Detection on drug resistance of Mycobacterium tuberculosis by microscopic observation drug susceptibility / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of microscopic observation drug susceptibility (MODS) in detecting susceptibility of Mycobacterium tuberculosis (MTB) onto four first line anti-tuberculosis drugs.</p><p><b>METHOD</b>The 24-hole cell culture plates were used to test drug susceptibility of MTB on liquid medium, and the best detecting condition of MODS assay was probed; 66 clinical isolates susceptibility to streptomycin (S), isoniazid (H), rifampin (R) and ethambutal (E) were evaluated by using MODS assay and Lowenstein-Jensen (L-J), thereafter, all the inconcordance of isolates between MODS and L-J were tested for the minimal inhibitory concentrations (MIC).</p><p><b>RESULTS</b>Concordance rate of the susceptibility to S, H, R and E in 66 clinical isolates detected by MODS and L-J was 97.0%, 90.9%, 95.5% and 86.4% respectively. If the results obtained by L-J were taken as a golden standard, the sensitivity, specificity, positive and negative predictive value (PPV and NPV) as well as accuracy of susceptibility test to S detected by MODS was 96.0%, 97.6%, 96.0%, 97.6% and 97.0%; 100%, 85.4%, 81.0%, 100% and 90.9% to H; 96.2%, 95%, 92.6%, 97.4% and 95.5% to R; 73.7%, 91.5%, 77.8%, 89.6% and 86.4% to E. There were 20 inconsistent results of 16 isolates by comparing MODS with L-J, and MIC yielded 16 results of those 14 isolates showing identical results with those of the MODS, while 4 results of other 4 isolates identical with L-J.</p><p><b>CONCLUSION</b>MODS method simultaneously provides drug susceptibility to S, H, R and E. MODS might be one of the rapid tools to diagnosing multidrug-resistant tuberculosis as it is rapid, simple, inexpensive and has high concordance with L-J drug susceptibility test.</p>

Expression and purification of CFP32 of Mycobacterium tuberculosis and its serodiagnostic analysis / 中华预防医学杂志

<p><b>OBJECTIVE</b>To establish a recombinant plasmid of CFP32 of Mycobacterium tuberculosis in E. coli, and to analyze its antigenicity.</p><p><b>METHODS</b>Rv0577 gene was amplified by polymerase chain reaction from genome of Mycobacterium tuberculosis, and then cloned into vector pMD18-T followed by the subclone into the expression vector pET21a. Recombinant CFP32 was expressed and purified. The antigenicity of the recombinant protein was analyzed by using Western-blot. The purified recombinant CFP32 protein was used as an antigen to screen the sera of 7 pulmonary TB patients (n = 97), as well as the other pulmonary disease patients (n = 25), and the clinically healthy controls (n = 38) by ELISA.</p><p><b>RESULTS</b>Recombinant plasmid of CFP32 was established, and be expressed efficiently in E. coli BL21 (DE3). The relative molecular mass of the protein was about 300,000 by SDS-PAGE analysis. The protein purified by Ni-NTA was in a purity over 90%, which was confirmed by Western-blot analysis. ELISA analysis showed its sensitivity and specificity were 63.9% (62/97) and 96.8% (2/63) respectively.</p><p><b>CONCLUSION</b>The recombinant expression plasmid pET21a CFP32 has been constructed and CFP32 proteins has been successfully expressed and be purified in E. coli and, ELISA analysis has identified the recombinant CFP32 as a candidate antigen for TB serodiagnosis.</p>