RESUMO
Agroforestry systems are examples of soil exploration that is closer to the natural form of the forest, with intercropping of several species within an area, thus being sustainable alternatives. Therefore, the objective of this work was to evaluate the weed community in agroforestry systems in two ecosystems: solid ground and floodplain in the state of Pará. Such collections were made in eight areas, with about one hectare each, cultivated in agroforestry systems, four of which are on dry land and four on floodplains, in the rural area of Cametá-PA. Four plots of one square meter per area were randomly sampled, where the species were identified, counted, and taken to weigh to evaluate the weed community. Among the evaluated environments, the species that stood out the most in the solid ground environment was Kyllinga brevifolia, leading most of the evaluated indices. In the lowland ecosystem, the Brachiaria species purpuracens were the most relevant.
RESUMO
Most of the knowledge of the virulence determinants of extraintestinal pathogenic Escherichia coli (ExPEC) comes from studies with human strains causing urinary tract infections and neonatal meningitis and animal strains causing avian colibacillosis. In this research, we analyzed the phylogenetic background, the presence of 20 ExPEC virulence factors, and the intrinsic virulence potential of 74 E. coli strains isolated in São Paulo, Brazil, from 74 hospitalized patients (43 males and 31 females) with unknown-source bacteremia. Unlike other places in the world, the bacteremic strains originated equally from phylogroups B2 (35%) and D (30%). A great variability in the profiles of virulence factors was noted in this survey. Nevertheless, 61% of the strains were classified as ExPEC, meaning that they possessed intrinsic virulent potential. Accordingly, these strains presented high virulence factor scores (average of 8.7), and were positively associated with 12 of 17 virulence factors detected. On the contrary, the non-ExPEC strains, isolated from 39% of the patients, presented a generally low virulence capacity (medium virulence factor score of 3.1), and were positively associated with only the colicin cvaC gene. These results show the importance of discriminating E. coli isolates that possess characteristics of true pathogens from those that may be merely opportunistic in order to better understand the virulence mechanisms involved in extraintestinal E. coli infections. Such knowledge is essential for epidemiological purposes as well as for development of control measures aimed to minimize the incidence of these life-threatening and costly infections.