**5. Conclusions**

Our findings indicate that *N. sativa* had a bactericidal effect against XDR methicillinresistant *Staphylococcus aureus*, even at low concentration. NS synergistically improved the efficacy of β-lactam antibiotics to which, ab initio, they had been resistant. The study also showed, by SEM and TEM molecular analysis, that NS used bacterial cell wall disruption as a possible mechanism of action. This appeared to have improved the binding of β-lactam antibiotics to PBP, as evident in the destruction of the MRSA cell wall and lysis shown in TEM micrographs. However, further studies will be needed to evaluate in detail the nature of this binding and to what type of membrane protein in rapidly emerging resistant bacterial strains.

**Author Contributions:** Conceptualization, methodology, formal analysis, and writing—original draft preparation, L.I.B.-E. and P.M.E.; software, P.M.E. and H.I.M.I.; validation, investigation, resources, data curation, and writing—review and editing, L.I.B.-E., P.M.E. and H.I.M.I.; funding acquisition, L.I.B.-E. All authors have read and agreed to the published version of the manuscript.

**Funding:** The Deanship of Scientific Research, King Faisal University (grant No. 186388) funded the research under Nasher Track.

**Institutional Review Board Statement:** Not required as isolates were routine diagnostic specimen.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data is contained within the article and correspondence author can be contacted for more information.

**Acknowledgments:** The authors acknowledge the Deanship of Scientific Research, King Faisal University for the financial support. The authors would like to thank Maged El-Sayed Mohamed, Hani Al-Rasasi, Hajer Salman Al-Dehailan, Fatimah Mohammed Alquaimy, and Fatimah Ahmad AlJaafari for their technical assistance.

**Conflicts of Interest:** The authors declare no conflict of interest with respect to the research, authorship nor in the article publication.
