Susceptibilities of Mycoplasma hominis, M-pneumoniae, and Ureaplasma urealyticum to GAR-936, dalfopristin, dirithromycin, evernimicin, gatifloxacin, linezolid, moxifloxacin, quinupristin-dalfopristin, and telithromycin compared to their susceptibilities to reference macrolides, tetracyclines, and quinolones

The susceptibilities of Mycoplasma hominis, Mycoplasma pneumoniae, and Urea plasma urcalyticum to eight new antimicrobial agents were determined by aga r dilution. AL pneumoniae was susceptible to the new glycylcycline GAR-936 at 0.12 mug/ml and evernimicin at 4 mug/ml, but it was resistant to linezol id. It was most susceptible to dirithromycin, quinupristin-dalfopristin, te lithromycin, reference macrolides, and josamycin. M. hominis was susceptibl e to linezolid, evernimicin, and GAR-936. It was resistant to macrolides an d the ketolide telithromycin but susceptible to quinupristin-dalfopristin a nd josamycin. U. urealytictan was susceptible to evernimicin (8 to 16 mug/m l) and resistant to linezolid. It was less susceptible to GAR-936 (4.0 mug/ nil) than to tetracycline (0.5 mug/ml). Telithromycin and quinupristin-dalf opristin were the most active agents against ureaplasmas (0.06 mug/ml). The new quinolone gatifloxacin was active against AL pneumoniae and M. hominis at 0.12 to 0.25 mug/ml and active against ureaplasmas at 1.0 mug/ml. The M ICs of macrolides were markedly affected by pH, with an 8- to 32-fold incre ase in the susceptibility of AL pneumoniae as the pH increased from 6.9 to 7.8. A similar increase in susceptibility with increasing pll was also obse rved with ureaplasmas. Tetracyclines showed a fourfold increase of activity as the pll decreased I U, whereas GAR-936 showed a fourfold decrease in ac tivity with a decrease in pH.