Clinical Efectiveness of a Multiplex PCR-Based Rapid Diagnostic Method in Bloodstream Infections

Bloodstream infections (BSIs) are associated with high morbidity and mortality, and delays in initiating appropriate antimicrobial therapy significantly worsen clinical outcomes. Conventional culture-based microbiological methods require 24-72 hours to provide definitive pathogen identification and antimicrobial susceptibility results, often leading to prolonged use of broad-spectrum empirical therapy. Rapid multiplex PCR-based diagnostic tests have the potential to shorten diagnostic timelines by identifying pathogens and resistance genes within approximately one hour; however, data on their real-world clinical impact remain limited. This prospective, randomized, controlled, single-center study aims to evaluate the clinical effectiveness and diagnostic performance of a multiplex PCR-based rapid diagnostic method applied directly to positive blood culture bottles in adult patients with bloodstream infections. A total of 300 patients (≥18 years) with positive blood culture signals will be randomized 1:1 to either a study group or a control group. In the study group, positive blood cultures will be analyzed using both standard microbiological methods and a multiplex PCR panel, while the control group will undergo standard microbiological diagnostics alone. The primary endpoint is time to optimal antimicrobial therapy (OTT), defined as the time from blood culture collection to initiation of the narrowest-spectrum, guideline-recommended antimicrobial agent active against the identified pathogen. Secondary endpoints include time to effective antimicrobial therapy (ETT), time to pathogen identification, antimicrobial escalation or de-escalation rates, length of hospital stay, total duration of antimicrobial therapy, and 28-day all-cause mortality. Clinical, demographic, and microbiological data will be collected prospectively, including comorbidity indices and severity scores. Randomization will be stratified by ICU versus ward admission, presence of neutropenia, and Charlson Comorbidity Index to ensure balanced groups. Diagnostic accuracy of the multiplex PCR panel will be assessed by calculating sensitivity, specificity, predictive values, and agreement with standard culture methods. This study seeks to determine whether rapid multiplex PCR diagnostics can meaningfully improve antimicrobial stewardship and clinical outcomes in patients with bloodstream infections compared with conventional diagnostic workflows.