The choice of antibiotics should be based on culture sensitivity testing. However, there is a subset of patients, reported to be 10% to 30% of all cases, who do not grow any organism
1). Typical spondylodiscitis is characterized by the involvement of a mobile segment, that is, 2 adjacent vertebrae and the intervening disk with destruction of endplates. Multifocal involvement of mobile segments despite continuous intravenous antibiotics, like that observed in our patient, has seldom been reported. No guideline has been issued regarding optimal antibiotic therapy in patients with microbiologically negative spondylodiscitis, and thus, it is suggested that empirical antibiotics (with staphylococcal cover) should be commenced intravenously. Patients usually require a minimum of 6 to 8 weeks of intravenous antibiotic therapy, and the majority of patients with a pyogenic spinal infection are managed successfully with antibiotic therapy based on culture and sensitivity results. Gillard et al.
4) proposed several explanations why discitis patients are sometimes culture negative. They insisted that false-negative biopsy results are influenced by inadequate specimen size. Although it still remains unclear whether open surgical biopsy is superior to percutaneous needle biopsy, open surgical biopsy provides larger specimens for microbiological and histologic studies, and thus, increase the likelihood of detecting an organism. Our patient was a 64-year-old man, whose MRI findings were, extended, skipped level increased signal intensity with contrast enhancement, indicated involvements of L1/L2 and of L4/L5, but microbiological tests, which included open surgical biopsy and histologic tests, were negative. MRI is the single most useful radiologic modality for investigating pyogenic spinal infections, and it is highly sensitive, specific, and accurate (96%, 94%, and 92%, respectively)
3). Accordingly, it is currently the investigation tool of choice for the management of spinal infections. Moreover, if the infective parameters remain persistently elevated with intravenous antibiotics, repeat studies including MRI should be considered to find relapse or newly developed spondylitis. Surgical intervention is warranted under a few specific circumstances. These include the development of neurologic signs, spinal instability, vertebral collapse, progressive spinal deformity, an abscess not responding to antibiotics, and failed radiologically guided biopsy necessitating open surgical biopsy
7). The goals of surgical intervention are to detect an organism, to preserve neurologic function, and to facilitate stable bony fusion without severe kyphosis.