Pubic symphysis septic arthritis is a rare condition mainly associated with pregnancy. Fewer than 35 cases have been reported. We report a case that occurred after delivery by caesarean section, and which was due to Cutibacterium acnes. Management involved three lines of antibiotic therapy and surgical debridement. The combination of this rare pathology and a germ often considered commensal led to an erratic diagnosis for almost six years. One of the consequences, in addition to chronic pain, was destabilization of the pelvic girdle, necessitating surgery. After more than 18 months of follow-up, there was no relapse.