Abstract:

Objective To evaluate the isothermal amplification fluorescence technique in detecting Mycobacterium tuberculosis in sputum of suspects in peripheral tuberculosis laboratory. Smear microscopy, L?wenstein-Jensen culture and isothermal amplification fluorescence tests were respectively performed to 4242 sputum samples from suspicious pulmonary tuberculosis patients in four county level laboratries in Henan province during 2014 to 2015, the sensitivity, specificity and detection time were compared with each method using Chi square test and the P value was set as <0.05. Of 4242 TB suspects’ samples, the number of smear positive cases 351 (8.21%), the number of culture positive was 576 (13.47%), the number of isothermal amplification fluorescence 733 (17.14%). The sensitivity of three detection methods were statistically significantly different, χ ²=153.412,P<0.001. The reporting time of the isothermal amplification fluorescence method was about 2 hours. Compared with culture as the standard, the sensitivity and specificity of the isothermal amplification fluorescence method were 86.81% (500/576) and 93.64% (3433/3666) respectively. Positive predictive value (PPV) and negative predictive value (NPV) of the isothermal amplification fluorescence method were 68.21% (500/733) and 97.83 (3433/3509) respectively. The sensitivity, specificity, PPV and NPV of sputum smear microscopy were 57.29% (330/576), 99.43% (3645/3666),94.02% (330/351),93.68% (3645/3891)respectively. The results of the isothermal amplification fluorescence method and sputum smear microscopy was consistent with L?wenstein-Jensen culture (Kappa values were 0.722 and 0.679). There was a statistically significantly difference in sensitivity between the isothermal amplification fluorescence method and sputum smear microscopy (χ ²=153.336,P<0.001). The isothermal amplification fluorescence method shows more sensitivity and specificity than the traditional methods, and is a rapid, sensitive, simple and specific method for the detection of Mycobacterium tuberculosis, then play an important role in diagnosing tuberculosis in peripheral laboratories .

Key words: Mycobacterium tuberculosis, Laboratory techniques and procedures, Nucleic acid amplification techniques, Fluoroimmunoassay, Data interpretation, statistical, Comparative study