Risk factors of delayed isolation of patients with pulmonary tuberculosis

Objectives: The aim was to examine the rate of delayed or no isolation of hospitalized patients with pulmonary tuberculosis (TB) and the causes for isolation failure. Methods: This retrospective study included patients with pulmonary TB at a university-affiliated hospital in South Korea between January 2015 and June 2018 after excluding those with a stay ≤2 days and those who only visited the emergency department. Patients who were not isolated for ≥3 days were classified as the delayed or no isolation group. We compared the clinical findings and diagnostic test results, between patients managed with delayed or no isolation (D-isolation) and timely isolation (T-isolation). Results: Of 486 patients with pulmonary TB, 222 patients were included. In 106 cases (47.7%), isolation was delayed or not applied, while in 116 cases, isolation was applied in a timely manner. Typical findings of TB were seen on the chest X-rays of 87 (75.0%) patients in the T-isolation group versus 25 (23.6%) patients in the D-isolation group (p < 0.001). Other factors significantly associated with delayed or no isolation on univariate analyses were older age, admission route (emergency room vs. other), admitting department, negative acid-fast bacilli (AFB) stain, and negative MTB PCR. On multivariate analysis, admission through an outpatient clinic, admission to a department other than infectious diseases or pulmonology, an atypical chest X-ray finding and negative sputum AFB stains were risk factors for isolation failure. Discussion: Delayed or no isolation of patients with pulmonary TB was attributed mainly to atypical radiological findings and negative findings of direct TB diagnostic tests.