Effects of new quinolones on Mycoplasma pneumoniae-infected hamsters

The efficacies of the new quinolones temafloxacin, ofloxacin, and ciprofloxacin were investigated against Mycoplasma pneumoniae in an experimental hamster pneumonia model. Hamsters were infected intratracheally with M. pneumoniae and sacrificed 18 h after the final medication, and their lungs were aseptically removed, homogenized, and cultured quantitatively. The efficacies of these drugs were determined by the CFU of M. pneumoniae in lungs. Temafloxacin and ofloxacin, but not ciprofloxacin, were active when the oral administration of 200 mg/kg of body weight per day (once per day) for 5 days was initiated 24 h after infection. Although no effect on the elimination of M. pneumoniae was observed after the administration of these drugs at 200 mg/kg/day at 5 days after infection, the continuous administration for 15 days of temafloxacin, but not ofloxacin or ciprofloxacin, significantly reduced viable M. pneumoniae in the lungs. These results suggest that temafloxacin and ofloxacin are effective in the acute phase of infection and, moreover, that temafloxacin is effective in the late stage of infection during which progressive lung alterations and continuous increases in mycoplasmal growth occurred. The peak levels of temafloxacin in sera and lungs after oral administration were similar to those of ofloxacin and higher than those of ciprofloxacin. The areas under the curve of temafloxacin in the lung tissue, however, were higher than those of ofloxacin and ciprofloxacin. On the basis of these results, temafloxacin and ofloxacin might be promising antimicrobial agents for the treatment of mycoplasmal infection.