Development of a CRISPR-CiRNA-based diagnostic assay for rapid detection of antimicrobial resistance genes in clinical isolates

Project Abstract

The rapid and accurate detection of antimicrobial resistance (AMR) determinants in clinical isolates is critical for guiding targeted therapy and curbing the spread of resistant pathogens. This study reports the development and validation of a CRISPR-CiRNA-based diagnostic assay that enables ultra-sensitive, sequence-specific, and rapid detection of key AMR genes directly from clinical samples. The assay integrates a CRISPR-CiRNA system engineered for programmable recognition of resistance determinants with isothermal amplification to achieve low detection limits while maintaining simplicity suitable for point-of-care settings. We designed and validated a panel of CiRNA guides targeting representative beta-lactamase genes (blaTEM, blaCTX-M, blaNDM), mecA/mecC, vanA/vanB, and plasmid-mediated colistin resistance genes (mcr-1/mcr-2), alongside lineage- and species-associated markers to ensure specificity. In vitro optimization addressed guide design, collateral cleavage control, and signal readout modalities, including fluorescence, lateral flow, and smartphone-based readouts. The assay exhibits a dynamic range spanning multiple orders of magnitude with limits of detection in the low-copy-number range for purified DNA and equivalent robustness in crude clinical matrices following minimal extraction steps, thereby reducing turnaround time to under 60 minutes. Specificity testing against a comprehensive panel of resistant and susceptible strains demonstrated zero false positives in non-target organisms and robust discrimination of target AMR genes even in the presence of homologous sequences. The CIRNA component enhances the trans-cleavage activity and improves the discrimination power against single-nucleotide polymorphisms that distinguish closely related resistance determinants, a common challenge in AMR diagnostics. The workflow was evaluated using a diverse set of clinical specimens, including blood, urine, wound swabs, and sputum, to reflect real-world diagnostic scenarios. Comparative analysis against standard phenotypic methods and conventional PCR-based assays showed higher concordance with sequencing data, faster results, and reduced requirement for culturing, thereby accelerating antimicrobial stewardship decisions. A semi-quantitative readout correlated with plasmid copy number and gene expression proxies, enabling gradient reporting of resistance potential. Reproducibility studies across multiple operators and instruments confirmed assay robustness and field-deployable potential. Economic modeling suggests favorable cost per test relative to established molecular diagnostics, particularly when deployed as a rapid triage tool in high-burden settings or resource-constrained environments. Potential limitations include the need for initial assay validation against regional resistance gene repertoires and the requirement for a compact incubator and simple detection device in some settings. Future work will expand the gene panel, incorporate multiplexing strategies to cover emergent AMR determinants, and integrate the diagnostic with a cloud-based data platform for real-time epidemiological surveillance. Overall, the CRISPR-CiRNA-based assay represents a versatile, rapid, and scalable approach to AMR detection with significant implications for clinical management and infection-control practices.

Project Overview

What This Project Is About

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A plain-language overview of the topic and what the project investigates.

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The Problem It Addresses

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What problem or gap this project tackles and why it matters to the field or society.

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Objectives of the Project

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1. Identify key antimicrobial resistance (AMR) genes commonly found in clinical isolates.
2. Develop a CRISPR-CiRNA based test that can indicate the presence of these AMR genes quickly.
3. Evaluate the test’s accuracy against standard laboratory methods.
4. Assess the test’s speed, cost, and ease of use in a clinical setting.

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What You Will Do Step by Step

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1. Review literature to select target AMR genes and understand CRISPR-CiRNA principles.
2. Design CRISPR-CiRNA probes tailored to chosen genes.
3. Assemble a small set of clinical isolates with known resistance profiles.
4. Test the CRISPR-CiRNA assay on these isolates and record results.
5. Analyze data to determine sensitivity, specificity, and speed.
6. Compare results with conventional methods like PCR or culture-based tests.
7. Refine assay design based on initial findings and repeat testing as needed.
8. Prepare a concise report and discuss practical deployment considerations.

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Expected Outcome

Expect a working, user-friendly diagnostic assay that can rapidly indicate the presence of key AMR genes in clinical samples, with documented performance metrics and potential for clinical trial readiness.