A 35-year-old male who had been receiving conservative treatment for L4 isthmic spondylolisthesis suffered from pyogenic spondylodiscitis in the degenerative L4/L5 intervertebral disc space, which could be identified by comparison with previous images. Symptoms improved with conservative antibiotic treatment. Neovascularization may occur in the annulus fibrosus of a degenerative intervertebral disc, which may increase the risk of hematogenous infection, leading to "discitis" even in adults.