Abstract: Objective To evaluate the value of loop-mediated isothermal amplification (LAMP) assay for the detection of Mycobacterium tuberculosis in the sputum.  Methods The sputum samples were collected from 350 patients from The Tuberculosis (TB) Clinic of Shenzhen Center for Chronic Disease Control between April and September 2013, which including 216 cases of TB and 134 cases of pseudophthisis. Of 216 TB patients, 93 were the cases newly diagnosed, including 41 smear-positive cases and 52 smear-negative cases; 123 were the cases follow-up therapy. There are 11 cases with nontuberculous Mycobacterium infection in pseudophthisis. The specimens were simultaneously detected using four methods (smear microscopy, L-J culture, real-time PCR and LAMP). The clinical dia-gnoses were used as the standard method, the sensitivity and specificity of LAMP method in newly diagnosed patients were calculated by SPSS 17.0. The detection efficiency between different methods was compared usingχ² test. P<0.05 was considered as significant difference. The concordance of LAMP and real time PCR method was evaluated by Kappa test.  Results The sensitivities of smear microscopy, L-J culture, LAMP and real-time PCR in newly diagnosed TB patients were 44.1%（41/93）, 52.7%（49/93）, 48.4%（45/93）and 48.4%（45/93）, respectively. There were statistic differences among four methods (P>0.05). The sensitivity of LAMP was 90.2% (37/41) in smear-positive TB patients, while the sensitivity in smear-negative TB patients was 15.4%（8/52）, and the specificity of LAMP was 100.0% (134/134). The positive rates of a single test using smear microscopy, L-J culture, real-time PCR and LAMP for 123 treated patients were 26.0%（32/123）, 14.6%（18/123）, 31.7%（39/123） and 30.9%（38/123）, respectively. The concordance of LAMP and real-time PCR was 96.9%(339/350). The Kappa value was 0.91.  Conclusion LAMP was a specific and simple method for the diagnosis of TB , and the performance of LAMP was high consistency with real-time PCR.

Key words: Mycobacterium tuberculosis, Sputum, Nucleic acid amplification techniques, Tuberculosis, pulmonary/diagnosis