Therapeutic effect of spiramycin in brucellosis

This study was undertaken to investigate the usefulness of spiramycin in treatment for brucellosis in an animal model.

Eighty-four Sprague-Dawley rats were infected by intraperitoneal injection of Brucella melitensis suspension. Seven days after inoculation, four rats were selected randomly, killed and spleen cultures and Brucella standard tube agglutination test were carried out. All four rats were found to be infected. Eighty adult rats were randomly divided into four groups of 20 rats each. Tap water was given to the first group. Rifampicin 50 mg/kg per day and doxycycline 40 mg/kg per day were given to the second group, spiramycin 50 mg/kg per day orally was given to the third group, and a combination of spiramycin and rifampicin at the same dose and period was given to the fourth group. Duration of therapy regimens in all groups was 21 days. The spleens of all 80 rats were removed aseptically, homogenized, and placed onto Brucella agar plates to determine if viable bacteria were present.

Bacterial growth occurred in all of the rats' spleens in the first group and in two rats' spleens in the spiramycin group. Mean colony forming unit (c.f.u.) values were at the highest in the first group. The effectivities of spiramycin and rifampicin-spiramycin were similar to rifampicin-doxycycline. There were no differences in the treatment results between the three groups that received combined rifampicin-doxycycline, rifampicin-spiramycin and only spiramycin (P>0.05).

The results show that spiramycin cures experimental rat brucellosis and may be an effective alternative in the therapy of human brucellosis.