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Life sciences · Journal article
Applied Microbiology · September 8, 2026
A consensus or society position rather than new primary data.
This is a narrative review that clarifies the complementary roles of PCR (genotypic detection) and bacterial culture/AST (phenotypic characterization) in infectious disease diagnostics, and proposes an integrated clinical framework for interpreting cycle threshold (Ct) values and PCR–culture discordance. The authors explicitly note that the proposed Ct categories and clinical framework should be viewed as assay-specific guidance rather than universally validated thresholds, and do not provide pooled estimates or systematic risk assessment.
Narrative review. Patients with suspected bacterial infectious disease requiring diagnostic confirmation and antimicrobial susceptibility guidance..
Ct values are frequently overinterpreted as direct surrogates for viable bacterial burden, obscuring the distinction between nucleic acid detection and microbial viability. PCR–culture discordance reflects complementary biological information: PCR detects target nucleic acid (genotype) while culture assesses viability and phenotypic traits including antimicrobial susceptibility. Ct is inherently assay-specific and non-portable across platforms due to variability in assay design, inhibition, and panel scope.
Safety was not reported in the material analysed. Check the source before drawing any conclusion about harm.
Clinicians should interpret PCR Ct values as qualified signals for rapid rule-in rather than standalone diagnostic truth, and should retain culture and AST for confirmation, phenotypic characterization, and stewardship-aligned treatment decisions. The proposed framework is assay-specific guidance and should not be applied universally without validation in local laboratory contexts.
A narrative review synthesizing heterogeneous evidence to provide a practical clinical framework for interpreting PCR, culture, and AST results in bacterial diagnostics, without pooled estimates or uniform risk-of-bias assessment.
As stated by the source record.
Clinicians should interpret PCR Ct values as qualified signals for rapid rule-in rather than standalone diagnostic truth, and should retain culture and AST for confirmation, phenotypic characterization, and stewardship-aligned treatment decisions. The proposed framework is assay-specific guidance and should not be applied universally without validation in local laboratory contexts.
Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.
What is missing. This record has no reported figures. That is a gap in the analysis, not a judgement about the study.
Real-time polymerase chain reaction (PCR) has reshaped bacterial infectious disease diagnostics, yet important interpretive gaps remain regarding the relationship among molecular detection, cycle threshold (Ct) values, microbial viability, culture findings, and phenotypic antimicrobial susceptibility. In particular, Ct values are frequently overinterpreted as direct surrogates for viable bacterial burden, and PCR–culture discordance may be interpreted without sufficient consideration of the distinct biological information provided by each method. This review therefore aims to clarify the complementary biological and analytical roles of PCR and bacterial culture, critically examine the determinants and limitations of Ct interpretation and PCR–culture discordance, and provide a practical framework for integrating molecular detection, culture, and antimicrobial susceptibility testing (AST) into clinically and stewardship-informed decision-making. The genotypic lens of PCR (detection of target nucleic acid and resistance genes) is contrasted with the phenotypic lens of bacterial culture and AST, emphasizing that genotype and phenotype distinguish biological layers and account for common PCR–culture discordance. Evidence on Ct variability, assay design, inhibition, and panel scope is synthesized to demonstrate why Ct is inherently assay-specific and non-portable across platforms. Accordingly, MIQE-aligned quality safeguards and assay-specific principles are presented to guide the interpretation of Ct values. Bedside decision tables then integrate Ct patterns, specimen sterility, and patient acuity to support treatment, observation, or additional testing. As a narrative review of heterogeneous evidence, this synthesis does not provide pooled estimates or a uniform risk-of-bias assessment. The proposed Ct categories and clinical framework should therefore be viewed as assay-specific guidance, not universally validated thresholds. Finally, a stepwise workflow is outlined in which PCR is used for rapid rule-in, while culture and AST are retained for confirmation, de-escalation, and dosing. This integrated approach reframes Ct as a qualified signal rather than a standalone truth, supporting faster yet biologically grounded and stewardship-consistent infectious disease management.
Taken from the source record, never inferred. Follow any of these and new work involving them reaches your briefing.