Brucellosis and tuberculosis: clinical overlap and pitfalls

To identify characteristic features of tuberculosis in patients with culture proven brucellosis.

A retrospective analysis was performed on patients diagnosed with culture proven brucellosis between January and December 2011, based on review of their medical records. Patients with demonstrable co-infection with tuberculosis were excluded. Clinical features, laboratory parameters and tissue histopathology reports where available were noted.

Thirty-two patients with brucellosis were included in the study. Twenty-one (65.63%) patients had chronic fever, thirteen (40.63%) had a productive cough, while significant weight loss, evening rise of temperature and night sweats were reported by eight (25.00%), eleven (34.38%) and five (15.63%) patients respectively. Nine (28.13%) patients had at least three of these symptoms. Lymphadenopathy, hepatomegaly and splenomegaly were noted on examination in seven (21.88%), fifteen (46.88%) and twelve (37.50%) patients respectively. Eight (25.00%) patients had hepato-splenomegaly, of these only two had associated significant lymphadenopathy. Respiratory examination was normal in all patients. Elevated ESR greater than 50 mm/hr was seen in eight (25.00%), it was greater than 100 mm/hr in five (15.63%) patients. Hypergammaglobulinemia was seen in eight (25.00%) cases. Bone marrow biopsy showed non-caseating granulomas in three (9.38%) cases, lymph node biopsy showed granulomas in one case. Overall, three (9.38%) patients had known risk factors for tuberculosis, while six (18.75%) had risk factors for brucellosis.

There is a clear overlap between brucellosis and tuberculosis both in terms of clinical presentation and laboratory parameters. It is essential to carefully rule out tuberculosis in all cases of suspected or proven brucellosis before initiating antimicrobial therapy, in order to forestall development of drug-resistant tuberculosis.