Administration of systematization projects

Estamos viviendo una época de continúos cambios imputables en gran parte al desarrollo espectacular de la ciencia y de la tecnología.We are living in a time of continuous changes attributable in large part to the spectacular development of science and technology

Avances recientes en métodos moleculares para el diagnóstico precoz y tuberculosis resistente al tratamiento

Tuberculosis (TB) remains the main infectious cause of deaths in the world. Due to the slow metabolism of the causative agent, Mycobacterium tuberculosis, the isolation, identification and drug susceptibility testing requires several weeks. New techniques have improved specificity, turnaround time and cost effectiveness. Although these methods yield results within hours from sample collection, the clinical significance of each positive result requires rigorous evaluation in most cases. Herein the advantages and disadvantages of the most promising molecular techniques for detection of TB and drug resistance are discussed.La tuberculosis sigue siendo la principal causa de mortalidad por un agente infeccioso a escala mundial. Debido al metabolismo lento de su agente etiológico, Mycobacterium tuberculosis, el aislamiento, la identificación y las pruebas de susceptibilidad tardan varias semanas. Nuevas técnicas moleculares desarrolladas ofrecen mejorías en la especificidad, el tiempo para la obtención de resultados y su costo-efectividad. Estas pruebas producen resultados en pocas horas a partir de la toma de muestra, pero su relevancia clínica requiere aún ser evaluada rigurosamente en la mayoría de los casos. En esta revisión se discuten las ventajas y las desventajas de las pruebas moleculares más promisorias desarrolladas para el diagnóstico de la tuberculosis y la tuberculosis resistente a medicamentos

Resultados de la cirugía antirreflujo utilizando el protocolo Reflujo – UNAL

La aplicación del protocolo RGO UNAL, pone de manifiesto la utilidad selectiva del uso de la manometria y phmetria esofágicas en los pacientes en los que se aplica el flujograma establecido por el protocolo. Se operaron 79 pacientes siguiendo el protocolo y se realizó el seguimiento inicial por 2 años prospectivamente, realizando valoraciones presenciales inicialmente en el postquirúrgico y luego, llamadas telefónicas para evaluar su calidad de vida y ausencia de síntomas. Se concluye que la aplicación de este protocolo es adecuada para decidir qué pacientes pueden beneficiarse de la cirugía

Phylogenomic analysis of the species of the Mycobacterium tuberculosis complex demonstrates that Mycobacterium africanum, Mycobacterium bovis, Mycobacterium caprae, Mycobacterium microti and Mycobacterium pinnipedii are later heterotypic synonyms of Mycobacterium tuberculosis

International audienc

Transcriptional Regulation of Multi-Drug Tolerance and Antibiotic-Induced Responses by the Histone-Like Protein Lsr2 in M. tuberculosis

Multi-drug tolerance is a key phenotypic property that complicates the sterilization of mammals infected with Mycobacterium tuberculosis. Previous studies have established that iniBAC, an operon that confers multi-drug tolerance to M. bovis BCG through an associated pump-like activity, is induced by the antibiotics isoniazid (INH) and ethambutol (EMB). An improved understanding of the functional role of antibiotic-induced genes and the regulation of drug tolerance may be gained by studying the factors that regulate antibiotic-mediated gene expression. An M. smegmatis strain containing a lacZ gene fused to the promoter of M. tuberculosis iniBAC (PiniBAC) was subjected to transposon mutagenesis. Mutants with constitutive expression and increased EMB-mediated induction of PiniBAC::lacZ mapped to the lsr2 gene (MSMEG6065), a small basic protein of unknown function that is highly conserved among mycobacteria. These mutants had a marked change in colony morphology and generated a new polar lipid. Complementation with multi-copy M. tuberculosis lsr2 (Rv3597c) returned PiniBAC expression to baseline, reversed the observed morphological and lipid changes, and repressed PiniBAC induction by EMB to below that of the control M. smegmatis strain. Microarray analysis of an lsr2 knockout confirmed upregulation of M. smegmatis iniA and demonstrated upregulation of genes involved in cell wall and metabolic functions. Fully 121 of 584 genes induced by EMB treatment in wild-type M. smegmatis were upregulated (“hyperinduced”) to even higher levels by EMB in the M. smegmatis lsr2 knockout. The most highly upregulated genes and gene clusters had adenine-thymine (AT)–rich 5-prime untranslated regions. In M. tuberculosis, overexpression of lsr2 repressed INH-mediated induction of all three iniBAC genes, as well as another annotated pump, efpA. The low molecular weight and basic properties of Lsr2 (pI 10.69) suggested that it was a histone-like protein, although it did not exhibit sequence homology with other proteins in this class. Consistent with other histone-like proteins, Lsr2 bound DNA with a preference for circular DNA, forming large oligomers, inhibited DNase I activity, and introduced a modest degree of supercoiling into relaxed plasmids. Lsr2 also inhibited in vitro transcription and topoisomerase I activity. Lsr2 represents a novel class of histone-like proteins that inhibit a wide variety of DNA-interacting enzymes. Lsr2 appears to regulate several important pathways in mycobacteria by preferentially binding to AT-rich sequences, including genes induced by antibiotics and those associated with inducible multi-drug tolerance. An improved understanding of the role of lsr2 may provide important insights into the mechanisms of action of antibiotics and the way that mycobacteria adapt to stresses such as antibiotic treatment

Rapid culture-based methods for drug-resistance detection in Mycobacterium tuberculosis.

Tuberculosis still represents a major public health problem, especially in low-resource countries where the burden of the disease is more important. Multidrug-resistant and extensively drug drug-resistant tuberculosis constitute serious problems for the efficient control of the disease stressing the need to investigate resistance to first- and second-line drugs. Conventional methods for detecting drug-resistance in Mycobacterium tuberculosis are slow and cumbersome. The most commonly used proportion method on Löwenstein-Jensen medium or Middlebrook agar requires a minimum of 3-4 weeks to produce results. Several new approaches have been proposed in the last years for the rapid and timely detection of drug-resistance in tuberculosis. This review will address phenotypic culture-based methods for rapid drug susceptibility testing in M. tuberculosis

Resistant mutants of Mycobacterium tuberculosis selected in vitro do not reflect the in vivo mechanism of isoniazid resistance

The high prevalence of isoniazid-resistant Mycobacterium tuberculosis is often explained by a high mutation rate for this trait, although detailed information to support this theory is absent. We studied the development of isoniazid resistance in vitro, making use of a laboratory strain of M. tuberculosis. Spontaneous isoniazid-resistant mutants were characterized by molecular methods allowing identification of the most commonly encountered resistance-conferring mutations. Additionally, we determined the in vitro mutation rates for isoniazid and rifampicin resistance, and characterized the genome of a triple-resistant strain. Results confirm that the in vitro mutation rate for isoniazid resistance (3.2 x 10(-7) mutations/cell division) is much higher than the rate for rifampicin resistance (9.8 x 10(-9) mutations/cell division). However, in the majority of the in vitro mutants katG was partially or completely deleted and neither of the two most common in vivo mutations, katG-S315T or inhA-C(-)15T, were found in 120 isogenic mutants. This implies that clinically prevalent resistance mutations were present in <0.8% of isoniazid-resistant strains selected in vitro (95% CI 0%-2.5%). The triple-resistant strain had acquired isoniazid resistance via a 49 kbp deletion, which included katG. Apart from previously identified resistance-conferring mutations, three additional point mutations were acquired during sequential selection steps. These outcomes demonstrate that the in vivo mechanism of isoniazid resistance is not reflected by in vitro experiments. We therefore conclude that the high in vitro mutation rate for isoniazid resistance is not a satisfactory explanation for the fact that isoniazid monoresistance is significantly more widespread than monoresistance to rifampici

gcType : a high-quality type strain genome database for microbial phylogenetic and functional research

Taxonomic and functional research of microorganisms has increasingly relied upon genome-based data and methods. As the depository of the Global Catalogue of Microorganisms (GCM) 10K prokaryotic type strain sequencing project, Global Catalogue of Type Strain (gcType) has published 1049 type strain genomes sequenced by the GCM 10K project which are preserved in global culture collections with a valid published status. Additionally, the information provided through gcType includes >12 000 publicly available type strain genome sequences from GenBank incorporated using quality control criteria and standard data annotation pipelines to form a high-quality reference database. This database integrates type strain sequences with their phenotypic information to facilitate phenotypic and genotypic analyses. Multiple formats of cross-genome searches and interactive interfaces have allowed extensive exploration of the database's resources. In this study, we describe web-based data analysis pipelines for genomic analyses and genome-based taxonomy, which could serve as a one-stop platform for the identification of prokaryotic species. The number of type strain genomes that are published will continue to increase as the GCM 10K project increases its collaboration with culture collections worldwide. Data of this project is shared with the International Nucleotide Sequence Database Collaboration. Access to gcType is free at http://gctype.wdcm.org/