Don’t Ask, Don’t Tell: Quality of β-Lactam Allergy Assessment in Patients with Methicillin-Susceptible Staphylococcus aureus (MSSA) Infections at a Tertiary-Care VA Medical Center

BACKGROUND: β-Lactams (BL) are optimal therapy for MSSA infections; however allergies to BL are reported frequently and may alter antibiotic selection for these infections. Limited data exist evaluating the frequency at which a new BL allergy history (AH) is taken when patients present with MSSA infections. METHODS: We conducted a 10-year retrospective review of patients treated for MSSA infections with report of BL allergy in the allergy section of the electronic medical record (EMR). Acquisition of new AH on initiation of empiric or definitive MSSA antimicrobial therapy was reviewed. Standard allergy characterization questions assess (1) age at BL reaction, (2) recollection of reaction, (3) timing from BL to reaction, (4) route of administration, (5) rationale for BL, (6) prior BL tolerance, (7) confounding medications, and (8) symptom resolution. A new AH was considered inappropriate if 0/8 items were addressed. Types of infection, types of allergic reaction, BL agents, adverse events and treatment failure rates were also analyzed. RESULTS: Providers seeing 142 MSSA-infected patients with EMR-based BL AH did not gather any new AH 59% of the time (83/142). Of those, 36% (30/83) of patients had an “unknown” AH in the EMR, yet no new AH was taken prior to MSSA therapy selection. When a new AH was taken, previous BL exposure (29%), recall of reaction (41%), and symptoms (83%) were the most asked questions The likelihood of exploring past BL exposure (predictor of ability to tolerate current BL) increased from 17 to 42% when 2 vs. 3 questions were assessed, respectively. Most interestingly, new provider-verified symptoms differed from prior documentation in the allergy section of the EMR 65% of the time. The most common MSSA infections treated were skin infections (34%) and bacteremia (32%). Overall, no significant differences in treatment failures and adverse events were found between patients treated with BL and non-BL therapy, perhaps due to heterogeneity of infection types. CONCLUSION: In ~40% of cases, new BL allergy histories were not obtained prior to initiating treatment of MSSA infections, despite our data suggesting AH reassessment uncovers new, clinically relevant information. Routine incorporation of better AH can enhance antimicrobial stewardship programs. DISCLOSURES: All authors: No reported disclosures.