Comparison of three blood culture techniques in the diagnosis of human Brucellosis

Background: Isolation of Brucella is the gold standard in the laboratory diagnosis of brucellosis. As Brucella is intracellular and the number of circulating bacteria is usually low, removal/dilution of antibacterial substances, concentration of bacteria and optimal culture conditions may enhance the rate of isolation. Aims and Objectives: The objective of the following study was to compare the lysis concentration (LC), clot culture and conventional Castaneda blood culture techniques for the isolation rate and recovery time in the diagnosis of human brucellosis. Materials and Methods: Blood cultures by LC, clot culture and conventional method were performed in 169 patients who had antibody titers ≥160 international units by the serum agglutination test. Results: Overall blood culture positivity was found to be 24.8%, 43.1% and 34.9% by conventional, LC and clot culture techniques in that order. The mean recovery time by LC and clot culture techniques was significantly less than conventional method, resulting in an overall difference of nearly 6 and 4 days respectively. Conclusions: For the isolation of Brucella from blood, LC and clot culture techniques are better than the conventional technique.