The Unique Efg1 Fungal Virulence Regulon in the Catheterized Bladder Environment

Urinary catheterization, a common procedure in hospitals and nursing home facilities, is a primary driver of hospital-acquired infections (HAI). These devices frequently lead to catheter-associated urinary tract infections (CAUTIs), which often progress to severe complication, sepsis, and ultimately death. The fungus Candida albicans has emerged as the second most common causative agent of CAUTIs; yet, its pathogenesis is poorly understood, which complicates development of efficient treatments. Previously, we identified the transcription factor Efg1 as a critical virulence driver in C. albicans CAUTIs. However, its specific downstream targets within the unique bladder microenvironment remained unknown. This study identifies, for the first time, the complete Efg1 regulon that is active during growth in human urine. We confirmed the clinical relevance of this discovery, finding that many of these Efg1-regulated factors are present and significantly upregulated in catheter samples from patients with C. albicans infections. Furthermore, we characterized two of these key factors, ECE1 and EED1, validating their roles both in vitro in urine conditions and in vivo using a CAUTI mouse model. Identifying the tissue-specific downstream targets of Efg1 elucidates the precise mechanism of fungal CAUTI. This knowledge provides a new roadmap for developing targeted therapeutics, offering vital antimicrobial-sparing strategies to combat these life-threatening infections.