New guidelines recommend that molecular testing replace sputum-smear microscopy to guide discontinuation of respiratory isolation in patients undergoing evaluation for active tuberculosis (TB) in health care settings.

To evaluate the implementation and impact of a molecular testing strategy to guide discontinuation of isolation.

Prospective cohort study with a pragmatic, before-and-after-implementation design of 621 consecutive patients hospitalized at Zuckerberg San Francisco General Hospital and Trauma Center who were undergoing sputum examination for evaluation for active pulmonary TB from January 2014 to January 2016.

Implementation of a sputum molecular testing algorithm using GeneXpert MTB/RIF (Xpert; Cepheid) to guide discontinuation of isolation.

We measured the proportion of patients with molecular testing ordered and completed; the accuracy of the molecular testing algorithm in reference to mycobacterial culture; the duration of each component of the testing and isolation processes; length of stay; mean days in isolation and in hospital; and mean cost. We extracted data from hospital records and compared measures before and after implementation.

Clinicians ordered sputum testing for TB for 621 patients at ZSFG during the 2-year study period. Of 301 patients in the preimplementation period with at least 1 sputum microscopy and culture ordered, clinicians completed the rapid TB testing evaluation process for 233 (77%).Among 320 patients evaluated in the postimplementation period, clinicians ordered molecular testing for 234 (73%) patients and received results for 295 of 302 (98%) tests ordered. Median age was 54 years (interquartile range, 44-63 years), and 161 (26%) were women. The molecular testing algorithm accurately diagnosed all 7 patients with culture-confirmed TB and excluded TB in all 251 patients with Mycobacterium tuberculosis (MTB) culture-negative results. Compared with the preimplementation period, there were significant decreases in median times to final rapid test result (39.1 vs 22.4 hours, P < .001), discontinuation of isolation (2.9 vs 2.5 days, P = .001), and hospital discharge (6.0 vs 4.9 days, P = .003), on average saving $13 347 per isolated TB-negative patient.

A sputum molecular testing algorithm to guide discontinuation of respiratory isolation for patients undergoing evaluation for active TB was safe, feasible, widely and sustainably adopted, and provided substantial clinical and economic benefits. Molecular testing may facilitate more efficient, patient-centered evaluation for possible TB in US hospitals.