INVITRO ACTIVITY OF DANOFLOXACIN, TYLOSIN AND OXYTETRACYCLINE AGAINSTMYCOPLASMAS OF VETERINARY IMPORTANCE

The activities of danofloxacin, a novel fluoroquinolone, and two other antimicrobials were determined in vitro against field isolates of sev en Mycoplasma species of veterinary importance isolated from cattle, s wine and poultry in five European countries. The minimum inhibitory co ncentrations (mic) of danofloxacin, tylosin and oxytetracycline were d etermined against a total of 68 isolates. Danofloxacin showed excellen t activity against isolates of all Mycoplasma species (range 0-008 to 0.5 mug ml-1), but in some isolates there was evidence of reduced sens itivity to tylosin (range 0.008 to 2.0 mug ml-1) and oxytetracycline ( range 0.008 to over 16.0 mug ml-1). Danofloxacin was more active than other antimicrobials against M hyopneumoniae, M dispar and M bovigenit alium, and showed activity similar to that of tylosin against M bovis and M gallisepticum. Tylosin was the most active against M synoviae an d M hyosynoviae. Generally, oxytetracycline showed the poorest activit y, but was superior to tylosin against M bovigenitalium. A second (fin al) mic reading was taken for all isolates 14 or 21 days after the ini tial reading, and mic values rose during that time. However, the incre ase seen in danofloxacin values (typically one to two dilutions) was l ess than that seen for tylosin and oxytetracycline. It is concluded th at danofloxacin is highly active in vitro against all of the Mycoplasm a species tested, and thus shows great potential for the treatment of respiratory and other infections caused by Mycoplasma species in cattl e, pigs and poultry.