Antibiotics for S aureus Bacteremia Adapted to Patient's Access to Treatment

Providing oral antibiotics after partial completion of an intravenous regimen for complicated Staphylococcus aureus bacteremia was found in a retrospective cohort study to improve outcomes for persons who inject drugs (PWID) and are unable to complete the 4 to 6 weeks of standard intravenous treatment.

The investigators point out that S aureus is the most common pathogen in serious infections in PWID, but that the standard treatment with multiple weeks of intravenous antibiotic, commonly completed in outpatient settings, is often not available for this population. This is also a vulnerable population for other health issues such as hepatitis and HIV.

"PWID are frequently considered ineligible for outpatient parenteral antibiotic therapy, and often choose to leave the hospital or skilled nursing facilities prior to completing a multiweek course of IV antibiotic therapy as inpatients," explain Laura Marks, MD, PhD, Division of Infectious Diseases, Washington University in St. Louis School of Medicine, St Louis, Missouri, and colleagues.

Marks described the patients for whom their findings are most valuable as those likely to struggle with staying in the hospital, or who have clear outside responsibilities that preclude the standard of care (SOC) intravenous regimen.

"I often see this with patients that might have upcoming court dates, or with patients that have left the hospital early on many occasions in the past, or even patients with young kids, where they can only leave them with friends or family for so many days," Marks told Contagion.

"In this cohort, having data on real world outcomes to present to patients early on, before I think they might leave, helps me provide them with an informed discussion of the risks and benefits of each antibiotic option, along with planning timing for the safest possible discharge, and making sure they have close follow-up if they choose to go home on oral antibiotics," she said.

Marks and colleagues compared outcomes of 3 groups of PWID hospitalized during the period between January 2016 through December 2021 with complicated S aureus bacteremia, including infective endocarditis, epidural abscess, vertebral osteomyelitis and septic arthritis: Those who received a full course intravenous SOC (n=122); an incomplete intravenous course without oral antibiotics on discharge (n=36); and those who were transitioned to oral antibiotics after an incomplete SOC (n=69).

A previously undertaken, and published initiative with the latter group to support adherence to the oral antibiotic regimen helped to validate the treatment condition, andfacilitated this comparison between treatment groups.

"Washington University in St Louis has invested heavily in improving care for PWID with invasive infections, and has funded a multidisciplinary team to provide intensive outpatient follow-up, including free infectious disease clinic visits and medications for uninsured patients, as well as health coaches and case management," Marks explained.

Marks and colleagues found that the patients who received oral antibiotics after an incomplete intravenous course were significantly less likely to experience microbiologic failure or death than those discharged after an incomplete intravenous antibiotic SOC without oral antibiotics. There was no significant difference in microbiologic failure rates between those completing SOC, and receiving oral antibiotics after completing at least 10 days of the intravenous regimen.

Although transitioning to oral antibiotics was beneficial to the cohort completing at least 10 days SOC, Marks emphasized that it cannot yet be a recommended course of treatment.

"I do not want these data to be construed as permission to not offer these patients SOC therapies, and instead develop a separate standard of care for patients based solely on a comorbid history of substance use disorder," Marks declared. "At least until we have further prospective randomized controlled trial data."

"If upcoming trials, like the SNAP trial, confirm no significant difference, then I think it is reasonable to assume that in the future we might want to limit the potential complications associated with outpatient parenteral antibiotic therapy, particularly for younger immunocompetent patients," Marks said.