EBUS-TBNA in the rapid microbiological diagnosis of drug-resistant mediastinal tuberculous lymphadenopathy

This study aimed to examine the use of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in the rapid diagnosis of mediastinal tuberculous lymphadenitis and drug-resistant mediastinal tuberculous lymphadenitis. A diagnosis of TB was confirmed by a positive Xpert MTB/RIF test or Mycobacterium tuberculosis culture. Rifampicin-resistant TB (RR-TB) or multidrug-resistant TB (MDR-TB) was diagnosed upon the detection of rifampicin resistance by Xpert MTB/RIF or resistance to rifampicin and isoniazid by phenotypic drug susceptibility testing (DST). Xpert MTB/RIF was positive in 43 of 56 patients (77%) and TB culture was positive in 31 of 56 patients (55%). Of these 56 patients, 25 (45%) were Xpert MTB/RIF positive and TB culture negative, 13 (23%) were Xpert MTB/RIF negative and TB culture positive, and 18 (32%) were Xpert MTB/RIF positive and TB culture positive. 11 patients (20%) had drug-resistant TB: seven with RR/MDR-TB, one with pre-extensively drug-resistant (XDR) TB, two with XDR-TB and one with isoniazid mono-resistance. An Xpert MTB/RIF assay carried out on EBUS-TBNA specimens provides rapid diagnosis of TB. Xpert MTB/RIF testing appears to have additional and more rapid sensitivity compared with culture alone. Culture-based DST provides an additional exclusive yield and the full resistance profile in addition to or instead of rifampicin resistance.
EBUS-TBNA has value in mediastinal adenopathy, including drug-resistant TB. Combined Xpert MTB/RIF and TB culture testing on EBUS-TBNA specimens helps in diagnosing rifampicin resistance missed by Xpert MTB/RIF. http://bit.ly/2LT2OOD