Highly Sensitive Lateral Flow Assay for Colistin Detection in Meat Products

Colistin is an antibiotic of critical importance in human medicine, while its use in animal production may result in the occurrence of residues in food products and contribute to the spread of antimicrobial resistance. Therefore, rapid and sensitive methods for monitoring colistin residues in meat are required. In this study, competitive lateral flow immunoassays (LFIAs) based on direct and indirect antibody labeling were developed and comparatively evaluated for the detection of colistin. In the direct format, gold nanoparticles (GNPs) were conjugated with specific anti-colistin antibodies, whereas the indirect format employed free specific antibodies and GNPs conjugated with anti-species antibodies. The direct LFIA provided visual and instrumental detection limits of 1.85 and 0.13 ng/mL, respectively. The indirect format demonstrated improved sensitivity, achieving visual and instrumental detection limits of 0.6 and 0.07 ng/mL, respectively. The developed assays were further evaluated using spiked chicken meat extracts. With four-fold dilution of the extracts in PBST, colistin recoveries ranged from 91 to 105% for the direct LFIA and from 90 to 117% for the indirect LFIA. The developed assay provides a rapid and sensitive approach for monitoring colistin residues in chicken meat and demonstrates the potential of indirect labeling as a strategy for improving the sensitivity of competitive lateral flow assays.