A previously healthy 11-year-old boy was admitted to our hospital with a 20-day history of low back soreness and difficulty walking and sitting up. There was no history of trauma, tooth extraction, or spinal surgery, but the patient had reported an episode of fever (39 C) within the previous 3 weeks. On examination, he had no fever, complained of lumbar soreness which was exacerbated by forward flexion of the trunk, and presented paraspinal muscle spasms. The neurological examination was otherwise normal. Laboratory tests revealed a serum WBC count of 9,800 leucocytes/mm3 (normal range is 4,500-13,500 leucocytes/mm3), a CRP (C-reactive protein) level of 35 mg/L (normal < 10 mg/L), and an ESR (erythrocyte sedimentation rate) of 48 mm/h (normal range 0-10 mm/h). Lumbar radiographs did not show any spinal lesions (Figure 1). An MRI (magnetic resonance imaging) scan revealed an abscess in the L3 vertebral body with an adjacent vertebral body hyperintensity indicative of a bone marrow oedema. There was also an extension to the soft tissues, with an intense oedema visible at the level of the right psoas (Figure 2). These findings were suggestive of a vertebral osteomyelitis without infectious intervertebral disc (IVD) damage. Because tuberculosis or a bone tumour could not be definitively ruled out, a surgical navigation-assisted aspiration biopsy of the L3 vertebral body was performed using a posterior transpedicular approach (Figure 3). The patient was stepped down to i.v. Flucloxacillin (1 g three times daily) monotherapy as soon as the aspiration biopsy was realized. Three days after admission, standard blood culture was positive for methicillin-sensitive Staphylococcus aureus (MSSA), and cultures of vertebral bone aspirate yielded growth, thus confirming MSSA as the pathogen. Bacteriological investigations demonstrated that the responsible strain of MSSA was resistant to penicillin G but sensible to all other tested antibiotics (Flucloxacillin, Gentamicin, Ciprofloxacin, Clindamycin, Erythromycin, Cotrimoxazole, Fosfomycin, Rifampicin, Tetracycline, Vancomycin, Teicoplanin, and Linezolid). Imaging studies confirmed that there was no evidence of endocarditis. Three additional sets of postoperative monitoring blood cultures were also positive, continuing up until 8 days after the surgical procedure. A standard X-ray of the lumbar column was carried out 4 days after surgery and revealed a sudden 30% decrease in the height of the disk space, together with erosions of the adjacent vertebral endplates (Figure 4). The patient went on to complete a two-week course of i.v. Flucloxacillin (1 g three times daily), followed by a four-week course of orally administered Clindamycin (30 mg/kg/j). He responded well to antibiotics and body orthosis and showed clinical and laboratory improvement durably after the end of antibiotic treatment. Nevertheless, 2 months after surgery, a new X-ray revealed a considerable progression of the initial lesion which now included the vertebral body of L4 as well as the L3-L4 disk; there had been complete collapse of the disc and major erosion of the upper vertebral endplate of L4 (Figure 5). Nevertheless, the patient no longer reported low back soreness and he was able to move freely.