>90% of patients placed in respiratory isolation because of concern for active TB are ultimately found not to have TB, but current evaluation algorithms based on smear microscopy require that patients remain in respiratory isolation for two or more days while multiple sputum samples are tested. We have recently shown in a non-interventional pilot study at SFGH that use of a novel rapid point of care assay, the Cepheid GeneXpert MTB/RIF test (Xpert), can evaluate a single sample in three hours or less with similar accuracy to the conventional microscopy-based algorithm. In the 133 SFGH patients we studied, Xpert would have reduced the duration of isolation of patients proven not to have TB by almost two days on average. We estimated that Xpert could save over 250 days of respiratory isolation room usage annually at SFGH, eliminate a number of hospital admissions for which the need for isolation was the only indication for admission, and speed the flow of patients through the emergency department. In a formal cost effectiveness analysis, we projected that such a program could generate savings of approximately $500,000 per year (PLoS ONE. 2013;8(11):e79669).

To realize these patient benefits and cost savings, support for testing reagents and cartridges would be required. We have already purchased the testing platform with support from the SFGH Hearts Foundation. and Infection Control has used it to develop similar strategies to improve the efficiency of isolation procedures for influenza and Clostridium difficile. These programs have provided major benefits to patients and providers, and we expect that point of care TB testing would provide similar benefits. The SFGH Clinical Microbiology Lab, SFGH Infection Control, SFDPH TB Control, and the Emergency Department have all endorsed such a point of care program for TB testing and isolation room triage if the costs of testing can be addressed. We expect that a similar program could also provide benefit at UCSF Medical Center.