An Antimicrobial Stewardship Program’s Evaluation of the Safety and Efficacy of Continuous Infusion of Nafcillin in the Treatment of Methicillin-Sensitive Staphylococcus aureus Bacteremia

International consensus recommendations for the use of prolonged-infusion beta-lactam antibiotics: Endorsed by the American College of Clinical Pharmacy, British Society for Antimicrobial Chemotherapy, Cystic Fibrosis Foundation, European Society of Clinical Microbiology and Infectious Diseases, Infectious Diseases Society of America, Society of Critical Care Medicine, and Society of Infectious Diseases Pharmacists

Intravenous β-lactam antibiotics remain a cornerstone in the management of bacterial infections due to their broad spectrum of activity and excellent tolerability. β-lactams are well established to display time-dependent bactericidal activity, where reductions in bacterial burden are directly associated with the time that free drug concentrations remain above the minimum inhibitory concentration (MIC) of the pathogen during the dosing interval. In an effort to take advantage of these bactericidal characteristics, prolonged (extended and continuous) infusions (PIs) can be applied during the administration of intravenous β-lactams to increase time above the MIC. PI dosing regimens have been implemented worldwide, but implementation is inconsistent. We report consensus therapeutic recommendations for the use of PI β-lactams developed by an expert international panel with representation from clinical pharmacy and medicine. This consensus guideline provides recommendations regarding pharmacokinetic and pharmacodynamic targets, therapeutic drug-monitoring considerations, and the use of PI β-lactam therapy in the following patient populations: severely ill and nonseverely ill adult patients, pediatric patients, and obese patients. These recommendations provide the first consensus guidance for the use of β-lactam therapy administered as PIs and have been reviewed and endorsed by the American College of Clinical Pharmacy (ACCP), the British Society for Antimicrobial Chemotherapy (BSAC), the Cystic Fibrosis Foundation (CFF), the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), the Infectious Diseases Society of America (IDSA), the Society of Critical Care Medicine (SCCM), and the Society of Infectious Diseases Pharmacists (SIDP).

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 (ADEs), and 30-day change in PSSA therapy due to ADEs. 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 ADEs 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 ADEs requiring a change in therapy.