In past years, several <i>Chlamydia</i> -related bacteria have been discovered, including <i>Simkania negevensis</i> , the founding member of the <i>Simkaniaceae</i> family. We evaluated the antimicrobial susceptibility patterns of this emerging intracellular bacterium and highlighted significant differences, compared with related <i>Chlamydiales</i> members. <i>S. negevensis</i> was susceptible to macrolides, clindamycin, cyclines, rifampin, and quinolones. Importantly, unlike other <i>Chlamydiales</i> members, treatment with β-lactams and vancomycin did not induce the formation of aberrant bodies, leading to a completely resistant phenotype.