Molecular and Genetic Characterization of Colicinogenic Escherichia coli Strains Active against Shiga Toxin-Producing Escherichia coli O157:H7

The objective of this work was to molecularly and genotypically characterize and test the inhibitory activity of six colicinogenic Escherichia coli strains (ColEc) and their partially purified colicins against STEC O157:H7 isolated from clinical human cases. Inhibition tests demonstrated the activity of these strains and their colicins against STEC O157:H7. By PCR it was possible to detect colicins Ia, E7, and B and microcins M, H47, C7, and J25. By genome sequencing of two selected ColEc strains, it was possible to identify additional colicins such as E1 and Ib. No genes coding for stx1 and stx2 were detected after analyzing the genome sequence. The inhibitory activity of ColEc against STEC O157:H7 used as an indicator showed that colicins are potent growth inhibitors of E. coli O157:H7, being a potential alternative to reduce the presence of pathogens of public health relevance.

Automated summary

The objective of this study was to characterize six colicinogenic Escherichia coli strains and test their inhibitory activity against STEC O157:H7. The results showed that these strains and their colicins have inhibitory activity against STEC O157:H7. PCR and genome sequencing identified various colicins and microcins in these strains, and no genes coding for stx1 and stx2 were detected. The results suggest that colicins could be a potential alternative for reducing the presence of STEC O157:H7.