Background: Toxin-antitoxin systems (TAs) are two-component elements, which are
extensive in the bacterial genome and have a regulatory role in many cellular activities including,
growth arrest, survival, biofilm formation, and bacterial persistence.
Objective: TAs have not well studied in Brucella spp.
Methods: We evaluated the presence of different toxin-antitoxin systems, including relE- rhhlike,
Fic- Phd, Cog- Rhh, and cogT- cogAT in 40 clinical Brucella melitensis isolates using PCRbased
Results: Our results showed the high presence of relE-rhh-like, Fic-Phd, Cog-rhh, and cogTcogAT
s TAs genes in B. melitensis isolates that were 96.25%, 92.5%, 96.25%, and 95%, respectively.
Conclusion: A high presence of TAs genes in clinical B. melitensis isolates revealed that the TA
system could be an antibacterial target in B. melitensis but more investigation is necessitated to
elucidate the exact roles of these genes.