Application of Mycobacterium tuberculosis RNA for the Rapid Diagnosis of Lymph Node Tuberculosis Using Different...

To evaluate the accuracy of Mycobacterium tuberculosis (MTB)-RNA in the rapid diagnosis of lymph node tuberculosis (LNTB). Moreover, the difference in the diagnostic accuracy of MTB-RNA using different specimens was determined.

We included patients with suspected LNTB who met the inclusion criteria and retrospectively analyzed their clinical data. The sensitivity, specificity, positive-predictive value (PPV), negative-predictive value (NPV), and area under the curve (AUC) of MTB-RNA and culture were calculated and its diagnostic accuracy for LNTB was evaluated in comparison with the final clinical diagnosis.

Overall, 285 patients were included in the study. The overall sensitivity, specificity, PPV, NPV, and AUC of MTB-RNA were 40.6%, 100.0%, 100.0%, 17.0%, and 0.70, respectively. These values were 30.8%, 100.0%, 100.0%, 16.0%, and 0.65, respectively, for tissue specimens; 34.2%, 100.0%, 100.0%, 24.6%, and 0.67, respectively, for puncture specimens; and 57.14%, 100.0%, 100.0%, 5.3%, and 0.79, respectively, for pus specimens. These values of culture were 24.4%, 100.0%, 100.0%, 13.9%, and 0.62, respectively, for all specimens; 17.6%, 100.0%, 100.0%, 13.8%, and 0.59, respectively, for tissue specimens; 25.3%, 100.0%, 100.0%, 22.4%, and 0.63, respectively, for puncture specimens; and 31.0%, 100.0%, 100.0%, 3.3%, and 0.65, respectively, for pus specimens.

The diagnostic efficacy of MTB-RNA for the rapid diagnosis of LNTB was moderate, but its sensitivity was low. The lymph node pus specimens were the most sensitive for MTB-RNA testing, followed by puncture specimens; tissues were the least sensitive. Pus specimens should be preferably obtained in case only this test is to be used for diagnosis.