Pelvic peritonitis during biologic therapy for rheumatoid arthritis: a case report and review of the literature

INTRODUCTION Infections are recognized as major complications during therapy with biologics and other immunosuppressant drugs. The respiratory tract, bone, joint, skin, and soft tissues are well known sites of infection in patients with rheumatoid arthritis (RA) treated by biologics or other immunosuppressants. It is known that patients with intra-abdominal infections may develop tuberculous peritonitis during biologic therapy. However, non-tuberculous pelvic peritonitis is rare. CASE DESCRIPTION A case of a 46-year-old patient with RA developed pelvic peritonitis during therapy with MTX, tacrolimus (TAC), and golimumab (GLM). The patient visited our hospital due to a fever and general malaise. Physical findings included lower abdominal tenderness and rebound tenderness. Abdominal computed tomography (CT) images showed an intrauterine foreign body and ascites. The contraceptive ring was removed. Streptococcus agalactiae and Streptococcus constellatus were cultured from the removed contraceptive ring. She was started on an antimicrobial agent, flomoxef (FMOX), at 2 g/day. The FMOX dosage was increased to 3 g/day from the 3rd day of disease and continued for 10 days. Her fever disappeared from the 4th disease day, and her inflammatory response then gradually decreased. No exacerbation of symptoms occurred even after the FMOX treatment was stopped, and the patient was discharged on the 14th disease day. DISCUSSION AND EVALUATION MTX and biologics were being administered at the time of onset of peritonitis. The peritonitis was diagnosed on the basis of the gynecological evaluation and CT imaging findings that were typical of peritonitis. The patient was in an immunosuppressed state during administration of anti-rheumatic drugs, and the peritonitis was thought to have developed due to an ascending infection via the long-term presence of the intrauterine contraceptive ring which had an attached string. CONCLUSIONS Before starting biological agents, patients must be questioned regarding the presence of an intrauterine foreign body.