Brucellosis laboratory tests in Syria: what are their diagnostic efficacies in different clinical manifestations?

INTRODUCTION Diagnosis of brucellosis in Syria is based on the presence of compatible symptoms in addition to positive agglutination results. This study investigated the potential of culture, ELISA and real-time PCR to support the diagnosis in different clinical manifestations of brucellosis. METHODOLOGY Peripheral blood samples from 34 suspected brucellosis patients and 42 probable chronic or relapsed brucellosis patients were tested by agglutination tests, culture, ELISA and real-time PCR. RESULTS Among 34 samples collected from suspected cases, 18/34 (53%) were agglutination tests positive, 12/34 (35%) were culture positive, 12/34 (35%) were Brucella IgG positive, and 10/34 (29%) were real-time PCR positive. Three out of 34 patients were positive by real-time PCR but not by agglutination tests or culture. Among 42 samples obtained from probable chronic or relapsed patients, 27/42 (64%) were agglutination tests positive, 26/42 (62%) were Brucella IgG positive, 4/42 (10%) were culture positive, and 1/42 (2%) was real-time PCR positive. CONCLUSION To rule in or rule out the diagnosis of brucellosis, a combination of several tests should be applied. Agglutination tests should be performed first considering their high sensitivity. If the agglutination test is negative, real-time PCR, and/or ELISA, and/or culture should be performed. When relapse or chronic brucellosis are suspected, agglutination tests and/or ELISA are recommended.