Clinical Outcomes with Penicillin Versus Alternative β‐Lactams in the Treatment of Penicillin‐Susceptible Staphylococcus aureus Bacteremia

Objectives To identify the impact of penicillin versus alternative β‐lactams on clinical outcomes in patients with penicillin‐susceptible Staphylococcus aureus ( PSSA ) bacteremia. Design Retrospective cohort study. Setting Academic medical center. Patients Adult patients with PSSA bacteremia treated with a β‐lactam as definitive therapy. Measurements The primary outcome was a composite end point of 30‐day clinical failure (change in PSSA therapy due to persistent or worsening signs and symptoms, PSSA bacteremia recurrence or persistence, and/or infection‐related mortality) in patients treated with penicillin versus alternative β‐lactams. Secondary outcomes included infection‐related and hospital length of stay ( LOS ), 90‐day recurrence, 90‐day infection‐related readmission, 30‐day all‐cause mortality, adverse drug events ( ADE s), and 30‐day change in PSSA therapy due to ADE s. A subgroup analysis comparing penicillin, nafcillin, and cefazolin was also conducted. Main Results For the 122 patients who were included, the most common definitive therapies were nafcillin (37%), cefazolin (29%), and penicillin (21%). No difference was found in 30‐day clinical failure (4% vs 11%, p=0.46), infection‐related LOS (12 days vs 11 days, p=0.39), hospital LOS (12.5 days vs 12 days, p=0.69), 90‐day recurrence (p=1.00), 90‐day infection‐related readmission (p=1.00), or 30‐day all‐cause mortality (p=0.45) between penicillin and other β‐lactams. The prevalence of ADE s was different among penicillin, nafcillin, and cefazolin (p=0.049), with nafcillin requiring more changes in therapy (p=0.005). Conclusions Definitive therapy with penicillin had similar efficacy compared with alternative β‐lactams for the treatment of PSSA bacteremia. However, nafcillin was associated with more ADE s requiring a change in therapy.