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.The routine acid-fast bacilli (AFB) culture of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) needle rinse fluid is useful to increase the diagnostic yield of tuberculous lymphadenitis in an intermediate tuberculosis (TB)burden country.

Clinical Usefulness of Fungal Culture of EBUS-TBNA Needle Rinse Fluid and Core Tissue

“…EBUS-TBNA needle rinse fluid can be quickly and easily collected by flushing 1 cc of sterile normal saline through the needle after EBUS-TBNA core tissue has been obtained. 8,12 Since most patients undergo EBUS-TBNA for cancer evaluation, it is important to obtain a sufficient amount of core tissue for histopathologic examination and molecular testing to allow a proper diagnosis and treatment. In these patients, it is typically difficult to obtain additional core tissue for the surveillance of infectious disease.…”

“…After the core tissues had been obtained, 1 cc of sterile normal saline was flushed through the needle to obtain a rinse fluid sample. 8 All rinse fluid samples were collected into an aseptic tube and sent for microbiological examination including fungal culture.…”

“…The pre-procedure diagnosis was prospectively recorded and classified as suspected or histologically confirmed primary lung cancer, other cancer, or other benign disease according to the opinion of the pulmonologists performing the EBUS-TBNA and based on the clinical presentation of the patient, as well as the results of imaging studies. 8 Data on the factors associated with immune status were also collected, and included previous cancer diagnosis, diabetes, immunosuppressive agent use, and absolute neutrophil count within the week before the procedure. Immunosuppressive agent use was defined as the use of any of the following within 6 months before the procedure: anti-cancer chemotherapy, corticosteroid (of ≥5 mg of prednisolone or its equivalent dose, for at least 1 month) and T-cell mediated immunosuppressants (e.g., azathioprine, tacrolimus, or mycophenolate for at least 1 month).…”

“…4 The indications for EBUS-TBNA have recently been expanded beyond malignant diseases to include benign diseases, such as sarcoidosis, tuberculous lymphadenitis, and fungal infections. [5][6][7][8] In addition, several studies of EBUS-TBNA in benign diseases mainly suspected tuberculosis and sarcoidosis showed a good diagnostic yield and low complication rates. 6,9,10 The material collected by EBUS-TBNA can be analyzed using several modalities, including cytology, flow cytometry, cell block preparation for immunohistochemical or molecular studies, and culture or other forms of microbiological testing.…”

Tuberculous mediastinal lymphadenopathy: Reaching the target

“…The question of whether all patients with mediastinal lymphadenopathy or only those with a higher pretest probability for tuberculous lymphadenopathy should be evaluated by NAAT and M. tuberculosis culture for active tuberculosis was recently addressed by investigators from Seoul, Republic of Korea, and the results were published in Respirology . The authors retrospectively analysed an impressive number of 4672 data sets of patients who underwent EBUS‐TBNA for the diagnosis of mediastinal lymphadenopathy.…”