Purpose: An independent study was conducted to validate this new method in comparison to the ISO/TS 22964 standard, as part of the NF Validation approval process and according to the ISO 16140-2 standard.
Methods: The alternative method includes single step enrichment in BPW for 16 h to 20 h at 37°C for infant formula, and in BPW supplemented with vancomycin for 18 h to 22 h at 37°C for environmental samples. After DNA extraction, PCR is run in the Thermo Scientific PikoReal Real-Time instrument.
Results: 64 infant formula samples with and without probiotics, and 64 environmental samples, were analyzed in a relative trueness study. The relative detection levels were determined in infant formula, infant formula with probiotics and process water. The results demonstrate equivalent performance between the alternative method and the ISO/TS 22964 method. The inclusivity and the exclusivity of the alternative method were assessed with 50 target and 30 non target strains. The alternative method was also evaluated in a ring trial involving 11 laboratories. The results of the calculated acceptability limits clearly show that the alternative method precision is equivalent to the ISO ISO/TS 22964 standard.
Significance: The Thermo Scientific SureTect Cronobacter Real-Time PCR Assay Kit is a reliable method for Cronobacter spp detection in infant formula with and without probiotics, as well as environmental samples, and offers important economic savings by reducing time to result and handling time.