Abstract:

Objective To investigate the application value of GenXpert MTB/RIF (Xpert) in diagnosis of newly active pulmonary tuberculosis (PTB) and rapid detection of rifampin-resistant.Methods The data of 268 clinical diagnosed PTB patients and 102 cases excluded from PTB from June to November 2015 in Dalian Tuberculosis Hospital were collected. Sputum smear, solid culture and Xpert were used to detect sputum samples, and results were compared. Based on clinical diagnosis, the sensitivity and specificity of solid culture and Xpert for PTB detection were compared, as were the results of drug sensitivity test of proportion method and Xpert for rifampin-resis-tant detection. SPSS 21.0 was used for data analysis and χ ² test was used for enumeration data, statistical significance was set at two-tailed P<0.05.Results The positive rates of the three tests were 29.5% (79/268), 43.7% (117/268) and 55.6% (149/268), respectively, the difference was statistically significant (χ ²=37.42, P=0.000). Of the 189 cases of PTB smear negative, the difference of positive rates of culture and Xpert MTB were statistically significant (20.1% (38/189) vs. 37.0% (70/189);χ ²=13.27, P=0.000). Based on clinical diagnosis, the sensitivities of culture and Xpert were 43.7% (117/268) and 55.6% (149/268), and the specificities of them were 99.0% (101/102) and 98.0% (100/102), respectively. There was statistically significant difference between the sensitivity of solid culture and that of Xpert (χ ²=7.64, P=0.006), but no difference was found in specificity (χ ²=0.00, P=1.000). Of the 113 cases of PTB with solid culture +/Xpert +, there were 11 drug-resistant cases confirmed by proportion method but one was sensitive by Xpert, and there was only one drug-resistant case in the left 102 cases confirmed by proportion. There was fine consistence between Xpert and proportion methods to detect rifampin resistant (Kappa=0.899).Conclusion Xpert is convenient, rapid, and of high sensitivity in diagnosis of newly active PTB and is valuable for rapid detect of rifampin-resistant.

Key words: Tuberculosis, pulmonary, Drug resistance, bacterial, Rifampin, Nucleic acid amplification techniques, Clinical laboratory techniques, Comparative study