Blood transcriptional profiling in a prospective observational cohort of South African adults referred for investigation of possible pulmonary tuberculosis

Blood transcriptional signatures may discriminate individuals with tuberculosis (TB) from disease-free controls, or from patients with other infectious or respiratory diseases. To systematically evaluate the diagnostic accuracy of published transcriptional signatures in a clinically relevant population with high burden of TB and human immunodeficiency virus (HIV), adults referred for investigation of possible pulmonary TB were consecutively recruited at a TB clinic in South Africa. At enrolment, peripheral blood was collected in Tempus tubes (for RNA sequencing) and patients provided two sputum samples (for Xpert and liquid culture). Amongst 181 patients (median age 35 years), 44 (24%) were infected with human immunodeficiency virus (HIV). 54 patients (30%) were diagnosed with Xpert- or culture-positive TB. No alternate diagnoses were available for Xpert- and culture-negative non-TB patients.