Identification and classification of Cronobacter spp. isolated from powdered food in Korea

Cronobacter is a major foodborne pathogen in powdered infant formula and can lead to serious developmental after-effect and death to infants. The contamination of Cronobacter may be a high risk for the powdered foods. To isolate and identify Cronobacter from the powdered foods such as powdered infant formula and Saengsik in Korea, a conventional culture method, rapid identification system, PCR, and 16S rDNA sequencing were performed. As the results of isolation, seven Cronobacter spp. were isolated from seven out of 102 powdered infant formulas and 41 Cronobacter were isolated from 41 out of 86 Saengsiks. Forty-eight Cronobacter isolates were identified to be C. sakazakii and C. dublenisis by 16S rDNA sequence analysis. Most of the isolates were C. sakazakii and 13% of the isolates were C. dublinesis. One fourth of the C. sakazakii isolates showed different biochemical characteristics of negative nitrate reduction and nonmotility activities compared with the other strains reported previously.