Abstract:

Objective To evaluate the performance of DNA microarray chip to detect Mycobacterium tuberculosis (MTB) and determine the susceptibility to isoniazid (INH) and rifampicin (RFP). A total of 814 specimens of sputum smear-positive (SS+) pulmonary tuberculosis cases registered in Guanyun County Center for Disease Control and Prevention between January 2011 and May 2017 were collected. Proportion method using L?wenstein-Jensen culture medium, drug susceptibility testing (DST) and DNA microarray chip were performed to detect MTB and to test the susceptibility to INH and RFP of the sputum specimens. The detection value of DNA microarray chip was assessed by using proportion method and DST as standard, respectively. DNA microarray chip showed a significant difference (χ ²=6.81, P<0.05) in the detection of MTB in SS+ cases with a detection rate of 86.1% (701/814), which was higher than that of proportion method (82.4%, 671/814). Taking proportion method as standard, the sensitivity and specificity of DNA microarray chip in detecting MTB were 92.4% (620/671) and 43.4% (62/143), Kappa value was 0.39, and positive predictive value (PPV) and negative predictive value (NPV) were 88.4% (620/701) and 54.9% (62/113), respectively. Taking DST as standard, analysis of 620 patients with complete results of INH- and RFP-resistance showed that the sensitivity of DNA microarray method for detecting INH and RFP resistance in new SS+ cases was 78.7% (37/47) and 84.6% (22/26), and the PPV was 69.8% (37/53) and 73.3% (22/30), respectively. The sensitivity of DNA microarray method for detecting INH and RFP resistance in relapse SS+ cases was 71.9% (23/32) and 89.3% (25/28), and the PPV were 85.2% (23/27) and 89.3% (25/28), respectively. Compared with proportion method, the detection rate of DNA microarray chip for MTB is higher. The testing performance of DNA microarray chip to detect INH- and RFP-resistance are sound regarding its high validity and reliability, which may be of great value in prevention and control of tuberculosis.

Key words: Mycobacterium tuberculosis, Tuberculosis, multidrug-resistant, Microchip analytical procedures, Evaluation studies