Comparison of bacteraemic & non-bacteraemic brucellosis: A retrospective analysis of 2 years

Background & objectives Brucellosis is a zoonotic infectious disease that affects both humans and animals, with diagnosis traditionally confirmed by bacteriological culture of blood or tissue samples. This study aimed to identify clinical, epidemiological, and laboratory parameters that predict culture positivity in brucellosis cases. Methods We conducted a retrospective, single-centre study including 130 patients with brucellosis diagnosed between January 2023 and December 2024. Patients were classified as bacteraemic (n=60) and non-bacteraemic (n=70). Demographic characteristics, clinical features, laboratory parameters, and treatment outcomes were compared between the two groups. Results Patients with bacteraemia had higher rates of summer admissions, more frequent exposure to animal husbandry, and shorter symptom duration. Clinical manifestations such as back pain, headache, weight loss, and abdominal pain were more common in them. Laboratory findings showed lower leukocyte and, neutrophil counts, lower haemoglobin, lower platelet counts, in bacteraemic patients. Erythrocyte sedimentation rate, C-reactive protein, alanine aminotransferase, and aspartate aminotransferase levels were significantly higher in bacteraemic vs non-bacteraemic patients. Receiver operating characteristic analysis indicated that AST had the highest diagnostic accuracy (AUC: 0.841, 95% CI: 0.758-0.924), with an optimal cut-off of 27.3 U/L, yielding 67.2 per cent sensitivity and 84.1 per cent specificity. Binary logistic regression analysis demonstrated that exposure history (OR=5.5), residence in a high-incidence geographic location (OR=10.0), and clinical features such as back pain (OR = 9.4), together with low haemoglobin and elevated AST levels, were independent predictors of blood culture positivity in brucellosis. Interpretation & conclusions It may be possible to predict bacteraemia in brucellosis by using a combination of epidemiology, clinical, and laboratory criteria.