocins produced by 70 strains of Enterococcus mun... more The aim of this study was to characterize bacteriocins produced by 70 strains of Enterococcus mundtii.Four strains exhibited antibiotic activity towards Listeria innocua, L. monocytogenes, Lactobacillus plantarum, and Salmonella Enteritidis. They remained active under temperatures of up to 121 o C for 20 min, and under pH treatments that varied from 2.0 to 10.0. Antimicrobial activity was maintained during the storage test for 60 days under freezing. The kinetics of production revealed the peak activity of 1600 AU /mL during the logarithmic growth phase and the molecular weight found was approximately 3.0 kDa. The characterization of the products with antimicrobial activity indicated their proteic nature, presenting a typical kinetics of primary metabolite and a molecular weight similar to many purified enterocins.
Brazilian Journal of Microbiology, 2009
Of 396 Pseudomonas aeruginosa strains isolated from hospital sewage, the blaSPM-1 gene was confir... more Of 396 Pseudomonas aeruginosa strains isolated from hospital sewage, the blaSPM-1 gene was confirmed in nine. This is the first report of environmental P. aeruginosa strains carrying the blaSPM-1 gene in Brazil. The carbapenem resistance, already disseminated among clinical isolates, has been detected among environmental isolates.
Revista Da Sociedade Brasileira De Medicina Tropical, 2009
Acinetobacter spp is an important pathogen that is responsible for nosocomial infections affectin... more Acinetobacter spp is an important pathogen that is responsible for nosocomial infections affecting immunocompromised patients, and it can easily acquire resistance to antimicrobial agents. Hospital sewage is an important means for disseminating genes for resistance to ...
Journal of Environmental Management, 2011
Many studies have reported the presence of antibiotic-resistant Pseudomonas aeruginosa in environ... more Many studies have reported the presence of antibiotic-resistant Pseudomonas aeruginosa in environmental samples such as hospital wastewater and surface water. The present study evaluated the contribution of untreated hospital wastewater to the dissemination of resistant P. aeruginosa strains in aquatic environments, through the analysis of their antibiotic susceptibility profile and genetic similarity. Wastewater samples were collected from two hospitals located in Rio Grande do Sul, RS, Brazil. Superficial water samples were collected from water bodies that received this wastewater discharge. The antibiotic susceptibility profiles of the strains were determined using the disk-diffusion technique and their genotyping was done by amplification of the Enterobacterial Repetitive Intergenic Consensus sequences (ERIC-PCR). The antibiotic resistance was higher among the hospital wastewater strains and the multiresistant phenotype was also observed only among these strains. The ERIC-PCR profiles did not reveal any genetic similarity among the P. aeruginosa strains from the wastewater and superficial water samples. On the contrary, they showed that genetically distinct populations were established in these different environments and probably that some other contamination source could be contributing to the presence of resistant strains in these water bodies.
Revista Da Sociedade Brasileira De Medicina Tropical, 2008
Revista da Sociedade Brasileira de Medicina Tropical 41(5):470-473, set-out, 2008
Journal of Endodontics, 2009
Introduction: During the preparation of curved canals, rotary nickel-titanium (NiTi) instruments ... more Introduction: During the preparation of curved canals, rotary nickel-titanium (NiTi) instruments are subjected to cyclic fatigue, which can lead to instrument fracture. Although several factors may influence the cyclic fatigue resistance of instruments, the role of the rotational speed remains uncertain. This study was intended to evaluate the effects of rotational speed on the number of cycles to fracture of rotary NiTi instruments. Methods: ProTaper Universal instruments F3 and F4 (Maillefer SA, Ballaigues, Switzerland) were used in an artificial curved canal under rotational speeds of 300 rpm or 600 rpm. The artificial canal was made of stainless steel, with an inner diameter of 1.5 mm, total length of 20 mm, and arc at the end with a curvature radius of 6 mm. The arc length was 9.4 mm and 10.6 mm on the straight part. The number of cycles required to fracture was recorded. Fractured surfaces and the helical shafts of the fractured instruments were analyzed by scanning electron microscopy. Results: The results showed approximately a 30% reduction in the observed number of cycles to fracture as rotational speed was increased from 300 to 600 RPM (p < 0.05). The morphology of the fractured surface was always of ductile type, and no plastic deformation was observed on the helical shaft of fractured instruments. Conclusions: The present findings for both F3 and F4 ProTaper instruments revealed that the increase in rotational speed significantly reduced the number of cycles to fracture. (J Endod 2009;35:1013-1016
Uploads
Papers by Alessandra Ferreira