Purpose: The selective enrichment broth(CES) for simultaneous growth of Cronobacter sakazakii, Escherichia coli O157:H7, and Salmonella spp. was developed and applied for the detection of pathogens from agricultural produces.
Methods: 120 strains of target and non-target bacteria were inoculated and incubated in CES for 24h to investigate the spectra of bacterial growth in CES. To examine the growth kinetics of each pathogen in CES, three target pathogens were simultaneously cultured in CES in various proportions (1:1:1, 1:10:100). Finally, the performance of CES was examined by PCR assay after enriching pathogen-inoculated produce.
Results: Growth of 74.3% of non-target bacteria were inhibited in CES. In mixed-culture experiments with the three species in equal concentrations or at a 1:10:1,00 ratio, the overall growth was proportional to the initial inoculation levels. CES was able to resuscitate acid- and cold-stressed cells and recovery was comparable to that in non-selective tryptic soy broth. Moreover, target pathogens were efficiently detected by PCR assay after enrichment in CES.
Significance: CES was demonstrated to be a promising new multiplex selective enrichment broth for the detection of the three foodborne pathogens by biochemical or nucleic acid-based methods.