Purpose: This study compared the performance of a LAMP-bioluminescence based method and the ISO 22964 (2006) standard for the detection of Cronobacter spp. from a variety of PIF manufacturing related products and environmental samples.
Methods: Inclusivity (106 Cronobacter spp. strains) and exclusivity (102 non-Cronobacter spp. strains) were assessed following AOAC guidelines. Method comparison was performed with 10-375 g portions of PIF (n=162), environmental samples (n=190), cereals (n=84), and raw materials (n=138) including mineral-vitamins, fatty acids, oils, flours, and probiotics. Samples were spiked with ≤ 5 CFU/portion of lyophilized Cronobacter spp. cultures. Portions were enriched with buffered peptone water ISO at 37±1°C for 18-24h. Detection was done by the LAMP-Bioluminescence assay. Enrichments were further confirmed following the ISO 22964 standard. The results from 10 g portions (n=319) were analyzed according to ISO 16140-2 and portions >10 g (n=255) were analyzed by Chi-square. Additionally, the probability of detection in 300 g portions and limit of detection were evaluated.
Results: Inclusivity and exclusivity were determined to be 100% for the LAMP-bioluminescence assay. Performance of the assay showed that there was no significant difference compared to the ISO-22964 standard. The LOD of the assay was 103CFU/mL in the enrichment and the lowest concentration detected was 1-2 CFU/300g portions.
Significance: The alternative LAMP-bioluminescence method offers a specific and rapid approach for the detection of Cronobacter spp., offering PIF manufacturers and commercial laboratories a next day result to evaluate the microbiological quality of these products.