Evaluating the effectiveness of low-dose oral switch therapy for uncomplicated streptococcal or enterococcal...

Although oral switch therapy (OST) is increasingly recognized as a viable option for uncomplicated gram-positive bloodstream infections (GP-BSI), its optimal dosage remains unclear. In Japan, high-dose regimens of key oral antimicrobials, such as amoxicillin (1000 mg thrice daily) or levofloxacin (750 mg once daily), are not approved. This study investigated the effectiveness of low-dose OST for GP-BSI in a population with a low prevalence of obesity.

This retrospective, single-centre study involved patients aged ≥18 years with monomicrobial, uncomplicated BSI caused by ampicillin- or amoxicillin-susceptible Streptococcus or Enterococcus species treated between 2010 and 2023. Patients eligible for OST were identified on day 5 of microbiologically active therapy. Demographic, clinical, laboratory, and microbiological data were analysed. Using overlap weighting, we compared 90-day all-cause mortality between OST and intravenous therapy (IVT) only groups.

A total of 172 patients (86 with OST and 86 with IVT only) were included. The median body mass index was 22.5 (interquartile range [IQR], 19.2-24.7), and the median duration of therapy was 14 days (IQR, 12-15 days). Common oral regimens included amoxicillin (n = 34, 39.5%), amoxicillin/clavulanate (n = 24, 27.9%), and levofloxacin (n = 12, 14.0%). No significant difference in 90-day all-cause mortality was observed between OST and IVT groups (odds ratio, 0.73; 95% confidence interval, 0.23-2.29).

Low-dose OST may be effective for clinically stable patients with uncomplicated GP-BSI in settings with low obesity prevalence.