1688Diagnosis of Pulmonary Tuberculosis among Admitted Patients at a Large, Urban Safety-net Facility — Los Angeles, 2010–2013

Background. Health care facilities face substantial challenges in diagnosis and infection prevention for patients suspected to have infectious tuberculosis (TB). LAC + USC Medical Center is a large, urban safety-net facility with 105 confirmed TB cases reported in 2013, >1% of all reported cases in the United States. Methods. We reviewed all inpatient admissions from January 2010 to September 2013 with at least one sputum specimen collected for acid fast bacilli (AFB) smear and culture (nucleic acid amplification tests (NAATs) were not routinely performed). Using AFB culture for Mycobacterium tuberculosis as the gold standard, we evaluated the sensitivity and specificity of the first 3 AFB sputum smears and the incremental yield of consecutive sputa. We examined demographic differences among patients by AFB culture result; the chi-square test was used to detect differences in proportions. We calculated inpatient length of stay stratified by AFB smear results. Results. Among 2,775 inpatient admissions (2,572 unique patients), median age was 51 (IQR 42–59), 2,023 (72.9%) were male, and 1,568 (56.5%) were foreign-born. At least one sputum culture grewM. tuberculosis for 219 (7.9%); a positive culture was more frequent among foreign-born (10.4%) compared to U.S.-born patients (4.6%) (P < .001). The sensitivity and specificity of the first 3 sputum smears were 58.9% (CI 52.1–65.5) and 99.5% (CI 99.2–99.8), respectively. The incremental yields for each of the first 3 sputa were 86.8%, 6.2%, and 7.0% (for smear) and 91.8%, 4.1%, and 4.1% (for culture). Median length of stay was greater for admissions where at least one of the first 3 smears was positive (14.7 days (IQR 8.1–23.5)) compared to admissions where the first 3 smears were all negative (4.9 days (IQR 2.7–9.8)). Among 12 admissions with a positive sputum smear but no positive culture for M. tuberculosis, the median length of stay was 9.7 days (IQR 6.1–21.8). Conclusion. One culture-confirmed pulmonary TB case was diagnosed for every 13 inpatient evaluations. The sensitivity of the first 3 sputum smears was low; although specificity was high, false-positive smears represent a burden on hospital resources. The improved sensitivity and specificity of NAATs might have substantial impact at this institution. Disclosures. All authors: No reported disclosures.