Comparison of oral versus intravenous antimicrobial therapy for patients who were diagnosed with bloodstream infections due to Gram-negative bacilli after discharge from the emergency department: A retrospective analysis.

Introduction: Infections caused by Gram-negative bacilli (GNB) in the emergency department (ED) are common, and the blood cultures taken at the visit can turn positive often after the discharge. However, the differences in the clinical outcomes depending on the subsequent decision-making, either to giving the patients intravenous or oral antibiotics remain unknown.

Methods: A single-center retrospective observational study was conducted for the outcome of the patients whose blood cultures at the visit turned positive and detected GNB. The primary outcomes were 30- and 90-day all-cause mortality from the first positive blood cultures, comparing intravenous treatment (IVT) and oral treatment (OT). The propensity score analysis was used to adjust potential confounders.

Results: A total of 283 patients with GNB bloodstream infections (BSIs) diagnosed after ED discharge. No death occurred in either group within 30 days, with the average treatment effect (ATE) of OT being <0.001 (p = 0.45) after inverse probability weighting (IPW). At 90 days, mortality was 2.5 % for the OT group and 0 % for the IVT group (ATE 0.051; 96%CI 0.013-0.098; p = 0.001).

Conclusion: All of patients treated with oral antibiotics were alive at 30 days, but had a higher 90-day mortality compared to those given intravenous agents. The results were consistent after adjusting the potential confounders by using IPW. Given the overall low mortality in both groups after 90 days, even though oral antibiotic therapy was associated with higher mortality statistically, one might consider this as an option especially when the patient's preference was compelling.