Performance of metagenomic next-generation sequencing, Xpert MTB/RIF and acid-fast staining for diagnosing tuberculous pleurisy and empyema.

BACKGROUND

The detection of Mycobacterium tuberculosis (MTB) is an important basis for the diagnosis of tuberculosis. Detecting fresh tissue, pus, and other samples is challenging. Both metagenomic next-generation sequencing (mNGS) and Xpert MTB/RIF have demonstrated excellent performance in the diagnosis of tuberculosis; however, their research base is still lacking in tissue or pus samples. We hope to explore the detection performance of mNGS and Xpert MTB/RIF in these sample types through this study.

METHODS

This study enrolled 154 patients suspected of having tuberculosis. Fresh tissues, pleural fluid or pus were collected from these patients and performed mNGS, Xpert, and acid-fast staining (AFS) tests. Their detection performance was statistically analyzed and compared.

RESULTS

Overall, the positivity rate of mNGS was 48.05% (74/154), Xpert was 44.44% (44/99), and AFS was 57.34% (82/143). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of mNGS were 55.22%, 100%, 100% and 25%, respectively. The sensitivity, specificity, PPV and NPV of Xpert were 48.35%, 100%, 100%, 18.97%, respectively. The sensitivity, specificity, PPV and NPV of acid-fast stain were 58.59%, 53.33%, 91.46%, 13.11%, respectively. A total of 93 samples underwent all three types of testing, and 45.16% (42/93) were completely consistent in the results of the three tests. The analysis results of these samples showed that the sensitivity, specificity, PPV and NPV of mNGS were 65.88%, 100%, 100%, 21.62%, respectively. The sensitivity, specificity, PPV and NPV of Xpert were 49.41%, 100%, 100%, 15.69%, respectively. The sensitivity, specificity, PPV and NPV of acid-fast stain were 57.65%, 62.50%, 94.23%, 12.20%, respectively. The sensitivity of mNGS was significantly higher than that of Xpert (P=0.01).

CONCLUSIONS

Our research results indicate that mNGS and AFS have higher sensitivity compared to Xpert, while mNGS and Xpert have higher specificity.