COMPARATIVE ACTIVITY OF AZITHROMYCIN AND DOXYCYCLINE AGAINST BRUCELLASPP INFECTION IN MICE

The activities of a short therapeutic regimen with azithromycin and th e classic treatment doxycycline with streptomycin were compared and ev aluated in mice infected with Brucella melitensis. In a chronic model, starting therapy 31 days after challenge, azithromycin (10 days, 50 m g/kg/day) significantly reduced the infection (2.9 logs, day 48 post-i nfection). The effectiveness of doxycycline (21 days, 50 mg/kg/l2 hour ly) was greater than azithromycin (4.1 logs of reduction, day 48 post- infection), and when doxycycline was administered for a period of 45 d ays, all the animals were bacteriologically cured from day 78. The com bination with streptomycin (14 days, 10 mg/kg/day) did not improve the effect of any of the regimens. In an acute model infection, treatment s with doxycycline or doxycycline-streptomycin, for a period of 3 days , starting 1 day after lethal challenge, were able to protect all the mice. In contrast, only 50% of the mice treated with azithromycin surv ived the challenge. In conclusion, although a short oral treatment wit h azithromycin was able to reduce the infection significantly, it was not able to cure the animals as effectively as the classic regimen wit h doxycycline administered for a longer period of time.