Two-Dose Therapy for S. Aureus Bloodstream Infections on Par with Standard Treatment

Colorized scanning electron micrograph of MRSA bacteria (gold) interacting with a human neutrophil (red).

Photo:  NIAID

An NIH-supported study has found that the outcome of treating complicated Staphylococcus aureus bloodstream infections with two intravenous (IV) doses of the antibiotic dalbavancin seven days apart is just as effective as daily IV doses of conventional antibiotics over four to six weeks. Nearly 120,000 S. aureus bloodstream infections and 20,000 associated deaths occurred in the U.S. in 2017.

The findings were published in the Journal of the American Medical Association.

Standard therapy for complicated S. aureus bloodstream infections, or bacteremia, involves inserting a long IV line known as a peripherally inserted central catheter (PICC) into a vein to deliver antibiotics through the blood for many weeks. The PICC line remains in place for the full duration of treatment and can cause additional complications. Dalbavancin therapy requires temporarily inserting a short catheter into a vein twice for an hour at a time.

The Phase 2b trial enrolled 200 adults with S. aureus bacteremia. They were randomly assigned to receive either dalbavancin intravenously on days one and eight, or standard therapy for four to eight weeks.

The researchers aimed to capture not only the result of antibiotic therapy, but also participants’ treatment-related experiences during therapy. The study team also compared the efficacy and safety of the two therapies.

Investigators found that a participant from the dalbavancin group was 47.7% likely to have a better overall treatment outcome than a counterpart from the standard therapy group, but the overall outcomes were similar for the two groups, suggesting that dalbavancin therapy and standard therapy were equally good. Study participants in the two groups reported a similar health-related quality of life.

As expected, the rate of side effects was greater in the standard therapy group than the dalbavancin therapy group. Yet the overarching similarities in the components of overall outcome diluted these differences.