Evaluation of GenoType MTBDRplus by Use of Extracted DNA from Formalin-Fixed Paraffin-Embedded Specimens

Microbiological confirmation of tuberculous pleurisy with medical thoracoscopy: targeted pleural washing and pleural biopsy

Background

Due to the pauci-bacillary nature of tuberculous (TB) pleurisy, clinical diagnosis is common, but microbiological confirmation is necessary to determine drug resistance. This study aimed to investigate the diagnostic yield of medical thoracoscopy (MT) for microbiological confirmation of TB pleurisy.

Methods

Medical records of patients diagnosed as TB pleurisy with microbiological or histologic evidence who underwent MT between May 2015 and July 2023 at Incheon St. Mary's Hospital were retrospectively reviewed. Sensitivities of microbiological results [acid-fast bacilli (AFB) culture or TB-polymerase chain reaction (PCR)] of pre-MT pleural fluid and those of targeted pleural washing fluid and pleural tissues obtained during MT were compared. Difference in sensitivity was verified with McNemar's test.

Results

A total of 72 patients were enrolled. With pre-MT pleural fluid, sensitivities of AFB culture and TB PCR were 5.6% (4/72) and 1.4% (1/72), respectively. With targeted pleural washing fluid, sensitivities of AFB culture and TB-PCR were 23.6% (17/72) and 12.5% (9/72), respectively. With pleural tissues, sensitivities of AFB culture and TB-PCR were 18.1% (13/72) and 40.3% (29/72), respectively. MT showed an additional 27.8% [95% confidence interval (95% CI): 14.2-40.1%, P<0.001] of sensitivity gain in AFB culture and 40.3% (95% CI: 25.7-52.5%, P<0.001) of sensitivity gain in TB-PCR. With pleural washing, additional 19.4% (95% CI: 6.8-31.6%, P=0.001) of sensitivity gain in microbiological confirmation was identified, whereas additional 37.5% (95% CI: 22.6-50.2%, P<0.001) of sensitivity gain was identified with pleural biopsy.

Conclusions

With MT, 44.4% of additional sensitivity gain in microbiological confirmation of TB pleurisy was identified. This underscores the role of MT in the diagnosis of TB pleurisy.

Performance of the MeltPro MTB Assays in the Diagnosis of Drug-Resistant Tuberculosis Using Formalin-Fixed, Paraffin-Embedded Tissues

OBJECTIVES

The MeltPro MTB assays for detection of resistance to antituberculosis (TB) drugs perform well in genotypic drug susceptibility testing (DST) of clinical samples, but their effectiveness with formalin-fixed, paraffin-embedded (FFPE) tissues is unknown.

METHODS

FFPE tissues were obtained from 334 patients with TB. Susceptibility to rifampicin (RIF), isoniazid (INH), and fluoroquinolones was examined using the MeltPro MTB assays, with Xpert MTB/RIF (Xpert) and/or phenotypic DST (pDST) results as references. Samples with discordant results were analyzed by multiplex polymerase chain reaction-targeted amplicon sequencing (MTA-seq).

RESULTS

With pDST as the reference, the MeltPro MTB assays sensitivity for RIF, INH, levofloxacin (LVX), and moxifloxacin (MXF) was 95.00%, 96.00%, 100%, and 100%, respectively, and the specificity was 95.15%, 95.92%, 94.69%, and 89.92%, respectively. Concordance was 99.08% between the MeltPro MTB and Xpert (κ = 0.956) for RIF and 95.12% (κ = 0.834), 95.93% (κ = 0.880), 95.12% (κ = 0.744), and 90.24% (κ = 0.367) between the MeltPro MTB and pDST for RIF, INH, LVX, and MXF, respectively. MTA-seq confirmed the discordancy between the MeltPro MTB and pDST for 26 (89.66%) of 29 samples.

CONCLUSIONS

The MeltPro MTB assays rapidly and efficiently predict Mycobacterium tuberculosis resistance to the main first- and second-line anti-TB drugs in FFPE tissues.