Impact of the penicillin allergy label on antibiotic use and clinical outcomes in Veterans with gram-positive bacteremia
Abstract
Abstract Objective: To describe antibiotic use and clinical outcomes in hospitalized patients with gram-positive bacteremia based on penicillin (PCN) allergy status. Design: Retrospective cohort study. Participants: 3,162 patients admitted to acute Veterans Health Administration facilities between January 2021 and December 2022 with ≥1 blood culture positive for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-susceptible Staphylococcus lugdunensis (MSSL), ampicillin-susceptible Enterococcus faecalis (ASEF), Streptococcus pneumoniae (Spne), or Streptococcus pyogenes. Methods: Calculated the prevalence ratio (PR) to determine the association, if any, between the PCN allergy label and ≥1 day alternate antibiotic use, completion of ≥50% of targeted therapy with alternate, resistant gram-positive infection (RGPI), and broad-spectrum hospital-onset infection (BSHOI) antibiotics, 7-day acute kidney injury (AKI), 60-day Clostridioides difficile infection, hospital length of stay, 90-day recurrence, and 90-day mortality. Results: Patients with ASEF and Spne bacteremia with a PCN allergy had higher rates of ≥1 day of alternate antibiotic use (ASEF PR 1.21 [95% CI 1.08–1.35]; Spne 1.73 [1.25–2.38]) and completing ≥50% of targeted therapy with an alternate antibiotic (ASEF 5.60 [4.22–7.42]; Spne 4.10 [1.93–8.69]). Additionally, in the ASEF bacteremia group, PCN allergy status was associated with higher rates of completing ≥50% of targeted therapy with RGPI (5.52 [4.17–7.31]) and BSHOI (2.04 [1.10–3.78]) antibiotics. Patients with MSSA/MSSL bacteremia with a PCN allergy had higher 90-day recurrence (3.68 [1.02–13.28]) and, if predominantly using vancomycin instead of cefazolin, 7-day AKI (4.48 [1.44–13.98]). Conclusions: Our findings highlight opportunities for optimizing antibiotic selection and clinical outcomes among PCN-allergic patients with MSSA/MSSL, ASEF, and Spne bacteremia.