Proteus organisms are rare causes of osteomyelitis. Vertebral osteomyelitis caused by this organism has only been reported in 21 cases over the last 75 years. Although Staphylococcus aureus is the most common cause of vertebral osteomyelitis, rare causes such as P. mirabilis may need to be considered in the context of recent urinary tract infection or urological surgery. Therefore biopsy should be undertaken to establish the causative organism and determine appropriate antibiotic susceptibility.