803. Risk factors associated with Clostridioides difficile infection in hospitalized patients with community-acquired pneumonia

BACKGROUND: Patients with community-acquired pneumonia (CAP) who are hospitalized and treated with antibiotics may carry an increased risk for developing Clostridioides difficile infection (CDI). Accurate risk estimation tools are needed to guide monitoring and CDI mitigation efforts. We aimed to identify patient-specific risk factors associated with CDI among hospitalized patients with CAP. METHODS: Design: retrospective case-control study of hospitalized patients who received CAP-directed antibiotic therapy between 1/1/2014 and 5/29/2018. Cases were hospitalized CAP patients who developed CDI post-admission. Control patients did not develop CDI and were selected at random from CAP patients hospitalized during this period. Variables: comorbidities, laboratory results, vital signs, severity of illness, prior hospitalization, and past antibiotic use. Propensity-score weights: identified via structural decomposition analysis of pre-treatment variables. Analysis: weighted classification tree models that predicted any CDI, hospital-onset CDI, and any healthcare-associated CDI according to CAP antibiotic treatment. Performance: percent accuracy in classification (PAC) and weighted positive (PPV) and negative predictive values (NPV). Modeling: completed using the ODA package (v1.0.1.3) for R (v3.5.1). RESULTS: A total of 32 cases and 232 controls were identified. Sixty pre-treatment variables were screened. Structural decomposition analysis, completed in two stages, identified prior hospitalization (OR 6.56, 95% CI: 3.01-14.31; PAC: 80.3%) and BUN greater than 29 mg/dL (OR 11.67, 95% CI: 2.41-56.5; PAC: 80.8%) as propensity-score weights. With respect to CDI, receipt of broad-spectrum anti-pseudomonal antibiotics was significantly (all P’s< 0.05) associated with any CDI (NPV: 90.29%, PPV: 27.94%), hospital-onset CDI (NPV: 97.53%, PPV: 26.86%), and healthcare-associated CDI (NPV: 92.89%, PPV: 27.94%). CONCLUSION: We identified risk factors available at hospital admission and empiric use of broad-spectrum Gram-negative antibiotics as being associated with the development of CDI. Model PPVs were over two-fold greater than our sample base rate. Increased monitoring and avoidance of overly broad antibiotic use in high-risk patients appears warranted. DISCLOSURES: All Authors: No reported disclosures