Errors in isolation of patients with infectious tuberculosis at a public teaching hospital in New York.

Background: Studies report variability in the rates and causes of isolation errors among in-patients with active tuberculosis (TB). We reviewed our experience with delays or premature discontinuation of airborne infection isolation (AII).

Methods: Medical records of patients admitted to the Bellevue Hospital Center, New York City Health & Hospitals, New York, NY, USA, between January 2006 and July 2012 with a positive respiratory culture for Mycobacterium tuberculosis were reviewed. Patients who were out of AII despite being infectious were identified, as the episodes had prompted a contact investigation.

Results: Of 246 admissions with positive respiratory cultures, 35 AII errors were identified among 27 patients. Most patients had signs or symptoms of TB on admission. Only four patients had positive sputum smears. In 16 (46%) episodes, the patients had never been isolated, 11 (31%) had delayed isolation, and 8 (23%) were prematurely taken off AII. The most common reasons for patients being off AII while infectious were an incorrect alternative diagnosis (15/35, 43%) or a dual diagnosis (9/35, 26%).

Conclusions: Particularly in smear-negative cases, AII errors due to TB may occur when providers conclude that another diagnosis explains their findings. In many cases, that diagnosis is correct, but TB is also present. This error rate might be a useful quality indicator.