PREreview of The RND efflux pump EefABC is highly conserved within lineages ofE. colicommonly associated with infection

1. Have the authors performed any validation experiments, for example, complementation tests, PCR or sequencing to confirm the deletions that have been made through cloning?

2. Was there any phenotypic change observed based on deletions? For example- any difference in bacterial growth or survival.

3. Deletion of the genes within the operons was made completely or partially.

4. Since this study provides descriptive data, it is difficult to conclude what type of activity these novel pumps are involved in. However, that can be an altogether different study, but, RNA-seq experiments could be performed to shed light on that aspect. Further validation and concluding experiments following RNA-seq could be performed in a separate paper. This is just a suggestion and does not harm our review of this paper.

5. For the experiment to study EtBr export in which the activity of EefABC expressing cells was observed only in the absence of AcrB needs more detailing in the methods and results section. Could other components or types of efflux pump presence affect EefABC activity? Please mention the appropriate controls used in this experiment more clearly.

6. Why two different standard methods CLSI and EUCAST were used for MIC, and not only one of them?

7. Missing supplementary data.

Decision: Accept the paper with minor revisions.

Competing interests

The authors declare that they have no competing interests.