Nosocomial tuberculosis exposure events in the era of nucleic acid amplification testing: A root cause analysis

OBJECTIVES: Despite the availability of rapid tuberculosis (TB) nucleic acid amplification (NAA) testing, prevention of TB transmission within healthcare facilities remains a challenge due to ongoing difficulties in promptly isolating infectious TB cases upon hospitalization. METHODS: We reviewed all hospitalized sputum culture-positive TB patients who were not immediately placed in airborne isolation before anti-TB treatment at a high caseload medical center in Taiwan during 2016-2019, and applied root cause analysis to systematically identify structural barriers to prompt isolation. RESULTS: Among 235 cases, 95 (40.4%) had non-suggestive chest radiography (CXR) findings (Category 1), 62 (26.4%) had suggestive findings but sputum testing was delayed (≥3 days; Category 2), and 78 (33.2%) had timely sputum testing but delayed positive results (Category 3,). In Category 1, 52.6% later developed typical CXR findings. In Category 2, 72.6% had misread CXRs and 27.4% had delayed review. In Category 3 (65.4% had sputum result turnaround time >3 days), TB-NAA test was not done in 24 (30.8%) patients (1 smear-positive and 23 smear-negative). Of the 13 false-negative TB-NAA cases, only one had repeat NAA testing. CONCLUSIONS: Prompt isolation requires clinical alertness, accurate CXR interpretations, frontline TB-NAA, and repeat testing when suspicion persists despite negative results.