Case of synovitis potentially caused by Dolosigranulum pigrum

We report a case of synovitis in a 64-year-old man who developed the infection while on steroid therapy for rheumatoid arthritis. Dolosigranulum pigrum, a gram-positive catalase-negative coccus, was isolated from two sets of blood cultures prior to antibiotic therapy. The patient was treated with 4 weeks of appropriate antibiotics, and the synovial inflammation resolved. Although synovial aspirates were never positive for any bacteria or fungi, the timing of positive blood cultures and absence of other pathogens suggest the possible etiology as D. pigrum.