Abstract: Objective To investigate the clinical characteristics of adult Brucella infection with positive blood culture. Methods The clinical data of 67 adult patients with blood culture-positive Brucella infection admitted to our hospital during Jan. 2015 and Jan. 2020 were retrospectively analyzed, and the clinical characteristics were described. According to the antibody titer of Brucella serum agglutination test(SAT)1∶400, the patients were divided into high-titer group(≥1∶400)and low-titer group(<1∶400). The differences in the clinical characteristics were compared between the two groups. Results The acute stage accounted for 86.15% of all patients, 4(5.97%)had no fever symptoms, 56(83.58%)were complicated with liver injury, and 4(5.97%)had negative serological tests. SAT indicated that the high-titer group had more males(62.96% vs 37.04%, P=0.009), and higher lymphocyte ratio ［34.08±11.87 vs 28.45±10.42, 95%CI: 5.64(-11.16-0.12), P=0.045］. There was no statistical difference between the two groups in general information, clinical symptoms, complications, laboratory tests, and positive blood culture time(P>0.05). Conclusion Most adult cases of Brucella infection with positive blood culture are in the acute stage with high risk of liver injury. As a few patients have no fever, or have negative serological test results, blood culture test can reduce missed diagnosis. Compared with the low-titer group, the high-titer group has more males and a higher proportion of lymphocytes.

Key words: Brucella, Bacteremia, Bloodstream infection, Clinical features, Serum agglutination test