Comparative genomic analysis of Mycobacterium tuberculosis Beijing-like strains revealed specific genetic variations associated with virulence and drug resistance.

Isolates of the Mycobacterium tuberculosis lineage 2/East-Asian are considered one of the most successful strains due to their increased pathogenicity, hyper-virulence associated with drug resistance, and high transmission. Recent studies in Colombia have shown that the Beijing-like genotype is associated with multidrug-resistance and high prevalence in the southwest of the country, but the genetic basis of its success in dissemination is unknown. In contribution to this matter, we obtained the whole sequences of six genomes of clinical isolates assigned to the Beijing-like genotype. The genomes were compared with the reference genome of M. tuberculosis H37Rv and 53 previously published M. tuberculosis genomes. We found that the six Beijing-like isolates belong to a modern Beijing sub-lineage and share specific genomic variants: i.e. deletion in the PPE8 gene, in Rv3806c (ubiA) responsible of high ethambutol resistance and in Rv3862c (whiB6) which is involved in granuloma formation and virulence, are some of them. Moreover, each isolated has exclusively single nucleotide polymorphisms (SNPs) in genes related with cell wall processes and cell metabolism. We identified polymorphisms in genes related to drug resistance that could explain the drug-resistant phenotypes found in the six isolates from Colombia. We hypothesize that changes due to these genetic variations contribute to the success of these strains. Finally, we analyzed the IS6110 insertion sequences finding very low variance between them, suggesting that SNPs is the major cause of variability found in Beijing-like strains circulating in Colombia.

Paradoxical results of two automated real-time PCR assays in the diagnosis of pleural tuberculosis.

Tuberculosis (TB) is a major cause of worldwide mortality. We report the case of a non-HIV-infected woman with clinical suspicion of pleural tuberculosis and contradictory results between Xpert® MTB/RIF and Abbott RealTime MTB assays from pleural fluid specimen. Liquid and solid cultures for tuberculosis were performed with negative results. The patient received treatment, and clinical improvement was observed. Both techniques detect Mycobacterium tuberculosis complex, but they have different targets and limits of detection. Abbott RealTime MTB results correlated well with the clinical findings of the patient.

Resistencia a isoniazida y rifampicina en aislados de Mycobacterium tuberculosis en pacientes con coexistencia de tuberculosis y Virus de la Inmunodeficiencia Humana, Colombia 2010 - 2012 / Isoniazid and rifampicin resistance in Mycobacterium tuberculosis isolated in patients with coexisting tuberculosis and Human Immunodeficiency Virus, Colombia 2010 - 2012

Introducción: la coexistencia de tuberculosis y el Virus de la Inmunodeficiencia Humana es un evento grave en salud pública que incrementa el riesgo de muerte, para el año 2013 la Organización Mundial de la Salud estimó nueve millones de personas con tuberculosis en el mundo, 1,1 millones (13%) serian positivos al Virus de la Inmunodeficiencia Humana y de estos, 360 000 morirían por esta causa. Objetivo: determinar la prevalencia de la resistencia a isoniazida y rifampicina en pacientes con coexistencia de tuberculosis y el Virus de la Inmunodeficiencia Humana durante los años 2010 a 2012. Materiales y Métodos: análisis de una serie de casos, que incluyo 902 casos de tuberculosis con coexistencia del Virus de la Inmunodeficiencia Humana; donde se evaluaron las variables de procedencia, sexo, edad, tipo de muestra y patrón de resistencia en casos nuevos y previamente tratados. Resultados: el 78,4% de los casos eran de sexo masculino, la mediana de edad fue 34 años, se identificó multirresistencia en casos nuevos en un 3,6% y una resistencia a isoniazida y rifampicina de 6,7% y 1,4% respectivamente. En los casos previamente tratados la multirresistencia fue de 16,2%, la resistencia a isoniazida de 6,3% y a rifampicina de 3,7%. Conclusión: se evidenció que la presencia de resistencia es mayor en previamente tratados, en casos nuevos se observó resistencia a rifampicina sin ser multirresistentes, algo que no se documentó en la última encuesta nacional, estos hallazgos indican que es fundamental realizar prueba de sensibilidad. MÉD.UIS. 2016;29(2):31-9.

Introduction: the coexistence of tuberculosis and HIV is a serious public health event that increases the risk of death by 2013 the World Health Organization estimated nine million people with tuberculosis in the world, 1,1 million (13%) would be positive to HIV and of these, 360 000 would die for this cause. Objective: to determine the prevalence of resistance to isoniazid and rifampicin in patients with coexisting tuberculosis and HIV during the years 2010 to 2012. Methods: analysis of a number of cases, which included 902 cases of tuberculosis with coexistence of HIV, the variables of origin, sex, age, sample type and pattern of resistance in new cases were evaluated and previously treated. Results: 78.4% of cases were male, the median age was 34 years multidrug resistance was identified in new cases and 3.6% resistance to isoniazid and rifampicin 6.7% and 1, 4% respectively. In cases previously treated multidrug resistance was 16.2%, resistance to isoniazid and rifampicin 6.3% from 3.7%. Conclusion: it was shown that the presence of drug resistance is higher in previously treated patients; in new cases rifampicin resistance without being multiresistant, something that was not documented in the latest national survey, these findings indicate that it is essential to conduct sensitivity test. MÉD.UIS. 2016;29(2):31-9.

Human Mycobacterium bovis infection in ten Latin American countries.

The aim of this work was to obtain the best possible estimate of the relevance of bovine tuberculosis (BTB) in humans in Argentina, Brazil, Chile, Colombia, Costa Rica, Dominican Republic, Ecuador, Peru, Uruguay and Venezuela. Sources of information were a questionnaire filled by the participant laboratories, and a search of published literature (1970-2007). Only four of these countries reported bacteriologically confirmed cases of BTB in humans. Most of these were diagnosed in Argentina, where the mean percentage of Mycobacterium bovis cases in relation to those due to Mycobacterium tuberculosis (2000-2006) ranged from 0.34% to 1.0%, according to the region. A slowly decreasing trend was observed in non HIV as well as in HIV/AIDS patients in Buenos Aires. In most of these countries, the low coverage of culture methods, especially of those including pyruvate-containing media, appropriate to isolate M. bovis, contributes to an underestimate of the problem. It was confirmed that BTB in humans exists, even though its relevance seems to be low. Milk pasteurization, sanitary controls to dairy products, and meat inspection at slaughterhouses contribute to the protection of human health. However, occupational aerogenous exposure to TB cattle and their carcasses remains a source of infection in the region.