RAPID DIAGNOSIS OF HUMAN BRUCELLOSIS BY PERIPHERAL-BLOOD PCR ASSAY

A single-step PCR assay with genus-specific primers for the amplificat ion of a 223-bp region of the sequence encoding a 31-kDa immunogenetic Brucella abortus protein (BCSP31) was used for the rapid diagnosis of human brucellosis, We examined peripheral blood from 47 patients, wit h a total of 50 cases of brucellosis, and a group of 60 control subjec ts, composed of patients with febrile syndromes of several etiologies other than brucellosis, asymptomatic subjects seropositive for Brucell a antibodies, and healthy subjects, Diagnosis of brucellosis was estab lished in 35 cases (70%) by isolation of Brucella in blood culture and in the other 15 cases (30%) by clinical and serological means, The se nsitivity of our PCR assay was 100%, since it correctly identified all 50 cases of brucellosis, regardless of the duration of the disease, t he positivity of the blood culture, or the presence of focal forms, Th e specificity of the test was 98.3%, and the only false-positive resul t was for a patient who had had brucellosis 2 months before and possib ly had a self-limited relapse, In those patients who relapsed, the res ults of our PCR assay were positive for both the initial infection and the relapse, becoming negative once the relapse treatment was complet ed and remaining negative in the follow-up tests at 2, 4, and 6 months , In conclusion, these results suggest that the PCR assay is rapid and easy to perform and highly sensitive and specific, and it may therefo re be considered a useful tool for diagnosis of human brucellosis.