Abstract: In this report,in vitro antibacterial activities of 6 antimicrobial agents against 30 strains of Urea plasma urealyticum (Un),30 strains of Mycoplasma hominis (Mh)were determined using agar dilution method.The results indicated that acetylspiramycin,norfloxacin and doxycycline are highly active against Uu and Mh.Acetylspiramycin is active against Uu,MIC₅₀ 0.25mg/L,and MIC₉₀ 1mg/L,against Mh,MIC₅₀ 0.5mg/L and MIC₉₀ 1mg/L.Norfloxacin is equally active against Un and Mh,MICS,0.5mg/L and MIC₅₀ 1mg/L.Doxycycline is active against Uu and Mh,for Un MIC₅₀ is 0.5mg/L and MIC₉₀ 1mg/L,and for Mh MIC₅₀ is 0.25 and MIC₉₀ 2mg/L.Mh is resistant to erythromycin (MIC₅₀ 60mg/L and MIC₉₀ 128mg/L).Six strains of Un and 4 strains of Mh are highly resistant to tetracycline (MIC₅₀ 64 to 128mg/L and MIC₉₀ 16 to 32mg/L)and yet still sensitive to the other antimicrobial agents.Berberine is equally active against Uu and Mh (MIC₅₀ 4mg/L and MIC₉₀,8mg/L) and is effective for the tetracycline resistant strains of Uu and Mh.

Key words: Ureaplasma urealyticum, Mycoplasma hominis, Antibiotics