Predictive Significance of Laboratory Tests in Bacteremic Brucellosis.

Background: Brucellosis is one of the most common zoonotic infections. Although culture is the gold standard diagnostic method, bacterial growth in blood cultures may not always occur due to various factors. We aimed to investigate demographic, clinical, and laboratory findings that may have predictive significance for bacteremia in brucellosis.

Methods: Patients older than 18 years of age followed up with a diagnosis of brucellosis between 2012 and 2022 were included in this retrospective multicenter study. They were divided into two main subgroups according to their Brucella species reproductive status as bacteremic and non-bacteremic.

Results: A total of 743 patients, 370 (49.80%) bacteremic and 373 (50.20%) non-bacteremic brucellosis patients, were enrolled. The mean age of the bacteremic group (36.74 years) was lower than the non-bacteremic group (43.18 yr). High fever, chills/cold, sweating, nausea, vomiting, and weight loss were more common in the bacteremic group. In the bacteremic group, white blood cell count, platelet count, hemoglobin level, mean platelet volume, eosinophil, and neutrophil counts were lower, and lymphocyte, erythrocyte sedimentation rate, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and ferritin levels were higher. According to the receiver operating characteristic (ROC) analysis, when the cut-off value of ferritin was considered 67, it was the parameter with the strongest predictive significance in Brucella bacteremia.

Conclusion: High ferritin level, low eosinophil count, and increased erythrocyte sedimentation rate were determined as the most critical laboratory findings in predicting bacteremia in brucellosis.