Risk factors, outcomes and time to detect positive blood culture among cases with acute brucellosis

BACKGROUND: Brucellosis causes a disabling human disease and loss of animals' lives. The clinical significance of Brucella bacteremia is still unclear and Brucella identification in blood culture is suboptimal. METHODS: This was a retrospective study conducted in Medina in Saudi Arabia from August 2016 to May 2019. We included cases with brucellosis symptoms and a positive culture or serological evidence for brucellosis, comparing bacteremic with non-bacteremic brucellosis cases for the rates of complications, infection relapses and brucellosis development. Also, we estimated blood culture positivity rates and the time to detect Brucella in an automatic blood culture instrument. RESULTS: Of the total number of 147 cases, 62 (42%) had a positive blood culture for Brucella, and the blood culture instrument (BACT/ALERT 3D) detected all positive blood cultures within 3 d of incubation. We found higher rates of chronic brucellosis in bacteremia than non-bacteremia cases (OR 7.25, 95% CI 1.41 to 37.23; p=0.018). Patients aged <15 y developed a higher rate of bacteremia than those aged ≥15 yr (OR 11.93 95% CI 1.37 to 103.75; p=0.025). CONCLUSION: Brucella bacteremia is an independent predictor for the development of chronic infection. Brucella bacteremia cases may need long follow-up periods and a more thorough evaluation to exclude deep-seated infection.