Refractory Azole-Resistant Candida albicans Renal and Perirenal Abscess Requiring Nephrectomy.

We describe a male in his fifties with a refractory azole-resistant Candida albicans renal and perirenal walled-off abscess. C. albicans developed acquired azole-resistance during fluconazole (FLCZ) therapy. Despite FLCZ penetrating the walled-off abscess (11.1 μg/g) with levels exceeding those in normal renal tissue, the infection persisted, necessitating nephrectomy. Despite no amino acid substitutions in the ERG11 gene as revealed by genetic analysis, a Rhodamine 6G assay demonstrated a 4.5- to 6.6-fold increase in efflux activity in the resistant isolates in comparison with the susceptible controls, suggesting efflux pump-mediated resistance. Following surgery, the patient developed emphysematous pyelonephritis in the contralateral kidney due to azole-resistant C. albicans. This case demonstrates that even substantial tissue penetration cannot overcome high-level, effluxmediated resistance within walled-off lesions, underscoring the critical importance of surgical source control.