Journal Club 

Shorter Course Strikes Again: Simple Methicillin-sensitive Staphylococcus aureus Bacteremia

By Erica Kaufman West, MD

Over the last decade, researchers have shown that shorter courses of antibiotics for multiple different infections have proven effective, including for intra-abdominal infections, gram-negative bacteremias, and others. For those wanting to delve deeper, a website created by Dr. Brad Spellberg outlines many of the studies that support shorter courses. However, Staphylococcus aureus has always been put on the pedestal that still requires 14-plus days of antibiotics. Until now.

Researchers in Denmark conducted a retrospective cohort study, recently published in Clinical Infectious Diseases, to evaluate a shorter course of therapy for patients with uncomplicated infections as defined by IDSA criteria. They included adults with methicillin-sensitive Staphylococcus aureus (MSSA)–positive blood cultures who received <16 days of antibiotics, as those with longer courses most likely had a complicated infection (osteomyelitis, endocarditis). Notably, they excluded patients who had positive blood cultures >48 hours into therapy. Short-course (SC) therapy was 6 to 10 days and prolonged-course (PC) therapy was 11 to 16 days. The primary outcome was death within 90 days, and a secondary outcome was 90-day relapse.

A total of 1,005 patients (291 SC and 714 PC) were included. There was no statistical difference in 90-day mortality or 90-day relapse. The SC group averaged 8 to 9 days of therapy and the PC group 13 to 14 days; importantly, the median treatment course in the SC group was 50% of the PC. The overall mortality rate ranged from 17% to 23%, a sobering reminder of how deadly this infection can be. The relapse risk was 7% overall. This study, while retrospective, gives promising results that uncomplicated MSSA bacteremias can safely be treated with a week of therapy rather than the 2 weeks we’ve all been taught was necessary.

(Thorlacius-Ussing et al. Clin Infect Dis. Published online: March 27, 2021.)