217 - Broad Spectrum Antibiotic use in Outpatient Parenteral Antibiotic Therapy (OPAT): Opportunities for Antibiotic Stewardship

Background: Broad-spectrum antibiotics are often chosen for OPAT due to the convenience of once daily dosing. Current literature suggests that at least 20-30% of these regimens could be narrowed, but this has not been well-defined.

Methods: This was a multicenter, retrospective cohort study of adult inpatients evaluated by the infectious diseases (ID) team with culture positive infections with susceptibilities (C&S) on select intravenous (IV) antibiotics (ampicillin, ampicillin-sulbactam, cefazolin, ceftriaxone, daptomycin, ertapenem, meropenem, nafcillin, penicillin, piperacillin-tazobactam, and vancomycin) enrolled in OPAT and discharged from January 1 - June 30, 2019. Susceptibilities were not required for Actinomyces, Streptococcus spp., Haemophilus spp., anaerobes, Corynebacterium spp., or coagulase-negative Staphylococcus spp. when considered a contaminant by ID. Patients were excluded if the regimen included oral antibiotics (not including rifampin or metronidazole). Primary outcome was the percent of broad-spectrum regimens that could’ve been narrowed based on C&S (alternative available therapy or AAT group). Secondary outcomes included comparison of baseline characteristics and 30-day readmission rates between patients on narrow-spectrum IV antibiotics (NSA) vs AAT group, and the documented reason(s) for broad-spectrum antibiotic selection.

Results: 113 patients met study criteria; majority were male (56%), and median age was 60 years. Sixty-four patients were discharged on a broad-spectrum regimen, and 32 (50%) met our AAT definition. Ceftriaxone was used in 75% of these cases (24/32), and mono-microbial Streptococcus spp. infection was the primary indication (54%). AAT group patients were more likely to have Enterobacterales (24.1% vs 1.9% p=< 0.001) or polymicrobial infections (28.1% vs 8.2% p=0.019) compared to NSA group. Reasons for broad-spectrum antibiotic selection were largely undocumented (71%). No significant differences were seen in 30-day readmission rates.

Conclusion: At our institution, 50% of select IV broad-spectrum OPAT regimens had the potential to be narrowed based on C&S data. This rate is higher than previously reported. It warrants further investigation into the barriers to narrower-spectrum antibiotic prescribing in OPAT.