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

Abstract

Purpose 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 outcome was 30- and 90-day all-cause mortality from the first positive blood cultures, comparing those who received intravenous treatment (IVT) and those who were given oral treatment (OT). The propensity score analysis was used to adjust the potential confounding factors. Results A total of 283 patients were diagnosed as GNB bloodstream infections (BSIs) after discharge from ED, and those whose each outcome was known were included in the analysis. 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). The 90-day mortality was 2.5% and 0% for the OT and IVT groups respectively (ATE 0.051; 96%CI 0.013–0.098; p = 0.001). Conclusion All of the patients with GNB-BSIs upon visiting ED who were treated with oral antibiotics were alive at 30 days but had higher mortality than those who received intravenous agents within 90 days. 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.