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An early switch to oral antibiotics in patients hospitalized with low-risk Staphylococcus aureus bloodstream infection was noninferior to IV antibiotics, according to the randomized controlled SABATO trial.

In the trial's intention-to-treat population, 13% of patients who switched to oral antibiotics developed complications related to S. aureus bloodstream infection (SAB) versus 12% in the group that remained on IV treatment, Achim Kaasch, MD, from Otto von Guericke University in Magdeburg, Germany, and colleagues reported in .

The 0.7% (95% CI -7.8 to 9.1) treatment difference between the two groups met the noninferiority margin of less than 10% (P=0.013). Hospital stays were also shorter in patients switched to oral treatment (median 12 vs 16 days, respectively).

"We had no clue whether noninferiority could be reached in the trial. It was rather a moment of relief rather than surprise that we could contribute meaningful results with the trial," Kaasch told 乌鸦传媒 in an email.

"Early oral antibiotics are safe and effective in low-risk Staphylococcus aureus bacteremia patients," Kaasch said. "This simplifies the treatment and may allow earlier discharge from hospital."

A numerically higher incidence of serious adverse events not related to SAB occurred in the group switched to oral antibiotics, but the difference was not statistically significant. In the oral-switch group, 34% of participants in the safety population had at least one serious adverse event versus 26% in the IV group (P=0.29).

Accurately identifying patients with low-risk versus high-risk SAB is a substantial hurdle to switching from IV to oral antibiotics, the authors acknowledged. In a , fewer than one in four patients with SAB actually met the criteria for low-risk infection, they pointed out, inferring that low-risk SAB is relatively uncommon. In another trial, one-third of patients with uncomplicated SAB were later diagnosed with complicated SAB, suggesting they had initially been miscategorized.

"The impact of these data on SAB management is limited given the diagnostic challenges of identifying patients with low-risk SAB," Julie Ann Justo, PharmD, from Dartmouth Hitchcock Medical Center in Lebanon, New Hampshire, and Jason Pogue, PharmD, from the University of Michigan College of Pharmacy in Ann Arbor, wrote in .

The study authors, as well as Justo and Pogue, pointed out that over half of the 14 SAB-related complications in the study -- defined as relapsing infection, development of deep-seated infection, or mortality attributable to S. aureus bloodstream infection -- occurred within 1 to 2 weeks after randomization, suggesting the complications may have been present but undetected at enrollment. However, when investigators excluded early complications from the primary endpoint, a switch to oral antibiotics was still noninferior to IV treatment.

Justo and Pogue also raised concerns about the numerically higher rate of all-cause mortality in the oral-switch group versus the IV group (16.4% vs 11%), although the difference was not statistically significant. Additionally, the study enrolled few patients with methicillin-resistant S. aureus (MRSA) infections (n=16), they pointed out, which typically has worse outcomes than methicillin-susceptible S. aureus. Two of six patients with MRSA who switched to oral treatment died within 90 days versus two of 10 in the IV group with MRSA, they noted.

enrolled 213 patients from 31 hospitals in Germany, France, the Netherlands, and Spain, who were diagnosed with low-risk SAB. (Patients with complicated SAB, severe comorbidities, or non-removable foreign devices were excluded from the trial.) Nearly 70% were male, and the mean age was 63.5 years. The most common foci of infections were peripheral venous catheters, central venous catheters, and skin and soft tissue infections.

After 5 to 7 days of IV antibiotic therapy, patients were randomized 1:1 to either continuation of IV therapy or a switch to oral treatment. Total antibiotic duration was 14 days in both groups. Physicians selected oral antimicrobials based on susceptibility results and MRSA status. Most patients in the oral treatment group were transitioned to co-trimoxazole (58%) or clindamycin (32%). In the IV group, most received cefazolin (44%) or flucloxacillin or cloxacillin (43%).

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