Résumé
Aim: Identification of anti-Mycobacterium tuberculosis agents of plant origin, against sensitive and multidrug resistant (MDR) strains. Study Design: Assessing anti-M. tuberculosis activity of five Indian medicinal plants, which have been reported in traditional literature for various uses including respiratory ailments. Place and Duration of Study: Mumbai, India; May 2009 – December 2011. Methodology of Study: The reference strain (H37Rv), three susceptible and three MDR clinical isolates of M. tuberculosis were used. Acetone, ethanol and aqueous extracts (prepared sequentially) of Acorus calamus L. (rhizome), Andrographis paniculata Nees. (leaf), Ocimum sanctum L. (leaf), Piper nigrum L. (seed) and Pueraria tuberosa DC. (tuber) were tested at 1, 10 and 100 μg/ml using the Microplate Alamar Blue Assay. The active extracts were assessed for cytotoxicity on the human lung epithelial cell line (A549) using the neutral red assay and a phytochemical analysis was made using High Performance Thin Layer Chromatography (HPTLC). Results: Among the plants tested, the acetone extract of P. nigrum appears promising. It was effective against H37Rv, all susceptible isolates and one MDR isolate at 100 μg/ml. The ethanol extract caused some inhibition of growth, though less than the cut-off of 99%. A combination of acetone and ethanol extracts at 50 μg/ml each was effective against all isolates tested. The known active phytoconstituent of P. nigrum, piperine (also an efflux pump inhibitor), was effective against H37Rv in the presence of suboptimal concentration of Rifampicin, but not against the clinical isolates tested. Presence of piperine in the acetone and ethanol extracts was confirmed by HPTLC. Extracts of P. nigrum and piperine were not cytotoxic to the A549 cell line. Conclusion: Amongst the five plants tested, P. nigrum was active. The acetone extract may have active components in addition to piperine. It is possible that the class and expression of efflux pumps in H37Rv is different from that in the clinical isolates, and hence piperine did not inhibit these isolates. Thus, it is necessary to screen clinical isolates in addition to reference strains. The observation of the increased efficacy of the combination of acetone and ethanol extracts is interesting.
Résumé
Background: Multidrug - resistant TB (MDR - TB) has emerged as a major threat to global TB control efforts in recent years. Facilities for its diagnosis and treatment are limited in many high - burden countries, including India. In hyper - endemic areas like Mumbai, screening for newly diagnosed cases at a higher risk of acquiring MDR - TB is necessary, for initiating appropriate and timely treatment, to prevent its further spread. Objective: To assess risk factors associated with MDR - TB among Category I, new sputum smear-positive cases, at the onset of therapy. Materials and Methods: The study applied an unmatched case - control design for 514 patients (106 cases with MDR - TB strains and 408 controls with non - MDR - TB strains). The patients were registered with the Revised National Tuberculosis Control Program (RNTCP) in four selected wards of Mumbai during April 2004 - January 2007. Data were collected through semi - structured interviews and drug susceptibility test results. Results: Multivariate analysis indicated that infection with the Beijing strain (OR = 3.06; 95% C.I. = 1.12 - 8.38; P = 0.029) and female gender (OR = 1.68; 95% C.I. = 1.02 - 2.87; P = 0.042) were significant predictors of MDR-TB at the onset of therapy. Conclusion: The study provides a starting point to further examine the usefulness of these risk factors as screening tools in identifying individuals with MDR-TB, in settings where diagnostic and treatment facilities for MDR-TB are limited.
Résumé
Background: Diagnosis of tuberculosis is difficult in HIV positive patients since they often present with atypical symptoms and are susceptible to pulmonary infections that mimic tuberculosis. Sputum collection may not be possible even in patients with pulmonary involvement since a productive cough is not always present. In such patients, blood smear and culture for AFB apart from serving as a diagnostic tool can be used for testing drug sensitivity. Objectives: This study was undertaken to explore the value of blood culture for diagnosis in patients with suspected TB. In addition, a comparison of drug sensitivity patterns of blood and sputum isolates in 10 of these patients was also carried out. Methods: Blood and sputum samples were processed, cultured and isolates tested for their drug susceptibility and for niacin production, nitrate reduction as well as catalase activity at 68o C. Results: All 24 blood samples were culture positive although only 6 were smear positive. On the basis of the biochemical investigations, 22 strains were identified as Mycobacterium tuberculosis. All the 10 sputum samples were culture positive despite 4 being smear negative. Comparison of drug sensitivity profiles from blood and sputum revealed concordance to five first or second line drugs in 5 of 10 patients. Additionally, 2 patients demonstrated discordance for only one first or second line drug. Conclusion: The study demonstrates the importance of blood culture in confirming diagnosis of tuberculosis and testing for drug sensitivity in HIV positive patients without a productive cough. The level of discordance in drug sensitivity profiles between blood and sputum the same individual is suggestive of infection with multiple strains. Testing for the occurrence of multistrain infections through individual colony examination of a single isolate is necessary since such infections would affect treatment of non-responder patients having HIV-TB dual infections.