1026. Is Empiric Coverage Necessary? Incidence of Pseudomonas aeruginosa and Methicillin-Resistant Staphylococcus aureus in Foot Infections

BACKGROUND: Empiric antibiotics for foot infections often include coverage of Pseudomonas aeruginosa (PA) and Methicillin-resistant Staphylococcus aureus (MRSA) due to their presumed frequency and ability to cause severe infection. The purpose of this study was to: 1) determine the incidence of PA and MRSA in foot infections; 2) identify variables associated with the presence of PA or MRSA; and 3) examine empiric antibiotic trends for foot infections to determine if empiric coverage of PA and MRSA is warranted. METHODS: Retrospective study of foot infections at five large urban hospitals in San Diego during 2018. Data were collected from the medical records including demographics, host factors, laboratory data, pathology and imaging data, culture results, and empiric antibiotics. Patients with a foot infection treated as an inpatient in our healthcare system who had a culture collected were included. RESULTS: 310 patients with foot infections were included. Mean age was 61.6 years; 220 (71%) were male; 248 (80%) had diabetes; 40 (13%) had end-stage renal disease (ESRD), and 122 (39%) had peripheral arterial disease (PAD). PA was present in 28 (9%) cases. No patient had a positive blood culture for PA. MRSA was present in 55 (18%) cases. Only one patient had a positive blood culture for MRSA. On univariate analysis, wound location not in the forefoot (p=0.047) and presence of PAD (p=0.048) were associated with PA. These failed to remain significant in multivariate analysis (OR=0.42, p=0.074 and OR=2.54, p=0.0504, respectively). Factors associated with MRSA included shallower depth of wound (OR=0.36; p=0.043). 199/310 patients (64%) received empiric antibiotic coverage for PA while 262/310 patients (85%) received empiric MRSA coverage. Of those who received empiric anti-PA coverage, 174 were overtreated (87%). Of those who received empiric anti-MRSA coverage, 218 (83%) were overtreated. CONCLUSION: The incidence of PA in foot infections was overall low, and none had positive blood cultures. MRSA was more often present, however, most patients did not have bacteremia or severe infections. In our study, the majority of empiric anti-PA, as well as anti-MRSA, antibiotic coverage for foot infections was unnecessary questioning the need for upfront, empiric coverage for these pathogens in foot infections. DISCLOSURES: All Authors: No reported disclosures