2183. Survival Impact and Clinical Predictors of Anaerobic Bloodstream Infection

BACKGROUND: Few controlled studies are available for the outcome and risk factor analysis of anaerobic bloodstream infection (BSI). We conducted a cohort study to identify the clinical predictors and survival impact of anaerobic BSI as compared with aerobic BSI. METHODS: Consecutive emergency department patients in a tertiary medical center with laboratory confirmed BSI between 2015 and 2016 were prospectively enrolled. We compared demographics, comorbidity, and sources of infection between anaerobic and aerobic BSI. We then constructed a multivariable logistic regression model to identify independent risk factors for anaerobic BSI. The survival impact of anaerobic BSI was evaluated by propensity score-matched analysis. RESULTS: We identified 1,166 episodes of BSIs during the 2-year study period, of which 61 (5.2%) were anaerobic BSI. Clinical variables predicted anaerobic BSI with moderate discrimination (optimism corrected C statistic = 0.75). Significant predictors included metastatic cancer (OR 6.03, 95% CI 2.78–13.09), intra-abdomen infection (OR 3.92, 95% CI 1.47–10.45), liver abscess (OR 2.65, 95% CI 1.26–5.62), skin and soft-tissue infection (OR 2.40, 95% CI 1.13–5.08) as the positive predictors. Urinary tract infection (OR 0.15, 95% CI 0.04–0.62), diabetes mellitus (OR 0.38, 95% CI 0.18–0.78), or thrombocytopenia (OR 0.33, 95% CI 0.18–0.60) were identified as the negative predictors of anaerobic BSI. Anaerobic BSI were not associated with worse prognosis in either adjusted (HR 1.08, 95% CI 0.68–1.72) or PS-matched analysis (HR 1.50, 95% CI 0.61–3.67). CONCLUSION: Anaerobic BSI accounted for a significant proportion (approximately 1 in 20) of community-onset BSI. Clinical predictors identified in this study may help guide the prescription of empiric anti-anaerobe antibiotics. The apparent adverse outcome associated with anaerobic BSI may be explained by the underline comorbidity, high-risk infection site, and inadequate initial antibiotics. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.