Study On The Value Of Cross-primer Isothermal Amplification In The Diagnosis Of Tuberculosis In Children

Objective: To evaluate the diagnostic value of cross-priming amplification(CPA)in children with tuberculosis.Methods: Date of 97 children cases of clinically suspected tuberculosis were collected(including 59 respiratory tract specimens,20 cerebrospinal fluid,11 pleural effusion,4 ascites,2 pericardial effusion and 1 synovial fluid)between June 2019 and December 2019.All specimens were detected by Microscopic examination of smear with acid-fast staining,solid culture,CPA array,Xpert MTB/RIF assay,T-cell spot of tuberculosis test(T-SPOT)respectively.The sensitivity and specificity of CPA assay were analyzed in those clinical specimens.Results: The sensitivity and specificity of CPA assay for MTB detection in 97 clinical specimens of suspected childhood tuberculosis were 43.5%(20/46)and 96.1%(49/51).The sensitivity of 59 pulmonary tuberculosis was 46.9%(15/32),the specificity was 93.1%(27/29),The sensitivity was 100% in smear-positive and culture-positive and smear-positive and culture-negative samples,and 83.3%(5/6)in smear-negative and culture-positive samples.The sensitivity of 38 children with suspected extrapulmonary tuberculosis was 35.7%(5/14),and the specificity was 93.1%(27/29).The sensitivity in cerebrospinal fluid was 50%,which was higher than the detection rate of serous effusion(16.7%).The sensitivity of CPA assay was higher than Xpert MTB/RIF assay,Microscopic examination of smear with acid-fast staining and culture,but lower than T-SPOT(P<0.05);there was no significant difference in sensitivity among Xpert MTB/RIF,smear and culture.The specificity of T-SPOT was the lowest,compared with the other four methods(P<0.05);the specificity among CPA,Xpert MTB/RIF,Microscopic examination of smear with acid-fast staining and culture was no significant difference.Conclusion: The sensitivity and specificity of CPA assay in detecting MTB in sputum,gastric juice,lavage fluid and cerebrospinal fluid are high,but it did not show obvious advantage in serous cavity effusion,but the advantages of rapidity,simplicity,low cost and simple operation can help children with tuberculosis,especially for the diagnosis of tuberculosis in primary laboratories.