SAN FRANCISCO – Cefazolin was better tolerated than nafcillin for the outpatient treatment of methicillin-sensitive Staphylococcus aureus among clinic patients included in a retrospective cohort study.
A number of drug-related adverse events occurred more often in 366 patients who received outpatient parenteral antimicrobial therapy (OPAT) with nafcillin, compared with 119 patients treated with cefazolin, including rash (13.9% vs. 4.2%), renal dysfunction (11.4% vs. 3.3%), and transaminitis (8.1% vs. 1.6%), Dr. Ilan Youngster reported at an annual scientific meeting on infectious diseases.
The patients in this study were adults with a mean age of 57 years in the nafcillin group and 56 years in the cefazolin group.
Furthermore, neutropenia developed in 8.4% of nafcillin patients, compared with 3.3% of cefazolin patients, and Clostridium difficile colitis developed in 2.4% vs. 0.8% of the nafcillin and cefazolin patients, respectively, said Dr. Youngster, a research fellow at Boston Children’s Hospital and Massachusetts General Hospital, Boston.
The discontinuation rate was significantly higher in the nafcillin group than in the cefazolin group, with 34% and 7% of patients in the groups, respectively, failing to complete the prespecified treatment course, he said. Nine patients who discontinued nafcillin switched over to cefazolin and completed treatment without any further drug-related adverse events.
The findings have implications for treatment of methicillin-sensitive Staphylococcus aureus (MSSA), which is a major pathogen in both community and health care–acquired infection, and one of the most common infections requiring prolonged antimicrobial administration.
Both nafcillin and cefazolin are considered first-line options for therapy for most MSSA infections, and recent studies suggest that the two beta-lactam antibiotics have similar efficacy, Dr. Youngster explained.
In addition to cost and efficacy, the differences in tolerability between these two drugs should be considered when deciding on long-term intravenous treatment for MSSA in the OPAT setting, he said. A failure to tolerate treatment will result in exposure to a partially treated infection should treatment be discontinued prematurely, or to the inconvenience of returning for another evaluation and a change of treatment.
Although the current study did not compare the efficacy of the two drugs, a clinical data collection system now in place will allow for such assessments going forward, he said.
IDWeek is the combined annual meetings of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association, and the Pediatric Infectious Diseases Society.
Dr. Youngster reported having no disclosures.