Abstract
Fungal periprosthetic joint infections (PJIs) are uncommon and diagnostically challenging, frequently associated with delayed recognition, complex antimicrobial management, and poor outcomes. Candida tropicalis PJIs are particularly difficult to manage due to variable antifungal susceptibility patterns. In the present study, a 72-year-old male developed a polymicrobial PJI following total knee arthroplasty (TKA) despite the absence of classic predisposing risk factors. Early postoperative symptoms were nonspecific, leading to empirical antibacterial therapy and debridement, antibiotics, and implant retention (DAIR) for presumed bacterial PJI. Persistent inflammation and radiographic changes prompted further investigation. Repeated synovial fluid analysis demonstrated elevated leukocyte counts with neutrophil predominance, and cultures yielded bacterial growth in addition to yeast. Targeted mycological cultures and molecular identification (ITS sequencing) confirmed Candida tropicalis. Antifungal susceptibility testing (CLSI M38-A2) revealed resistance to fluconazole, voriconazole, and caspofungin, with susceptibility to amphotericin B and itraconazole. Ongoing infection necessitated progression to the first stage of a two-stage exchange with prosthesis removal and spacer placement, followed by reimplantation (second stage). Clinical relapse after reimplantation was successfully managed with liposomal amphotericin B-based therapy, resulting in sustained clinical and laboratory improvement. This case highlights the difficulty of diagnosing fungal and polymicrobial PJI due to nonspecific clinical presentation and prolonged response to antibacterial therapy and shows the critical role of antifungal susceptibility testing in guiding treatment. Early incorporation of fungal diagnostics and standardized PJI management strategies is essential to optimize outcomes in complex cases involving Candida tropicalis.