In Vitro Susceptibility of Ureaplasma urealyticum and Mycoplasma hominis Isolates in Argentina

Objective: Our goal was to determine the in vitro susceptibility of Ureaplasma urealyticum and Mycoplasma hominis isolates to several antibiotics in Argentina. Methods: Ninety-four strains of U. urealyticum and 18 strains of M. hominis isolated from cervical and urethral specimens were studied. Broth microdilution and agar dilution tests for minocycline, tetracycline, erythromycin, ciprofloxacin, and ofloxacin were performed. Results: Both methods proved to be reliable and reproducible for U. urealyticum and M. hominis, with no major differences in results. The U. urealyticurn strains were inhibited by erythromycin at MICs ranging from ≤0.5 to >8 μ/ml. Ofloxacin showed the highest activity against this latter organism. No differences between tetracycline and minocycline MICs were observed with U. urealyticum. Two M. hominis strains displaying high MICs both to tetracycline and to minocycline were detected. Conclusions: The emerging resistance of mycoplasmas to certain antibiotics emphasizes the need to undertake further surveillance studies on the clinical isolates of such organisms.