ABSTRACT
Resumen Diversos estudios han evidenciado una resistencia cruzada entre isoniacida y etionamida, 2 de los fármacos utilizados en el tratamiento de la tuberculosis multirresistente.El objetivo del presente estudio fue determinar la resistencia cruzada entre ambos fármacos en aislados de Mycobacterium tuberculosis obtenidos en un hospital de Lima (Perú), conalta proporción de pacientes con tuberculosis. Se calculó la frecuencia de mutaciones asociadas con la resistencia a la isoniacida (INH) evaluando el gen katG y la región promotorainhA mediante la prueba molecular Genotype MTBDRplus v2.0. El método gold standard conocido como agar proporciones en placa (APP) permitió la identificación de resistencia a INH yetionamida. De 107 aislamientos resistentes a INH, 54 fueron multirresistentes (identificadosmediante la prueba Genotype MTBDRplus) y 49 (es decir, el 45,8% del total) también fueronresistentes a etionamida por el método APP. En los aislamientos resistentes a INH, se encontraron mutaciones en el gen katG en el 50,5% (54/107); en la región promotora inhA en el23,3% (25/107), y un 14,0% (15/107) presentaron mutaciones en ambos. Un 12,1% (13/107)fueron resistentes a INH por ausencia de banda wild type y banda de mutación. La mutaciónC-15T en la región promotora inhA presentó una fuerte asociación con la resistencia a etionamida y alcanzó el 73,4% (36/49) de los aislamientos resistentes a dicho fármaco. Los resultadosdel presente estudio sugieren que la identificación de mutaciones relacionadas con resistenciaa INH, sobre todo en la región promotora inhA, podría ser de gran utilidad para identificarla resistencia cruzada a etionamida y mejorar el tratamiento de las personas afectadas portuberculosis.© 2019 Asociacion Argentina de Microbiolog´ía. Publicado por Elsevier Espana, S.L.U. Este es unart´ículo Open Access bajo la licencia CC BY-NC-ND (https://creativecommons.org/licenses/by-nc-nd/4.0/).
Abstract Several studies have shown cross-resistance between isoniazid and ethionamide, 2of the drugs used in the treatment of multidrug-resistant tuberculosis. The objective of this study was to determine the cross-resistance between both drugs in Mycobacterium tuberculosis isolates from a hospital with high incidence of tuberculosis in Lima, Peru. The frequency of mutations to isoniazid in the katG gene and the inhA promoter region was identified by the Genotype MTBDRplus v2.0 molecular test. The gold standard Agar Proportion method (APM) allowed todetect resistance to isoniazid and ethionamide. Of 107 isoniazid-resistant isolates (54 multidrug-resistant isolates identified by the Genotype MTBDRplus test, 45.8% (49/107) were also resistant to ethionamide by the APM. Mutations were found in the katG gene in 50.5% (54/107), in the promoter region inhA in 23.3% (25/107) and 14.0% (15/107) that share both mutations in the resistant isolates to INH. The absence of the wild type and mutation bands indicated that 12.1% (13/107) of the isolates were resistant to INH. The mutation C-15T in the inhA promoter region showed a strong association with resistance to ethionamide in 73.4% (36/49) of the isolates analyzed. The results of the present study suggest that the identification of mutations related to resistance to isoniazid, especially in the inhA promoter region, could be very useful to identify cross-resistance to ethionamide and improve the treatment of individuals suffering from this disease.
Subject(s)
Humans , Tuberculosis, Multidrug-Resistant/genetics , Ethionamide/pharmacology , Isoniazid/pharmacology , Mutation , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/genetics , Antitubercular Agents/pharmacology , Peru , Drug Interactions , Genotype , Mycobacterium tuberculosis/isolation & purificationABSTRACT
Introducción. Una parte de los aislamientos de Mycobacterium tuberculosis multirresistente también presenta resistencia a la etionamida. Es importante determinar si la resistencia a la isoniacida es independiente o se cruza con la resistencia a la etionamida, ya que si sucede lo segundo habría que reevaluar el tratamiento antituberculoso de segunda línea. La prueba molecular GenoType MTBDR plus ® detecta las mutaciones asociadas con la resistencia a isoniacida y podría detectar la resistencia cruzada a la etionamida. Objetivo. Evaluar la prueba GenoType MTBDR plus ® y comparar su desempeño con el de la secuenciación, en la detección de mutaciones en el gen katG y en el promotor inhA en aislamientos clínicos de M. tuberculosis multirresistente. Materiales y métodos. Se utilizaron el estuche comercial GenoType MTBDR plus 1.0 ® y la secuenciación para evaluar mutaciones en el gen katG y en el promotor inhA en 30 aislamientos de M. tuberculosis multirresistente con resistencia a la etionamida. La cepa de laboratorio H37Rv y tres aislamientos sensibles a los medicamentos de primera línea, sirvieron de control. Resultados. Al comparar los resultados de la secuenciación y de la prueba GenoType MTBDR plus ® , el índice kappa fue de 1. Todos los aislamientos resistentes a la isoniacida y la etionamida tenían las mutaciones detectadas con la prueba GenoTypeMTBDR plus ® en el gen katG, y 40 % de ellos, las detectadas en el promotor inhA. Mediante secuenciación se encontraron, además, mutaciones en katG en posiciones diferentes a las detectadas por la prueba GenoType MTBDR plus ® . Conclusión. La prueba GenoTypeMTBDR plus ® tiene la capacidad de detectar rápidamente la resistencia a isoniacida. Además, los resultados del estudio sugieren que también podría utilizarse como prueba de tamización para detectar la resistencia cruzada a etionamida.
Introduction: A variable proportion of isolates of multidrug-resistant Mycobacterium tuberculosis also presents resistance to ethionamide. It is important to determine whether resistance to isoniazid is independent or crossed with resistance to ethionamide, given that this could lead to the re-evaluation of second-line anti-tuberculosis treatment. The GenoType MTBDR plus ® molecular test is used for the detection of MDR-MTB, as it identifies mutations associated with resistance to isoniazide and could detect cross-resistance with ethionamide. Objective: To evaluate the performance of GenoType MTBDR plus ® in comparison with sequencing in the detection of mutations in gene katG and promotor inhA in clinical isolates of multidrug-resistant M. tuberculosis . Materials and methods: The GenoType MTBDR plus 1.0 ® commercial kit and sequencing were used to evaluate mutations in gene katG and promotor inhA in 30 multidrug-resistant M. tuberculosis isolates that were resistant to ethionamide. The laboratory strain H37Rv and three pan-sensitive isolates acted as controls. Results: The kappa index for the comparison between the results of sequencing and GenoType MTBDR plus ® was 1. All the isolates resistant to isoniazid and ethionamide had the mutations detected by GenoTypeMTBDR plus ® in the katG gene and 40% of them in promotor inhA. Sequencing also revealed katG mutations in positions different to those detected by GenoType MTBDR plus ® . Conclusion: GenoType MTBDR plus ® is able to detect resistance to isoniazid rapidly. Our results suggest that it could also be used to screen for cross-resistance with ethionamide.
Subject(s)
Humans , Oxidoreductases/genetics , Bacterial Proteins/genetics , Catalase/genetics , Bacterial Typing Techniques/methods , Sequence Analysis, DNA/methods , Tuberculosis, Multidrug-Resistant/microbiology , Drug Resistance, Multiple, Bacterial/genetics , Ethionamide/pharmacology , Genotyping Techniques , Isoniazid/pharmacology , Mycobacterium tuberculosis/drug effects , Antitubercular Agents/pharmacology , DNA, Bacterial/genetics , Polymerase Chain Reaction/methods , Promoter Regions, Genetic/genetics , Ethionamide/metabolism , Genotype , Isoniazid/metabolism , Mycobacterium tuberculosis/isolation & purification , Mycobacterium tuberculosis/enzymology , Mycobacterium tuberculosis/genetics , Antitubercular Agents/metabolismABSTRACT
To determine the sensitivity of clinical isolates of Mycobacterium tuberculosis isolates against ethionamide, and clarithromycin. Cross-sectional study. Department of Microbiology, Armed Forces Institute of Pathology [AFIP] Rawalpindi from June 2003 to June 2004. All routine clinical samples received for acid fast bacilli [AFB] culture and yielding positive growth on Lowenstien Jensen medium and Bactec 460 were included in the study. The isolates were from sputum [n=70], bronchioalveolar lavage [n=10], fine needle aspiration [n=6], lymph nodes [n=7], pleural fluid [n=4], endometrium [n=3]. After the identification of M. tuberculosis [MTB] sensitivity was performed against first-line antituberculosis drugs. Then susceptibility of M. tuberculosis isolates against ethionamide and clarithromycin was performed on LJ medium. Mycobacterium H37Rv was used as control strain. Results were interpreted using resistance ratio method. Out of 100 M. tuberculosis isolates, sensitivity to ethionamide was 93% and 9% to clarithromycin. Clarithromycin when used alone is ineffective as antituberculosis drug but its efficacy in combination needs to be tested. However ethionamide may be used as an alternative antituberculosis drug