2793. Influenza and Bacterial Pneumonia Coinfection: Rates and Outcomes

BACKGROUND: Limited evidence suggests that influenza leads not only to bacterial colonization and greater risk of bacterial pneumonia, but to poor outcomes and increased mortality. We compared bacterial culture results between patients positive (FLU+) and negative (FLU-) for influenza in the setting of community-acquired pneumonia (CAP). Among FLU+ patients we compared bacterial etiology, characteristics, treatment and outcomes between patients with and without bacterial coinfection. METHODS: We included adults admitted with pneumonia 2010–2015 to 179 US hospitals participating in the Premier database. Pneumonia was identified using an ICD-9-CM algorithm. Among patients tested for FLU, we limited the microbiology results to the first 14 hospital days. We assessed inpatient mortality, ICU admission, use of vasopressors, mechanical ventilation (MV), cost, and LOS using mixed multiple logistic regression and gamma generalized linear mixed models. RESULTS: Among 166,273 patients hospitalized with CAP, 38,665 (23.3%) were tested for influenza and 4,313 (11.15%) were positive. In FLU+ patients the most common bacterial co-infection was Staphylococcus aureus (37.6%) followed by Streptococcus pneumoniae (25.9%) and Pseudomonas aeruginosa (10.9%), varying based on the day of coinfection (days 1–3 vs. days 4–14) (Figure 1). In FLU- patients, S. pneumoniae (30.5%) and S. aureus (30.3%) were similarly common, followed by P. aeruginosa (10.0%). FLU+ patients with bacterial co-infection were younger (66.3 vs. 69.1 years), with more comorbidities (3.2 vs. 2.7) than influenza patients with no bacterial co-infection (all comparisons P < 0.001). Bacterial co-infection was also associated with increased odds of in-hospital mortality (OR 1.86, 95% CI,1.31–2.65), ICU admission (OR 3.46, 2.44–4.9), use of vasopressors (OR 3.74, 2.61–5.36), and MV (OR 3.51, 2.49–5.36), increased cost (risk-adjusted ratio of geometric means, 1.6, (1.47–1.73) and LOS (risk-adjusted ratio of geometric means 1.42, (1.33–1.52). CONCLUSION: In a large US inpatient sample hospitalized for CAP, 11% of patients with influenza had or acquired a bacterial co-infection. Bacterial co-infection was associated with significantly worse outcomes and higher cost. [Image: see text] DISCLOSURES: All authors: No reported disclosures.