Objective: Tuberculosis (TB) transmission in healthcare facilities is still a concern in low-income countries, where airborne isolation rooms are scarce due to high costs. We evaluated the use of single GeneXpert MTB/RIF, the molecular Mycobacterium tuberculosis (MTB) DNA and resistance to rifampicin (RIF) test, as an accurate and faster alternative to the current criteria of 3 negative acid-fast bacilli (AFB) smears to remove patients from airborne isolation.
Methods: In this real-world investigation, we evaluated the impact of a single GeneXpert MTB/RIF on the decision making for discharging patients from respiratory isolation. We enrolled patients with suspected pulmonary TB in a public hospital that provides care for high-complexity patients in Brazil. We studied the performance, costs, and time saved comparing the GeneXpert MTB/RIF with AFB smears.
Results: We enrolled 644 patients in 3 groups based on the number of AFB smears performed (1, 2, and 3, respectively) on respiratory specimens. GeneXpert MTB/RIF demonstrated good performance compared to AFB smear to rule out TB in all groups. The negative predictive value for AFB smear was 94% (95% confidence interval [CI], 0.90-0.97) and 98% (95% CIs, 0.94-0.99) for GeneXpert MTB/RIF in G3. The isolation discharge based on 3 AFB smears took 84 hours compared to 24 hours with GeneXpert MTB/RIF, which represents 560 patient-days saved in the isolation rooms.
Conclusion: A single GeneXpert MTB/RIF is a fast and strong predictor for TB absence in a high-complexity hospital, which is quite similar to results obtained in recent studies in low-burden settings. This molecular test may also increase patient rotation through isolation rooms, with a positive impact in the emergency room and infectious diseases wards.