Antimycoplasmal activities of (S)-(-)-9-fluoro-2,3-dihydro-3-methyl-10 -[4-(2-pyridyl)-1-piperazinyl]-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine -6-carboxylic acid (YH-6) in comparison with other antibiotics in vitro.
OBJECTIVE
To determine the susceptibilities of Mycoplasma and Ureaplasma to (S)-(-)-9-fluoro-2,3-dihydro-3-methyl-10 -[4-(2-pyridyl)-1-piperazinyl]-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine -6-carboxylic acid (YH-6) and to compare it with those referential quinolones, macrolides, and tetracyclines.


METHODS
The minimum inhibitory concentration (MIC) were determined by microdilution method in vitro.


RESULTS
The MIC of YH-6 for Ureaplasma urealyticum (Uu: 250 micrograms.L-1), Mycoplasma hominis (Mh: 500 micrograms.L-1), M orale (Mo: 125 micrograms.L-1) and M salivarium (Ms: 125 micrograms.L-1) were closely similar to those of macrolides (erythromycin and leucomycin) and were 2-8 folds greater than those of ofloxacin (Ofl). Uu and Mh easily induced resistance to erythromycin and tetracycline. They did not easily form resistance to quinolone (YH-6, Ofl), josamycin and tylosin. Tetracycline-resistance (Tcr) or erythromycin-resistance (EMr) strains of Uu (or Mh) had cross-resistance to erythromycin or tetracycline. However, they had no cross-resistance to quinolone, josamycin and tylosin.


CONCLUSIONS
YH-6 was a highly active quinolone against Mycoplasma, but could hardly induce resistance to Uu. EMr- or Tcr- strains of Uu (or Mh) had no cross-resistance to YH-6.
Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 200032, China.
H
H
Ye
J M
JM
Wu
Y S
YS
Yang
R Y
RY
Ji
K X
KX
Chen
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004917:Erythromycin / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009174:Mycoplasma / Q000187:drug effects*; D010078:Oxazines / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D013752:Tetracycline / Q000494:pharmacology; D014509:Ureaplasma / Q000187:drug effects*
C421367:9-fluoro-2,3-dihydro-3-methyl-10-(4-(2-pyridyl)-1-piperazinyl)-7-oxo-7H-pyrido(1,2,3-de)(1,4)benzoxazine -6-carboxylic acid; D000900:Anti-Bacterial Agents; D010078:Oxazines; D010879:Piperazines; D004917:Erythromycin; D013752:Tetracycline