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.