Late infections with Actinomyces israelii have been described for prosthetic hip joints but not in association with intravenous drug use. We present a case of a 43-year-old intravenous drug user who developed A. israelii infection in connection with a hip prosthesis 11 years after implantation, and we review four previously reported cases of Actinomyces prosthetic joint infections.
CASE REPORTA 43-year-old female, an active intravenous drug user with avascular necrosis of the head of the femur as a consequence of steroid use for treatment of Guillain-Barré syndrome, was treated with a total right hip arthroplasty at the age of 30. She required revision of the procedure a year later for unclear reasons. Eleven years later, she developed gradual and progressive pain at the site of the arthroplasty. The patient sought medical attention 5 months later. The patient denied having a history of recent dental manipulation or intrauterine device use.On physical examination, the following vital signs were noted: a temperature of 38.3°C, a heart rate of 101 beats per min, a respiratory rate of 20 breaths per min, and a blood pressure of 143/77 mm Hg. The patient's dental hygiene was good. Examination of the heart revealed no murmurs. The right lower extremity was painful and short by 5 in. and had limited range of motion.The peripheral blood leukocyte count was 6,400/ml with a normal differential. The sedimentation rate was 120 mm/h. X rays of the hip showed cortical irregularity and lucency of the femur shaft. Analysis of the aspirated synovial fluid revealed a leukocyte count of 37,000/ml with 95% being neutrophils. A Gram stain showed a moderate number of polymorphonuclear leukocytes without organisms. Anaerobic cultures on prereduced sheep blood agar plates grew many opaque white colonies of gram-positive, irregular bacilli. The organism was identified as Actinomyces israelii with the RapID ANA II preformed enzyme detection panel (Remel Inc., Norcross, Ga.) and by the presence of moderate acetic acid and major succinic acid peaks on gas-liquid chromatography. Antibiotic susceptibility testing was done by Etest (AB Biodisk, Solna, Sweden) and revealed susceptibility to cefotaxime (MIC of 0.125 g/ ml), cefoxitin (MIC of 0.19 g/ml), metronidazole (MIC of 2 g/ml), penicillin (MIC of 0.125 g/ml), and clindamycin (MIC of 0.094 g/ml).The patient refused surgery at the time and returned 2 months later with persistent symptoms. A repeat Gram stain of the synovial fluid revealed rare polymorphonuclear leukocytes without organisms, and cultures again grew Actinomyces. Following this result, the patient was admitted to the hospital. She underwent surgery, where loosening of the prosthesis and the presence of necrotic tissue were noted. The prosthesis was removed, and intra-articular vancomycin and tobramycin antibiotic beads were inserted. In addition, 3 g of ampicillin was administered every 6 h. After being in the hospital for 20 days, the patient left against medical advice and was lost to follow-up.A. israelii is a gram-posit...