G.P.68 Survival versus a fatal outcome in two cases of Anncaliia algerae microsporidial myositis

Abstract

Two cases of Anncaliia (previously Brachiola, previously Nosema) algerae microsporidial parasitic myositis in patients with rheumatoid arthritis (RA) treated with immunosuppression are presented with one surviving; the factors that may have contributed to survival are discussed. A 66 year old man with RA and renal impairment treated with methotrexate; the prednisone dose had recently increased as high as 50 mg daily for increasing muscle pain over a month. He was admitted febrile with a peak CK 6630 U/L (<200). He was treated empirically for sepsis, viral myositis, then fungal myositis; corticosteroids were continued at a reducing dose. He died 4 weeks after admission. Subsequently, Brachiola algerae were demonstrated on electron microscopy of biopsied muscle, and confirmed on PCR. A 68 year old man with RA treated with etanercept and leflunomide; these were sequentially ceased for diarrhoea several weeks prior to admission; the prednisone dose had recently increased to 35 mg daily for increasing muscle pain over this month. He was admitted afebrile with a peak CK of 1141. A muscle biopsy was immediately performed for infective myositis as the critical diagnosis of exclusion. This demonstrated microsporidial structures later confirmed as Brachiola algerae. Prednisone was weaned to 5 mg daily whereupon he became febrile, leflunomide was “washed out”. Albendazole, pyrimethamine and sulfadiazine were administered. He reached a clinical nadir after a further week and recovered over two months. This report is of the third and fourth cases of Anncaliia algerae myositis. The second case appears to the first patient to survive Anncaliia algerae myositis, and one of the few to survive any parasitic myositis with systemic infection. We suspect that the combination of rapid diagnosis before the patient was moribund, rapid reversal of immunosuppression and early administration of albendazole and other antibiotics are likely to have contributed to the patient surviving.