Rapid Diagnostic Testing in Bloodstream Infections: A Retrospective Clinical and Economic Evaluation from a University Hospital in Bulgaria

Rapid diagnostic tests enable earlier pathogen identification in bloodstream infections compared with conventional culture-based methods and may improve clinical and economic outcomes, particularly when integrated with antimicrobial stewardship programs. Evidence suggests that while mortality benefits are context-dependent, rapid diagnostics can optimize antibiotic use and hospital resource allocation. The present study aimed to evaluate the clinical and economic impact of rapid diagnostic approaches compared with conventional microbiological culture in patients with confirmed bacteremia or fungemia hospitalized in a tertiary care setting in Bulgaria. A retrospective observational study was conducted between January 2015 and August 2020 at University Hospital "St. George," Plovdiv. A total of 115 patients with confirmed bacteremia or fungemia were included and allocated to either a rapid diagnostic testing group (<i>n</i> = 77) or a standard culture group (<i>n</i> = 38). Mortality rates were comparable between groups (54.5% vs. 55.3%; OR 0.97, 95% CI 0.45-2.12; <i>p</i> = 0.942). Median length of stay was 20 days (12-35) in the rapid-test group versus 16 days (10-31) in the culture group (<i>p</i> = 0.505). Targeted antibiotic therapy duration was longer in the rapid-test group (median 12 vs. 6 days; <i>p</i> = 0.070). Median direct hospital costs were BGN 2319.40 versus BGN 1855.52, and indirect costs were BGN 19,388.80 versus BGN 15,511.04 (both <i>p</i> = 0.505). Diagnostic costs were significantly higher in the rapid-testing group (BGN 55.00 vs. BGN 38.00; <i>p</i> = 0.002). Rapid diagnostic testing produced clinical outcomes comparable to standard culture while demonstrating context-dependent economic differences in hospital resource utilization. Conclusions: Rapid diagnostic testing for bloodstream infections provides clinical outcomes comparable to standard culture-based methods while offering potential economic differences associated with the diagnostic strategy. When combined with antimicrobial stewardship interventions, rapid diagnostics support optimized antibiotic use and more efficient hospital resource utilization in critically ill patients.