Propionibacterium acnes was previously considered a contaminant and its role in spine infection has been understated. Although rare, such infections are present especially after instrumented spine surgery. They are usually delayed and hard to diagnose. Delayed infection should be suspected in patients with pain and a history of spine surgery. In this article, we review the diagnostic challenges associated with delayed P. acnes infection after spine surgery, guided by relevant studies in the literature. The medical databases of PubMed, Medline and Embase were searched for the literature on delayed spine infections and osteomyelitis following spinal procedures. The medical literature was reviewed for articles published between 1955 and 2008. Our review of the literature revealed 13 cases of P. acnes osteomyelitis following surgical procedures involving the spine. We also present a clinical case of delayed P. acnes osteomyelitis following discectomy and fusion with instrumentation.