Caracterización de los plásmidos de cepas de escherichia coli aislados de coprocultivos de niños sanos / Characterization of plasmids of escherichia coli strains isolated from stool culture of healthy children

La microbiota intestinal representa una reserva potencial de organismos resistentes a los antimicrobianos, y el sitio donde los genes de resistencia pueden ser transferidos desde la microbiota comensal a los microorganismos virulentos. En este trabajo se caracterizaron los perfiles fenotípicos de resistencia a diversos agentes antimicrobianos, en aislados de Escherichia coli, obtenidos de niños sanos, menores de 5 años de edad, y la capacidad de transmisibilidad de esos determinantes de resistencia, mediante ensayos de conjugación. Los aislados de E. coli se obtuvieron partir de coprocultivos de niños sanos mediante el uso de placas de Mc Conkey suplementadas con ampicilina y se les determinó el perfil de resistencia a diversos antibióticos, para luego realizar ensayos de conjugación. A partir de 90 coprocultivos, fueron aisladas 33 cepas de E. coli resistentes a algún antibiótico, presentándose un 66,6% del total de las cepas resistentes en al menos dos antibióticos. Luego de los ensayos de conjugación, se encontró que un 47,4% de las cepas presenta plásmidos conjugativos, transfiriendo marcadores de resistencia. Los patrones generados por enzimas de restricción fueron distintos entre ellos. Estos resultados nos permiten sugerir que estos elementos extracromosomales sean los responsables de la rápida diseminación de la resistencia a los antimicrobianos en la población bacteriana de niños sanos.

Gastrointestinal microbiota represents the potential reserve of antimicrobial-resistant organisms, and the site where resistance genes can be transferred from the commensally microbiota to virulent microorganisms. In this work we characterized the phenotypic resistance profiles to various antimicrobial agents in strains of Escherichia coli isolated from healthy children, less than 5 years of age, and the ability of these determinants of resistance to be mobilized by conjugation. The isolation of E. coli strains from stool culture from healthy children was made through the use of Mc Conkey media supplemented with ampicillin. The profile of resistance to various antibiotics was determined and then conjugation was carried out. From 90-stool culture 33 strains of E. coli resistant to some antibiotic were isolated, 63.6% of bacteria were resistant to -at least- two antibiotic. It have be demonstrated that 47.4% of the isolates harbored conjugative plasmids, which can mobilize markers of resistance. Restriction profiles analysis showed that all patterns were different. These results allow us to suggest that these extracromosomals elements are responsible for the rapid spread of resistance to antimicrobials in the bacterial population of healthy children.

Resistencia antimicrobiana de bacterias aisladas de clínicas veterinarias de la ciudad de Ibagué, Colombia / Antimicrobial resistance of bacteria isolated from veterinary clinics in the city of Ibague, Colombia

Objetivo: Aislar bacterias que circulan en clínicas veterinarias de la ciudad de Ibagué, conocer su perfil de resistencia a antimicrobianos y en algunas, su capacidad de transferir dicha resistencia a bacterias sensibles. Materiales y métodos: Se tomaron muestras de 10 clínicas a las que se les realizó cultivo bacteriológico, identificación bioquímica, antibiograma y pruebas de conjugación bacteriana para transmitir dicha resistencia. El diseño metodológico fue de tipo cuasi-experimental, el análisis de los resultados se hizo mediante estadística descriptiva. Resultados: En todas las áreas de las 10 clínicas se encontraron bacterias potencialmente patógenas multirresistentes que pertenecían a 8 de 16 especies aisladas. Los microorganismos que aparecieron con mayor frecuencia en los diferentes sitios de las clínicas fueron: Staphylococcus intermedius, Acinetobacter baumannii, Pantoea agglomerans, Klebsiella pneumoniae y Burkhordelia cepacia. Los lugares donde se aislaron microorganismos multirresistentes con más frecuencia fueron el piso de consulta externa y la mesa de examen clínico. La resistencia se presentó principalmente a amoxicilina y cloranfenicol. El estudio muestra la presencia de patógenos potenciales de causar infecciones nosocomiales, que se constituyen en reservorio de genes de resistencia a los antibióticos para las bacterias patógenas no resistentes.

Objective: To isolate bacteria circulating in veterinary clinics in the city of Ibague for knowing its antimicrobial resistance profile and in some cases, its ability to transfer this resistance to susceptible bacteria. Materials and Methods: Samples of 10 clinics that underwent bacterial culture, biochemical identification, antimicrobial susceptibility testing and bacterial conjugation to transfer this resistance were taken. The methodological design was quasi-experimental and the analysis of the results was made using descriptive statistics. Results: In all areas of the 10 clinical multiresistant potentially pathogenic bacteria which belonged to 8 of 16 species isolated were found. The microorganisms that occurred more frequently in different clinical places were: Staphylococcus intermedius, Acinetobacter baumannii, Pantoea agglomerans, Klebsiella pneumoniae and Burkhordelia cepacia. The places where multiresistant microorganisms were most frequently isolated were the outpatients' floor and the clinical examination table. The resistance occurred mainly to amoxicillin and chloramphenicol. The study shows the presence of potential pathogens causing nosocomial infections, which constitute a reservoir of resistance genes to antibiotics for non-resistant pathogenic bacteria.

Re-engineering the mitochondrial genomes in mammalian cells / 대한해부학회지

Mitochondria are subcellular organelles composed of two discrete membranes in the cytoplasm of eukaryotic cells. They have long been recognized as the generators of energy for the cell and also have been known to associate with several metabolic pathways that are crucial for cellular function. Mitochondria have their own genome, mitochondrial DNA (mtDNA), that is completely separated and independent from the much larger nuclear genome, and even have their own system for making proteins from the genes in this mtDNA genome. The human mtDNA is a small (~16.5 kb) circular DNA and defects in this genome can cause a wide range of inherited human diseases. Despite of the significant advances in discovering the mtDNA defects, however, there are currently no effective therapies for these clinically devastating diseases due to the lack of technology for introducing specific modifications into the mitochondrial genomes and for generating accurate mtDNA disease models. The ability to engineer the mitochondrial genomes would provide a powerful tool to create mutants with which many crucial experiments can be performed in the basic mammalian mitochondrial genetic studies as well as in the treatment of human mtDNA diseases. In this review we summarize the current approaches associated with the correction of mtDNA mutations in cells and describe our own efforts for introducing engineered mtDNA constructs into the mitochondria of living cells through bacterial conjugation.