Do Brucella Antibody Titers Correlate with Clinical Outcomes and Culture Positivity of Brucellosis?

Brucellosis is a zoonotic disease caused by Brucella spp., namely B. meletinsis and B. abortus in humans. Studies on the correlation between Brucella antibody titers and clinical outcomes are limited. Therefore, this study assessed such correlation and evaluated the correlation between baseline serologic results with culture positivity and clinical picture. Patients tested positive for Brucella antibodies at baseline and diagnosed with brucellosis between January 2008 and December 2018 were included. Collected data included clinical outcomes, baseline culture positivity, arthralgia, baseline and EOT temperature, white blood cell (WBC) count, C-reactive protein level, and erythrocyte sedimentation rate. Of 695 patients tested for Brucella antibodies, only 94 had positive baseline serology and diagnosed with brucellosis, among whom 63 had EOT serology. No significant correlations were found between EOT antibody titers of both Brucella spp. and clinical cure, mortality, length of stay, and duration of therapy. Additionally, no correlations were found between baseline serology and culture positivity, arthralgia, temperature, and other lab values. Brucella serology does not correlate with clinical outcomes at EOT nor with culture positivity at baseline. Therefore, healthcare providers are advised to consider the whole clinical picture of a brucellosis patient without relying solely on serologic results during follow up and not replace culturing with serology testing alone at the time of diagnosis.