Risk Factors Of BALF Positive In Sputum-negative Pulmonary Tuberculosis And Diagnostic Value Of BALF Acid-fast Staining,Xpert MTB/RIF And LAMP

Objective: To compare the diagnostic value of BALF acid-fast staining,Xpert MTB/RIF and LAMP in sputum-negative pulmonary tuberculosis in high incidence area of tuberculosis.To identify clinical parameters associated with a positive test for BALF mycobacterium tuberculosis in an attempt to maximize the benefit of bronchoscopy in suspected tuberculosis patients.Methods : Patients with suspected PTB in the affiliated Hospital of Qinghai University from January 2018 to September 2021 were randomly selected and examined by bronchoscopy.BALF samples should be detected by Xpert MTB/RIF,LAMP and acid-fast staining.According to the gold standard of clinical diagnosis,77 patients with sputum-negative pulmonary tuberculosis were divided into bacterial negative pulmonary tuberculosis group(n=77)and non-tuberculosis pulmonary disease group(n=18).The diagnostic value of three methods was compared.The sputum-negative pulmonary group was divided into BALF positive group and BALF negative group according to whether MTB was detected.The correlation factors between the two groups were analyzed.Results: Among the 95 BALF samples included,the positive rates detected by Xpert MTB/RIF,LAMP and acid-fast staining were 35.06%,20.78% and 5.20%,respectively.The sensitivity of Xpert MTB/RIF detection is 35.06%,the specificity is94.44%,the sensitivity of LAMP detection is 20.78%,the specificity is 100%,and the sensitivity of acid fast staining is 5.20%,and the specificity is 100%.There was no significant difference in age,sex,previous tuberculosis history,smoking history,tuberculosis antibody,PPD and concomitant disease between BALF positive group and negative group,but there was significant difference in positive interferon-γ,pulmonary cavity and tuberculosis antibody.Regression analysis showed that pulmonary cavity and positive interferon-γ were independent risk factors for MTB detected by BALF.Conclusions:1.Xpert MTB/RIF has the highest sensitivity among the three diagnostic methods of sputum-negative pulmonary tuberculosis.2.The combined detection of Xpert MTB/RIF,LAMP and acid-fast staining microscope can improve the detection rate of MTB.3.Cavity and positive interferon-γ are the risk factors for detection of Mycobacterium tuberculosis by BALF.