RESUMEN
OBJECTIVES: To evaluate a new tool for the early diagnosis of tuberculosis. METHODS: A total of 374 smear-negative clinical specimens from patients with suspected tuberculosis were evaluated using a new procedure consisting of a preliminary step of culture in broth bottles followed by the detection of Mycobacterium tuberculosis complex (Mtb) and rifampicin resistance by the Xpert MTB/RIF assay (XMTB-RIF). RESULTS: A total of 30 Mtb strains were isolated, all susceptible to rifampicin. When broth cultures were subjected to XMTB-RIF analysis after 15 days of incubation, sensitivity, specificity, PPV, and NPV were each 100% when compared with liquid culture. CONCLUSION: The XMTB-RIF assay used in 15-day broth cultures may provide a final culture result for smear-negative specimens. This process, combined with clinical signs, may contribute to rapidly diagnosing tuberculosis and also to the early reevaluation of empirical antituberculosis treatment.