Evaluation of a Revised U.S. Food and Drug Administration Method for the Detection of Cronobacter in Powdered Infant Formula: A Collaborative Study

A revised U.S. Food and Drug Administration (FDA) method for the isolation and detection of Cronobacter from powdered infant formula was recently developed, which combines real-time PCR, chromogenic agars, and RAPID ID 32E biochemical tests. This method provides an expedient analysis within 24 to 48 h. A collaborative validation study involving four different laboratories was conducted to compare the revised FDA method with the reference FDA method using casein- and soy-based powdered infant formula inoculated with different Cronobacter strains. Valid results from 216 test portions and controls from collaborating laboratories were obtained and showed that the revised FDA method performed significantly better than the reference FDA method. Newly revised PCR protocols and VITEK 2 were also evaluated to be integrated into the complete detection procedure.