| Objective To evaluate the clinical application value of parallel tests using Rifampicin resistant Mycobacterium tuberculosis real-time fluorescent quantitative nucleic acid amplification(Gene Xpert)and Gene chip in smear negative tuberculosis patients.Method From August 2018 to November 2019,117 suspected tuberculosis patients in the tuberculosis area of the First Affiliated Hospital of Chongqing Medical University were included,who were negative in sputum smear and sent to the modified Roche culture method,Gene Xpert and Gene chip method for detection of Mycobacterium at the same time.Calculate and compare the positive rate of MTB detected by three independent methods and two molecular biological methods combined application(referred to as "combined application",Gene Xpert or Gene chip method is positive,and the result of combined application is positive);calculate and compare the four methods of culture,Gene Xpert,Gene chip method and combined application respectively about the sensitivity,specificity,accuracy,positive predictive value,negative predictive value and consistency of smear negative pulmonary tuberculosis were evaluated based on the standard of culture method and clinical final diagnosis.At the same time,the drug sensitivity test was carried out on the samples with positive results detected by three independent methods,and the efficacy of two molecular biological methods in the early diagnosis of drug-resistant tuberculosis was evaluated with culture DST as the standard.? 2 test was used for the comparison of rates,and Kappa test was used for consistency analysis.Result1.76 cases were clinically diagnosed as pulmonary tuberculosis and41 cases as Non tuberculosis.The positive rates of modified Roche culture,Gene Xpert,Gene chip technology and combined application were 29.1%,39.3%,32.5% and 46.2% respectively.The combined application was the highest,and the difference was statistically significant compared with the three methods.2.According to the standard of modified Roche culture method : The sensitivity of Gene Xpert,Gene chip technology and combined application to detect MTB were 79.41%,76.41% and 91.18%,respectively,the specificity was 77.11%,85.54%,72.29%,the accuracy was 77.78%,82.91%,77.88%,the positive predictive value was 58.70%,68.42%,57.40%,the negative predictive value was 90.10%,89.87%,95.24%,respectively.There was a moderate consistency between the combined application and culture(Kappa = 0.541,P < 0.05).3.Based on clinical diagnosis: The sensitivity of modified Roche culture,Gene Xpert,Gene chip technology and combined application were44.74%,56.58%,50.00% and 77.11% respectively,the specificity was100.0%,92.68%,100.0% and 92.68% respectively,the accuracy was64.1%,69.23%,67.52% and 76.07% respectively,the positive predictive value was 100.0%,93.43%,100.0% and 94.44%,the negative predictive value was 49.40%,53.52%,51.90% and 60.32% respectively.The consistence of the improved Roche culture method,Gene Xpert,Gene chip technology and combined application with clinical diagnosis was 0.362,0.422,0.412 and 0.532,respectively.The combined application improved the diagnostic value,and the consistency with the final clinical diagnosis was the best(Kappa = 0.532,P < 0.05).4.The drug resistance of 33 samples were detected by traditional,Gene Xpert and Gene chip methods.Four cases(4/33,12.12%)of drug-resistant tuberculosis were found,including 3 MDR-TB and 1 HR-TB.The results of Gene Xpert and Gene chip methods were consistent with those of traditional DST,and the diagnostic value was good.Conclusion1.Combined application can improve the positive rate of smear negative pulmonary tuberculosis,and can quickly get the results,improve the detection efficiency.It can be used as a rapid diagnostic method for smear negative patients with difficult specimen acquisition or severe cases,especially for severe patients with more early diagnostic value.2.Both of detection methods of molecular biology can be used as effective diagnostic methods for drug-resistant tuberculosis. |
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