Rapid molecular assays versus blood culture for bloodstream infections: a systematic review and meta-analysis.

Summary

Across 75 studies, rapid molecular assays had high specificity but only moderate sensitivity versus blood culture (patient-level sensitivity 0.659), with wide variation across platforms. The authors conclude RMAs should not replace blood culture but can serve as add-on tests to increase pathogen detection, calling for higher-sensitivity assays and better implementation studies.

Key Findings

• Pooled patient-level specificity was 0.858 (95% CI 0.830–0.883) and sensitivity was 0.659 (95% CI 0.594–0.719) versus blood culture.
• Sensitivity varied substantially by platform (e.g., IRIDICA 0.783; MagicPlex 0.492), and specificity varied by care setting (lower in ICU than ED).
• Given low sensitivity, RMAs cannot replace blood culture but may increase pathogen detection as add-on tests; higher-sensitivity designs and larger blood volumes are needed.

Clinical Implications

Use RMAs as adjuncts to blood culture to accelerate organism identification while recognizing false negatives; do not discontinue cultures. Prioritize platforms with higher sensitivity where available and consider larger blood volumes.

Limitations

• High risk of bias across included studies and substantial heterogeneity between platforms and settings
• Use of blood culture as imperfect reference standard and limited standardized reporting across studies

Future Directions

Develop higher-sensitivity, broader-coverage RMAs using larger blood volumes; conduct pragmatic implementation studies with standardized endpoints to quantify time-to-targeted-therapy benefits.