Risk Factors for Pseudomonas aeruginosa in Diabetic Foot Infections

BACKGROUND: Infectious Diseases Society of America guidelines for the management of diabetic foot infections (DFIs) suggest 15 different antibiotic treatment options for moderate-to-severe infections. All treatment options provide coverage for Gram-positive cocci, and some provide coverage for Gram-negative pathogens, including Pseudomonas aeruginosa (PSA). However, there is minimal guidance in determining which patients require anti-PSA therapy. METHODS: This single-center retrospective case–control study included patients hospitalized between October 2013 and September 2015. Adult patients admitted with a DFI were identified using a combination of ICD-9 codes for diabetes with complications and cellulitis. The primary outcome was identification of risk factors associated with PSA DFIs. A multivariable model using logistic regression was constructed, and a receiver operator characteristic (ROC) curve was generated to assess the sensitivity and specificity of the model. RESULTS: 262 patients were included and 12 (4.6%) patients had cultures with PSA. Multivariable analysis yielded six risk factors for PSA DFIs (see Table). ROC construction yielded an area under the curve of 0.895. CONCLUSION: The incidence of PSA from DFIs is low. A model with excellent performance characteristics demonstrated that risk factors for PSA DFIs include age > 65, BMI ≥ 35, former or current smoker, history of lower extremity bypass procedure, and cardiovascular disease. Future validation of these factors could help stewardship programs reduce unnecessary antibiotic utilization. DISCLOSURES: All authors: No reported disclosures.