RESUMEN
One hundred thirty-four bla(CMY-2) plasmids from Salmonella and Escherichia coli strains from animals and food in Canada were characterized. Five plasmid groups were identified based on replicon type and restriction profiles. Three groups contained E. coli plasmids only. IncA/C plasmids included most multiresistant plasmids and all those of bovine origin.
Asunto(s)
Animales Domésticos/microbiología , Escherichia coli/aislamiento & purificación , Microbiología de Alimentos , Plásmidos/aislamiento & purificación , Salmonella/aislamiento & purificación , beta-Lactamasas/genética , Animales , Canadá , Análisis por Conglomerados , Dermatoglifia del ADN , Escherichia coli/enzimología , Escherichia coli/genética , Genotipo , Polimorfismo de Longitud del Fragmento de Restricción , Salmonella/enzimología , Salmonella/genéticaRESUMEN
Treatment of salmonellosis with antibiotics is controversial and may prolong carriage and shedding. Therefore, this study sought to investigate if exposure to antimicrobials influences the expression of factors involved in virulence and host colonization. The effect of subinhibitory tetracycline treatment (16 microg/ml, 30 min) on a multi-drug resistant Salmonella Typhimurium DT104 strain was investigated using a targeted microarray. Real-time reverse transcriptase PCR was used to confirm and further assess transcription of 10 selected genes. An in vitro cell invasion assay was performed to assess the invasiveness of the tetracycline-treated isolate. Out of 323 genes, 11 were significantly up-regulated and four were down-regulated in the microarray assays. The hilD and hilA genes, both regulators of Salmonella Pathogenicity Island 1, were up-regulated. Other up-regulated genes included the fliC, fliD, motA and motB genes, involved in motility, the fur gene, an important regulator of iron acquisition systems and of acid tolerance. The drug-exposed replicates showed a 2.5-fold increase in intracellular bacteria over the non-exposed control in cell cultures. These findings suggest a drug-induced expression profile consistent with the early stages of Salmonella infection and invasion concomitant with an increased ability to invade epithelial cells in vitro.
Asunto(s)
Antibacterianos/farmacología , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Salmonella typhimurium/efectos de los fármacos , Tetraciclina/farmacología , Factores de Virulencia/biosíntesis , Proteínas Bacterianas/biosíntesis , Recuento de Colonia Microbiana , Citoplasma/microbiología , Farmacorresistencia Bacteriana Múltiple , Células Epiteliales/microbiología , Perfilación de la Expresión Génica , Células HeLa , Humanos , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Bacteriano/biosíntesis , ARN Mensajero/biosíntesis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Regulación hacia ArribaRESUMEN
Brighter SERRS nanotags ideal for improved SERRS imaging were prepared by the controlled addition of electrolyte producing a dimer enriched solution, which was incubated with a Raman reporter before being stabilised by a polyethylene glycol (PEG) shell.