**5. Conclusions**

Chronic antibiotic administration known to deplete some gram negative bacteria, primarily Bacteroidetes, while expanding the Proteobacteria phylum provided protective benefit from the development of post-traumatic osteoarthritis after joint injury.

**Author Contributions:** Study design: M.E.M. and G.G.L.; Data acquisition: M.E.M., D.K.M., N.R.H., S.A.M., E.A.K., and B.A.C. Data analysis and interpretation: M.E.M., A.S., B.A.C., and G.G.L., M.E.M. and G.G.L. wrote the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** M.E.M: D.K.M, A.S, N.R.H and G.G.L were supported by Lawrence Livermore National Laboratory LDRD grants 20-LW-002 and 16-ERD-007. G.G.L was also supported in part by DOD grant PR180268.

**Acknowledgments:** This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-JRNL-812395.

**Conflicts of Interest:** The authors declare no conflict of interest.
