Modern chemotherapy for brucellosis in humans.

The most effective, least toxic chemotherapy for human brucellosis is still undecided. In vitro, the antibiotics most active against Brucella include the tetracyclines, the aminoglycosides, the aminopenicillins, some cephalosporins, trimethoprim-sulfamethoxazole, erythromycin, rifampin, and some new fluorinated quinolones. Because Brucella species are facultative intracellular parasites, the penetration of drugs into and within phagocytes and phagosomes can be problematic and can best be studied in experimental animals or tissue cultures. In humans, the effectiveness of various regimens of chemotherapy has been compared best in acute bacteremic infections by assessment of the control of symptoms, bacteremia, complications, and relapses. The standard therapy against which all other therapies have been judged is a combination of tetracycline and streptomycin, which is almost universally effective but fails to prevent relapse in 10% of cases. A combination of oral doxycycline and rifampin is convenient and currently popular; it is highly effective, with an average relapse rate of only 8.4%. Trimethoprim-sulfamethoxazole is less effective in controlling bacteremia and other manifestations: in collected series, 5.7% of cases did not respond and 12% relapsed. Drug-resistant Brucella strains are rarely a cause of therapy failure. Localized brucellosis poses special problems, often requiring surgery in addition to prolonged combined chemotherapy.