Plasmid-borne mcr genes, particularly mcr-1, mediate transferable resistance to colistin and represent a significant One-Health challenge because they circulate across human, animal, and environmental reservoirs. Surveillance for mcr-1 is limited in many settings by the lack of rapid, affordable, and field-deployable molecular tools. The authors frame their work as addressing these surveillance gaps by producing an integrated molecular and hardware solution to enable decentralized monitoring in resource-limited environments.
C12amcr is described as an integrated molecular toolbox combining three core elements: PCR-based pre-amplification of the target sequence, a fluorescent readout mediated by a CRISPR-Cas12a assay that targets a conserved region of mcr-1, and a custom, low-cost 3D-printed handheld portable fluorometer for signal detection. The workflow couples standard nucleic acid amplification with CRISPR-driven fluorescence to provide sequence-specific detection, while the device is intended to replace or mirror laboratory fluorescence readout equipment in field contexts. The authors emphasize that the platform uses locally producible reagents and straightforward protocols to facilitate decentralized implementation.
Under optimized conditions reported by the authors, the C12amcr assay achieved a laboratory limit of detection of 630 cells/mL. This figure represents analytical sensitivity under the assay conditions used in the study; details of the amplification parameters, reaction volumes, or exact concentration-to-signal conversion were not provided in the abstract and would require consulting the full manuscript for protocol specifics.
To assess performance in a complex biological matrix, the authors evaluated C12amcr on poultry feces spiked with mcr-1–positive E. coli. In this matrix the reported detection threshold was 1,800 cells/mL, indicating some loss of sensitivity relative to buffer or cleaner sample types, as often occurs when inhibitors or particulate matter are present. The abstract reports this detection level as the lowest spiked concentration reliably detected in that test.
C12amcr was tested on a panel of 22 community-derived E. coli isolates. The assay demonstrated 100% concordance with two reference approaches: next-generation sequencing for the presence of mcr-1 and phenotypic colistin susceptibility testing by broth microdilution. These results indicate that, for this isolate set, the molecular readout matched both genotypic and phenotypic reference standards reported in the study.
The custom handheld fluorometer is reported to perform equivalently to a laboratory microplate reader for the assay outputs evaluated by the authors. The device is 3D-printed and low-cost, designed to be compatible with portable PCR platforms to enable fully decentralized workflows. The authors position this combination—portable amplification, CRISPR-fluorescent detection, and a field-ready reader—as a practical solution to deploy molecular surveillance outside conventional laboratories.
The authors highlight features intended to support implementation in resource-limited settings, including locally produced reagents and simplified protocols. The manuscript is a preprint and therefore has not undergone peer review; additional implementation details, step-by-step protocols, reagent formulations, cost breakdowns, and long-term field validation data are not included in the abstract and would need to be obtained from the full text.
A competing interest statement notes that two authors, Carlos Herrera and Carlos Raymundo, are named inventors on a patent application for the portable fluorometer design. Funding sources declared include Universidad Peruana de Ciencias Aplicadas and the National Council for Science, Technology and Technological Innovation (CONCYTEC) through PROCIENCIA grants and institutional awards.
The authors present C12amcr as an integrated, field-oriented platform combining PCR pre-amplification, a fluorescent CRISPR-Cas12a assay targeting mcr-1, and a low-cost handheld portable fluorometer. Reported analytical sensitivity was 630 cells/mL in optimized conditions and 1,800 cells/mL in spiked poultry feces. In a panel of 22 E. coli isolates, the assay showed complete concordance with next-generation sequencing and broth microdilution for detection of mcr-1 and colistin resistance. The portable reader performed comparably to a laboratory microplate reader and the system is presented as a practical approach to overcome barriers to decentralized One-Health AMR surveillance in resource-limited settings. The work is reported as a preprint and further methodological and field-deployment data should be consulted in the full manuscript.