Date Published: July 16, 2019
Publisher: F1000 Research Limited
Author(s): Dilshaad Fakey Khan, Moosa Suleman, Prinita Baijnath, Rubeshan Perumal, Vedanthi Moodley, Zoey Mhlane, Taryn Naidoo, Thumbi Ndung’u, Emily B. Wong.
Background: Bronchoalveolar lavage (BAL) is indicated for medical evaluation of complex cases of lung disease. There is limited data on the performance of tuberculosis (TB) microbiologic tests on BAL in such patients, particularly in human immunodeficiency virus (HIV) and TB endemic areas.
Globally, tuberculosis (TB) is the ninth leading cause of mortality with an estimated 1.6 million deaths reported in 2016
1. South Africa has one of the world’s highest burdens of TB with an estimated incidence of 438 000 cases in 2016
2. The “End TB Strategy” aims to reduce global TB incidence by 90% and TB-related deaths by 80% by 2030
In this medically complex cohort of patients with high rates of HIV-infection and comorbidities necessitating therapeutic immunosuppression, TB was the single leading cause of lung disease at the time of bronchoscopy.
Our study shows that in a medically complex group of patients from a high HIV and TB endemic setting, TB remains the leading cause of lung disease but a significant proportion of patients have paucibacillary disease lowering the sensitivity of M.tb diagnostic tests. In this setting, negative TB diagnostic tests should be interpreted with caution. We urge clinicians to consider submitting additional Xpert MTB/RIF tests in patients with a clinical suspicion of TB as we have shown an improved yield of 11% with a single Xpert MTB/RIF and a further 16% with a second Xpert MTB/RIF assay. We recommend that when conducting a diagnostic evaluation of such patients, BAL testing should be augmented by sending additional specimens that may further increase diagnostic yield. Submission of expectorated or induced sputum or pooled endotracheal aspirate alongside BAL fluid has the potential to improve diagnostic yield (
Box 1). Additional research to improve the sensitivity of TB diagnostics in medically complex patients is urgently needed.