The value of GeneXpert MTB/RIF in bronchoalveolar lavage fluid in the diagnosis of smear-negative pulmonary tuberculosis

Abstract

This study aims to evaluate the diagnostic value of Xpert MTB/ RIF assay in bronchoalveolar lavage fluid (BALF) in subjects with smear-negative pulmonary tuberculosis. From January 2019 to December 2019, 197 patients with suspected pulmonary tuberculosis were recruited, and bronchoalveolar lavage fluid was collected for acid-fast staining smear, liquid culture of Mycobacterium combined drug sensitivity and Xpert MTB/RIF detection. The sensitivity, specificity, positive predictive value and negative predictive value of Xpert MTB/RIF in bronchoalveolar lavage fluid (BALF) were calculated with smear-negative pulmonary tuberculosis as the reference standard. The consistency of xpert MTB/RIF in the diagnosis of rifampicin resistance was evaluated, with the results of Mycobacterium liquid culture drug sensitivity test and drug sensitivity test as the gold standards. The results showed that among 197 suspected tuberculosis patients, 55 patients were not diagnosed with tuberculosis and 142 patients were diagnosed with smear-negative pulmonary tuberculosis. One hundred and twenty three cases (86.62%) were positive for Xpert MTB/ RIF in bronchoalveolar lavage fluid, 15 cases (10.56%) were positive by acid-fast staining smear method, and 88 cases (61.97%) were positive by the liquid culture method. The positive rate of Xpert MTB / RIF was 93.18% (82 / 88), which was higher than that of 75.93% (41 / 54) of the negative BALF mycobacterium culture (χ 2 = 8.598, P<0.01). The sensitivity and specificity of Xpert MTB/RIF for rifampicin resistance were 100.00% and 97.30%, respectively. Therefore, the diagnostic value of Xpert MTB/RIF in bronchoalveolar lavage fluid for bacterialnegative pulmonary tuberculosis is superior to the acid-fast staining smear of lavage fluid and the mycobacterium culture method.