Isolation and antimicrobial resistance profiles of enterobacteria from nestling grey-breasted parakeets (Pyrrhura griseipectus)

The psittacine Pyrrhura griseipectus is a threatened species currently only found in Ceará State, Brazil. A microbiological survey was conducted to determine the composition of the enteric microbiota of this species, as well as the phenotypic profiles of antimicrobial susceptibility presented by the isolates. Cloacal swabs were collected from individual birds and submitted to microbiological processing. Antimicrobial susceptibility profiles were evaluated using the disk diffusion method. Bacteria of the genus Escherichia, Proteus, Citrobacter, Pantoea, Klebsiella, Enterobacter, Morganella, Hafnia, Enterobacter, and Serratia were isolated. The most frequently isolated species were Escherichia coli, Proteus mirabilis and Proteus vulgaris, corresponding to 36.1%, 26.4%, and 8.3%, respectively. Isolates were more frequently resistant to azithromycin and tetracycline, while Escherichia coli was the main species presenting multidrug resistance. In conclusion, free-living grey-breasted parakeets may harbor enterobacteria with high antimicrobial resistance rates.(AU)

Isolation and antimicrobial resistance profiles of enterobacteria from nestling grey-breasted parakeets (Pyrrhura griseipectus)

The psittacine Pyrrhura griseipectus is a threatened species currently only found in Ceará State, Brazil. A microbiological survey was conducted to determine the composition of the enteric microbiota of this species, as well as the phenotypic profiles of antimicrobial susceptibility presented by the isolates. Cloacal swabs were collected from individual birds and submitted to microbiological processing. Antimicrobial susceptibility profiles were evaluated using the disk diffusion method. Bacteria of the genus Escherichia, Proteus, Citrobacter, Pantoea, Klebsiella, Enterobacter, Morganella, Hafnia, Enterobacter, and Serratia were isolated. The most frequently isolated species were Escherichia coli, Proteus mirabilis and Proteus vulgaris, corresponding to 36.1%, 26.4%, and 8.3%, respectively. Isolates were more frequently resistant to azithromycin and tetracycline, while Escherichia coli was the main species presenting multidrug resistance. In conclusion, free-living grey-breasted parakeets may harbor enterobacteria with high antimicrobial resistance rates.

Adequacy assessment of mathematical models in the dynamics of litter decomposition in a tropical forest Mosaic Atlantic, in southeastern Brazil / Adequação da utilização de modelos matemáticos em estudos da dinâmica de decomposição da serapilheira em um Mosaico de Floresta Tropical Atlântica, no sudeste do Brasil

The study of litter decomposition and nutrient cycling is essential to know native forests structure and functioning. Mathematical models can help to understand the local and temporal litter fall variations and their environmental variables relationships. The objective of this study was test the adequacy of mathematical models for leaf litter decomposition in the Atlantic Forest in southeastern Brazil. We study four native forest sites in Parque Estadual do Rio Doce, a Biosphere Reserve of the Atlantic, which were installed 200 bags of litter decomposing with 20×20 cm nylon screen of 2 mm, with 10 grams of litter. Monthly from 09/2007 to 04/2009, 10 litterbags were removed for determination of the mass loss. We compared 3 nonlinear models: 1 Olson Exponential Model (1963), which considers the constant K, 2 Model proposed by Fountain and Schowalter (2004), 3 Model proposed by Coelho and Borges (2005), which considers the variable K through QMR, SQR, SQTC, DMA and Test F. The Fountain and Schowalter (2004) model was inappropriate for this study by overestimating decomposition rate. The decay curve analysis showed that the model with the variable K was more appropriate, although the values of QMR and DMA revealed no significant difference (p> 0.05) between the models. The analysis showed a better adjustment of DMA using K variable, reinforced by the values of the adjustment coefficient (R2). However, convergence problems were observed in this model for estimate study areas outliers, which did not occur with K constant model. This problem can be related to the non-linear fit of mass/time values to K variable generated. The model with K constant shown to be adequate to describe curve decomposition for separately areas and best adjustability without convergence problems. The results demonstrated the adequacy of Olson model to estimate tropical forest litter decomposition. Although use of reduced number of parameters equaling the steps of the decomposition process, no difficulties of convergence were observed in Olson model. So, this model can be used to describe decomposition curves in different types of environments, estimating K appropriately.(AU)

O estudo da ciclagem de nutrientes através da decomposição de serapilheira é essencial para conhecer a estrutura e funcionamento das florestas tropicais nativas. Em decorrência da sua dependência de variáveis ambientais, o uso de modelos matemáticos pode ajudar a compreender as variações locais e temporais da decomposição do folhedo. O objetivo deste estudo foi testar a adequação dos modelos matemáticos para avaliar a dinâmica da decomposição da serapilheira em um mosaico de Floresta Tropical Atlântica no sudeste do Brasil. O estudo foi realizado em quatro remanescentes de mata nativa no Parque Estadual do Rio Doce, parte da Reserva da Biosfera da Mata Atlântica, onde se instalou 200 bolsas decompositoras feitas de tela de nylon 20×20 cm de 2 mm, com 10 gramas de serapilheira recém-colhida. Mensalmente, de 09/2007 a 04/2009, 10 litterbags foram removidos por área, para limpeza, secagem e posterior determinação da perda de massa. Comparamos três modelos não lineares: 1 Modelo exponencial de Olson (1963), que considera a constante K, 2 Modelo proposto por Fountain and Schowalter (2004), 3 Modelo proposto por Coelho e Borges (2005), que considera a variável K através do QMR, SQR, SQTC, DMA e Teste F. O modelo de Fountain and Schowalter (2004) mostrou-se inadequado por superestimar a taxa de decomposição. A análise mostrou que a curva de decaimento do modelo com K variável foi o mais adequado, embora os valores de QMR e DMA não revelaram nenhuma diferença significativa (p> 0,05) entre os modelos. A análise mostrou um melhor ajustamento do DMA usando a variável K, que foi reforçada com os valores do coeficiente de calibração (R2). No entanto, problemas de convergência foram observados neste modelo, que não foi capaz de estimar com precisão os valores “outliers” para cada área de estudo, o que não ocorreu com o modelo de Olson. Entretanto, parece que os problemas de não convergência podem estar relacionados ao ajuste não linear dos dados de massa por tempo, utilizados para gerar o modelo. Quando submetido ao ensaio de parâmetros iguais, o modelo com K constante (Olson, 1963) mostrou-se adequado para descrever a curva de decomposição por áreas de estudo separadamente, de modo que o seu melhor ajuste não compensou os problemas de convergência encontrados. Os resultados demonstraram a aptidão do modelo proposto por Olson (1963) para estimar a decomposição de serapilheira de florestas tropicais, mesmo que eventualmente não detecte diferenças entre as etapas do processo de decomposição. Este modelo não apresenta dificuldades de convergência, permitindo descrever as curvas de decomposição em diferentes tipos de ambientes, estimando os valores de K mais apropriadamente e com mais acurácia.(AU)