Identification of prosthetic joint infection by Candida using metagenomic shotgun sequencing

BACKGROUND. Periprosthetic joint infection (PJI) is a serious complication after total knee arthroplasty. Fungal infections are prone to biofilm formation, which makes it hard to diagnose and clarify the pathogenic species. CASE PRESENTATION. This case study provides evidence of a novel PJI pathogen that is otherwise difficult to detect using conventional methods. A patient was reviewed with persistent postoperative pain, swelling and eventually drainage around the left knee after undergoing a bilateral total knee arthroplasty 2 years previously for progressive osteoarthritis. By using metagenomic shotgun sequencing to analyse both bacterial and fungal agent sequences, we were able to identify fungal strains of Candida tropicalis, a rarely reported and difficult-to-culture PJI pathogen. CONCLUSION. Metagenomic shotgun sequencing enables the detection of difficult-to-detect pathogens and the formulation of treatment recommendations for fungal infections with low positive rates based on gene content analysis.