Abstract: In this study, recombinase polymerase isothermal amplification (RPA) combined with lateral flow test strips (LF) was developed to quickly and reliably detect Cronobacter sakazakii. RPA using the primers modified with biotin and digoxin produced large amounts of double-stranded DNA products labeled with biotin and digoxin at each end. The products could interact with gold-labeled anti-digoxin antibody and streptavidin fixed on the LF, giving visible results on the strip. The RPA-LF method showed a limit of detection (LOD) of 1.7 × 102 CFU/mL for C. sakazakii in pure culture with no cross-reactivity with other common pathogens. The LOD of the RPA-LF was 1.7 × 100 CFU/g after 4 or 6 h enrichment for different types of atrifically contaminated food samples. In order to further evaluate its performance, 20 real food samples were detected by the RPA-LF in comparison with the national standard method. The results obtained were consistent with each other.

Key words: recombinase polymerase isothermal amplification, lateral flow test strips, Cronobacter sakazakii, rapid detection