RESUMO
Genetic characterization of plasmids from bacterial strains provides insight about multidrug resistance. Ten wild type Escherichia coli (E. coli) strains isolated from cow fecal samples were characterized by their antibiotic resistance profile, plasmid patterns and three different identification methods. From one of the strains, a fertility factor-like plasmid was replicated using tandem shock wave-mediated transformation. Underwater shock waves with a positive pressure peak of up to approximately 40 MPa, followed by a pressure trough of approximately -19 MPa were generated using an experimental piezoelectric shock wave source. Three different shock wave energies and a fixed delay of 750 µs were used to study the relationship between energy and transformation efficiency (TE), as well as the influence of shock wave energy on the integrity of the plasmid. Our results showed that the mean shock wave-mediated TE and the integrity of the large plasmid (~70 kb) were reduced significantly at the energy levels tested. The sequencing analysis of the plasmid revealed a high identity to the pHK17a plasmid, including the replication system, which was similar to the plasmid incompatibility group FII. It also showed that it carried an extended spectrum beta-lactamase gene, ctx-m-14. Furthermore, diverse genes for the conjugative mechanism were identified. Our results may be helpful in improving methodologies for conjugative plasmid transfer and directly selecting the most interesting plasmids from environmental samples.
Assuntos
Farmacorresistência Bacteriana Múltipla , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Fator F/análise , Técnicas de Transferência de Genes , Transformação Bacteriana , Animais , Bovinos , Conjugação Genética , DNA Bacteriano/química , DNA Bacteriano/genética , Escherichia coli/isolamento & purificação , Fezes/microbiologia , Análise de Sequência de DNA , Homologia de Sequência , beta-Lactamases/genéticaRESUMO
Methods to predict fragmentation efficiency are still needed for extracorporeal shock wave lithotripsy (ESWL). Imaging studies of kidney stones could be a useful tool to guide ESWL. Artificial and real kidney stones were analyzed using standard clinical CT imaging procedures. The objective was to compare CT image properties of phantom and real kidney stones. Image properties of both groups were compared and show a good agreement between them. These preliminary images will be used to measure CT attenuation coefficients of real and artificial stones and find a relationship between attenuation values and the fragmentation coefficient of renal calculi exposed to shock waves.