Abstract:

Cronobacter isolates including 5 standard strains and 38 isolates from infant foods were studied for
biofil-formating capability and antibiotic sensitivity. The fusA sequence analysis was used to identify the species of these
isolates. Then the isolates were tested for biofilm-forming capability by crystal violet staining. And 11 antibiotics belonging
to 8 categories were selected to test their antibiotic sensitivity. Totally 34 C. sakazakii, seven C. malonaticus and two
C. dublinensis strains were identified. All these isolates were able to form biofilm. C. malonaticus showed stronger
biofilm-forming capability. The resistance to tetracycline and vancomycin was higher. Totally 14 antibiotic resistance
homologies were identified. The resistance to tetracycline correlated with biofilm-forming capability. All the Cronobacter
isolates investigated showed biofilm-forming capability and antibiotic resistance to some extent, which pose a challenge the
disinfection and sterilization methods used in food industries and clinical therapy.

Key words: Cronobacter, identification, biofilm, antibiotic susceptibility