LB-2112-24 Diagnostic accuracy, clinical impact and antimicrobial resistance consequences of using trial-of-antibiotics for tuberculosis diagnosis: a randomised controlled trial in Malawi (ACT-TB study)

Background: Tuberculosis (TB) diagnostic algorithms often include ‘trial-of-antibiotics’— empirical antibiotics for mycobacteriology-negative individuals to treat infectious causes other than tuberculosis, as a ‘rule- out’ diagnostic test for tuberculosis. We investigated the effect of trial-of-antibiotics among adults being investigated for TB on diagnostic accuracy, clinical outcomes, and antimicrobial resistance (AMR). Methods: We randomised (1:1:1) Malawian adults (≥18 years) attending primary care for illness ≥2 weeks in- cluding cough not previously treated with antibiotics to receive: azithromycin (500mg once daily, 3 days), amoxi- cillin (1g three times/day, 5 days), or standard-of-care (SOC, no immediate antibiotic). Sputum taken at enrol- ment and day 8 was tested using mycobacteriology (mi- croscopy, Xpert MTB/RIF, and TB culture). Nasopha- ryngeal swabs at enrolment and day 29 were cultured onto blood agar. Primary outcomes were specificity, de- fined as proportion reporting symptom improvement on