Clinical usefulness of routine AFB culture and MTB PCR of EBUS‐TBNA needle rinse fluid

Abstract

Background and objective

We evaluated the usefulness of acid‐fast bacilli (AFB) culture and Mycobacterium tuberculosis (MTB) polymerase chain reaction (PCR) of endobronchial ultrasound‐guided transbronchial needle aspiration (EBUS‐TBNA) needle rinse fluid for diagnosing tuberculous lymphadenitis.

Methods

EBUS‐TBNA needle rinse fluid was routinely used for AFB culture and MTB PCR. The patients were categorized according to the pre‐procedural diagnosis (Group A, suspected/histology‐confirmed lung cancer; Group B, extrapulmonary malignancy; and Group C, other benign diseases).

Results

Of the 4672 subjects, 104 (2.2%) were diagnosed with tuberculous lymphadenitis; 1.0%, 4.6% and 12.7% of Group A, B and C, respectively. Tuberculous lymphadenitis was diagnosed in 0.2%, 1.0% and 4.5% Group A, B and C patients, respectively, by histopathology. On addition of AFB culture to histopathology, tuberculous lymphadenitis was diagnosed in 1.0%, 4.4% and 10.3% of Group A, B and C patients, respectively (P < 0.001, P = 0.001 and P = 0.005, respectively). On addition of MTB PCR to histopathology, tuberculous lymphadenitis was diagnosed in 0.4%, 1.9% and 8.8%, respectively (Group C; P = 0.029).

Conclusion

Routine AFB culture of needle rinse fluid was useful to increase the diagnostic yield of tuberculous lymphadenitis for all subjects who underwent EBUS‐TBNA regardless of pre‐procedural diagnosis in an intermediate tuberculosis (TB)‐burden country. However, MTB PCR was only useful in subjects with pre‐procedural diagnosis of benign pulmonary diseases.