Estudio molecular de 6 episodios de infección intrahospitalaria causados por staphylococcus aureus meticilino-resistente / Molecular study of 6 episodes of intrahospitalary infection due to methicillin resistant staphylococcus aureus

A critical step in any epidemiologic research concerning nosocomial infections is the precise identification of the responsible pathogen. The present work utilized a molecular approach-plasmids identification, restriction lengght polymorphism DNA analysis and random amplified polymorphic DNA for the characterization of 6 nosocomial outbreaks due to 52 strains of methicillin-resistant staphylococcus aureus (MRSA). In these episodes, the clinic-epidemiologic and phenotipic analysis (antibiotype) pointed to a nosocomial infection. Through molecular analysis it was possible to establish in a very precise way, clonality due to MRSA strains in 2 of the studied outbreaks; the same type of analysis allowed to eliminate a MRSA clonal origin in the remainder 4 episodes. The antibiogram was not an useful analytic tool due to its poor discriminatory power. Also, through a PCR procedure, it was possible to identify the presence of the gen mecA in every of the 52 MRSA strains studied

Clonación y caracterización del sistema de restricción-metilación Pvull de Proteus vulgaris: purificación de la restrictasa recombinante / Cloning and characterization of the Pvull restriction-modification system from proteus vulgaris: purification of the recombinant restrictase

El sistema de restrición-metilación (RMSII) Pvull de P. vulgaris fue clonado y expresado con altos niveles en E. coli. Se estudió el efecto de la alta expresión de restrictasa y metilasa en diferentes cepas de E, coli, resultando la cepa HB101 (mrcB) la única eficientemente transformable con plasmidios portadores de RMSII Pvull. Se aplicó un nuevo procedimiento para la purificación de la restrictasa Pvull recombinante utilizando cromatografía de intercambio iónico. Los métodos empleados permitieron la obtención de grandes cantidades de restrictasa Pvull, libre de exonucleasas y endonucleasas inespecíficas

Restriction endonucleases from microorganisms isolated in Brazil: an isoschizomer of Hae III from a thermophilic Bacillus SP

The isolation and characterization of a restriction endonuclease from a thermophilic strain of Bacillus is described. The enzyme recognizes the palindromic sequence 5'...GGCC...3' as determined by PEI-cellulose chromatography of pancreativc DNAse and snake venom phosphodieterase digestion products of labelled DNA fragments, analysis of restriction digests and direct sequence analysis. The enzyme, denominated BspBR, is an isoschizomer of HaeIII and BspRI