Biofilm formation and genetic characterization of New Zealand Cronobacter isolates

The study aimed to determine genetic diversity of a collection of New Zealand Cronobacter isolates collected from different sources and their ability to form a biofilm on different materials under different conditions. Isolates were screened for the presence of biofilm associated genes. Furthermore, suppression subtractive hybridization (SSH) was used to identify unique genes, present in a C. sakazakii strain (isolate ES191) which forms a stronger biofilm than the reference strain C. sakazakii BAA894. Results indicated that New Zealand Cronobacter spp. strains were genetically diverse. Biofilm formation was both temperature and nutrient dependent and varied widely within and between clinical, dairy, and environmental isolates. Moreover, C. akazakii adhered more to polyvinyl chloride followed by silicone, polyurethane and stainless steel and all the isolates harboured biofilm related genes. Of the 72 PCR products sequenced from the SSH library, 16 unique gene sequences were identified, of which nine were expressed only in ES191 and were found to be involved in hypothetical protein, energy production, and virulence. This study suggests the choice of enteral neonatal feeding tube material could dramatically influence the attachment, growth, and biofilm formation of C. sakazakii.