Susceptibilities of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum to a New

The susceptibilities of mycoplasmas to a new quinolone, trovafloxacin (CP-99,219), were compared with those to sparfloxacin and ofloxacin. Mycoplasma pneumoniae was as susceptible to trovafloxacin (MIC 5 0.25 mg/ml) as to sparfloxacin and fourfold less susceptible to ofloxacin.Mycoplasma hominis was highly susceptible to trovafloxacin (MIC 5 0.06 mg/ml) and sparfloxacin (MIC 5 0.03 mg/ml) and less susceptible to ofloxacin (MIC5 0.5 mg/ml). Ureaplasma urealyticum was most susceptible to trovafloxacin, with susceptibilities ranging from 0.06 to 0.5 mg/ml compared with 0.25 to 1.0 mg of sparfloxacin per ml and 1 to 4 mg of ofloxacin per ml. The susceptibilities of Mycoplasma pneumoniae and Myco-plasma hominis to quinolones roughly parallel each other and the susceptibilities of gram-positive organisms such as Staphy-lococcus aureus (7). Susceptibilities of Ureaplasma urealyticum show less correlation with those of gram-positive bacteria. A new quinolone, trovafloxacin, 7-(3-azabicyclo[3.1.0]hexyl)naph-thyridone (3), with known high activity against gram-positive organisms (2, 3) was tested for activity against M. hominis, M. pneumoniae, and U. urealyticum in comparison with ofloxacin and sparfloxacin