Diagnostic Accuracy of Conventional Culture and Molecular Methods for Rapid Detection of Bloodstream Infections and Antimicrobial Resistance

Abstract

Bloodstream infections (BSIs) require rapid, accurate identification of pathogens and antimicrobial-resistance determinants because treatment decisions are often made before definitive microbiological results are available. This review evaluated the diagnostic accuracy of conventional blood culture and molecular methods for detecting BSIs and antimicrobial resistance. Conventional culture remained essential because it recovered viable organisms, supported phenotypic antimicrobial susceptibility testing, and enabled further characterization. However, its performance was influenced by blood volume, prior antimicrobial exposure, contamination, organism growth requirements, and turnaround time. Molecular methods, including multiplex PCR, direct-from-blood assays, targeted sequencing, and metagenomic next-generation sequencing, provided faster pathogen detection and identification of selected resistance genes, but their sensitivity, specificity, target coverage, and genotype–phenotype relationships varied across platforms and populations. A qualitative systematic/narrative literature review compared diagnostic accuracy, turnaround time, resistance detection, clinical actionability, antimicrobial stewardship, implementation, and equity. Evidence indicated that rapid molecular assays often showed high specificity but variable sensitivity and therefore did not fully replace culture. The review concluded that accurate BSI diagnosis was best achieved through a complementary approach in which blood culture remained foundational, while molecular tests were selected according to clinical urgency and validated target scope. Resistance findings were interpreted alongside phenotypic AST, local epidemiology, clinical context, and stewardship interventions, with particular consideration of infrastructure, financing, quality systems, workforce, and equitable implementation in Pakistan and other developing economies.