P152 African Woman With a Knee Knocked by a Rare Dematiaceous Fungi

Abstract Poster session 2, September 22, 2022, 12:30 PM - 1:30 PM Objectives/Introduction Incidence of fungal peri-prosthetic joint infection (PJI) is rare (1%-3%) and the majority are caused by Candida and Aspergillus. We report a peri-prosthetic knee joint infection caused by a rare dematiaceous fungi—pleurostomophora richardsiae, probably the first case in the world. Methods/Case Details A 78-year-old East African female from Malawi, housewife, with no known medical comorbidities presented with a chronic history of left knee pain and pus discharge. She had left knee pain since 2008 and was given several intra-articular injections between 2008 and 2010 for pain relief suspecting osteoarthritis. She denied a history of splinter injuries, trauma, systemic, or constitutional symptoms. In 2010 she underwent left total knee replacement (TKR) in the USA, but the pain persisted post-operatively associated with intermittent swelling of both knees. She was evaluated again in 2015 and revision left TKR done with single stage exchange. She was asymptomatic for a few years but symptoms worsened again and drainage of pus from her left knee started in December 2019. She was treated in Malawi with multiple courses of parenteral and oral antibiotics but did not improve. She presented to our hospital in January 2022 with swelling in left knee and restriction of movements. On examination, a discharging sinus was noted over the medial aspect of left knee. She was anemic with a normal leucocyte count, HIV negative, ESR of 85 mm/h, and CRP of 23 mg/L. Her renal and liver function tests were normal. CT left leg with sinogram showed features of chronic osteomyelitis of left distal femur and proximal tibia with active sinus tract in left tibia. Sinus tract excision with removal of prosthesis, debridement, and antibiotic cement spacer insertion was done. Bone and peri-prosthetic tissue were sent for histopathology and microbiological analysis including fungal and mycobacterial cultures. Xpert MTb was negative. Histopathology showed granulomatous synovitis with fungal hyphae and spores. Cultures grew a slender septate dark pigmented fungus, Pleurostomophora richardsiae which was confirmed by fungal PCR sequencing of internal transcribed spacer (ITS) region. Results/Treatment She was treated with Liposomal amphotericin B 5 mg/kg IV OD for 2 weeks followed by oral Itraconazole. She had persistent raised inflammatory markers at 4 weeks which settled after changing to posaconazole for 2 weeks. Conservative management will continue for 3-6 months with second stage revision arthroplasty/arthrodesis later. Conclusion Dematiaceous fungi usually cause skin and soft tissue infections and they are extremely rare in causing prosthetic joint infection. Case reports of P. richardsiae causing osteomyelitis of foot and endocarditis are available but we couldn't find a published case of prosthetic joint infection caused by it. Identifying the causative organism in PJI is the most important step because the management depends mainly on it. Two-stage exchange in combination with antifungal administration between stages and post-revision should be the procedure of choice for fungal PJI. Incorporation of antifungal agents into cement spacers appears to be effective in eradicating local infections and reducing the duration of antifungal treatment and should be strongly considered.