[Evaluation of Serum LL-37 Levels in Patients with Brucellosis and Their Relationship with Clinical Course]

This study aimed to determine the serum levels of the LL-37 molecule, associated with the pathophysiology of Brucellosis, in patients diagnosed with Brucellosis and to investigate the relationship between these levels and the clinical course of the disease. The study included 45 acute, 30 subacute, 26 chronic and 19 relapsed patients diagnosed according to clinical, bacteriological and serologic results as Brucellosis, as well as 60 healthy volunteers. Serum LL-37 levels were measured using the enzyme-linked immunosorbent assay method and the results were compared with the clinical data of the patients. Serum LL-37 levels were significantly higher in Brucellosis patients compared to the control group, with variations observed among clinical subgroups. A weak positive correlation was found between serum LL-37 levels and alanine transaminase, C-reactive protein and erythrocyte sedimentation rate values in patients with Brucellosis. Serum LL-37 levels were higher in patients with Brucella spp. growth in blood cultures compared to those without growth. Additionally, patients with complicated Brucellosis involving osteoarticular involvement had significantly higher serum LL-37 levels than those without such complications. Serum LL-37 levels with a cut-off value of 18.26 ng/mL demonstrated a sensitivity of 92% and a specificity of 88% in distinguishing Brucellosis cases from healthy individuals, with a positive predictive value of 82% and a negative predictive value of 91% (area under curve= 0.956, p< 0.001, 95% confidence interval= 0.93-0.98, negative likelihood ratio= 0.09, positive likelihood ratio= 7.66). No previous studies on serum LL-37 levels in Brucellosis were found in the literature. LL-37 appears to have potential as a biomarker for the diagnosis and prognosis of Brucellosis.