First described by Kulowski and Vinke in 1932, the involvement of the spine in brucellosis most commonly affects the lumbosacral region while the thoracic and cervical spines are rarely involved. In some cases, the destruction may be extensive involving different regions at the same time especially in those for which the institution of a specific treatment comes too late because of a delay in the diagnosis.

An accompanying proliferative sclerotic reaction to a destructive process involving the articular structures of the vertebral body is the main pathological finding in spinal involvement which slowly develops into ankylosis of the involved area during a long period as months or years [20, 24].

The superior endplate, with its rich blood supply, usually represents the first area to be involved in spinal brucellosis, but infrequently, the inferior endplate may also be affected. The size of the initial inoculum, the virulence of the organism, and the immunity of the host are crucial parameters for the progression of the infection that may either regress to heal completely or progress to involve the entire vertebral body, intervertebral disc space, and then neighbouring vertebrae [28–31].

Spinal brucellosis is frequently caused by B. melitensis, the most virulent and invasive ones among the different Brucella species, but also by B. suis. The extent of spinal damage may be severe. In accord with Madkour and Sharif classification of spinal brucellosis [23], we can classify it as early and advanced stages. In the early form, where the organism is localized in the ventral aspect of a superior cartilage endplate, with a small area of osseous destruction, the disease continues with the formation of an osteophyte called “parrot’s beak”. In the advanced form, the entire vertebral body is involved with a chronic inflammation composed of plasma cells, lymphocytes, histiocytes, and polymorphonuclear cells; at times or randomly or infrequently, granulomatous tissue may develop. As a general rule, there is no necrosis or central caseation [9–11].

Although vertebral involvement in brucellosis can occur at any level, the disease was commonly reported to settle in the lumbar spine, in particular at the level of L4–L5. In only 9 % of all cases, multiple levels are involved.

A constant symptom is pain, relieved by rest, lasting late into the convalescent period and localized to the diseased region of the spine. This stage is usually not identified as brucellosis usually occurring before radiographic findings have appeared. In more than one-half of the cases, a girdle pain radiating into the extremities is present with muscle spasm, restriction of movement, tenderness, and signs of involvement of nerve root. Paravertebral abscess and extradural compression may also occur especially in severe infections [13, 14].

Both cellular and humoral mechanisms work to get immunity following active infection with Brucella spp. The IgM antibodies are the first to increase after the Brucella infection and may persist for several years. Following the progression of the disease, IgM declines and IgG increases, but the IgG level decreases gradually and gets lost within 6–18 months after adequate treatment. By using the 2-mercaptoethanol extracts, determination of IgG is possible without any difficulty and elevated IgG level signifies an active disease process, suggesting the need for medical treatment. It is important to keep in the mind that false-positive reactions can be seen owing to cross-reacting antibodies during certain infections including Yersinia enterocolitica, Salmonella strains, and Francisella tularensis and following cholera vaccine [1, 18, 26].

A small number of organisms make the microscopic diagnosis harder in specimens obtained by biopsy or surgical intervention and they can therefore be identified by culture. Regarding the blood culture in many cases, the test may fail. The causes can be the no-bacteremic state and the prolonged time required by the test (up to 6 weeks) to become positive. The use of antibiotics before the confirmation of the diagnosis is an important topic in the case of negative Brucella culture result. Also, patients with spinal brucellosis have a positive blood culture less frequently than patients with systemic brucellosis [16, 17].

Radiologic imaging has a critical role in the evaluation of these lesions to provide information about the disease process, to guide biopsy procedure with/without drainage, and to guide the selection of appropriate treatment method, medical and/or surgical, and the monitoring of treatment response [34]. Magnetic resonance imaging (MRI) with gadolinium enhancement has become the gold standard approach for assessing the neural structures with high-resolution images [12]. Also, radiographs of the spine and computed tomography (CT) may provide some information. From these, CT imaging is useful in making image-guided biopsies of the vertebral body or aspiration of the paravertebral abscesses, although it is less sensitive than MRI. In particular, CT scan is invaluable in the differential diagnosis of Brucella involving the spine from other spinal diseases [8].

Tuberculosis of the spine, pyogenic osteomyelitis due to other bacteria, herniated disc, and metastatic lesion have to be considered in the differential diagnosis. While in tuberculosis the changes appear relatively early and in osteoporosis the changes are more marked and the destruction more severe, in the healing stage of brucellosis, the proliferative changes are not seen in tuberculosis. Paravertebral abscesses and vertebral collapses are more common in tuberculosis. In a pyogenic infection due to other bacteria, the onset is usually more rapid and the disease is more acute with early destruction of the bone. A herniated disc does not show the severe bone destruction observed in untreated brucellosis. Metastatic deposits do not usually involve two neighbouring vertebral bodies and the intervening intervertebral disc is usually spared [32, 36, 38, 40–42].