摘要
Enterobacteriaceae species have caused foodborne illnesses through consumption of a variety of foods,including infant foods.A total of 915 samples representing 4 types of samples,were collected from 7 powdered infant formula factories in Heilongjiang Province,China.All samples were processed for enumeration of Enterobac-teriaceae and isolation of Cronobacter sakazakii,which were detected using the ISO enrichment procedure and a chromogenic medium.Multi-locus sequence typing(MLST),and pulsed field gel electrophoresis(PFGE)were applied to characterize the C.sakazakii isolates to trace back the original source of contamination.Samples were considered Enterobacteriaceae positive at 10 CFU/g in powdered samples,1 CFU/mL in water samples,and 10 CFU/100 cm^(2) or larger surface area.Enterobacteriaceae positive rate were 0/35 water samples associated with production,11/56 raw materials,147/761 environmental samples and 3/63 finished products respectively.C.sakazakii strains were isolated from 7.0%of environmental samples followed by 1.6%of the finished products.A total of 20 C.sakazakii isolates were recovered in Factory 4,1 strain derived from a final product and 19 strains recovered from the environment representing 4 MLST sequence types and 10 PFGE pulse types.Most environ-mental sites positive for C.sakazakii had higher counts of Enterobacteriaceae,except for 11 sites where Enterobacteriaceae did not reach minimal levels for reporting a positive sample.The present study,provides insight to the correlation between the prevalence of Enterobacteriaceae and contamination of C.sakazakii in powdered infant formula factories;there is no one-to-one relation between number of Enterobacteriaceae and C.sakazakii.Identifying environmental sites positive for C.sakazakii and/or Enterobacteriaceae will aid in development of appropriate corrective measures to improve environmental hygiene and enhance safety of powdered infant formula.
基金
supported by the Natural Science Foundation Project of Heilongjiang Province,China(Joint Guidance Project)
Project title:“Prevalence and exposure risk assessment of pathogenic strains from infant formula processing environments(LH2023C110)".
