The manuscript by Titz and Hirsch describe their efforts to design dual inhibitors of virulence factors LecA and LasB against P. aeruginosa. This is an important topic, and new therapies are greatly needed to address this pathogen. As articulated by the authors, they leveraged two existing inhibitors to serve as starting points for the creation of their chimeric compound. Further, they speculate that this molecule would then dimerize inside the bacterial cell (validated) and serve as a divalent inhibitor (maybe) increasing its potency. The manuscript also includes their synthetic efforts toward making these compounds, biological testing, and crystallography. Aside from some minor concerns about compound purity of the enantiopure molecules (13-25) which all lack optical rotations and spectral data (not solely the tabulated peaks), the results appear to be consistent and reliable. This reviewer is not convinced that LecA inhibitory activity is benefiting from the dimeric compound formation as one would expect. The authors show this dimerization can take place in PA, however, that does not necessarily mean it’s the active form that binds to the target. One would likely expect a more significant increase in activity than what is seen but this is a minor point.

After reviewing the revised manuscript and previous reviews, I also find myself revisiting the Chemical Science guidance for reviewers, particularly the point that states “Note that routine or incremental work should not be recommended for publication”. Given that the most significant findings here, which are quite strongly stated in the manuscript (authors state: “Quite remarkably, our dual inhibitors displayed improved inhibitory activity and affinity for both targets down to 220 nM for LasB and 18 μM for LecA, compared to the individual predecessors of 400 nM and 53 μM, respectively.”), are only a 2-fold and 3-fold improvement of activity over previously published molecules, I would agree with Reviewer 1 and find these findings are incremental. Again, this should not take away from the authors’ work at all, but the venue of Chemical Science does not seem appropriate for the work presented, and a better venue would be RSC Medicinal Chemistry or ChemMedChem given the scope and impact.