Whole-Genome Sequence of a Colombian Acinetobacter baumannii Strain, a Coproducer of OXA-72 and OXA-255-Like Carbapenemases.

Colombian Acinetobacter baumannii strain ST920 was isolated from the sputum of a 68-year-old male patient. This isolate possessed blaOXA-72 and blaOXA-255-like genes. The assembled genome contained 4,104,098 pb and 38.79% G+C content. This is the first case reported of the coproduction (blaOXA-72 and blaOXA-255-like) of carbapenem-hydrolyzing class D ß-lactamases (CHDLs) in Acinetobacter baumannii.

Draft Genome Sequences of Multidrug-Resistant Acinetobacter sp. Strains from Colombian Hospitals.

The draft genome sequences of the strains Acinetobacter baumannii 107m, Acinetobacter nosocomialis 28F, and Acinetobacter pittii 42F, isolated from Colombian hospitals, are reported here. These isolates are causative of nosocomial infections and are classified as multidrug resistant, as they showed resistance to four different antibiotic groups.

Computational prediction and experimental assessment of secreted/surface proteins from Mycobacterium tuberculosis H37Rv.

The mycobacterial cell envelope has been implicated in the pathogenicity of tuberculosis and therefore has been a prime target for the identification and characterization of surface proteins with potential application in drug and vaccine development. In this study, the genome of Mycobacterium tuberculosis H37Rv was screened using Machine Learning tools that included feature-based predictors, general localizers and transmembrane topology predictors to identify proteins that are potentially secreted to the surface of M. tuberculosis, or to the extracellular milieu through different secretory pathways. The subcellular localization of a set of 8 hypothetically secreted/surface candidate proteins was experimentally assessed by cellular fractionation and immunoelectron microscopy (IEM) to determine the reliability of the computational methodology proposed here, using 4 secreted/surface proteins with experimental confirmation as positive controls and 2 cytoplasmic proteins as negative controls. Subcellular fractionation and IEM studies provided evidence that the candidate proteins Rv0403c, Rv3630, Rv1022, Rv0835, Rv0361 and Rv0178 are secreted either to the mycobacterial surface or to the extracellular milieu. Surface localization was also confirmed for the positive controls, whereas negative controls were located on the cytoplasm. Based on statistical learning methods, we obtained computational subcellular localization predictions that were experimentally assessed and allowed us to construct a computational protocol with experimental support that allowed us to identify a new set of secreted/surface proteins as potential vaccine candidates.

Fundamentos de criopreservación / Basic points in cryopreservation

El entender y aplicar adecuadamente la criopreservación de material biológico es fundamental en laboratorios y bancos de células. Sin embargo, aunque se han implementado protocolos para criopreservación, aún no se tienen los ideales en la mayoría de los casos. El objetivo de esta revisión es dar a conocer ciertos parámetros inherentes al proceso de criopreservación y la importancia de conocer ciertas características de la célula que pueden incidir con la viabilidad del producto congelado para lograr la técnica adecuada. Para alcanzar este propósito, el documento se basará en el conocimiento de las propiedades fisicoquímicas de la célula y/o el tejido, pues este proceso es afectado por diferentes variables como permeabilidad celular, volumen osmóticamente inactivo y relación superficie/área de la célula, la cual es variable de acuerdo a la especie, tipo y estadio de la célula a congelar. La estructura y composición de las membranas plasmáticas determinan los principales eventos celulares que tienen lugar durante los procesos de criopreservación; las bajas temperaturas afectan la difusión y ósmosis a través de las membranas y cada célula maneja su propio perfil biofísico el cual interactúa con diferentes criopreservantes celulares. El hallar el protocolo adecuado será lo que garantice la viabilidad y funcionabilidad celular.