Objectives: To describe the clinical, serological, and prognostic features of bacteraemic brucellosis in an endemic region.

Methods: Retrospective case series of 160 patients admitted from 1983 to 1995 to a hospital providing secondary and tertiary level medical care in Saudi Arabia. All patients had positive blood cultures forBrucella species , predominantly Brucella melitensis.

Results: Bacteraemia was documented in 38% of 545 cases of brucellosis admitted to our institution during the study period. The main clinical syndromes were febrile illness alone (44%) or fever with arthritis (42%). Of 68 isolates that were speciated, 93% wereBrucella melitensis . Initial agglutinating antibody titre was ≥ 1:320 in 96% of the patients. Antimicrobial resistance of B.melitensis isolates was: co-trimoxazole, 29%; rifampicin, 3.5%; streptomycin, 0.6%; and tetracycline, 0.6%. No increase in resistance was noted over the 13-year study period. Commonly used antimicrobial regimens consisted of streptomycin plus tetracycline or rifampicin plus doxycycline given for 6 weeks. Seven patients (5%) had relapse of their symptoms after antimicrobial therapy. Three of these had infective endocarditis with repeated bacteraemia. These patients required aortic valve replacement and recovered after surgery. The remaining four patients responded to a second course of therapy.

Conclusions: Brucella bacteraemia is an acute febrile disease often associated with rheumatologic complaints. Most patients have an agglutinating antibody titre ≥1:320 and respond well to standard chemotherapy regimens with low mortality.