Evaluation of the Clinical Efectiveness of a Multiplex PCR-Based Rapid Diagnostic Method in Bloodstream Infections: A Prospective Randomized Controlled Study

Bloodstream infections (BSIs) are among the most severe infectious diseases encountered in hospitalized patients and are associated with significant morbidity and mortality. Early initiation of appropriate antimicrobial therapy is one of the most important determinants of survival in these patients. However, timely optimization of antimicrobial treatment is frequently limited by delays inherent to conventional culture-based microbiological diagnostic methods, which typically require 24-72 hours to provide definitive pathogen identification and antimicrobial susceptibility results. As a consequence, clinicians often rely on prolonged broad-spectrum empirical antimicrobial therapy, which contributes to antimicrobial resistance, drug-related adverse events, and increased healthcare costs.

Recent advances in molecular diagnostics have enabled the development of multiplex polymerase chain reaction (PCR)-based assays capable of rapidly detecting common bloodstream pathogens and selected antimicrobial resistance genes directly from positive blood culture bottles. These tests can provide results within approximately one hour, offering the potential to significantly shorten diagnostic timelines and support earlier antimicrobial escalation, de-escalation, or optimization. Despite their increasing availability, there remains limited high-quality evidence regarding the real-world clinical effectiveness of these rapid diagnostic tools, particularly with respect to their impact on antimicrobial stewardship and patient-centered outcomes.

This study is designed as a prospective, randomized, controlled, single-center clinical trial to evaluate the clinical effectiveness and diagnostic performance of a multiplex PCR-based rapid diagnostic panel applied directly to positive blood culture samples in adult patients with bloodstream infections. The study will be conducted in an 810-bed tertiary university hospital and is planned to enroll a total of 300 patients over a 12-month period.

Adult patients (≥18 years of age) with clinical suspicion of bloodstream infection and a positive blood culture signal will be screened for eligibility. Following confirmation of eligibility and informed consent, patients will be randomized in a 1:1 ratio to either the study group or the control group. Randomization will be performed using a computer-generated permuted block randomization method and will be stratified by intensive care unit (ICU) versus ward admission, presence of neutropenia, and Charlson Comorbidity Index category to ensure balanced distribution of baseline risk factors between the study arms.

In the study group, positive blood culture samples will undergo rapid testing using a multiplex PCR-based in vitro diagnostic panel in addition to standard microbiological diagnostic methods. The multiplex PCR assay is designed to detect predefined bacterial and fungal pathogens as well as selected antimicrobial resistance genes directly from positive blood culture bottles. DNA extraction will be performed using a rapid, automated nucleic acid extraction system according to the manufacturer's instructions, followed by real-time PCR amplification and detection. Results of the multiplex PCR assay will be available within approximately one hour and will be promptly reported to the treating clinical team. These results may be used to guide antimicrobial management decisions, including early escalation, de-escalation, or optimization of therapy, in conjunction with clinical judgment and institutional treatment guidelines.