Detection of Cronobacter species in powdered infant formula using immunoliposome-based immunomagnetic concentration and separation assay

Cronobacter species are foodborne pathogens that can affect the human central nervous system. Survivors of Cronobacter infections often suffer from severe neurological impairments, including hydrocephalus, quadriplegia, and developmental delays in all ages, especially in infants and the immunocompromised. Moreover, Cronobacter species pose a high risk in powdered infant formula (PIF) because PIF is a major source of nutrition for infants worldwide. To develop a rapid and sensitive detection method for Cronobacter species in PIF, immunoliposomes and immunomagnetic nanoparticles were synthesized, after which an immunoliposome-based immunomagnetic concentration and separation assay was developed and applied to PIF for the detection of Cronobacter species. The detection limits of the developed assay were 5.9 × 103 ± 0.7-4.8 × 104 ± 0.2 CFU/mL for Cronobacter species in pure culture with no cross-reactivity with 13 other tested non-Cronobacter strains. Additionally, the developed assay could provide results in 3 h when the contaminated level was higher than 104 CFU/25 g PIF and in 9 h when the contaminated level was 10 CFU/25 g PIF. The developed immunoliposome-based immunomagnetic concentration and separation assay is rapid, sensitive, and simple and thus has great potential for use in the detection of Cronobacter species in PIF.