Isolation and phenotypic characterization of Cronobacter from dried edible macrofungi samples

Cronobacter is a group of food-borne pathogens including 10 species associated with severe infections in infant by consumption of contaminated powdered infant formula. The information about the prevalence of Cronobacter in dried edible macrofungi samples is also not available. In combination with PCR targeting gluB gene, the traditional ISO method was modified for determining the prevalence of Cronobacter in dried edible macrofungi samples. In addition, the antibiotics susceptibility test, biofilm formation, osmotic, and desiccation resistance of Cronobacter strains were also tested. Results indicated that 18 dried edible macrofungi samples (n = 60) were found to be positive for Cronobacter. All isolated Cronobacter strains were resistant to vancomycin and penicillin G, and sensitive to chloramphenicol, norfloxacin, streptomycin, tetracycline, and cephazolin. The abilities to form biofilm and survive when exposed to osmotic and dry stresses were different. This study contributes to a valid method for detection of Cronobacter and phenotypic characterization of Cronobacter, promoting the necessary measures for control and precaution of Cronobacter in dried edible macrofungi samples.

In this study, the traditional ISO method was modified for detecting successfully Cronobacter in dried edible macrofungi samples. Severe contamination rate of Cronobacter (18/60, 30%) in dried edible macrofungi promotes risk analysis and assessment about Cronobacter. In addition, phenotypic characterization of Cronobacter is also helpful for understanding about control and precaution of Cronobacter in dried edible macrofungi samples.