Negative serology: could exclude the diagnosis of brucellosis?

Two cases of brucellar spondylodiscitis of the lumbar area were presented. Although both cases showed typical radiological changes, serological tests could not detect Brucella agglutinating antibodies. One of the patients was bacteremic and Brucella spp. was identified from blood culture. In the second patient needle biopsy was required for definite diagnosis. Although small, serologic tests have a certain rate of false negative results in brucellosis. Thus, a negative serology should not exclude the diagnosis of brucellosis, as it is demonstrated in the current cases.