Case of synovitis potentially caused by Dolosigranulum pigrum

We report a case of synovitis in a 64-year-old man who developed the infect ion while on steroid therapy for rheumatoid arthritis. Dolosigranulum pigru m, 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. A lthough synovial aspirates were never positive for any bacteria or fungi, t he timing of positive blood cultures and absence of other pathogens suggest the possible etiology as D. pigrum.