First case of prosthetic knee infection with Granulicatella adiacens in the United States

A 64 year old white male patient was referred to our infectious disease office with persistent and worsening left knee swelling for the past year. Seven years ago he underwent left total knee arthroplasty. Seven months ago he underwent root canal procedure on his left lower molars. He was not on any antimicrobial prophylaxis for this procedure. Few days after the procedure he noticed that the left knee was swollen without pain or fever. Joint swelling was slightly restricting his movements, otherwise he was totally asymptomatic. Swelling worsened day by day. Finally he saw the orthopedic surgeon who had performed his total knee arthroplasty. Knee joint was tapped in the office. The Synovial fluid was clear. Fluid analysis showed 38,255 WBC with 98% PMNs and 10000 RBC. Fluid cultures were negative. 16 s RNA study was positive for Granulicatella adiacens.Despite nutritional supplementation in the thiol broth we could not grow enough organisms to assess for sensitivities. He underwent resection of the left knee arthroplasty with irrigation and debridement including the bone and placement of antibiotic cement articulating spacer. Synovial fluid this time showed 25926 WBC with 91% PMNs.RBC were still 10000. Fluid cultures were again negative but 16 s RNA was again positive for the same pathogen. Pathology of the joint showed severe inflammation of the synovium with giant cell granuloma formation. Patient worked as a sales agent and opted for a single day regimen. A PICC line was placed and he was discharged home on IV ertapenem 1 gm daily for 6 weeks. Later he underwent revision left total knee arthroplasty (resection of cemented Prostalac and conversion to standard total knee arthroplasty).Peri operatively he received cefazolin for 3 days only. Repeat synovial fluid analysis showed only 286 WBC with 1000 RBC. 16 s RNA was again negative this time. The Patient was seen in the office post operatively and he remained symptomatic for the past 8 months. Discussion