Application Of GeneXpert MTB/RIF In Patients With Systemic Autoimmune Diseases Complicated With Pulmonary Tuberculosis

Objective By exploring the application value of mycobacterium tuberculosis/rifampicin resistance real-time fluorescence nucleic acid amplification（GeneXpert MTB/RIF）in the diagnosis of patients with systemic autoimmune disease（SAD）complicated with pulmonary tuberculosis（PTB）,the thesis aims to provide reference for the clinical diagnosis of SAD combined with PTB.Methods 350 SAD patients with PTB admitted to Zaozhuang Municipal Hospital and Shandong Thoracic Hospital from January 2017 to March 2018 were selected as the observation group,and 50 SAD patients without PTB in the same period were selected as the control group.Sputum specimens of all the selected participants were collected and divided into three parts.Three sputum samples were detected by acid-fast staining,BACTEC^TMMGIT^TM960 automatic rapid mycobacterium culture and identification drug sensitive instrument（MGIT960 liquid culture）and GeneXpert MTB/RIF technique respectively.In addition,5ml of whole blood was collected from all the selected participants and tested by T-cell dot test（T-SPOT）.Based on clinical diagnosis and imaging examination as the gold standard for the diagnosis of systemic autoimmune diseases complicated with pulmonary tuberculosis,the detection rates of pulmonary tuberculosis in different systemic autoimmune diseases by using the methods of GeneXpert MTB/RIF,MGIT960 liquid culture,T-SPOT and acid-fast staining were calculated,and the sensitivity and specificity of GeneXpert MTB/RIF,MGIT960 liquid culture,T-SPOT and acid-fast staining were compared.The value of GeneXpert MTB/RIF in the detection of rifampicin resistance was analyzed by using the liquid drug susceptibility test of mycobacterium tuberculosis as the gold standard.The semi-quantitative results of GeneXpert MTB/RIF system were compared with the bacterial counts obtained by MGIT960 liquid culture,T-SPOT and acid-fast staining.Results（1）In systemic vasculitis,the tuberculosis detection rate of GeneXpert MTB/RIF was markedly higher than that of MGIT960 liquid culture and acid-fast staining,and the difference was statistically significant（P<0.05）.In systemic lupus erythematosus,dermatomyositis and mixed connective tissue disease,the tuberculosis detection rate of GeneXpert MTB/RIF was considerably higher than that of MGIT960liquid culture and acid-fast staining,and the difference was statistically significant（P<0.05）.In scleroderma and Sjogren’s syndrome,the tuberculosis detection rate of GeneXpert MTB/RIF was significantly higher than that of acid-fast staining,and the difference was statistically significant（P<0.05）.In rheumatoid arthritis,the tuberculosis detection rate of GeneXpert MTB/RIF was greatly higher than that of T-SPOT and acid-fast staining,and the differences were statistically significant（P<0.05）.（2）The sensitivity of GeneXpert MTB/RIF,MGIT960 liquid culture,T-SPOT and acid-fast staining in the detection of SAD with pulmonary tuberculosis was 95.14%,84.00%,89.71%and 56.86%respectively.The sensitivity detected by GeneXpert MTB/RIF was consistent with that by MGIT960 liquid culture and T-SPOT（χ²=1.73、1.39,P>0.05）,which was much higher than acid-fast staining（χ²=36.60,P<0.05）.The specificity detected by GeneXpert MTB/RIF was consistent with that by MGIT960 liquid culture and acid-fast staining（χ²=1.42、0.15,P>0.05）,which was significantly higher than T-SPOT（χ²=17.53,P<0.05）.（3）The drug resistance of rifampicin was detected in 156 out of 350 patients with GeneXpert MTB/RIF,and the results showed that 53 of them had rifampicin resistance.The sensitivity and specificity of this method were 86.00%and90.56%respectively.（4）The detection results of GeneXpert MTB/RIF system for tuberculosis bacteria were divided into five orders of magnitude:undetected,extremely low,low,medium and high.In the undetected magnitude,the tuberculosis detection rate of GeneXpert MTB/RIF system was significantly lower than that of MGIT960 liquid culture and T-SPOT,and the difference was statistically significant（χ²=4.026、5.835,P<0.05）.In extremely low and low magnitudes,the tuberculosis detection rate of GeneXpert MTB/RIF system was evidently higher than that of MGIT960 liquid culture,T-SPOT and acid-fast staining,and the difference was statistically significant（χ²=5.172-18.935,P<0.05）.In the high magnitude,the tuberculosis detection rate of GeneXpert MTB/RIF system was significantly higher than that of MGIT960 liquid culture and T-SPOT,and the difference was statistically significant（χ²=4.374、4.286,P<0.05）.Conclusion（1）GeneXpert MTB/RIF is a rapid and accurate method for the diagnosis of systemic autoimmune diseases with pulmonary tuberculosis and for the detection of rifampicin resistance.It has clinical significance for the early diagnosis of different systemic autoimmune diseases with pulmonary tuberculosis.（2）Combined with traditional MGIT960 liquid culture,T-SPOT and acid-fast staining,this method can significantly improve the tuberculosis detection rate of systemic autoimmune diseases with pulmonary tuberculosis.