|HOEFFLER, RAEGAN - Iowa State University
Submitted to: The Open Microbiology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2021
Publication Date: 11/17/2021
Citation: Hoeffler, R.S., Kudva, I.T. 2021. EDL933 Strains of Escherichia coli O157 can demonstrate differential adherence to bovine recto-anal junction squamous epithelial cells. Letters in Applied Microbiology. 15(1):129-138. https://doi.org/10.2174/1874285802115010129.
Interpretive Summary: Escherichia coli O157 (O157) strain EDL933 caused a multi-state outbreak through contaminated ground beef in 1982. Since then this O157 strain EDL933 has been used as a standard control in most O157-related experiments in different laboratories. However, bacteria can acquire changes in their genes, over time, that affects ability of bacteria to bind cells or express toxins which in turn can cause variations between experiments. In this study, we sought to determine if the EDL933 strains obtained from three different laboratories would be similar or different in their genetic profile and ability to adhere to epithelial cells. Using standardized assays in our laboratory we found that these EDL933 strains differed between sources and at times from the same source especially in their adherence to bovine epithelial cells. This observation highlights the need to carefully evaluate bacteria even if belonging to the same strain type prior to using in experiments to ensure reproducibility of results.
Technical Abstract: Differences between Escherichia coli O157 (O157) strains is well-established with some of these strains being associated with major outbreaks in the US. EDL933 is one such O157 strain that caused the multistate outbreak in 1982, and has since been used as a prototype in various O157-related experiments. However, as O157 can readily acquire mutations in their genes, we sought to determine if the genetic and phenotypic profiles of EDL933 from across laboratories would remain consistent. Towards this end we evaluated both wild-type and mutant derivatives of the EDL933 obtained from different laboratories in the bovine rectal-anal junction squamous epithelial (RSE) cell- and HEp-2 cell- adherence assays, and by Polymorphic Amplified Typing Sequence (PATS) assay. Our results show that phenotypic (adherence to RSE cells) and genetic (PATS profile) differences can occur between EDL933 from different or even the same source. Hence, a comprehensive characterization of bacterial isolates prior to use in experiments is warranted to ensure reproducibility of results.