Comparison of acid-fast stain and culture for Mycobacterium tuberculosis in pre- and post-bronchoscopy sputum and bronchoalveolar lavage in HIV-infected patients with atypical chest X-ray in Ethiopia

Abstract

<b>Background :</b> Smear-negative tuberculosis occurs more frequently in human immunodeficiency virus (HIV)-infected patients than in non-HIV-infected patients. Besides, there are substantial numbers of patients who cannot produce sputum, making the diagnosis of pulmonary tuberculosis (PTB) difficult. <b> Aims :</b> To evaluate the relative yield of pre- and post-bronchoscopy sputum and bronchoalveolar lavage (BAL) in &#x2032;sputum smear&#x2032;-negative, HIV-positive patients. <b> Settings :</b> A tertiary care referral hospital in Addis Ababa. <b> Materials and Methods :</b> Acid-fast stain (AFS) using the concentration technique was done on 85 pre-bronchoscopy sputum and 120 BAL samples. Direct AFS was done on all BAL and 117 post-bronchoscopy sputum samples. Culture for <i> Mycobacterium tuberculosis</i> (MTB) was done for all sputa and BAL. <b> Results :</b> MTB was isolated from 26 (21.7&#x0025;), 23 (19.7&#x0025;) and 13 (15.3&#x0025;) of BAL, post- and pre-bronchoscopy sputum cultures respectively. AFS on pre-bronchoscopy sputum using concentration technique and direct AFS on BAL together detected 11 (41&#x0025;) of the 27 culture-positive cases. In patients who could produce sputum, the sensitivity of pre-bronchoscopy sputum culture (13/85, 15.3&#x0025;) was comparable to BAL (12/85, 14&#x0025;) and post-bronchoscopy sputum (12/85, 14&#x0025;). In patients who could not produce sputum, however, both BAL (12/35, 40&#x0025;) and post-bronchoscopy sputum (12/32, 31.4&#x0025;) detected significantly more patients than those who could produce sputum (<i> P</i> =0.002, <i> P</i> =0.028 respectively). <b> Conclusion</b>: In HIV-infected patients, AFS by concentration method on pre-bronchoscopy sputum and direct AFS on BAL in patients who cannot produce sputum are the preferred methods of making a rapid diagnosis. BAL culture seems to add little value in patients who can produce sputum; therefore, bronchoscopy should be deferred under such circumstances