Cell death of THP-1 induced by puried Rv3671c protein of tuberculosis and the detection of TNF-α and IL-1β in Mycobacterium tuberculosis / 中华预防医学杂志

<p><b>OBJECTIVE</b>To assess the response in THP-1 treated with Rv3671c protein in Mycobacterium tuberculosis (M.tuberculosis).</p><p><b>METHODS</b>The gene encoding Rv3671c protein of M.tuberculosis was cloned into pET-28a vector and then expressed in Escherichia coli. The Rv3671c was purified with Ni-NTA affinity and ion exchange chromatography. The detection of protein concentration was by Lowry method.THP-1 cell was stimulated with Rv3671c protein and cells were analyzed by Hochest staining under fluorescence microscopy to assay cell death (apoptosis and necrosis). TNF-α and IL-1β were detected by ELISA at each stimulating time.</p><p><b>RESULTS</b>The Rv3671c protein of M.tuberculosis was successfully expressed in Escherichia coli. The purity of recombinant Rv3671c protein was 95%, and the protein concentration was up to 0.4 mg/ml. The nucleus of THP-1 was isolated and necrosis-like under fluorescence when cells were stimulated by Rv3671c protein. The levels of TNF-α and IL-1β in supernatant were 19 000 and 16 500 pg/ml respectively, and were significantly higher than control cells with the levels of 2100 and 3800 pg/ml separately.</p><p><b>CONCLUSION</b>The necrosis of THP-1 cells could be stimulated by Rv3671c protein of M.tuberculosis and it was probably associated with high cytokines TNF-α and IL-1β levels.</p>

Fast identification of mycobacteria in microtiter liquid culture / 中华预防医学杂志

<p><b>OBJECTIVE</b>This research was to establish a method for fast identification of mycobacteria in microtiter liquid culture and to evaluate its clinical value.</p><p><b>METHODS</b>2-thiophenecarboxylic acid hydrazide (TCH) and paranitrobenzoic acid (PNB) at different concentrations were added into liquid culture in 96-well plate. Different mycobacterium standard strains were incubated in liquid culture with PNB and TCH for 7 to 10 days. According to the growth assay for 15 mycobacterium strains and 30 mycobacterium tuberculosis strains, the best PNB and TCH concentration were determined. A total of 424 clinical mycobacterium isolates were identified by microtiter liquid culture at the best PNB and TCH concentration. The results of microtiter liquid culture were compared with those of PCR and DNA sequencing.</p><p><b>RESULTS</b>The best concentration of PNB was 200 µg/ml in microtiter liquid culture. Compared with the results of PCR, the sensitivity and specificity for identification of mycobacterium tuberculosis complex in microtiter liquid culture were 97.8% (306/313) and 100.0% (107/107) respectively and those for non-tuberculosis mycobacteria in microtiter liquid culture were 100.0% (107/107) and 96.5% (306/317) respectively. The best concentration of TCH was 0.5 µg/ml. Compared with the results of PCR, the sensitivity of mycobacterium tuberculosis in microtiter liquid culture was 100.0% (305/305). The specificity remained under and more studies were needed.</p><p><b>CONCLUSION</b>In microtiter liquid culture with PNB and TCH, mycobacteria can be identified in 7 to 10 days. The results were accurate and the process was simple without expensive equipments. This method meets clinical needs and can be used in all level hospitals in China.</p>

Evaluation of microscopic observation drug susceptibility for drug susceptibility testing of mycobacterium tuberculosis in smear-positive sputum / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate microscopic observation drug susceptibility (MODS) for mycobacterium tuberculosis drug susceptibility in smear-positive sputum.</p><p><b>METHODS</b>Drug susceptibility of mycobacterium tuberculosis in 275 smear-positive sputum samples collected from TB patients were detected directly by MODS. The susceptibility of seven antimicrobials including streptomycin, isoniazid, rifampicin, ethambutol, levofloxacin, amikacin and capromycin were detected MODS. At the same time the sputum sample were cultured in MGIT 960 tube and the positive isolates were tested for drug susceptibility by MGIT 960 system. The results of MODS were analyzed and compared with that of MGIT 960.</p><p><b>RESULTS</b>Of 275 smear-positive sputum, MODS detected 235 (85.45%). Results of MODS were obtained in a median time of 18 days (5 - 39 d). For the 235 MODS-positive samples, the compliance rates of MODS to MGIT of 7 drugs were 90.21% (212/235), 88.09% (207/235), 93.62% (220/235), 87.23% (205/235), 92.34% (217/235), 88.51% (208/235) and 86.81% (204/235) respectively. The sensitivity of MODS method were 83.33% (90/108), 85.11% (120/141), 90.74% (98/108), 85.71% (78/91), 86.73% (85/98), 76.92% (40/52) and 77.08% (37/48). The specificities of MODS method were 96.06% (122/127), 92.55% (87/94), 96.06% (122/127), 88.19% (127/144), 96.35% (132/137), 91.80% (168/183) and 89.30% (167/187) respectively.</p><p><b>CONCLUSION</b>MODS is an optimal alternative method for direct and rapid drug susceptibility of sputum with high accuracy in a timely and affordable way in resource-limited settings.</p>