Evaluation of Whole Genome Mapping as a Fast and Automated Molecular Epidemiological Tool for the Study of Cronobacter spp. in Powdered Infant Formula Processing Facilities

Cronobacter has been identified as the causative agent of outbreaks or sporadic cases of meningitis, necrotizing enterocolitis, and septicemia associated with powdered infant formula. Food processing environments may provide a possible contamination route. The purpose of this study was to evaluate whole genome mapping (WGM) as a fast and automated molecular epidemiological method for characterizing Cronobacter spp. in the processing environment. This is the first study indicating the applicability of WGM to Cronobacter. WGM was compared with ribotyping, which is often used as an automated typing tool, and with pulsed-field gel electrophoresis, which is a well-known and highly discriminating tool that is also based on restriction site analysis. The comparison of the three tools was carried out on a subset of Cronobacter isolates collected from 2011 to 2014 through a monitoring program. The performance characteristics of WGM have not yet been described; therefore, in the current study its performance was evaluated based on five criteria: typeability, reproducibility, stability, epidemiological concordance, and the discrimination power. WGM was shown to produce typeable, reproducible, and stable results. With a similar cut-off of 98%, WGM was shown to have a discriminatory power equivalent to pulsed-field gel electrophoresis and higher than ribotyping. Future studies are needed to confirm the indicated cut-off level of 98%.