Outcomes of Partial Oral Antibiotic Treatment for Complicated Staphylococcus Aureus Bacteremia in People Who Inject Drugs

For patients with injection drug use associated Staphylococcus aureus bacteremia who struggle to complete prolonged courses of intravenous (IV) antibiotics, transition to oral antibiotics is safest when patients complete at least 10 days of IV antibiotics following clearance of bacteremia. Background Staphylococcus aureus represents the leading cause of complicated bloodstream infections among persons who inject drugs (PWID). Standard of care (SOC) intravenous (IV) antibiotics result in high rates of treatment success but are not feasible for some PWID. Transition to oral antibiotics may represent an alternative treatment option. Methods We evaluated all adult patients with a history of injection drug use hospitalized from January 2016 through December 2021 with complicated S. aureus bloodstream infections, including infective endocarditis, epidural abscess, vertebral osteomyelitis, and septic arthritis. Patients were compared by antibiotic treatment (standard of care intravenous [SOC IV] antibiotics, incomplete IV therapy, or transition from initial IV to partial oral) using the primary composite endpoint of death or readmission from microbiologic failure within 90 days of discharge. Results Patients who received oral antibiotics after an incomplete IV antibiotic course were significantly less likely to experience microbiologic failure or death than patients discharged without oral antibiotics (P < .001). There was no significant difference in microbiologic failure rates when comparing patients who were discharged on partial oral antibiotics after receiving at least 10 days of IV antibiotics with SOC regimens (P > .9). Conclusions Discharge of PWID with partially treated complicated S. aureus bacteremias without oral antibiotics results in high rates of morbidity and should be avoided. For PWID hospitalized with complicated S. aureus bacteremias who have received at least 10 days of effective IV antibiotic therapy after clearance of bacteremia, transition to oral antibiotics with outpatient support represents a potential alternative if the patient does not desire SOC IV antibiotic therapy.