# The fungal stronghold: biofilms in hemodialysis catheters, diagnostic pitfalls, and the challenge of catheter salvage

## TL;DR

This review explores the challenges of managing fungal infections in hemodialysis catheters, focusing on biofilm resistance and the dilemma of catheter removal versus salvage.

## Contribution

The paper provides a detailed analysis of fungal biofilm mechanisms and evaluates antifungal lock therapy as a salvage strategy for hemodialysis catheters.

## Key findings

- Fungal biofilms, especially from Candida, are difficult to treat due to their extracellular matrix and persister cells.
- Antifungal Lock Therapy (ALT) is proposed as a bridging strategy when catheter removal is not feasible.
- Candida parapsilosis is increasingly prevalent in hemodialysis catheter infections due to its affinity for foreign bodies.

## Abstract

The management of fungal catheter-related bloodstream infections (CRBSIs) in the hemodialysis population represents a critical collision between rigorous infectious disease guidelines and the grim clinical reality of vascular access exhaustion. While guidelines from the IDSA and KDIGO unequivocally recommend immediate catheter removal to prevent metastatic complications, nephrologists are frequently confronted with patients for whom the current catheter represents the last viable lifeline. This review provides a comprehensive analysis of the “catheter salvage” dilemma, moving beyond superficial treatment algorithms to explore the molecular and structural mechanisms that make fungal biofilms a formidable adversary. We dissect the pathogenesis of Candida colonization on abiotic surfaces (silicone and polyurethane), detailing the transition from yeast to hyphal structures and the secretion of a complex extracellular matrix (ECM). We highlight how the ECM, rich in β-1,3 glucan, acts as a physical shield that sequesters azoles, rendering standard systemic therapy ineffective despite in vitro susceptibility. Furthermore, we discuss the role of metabolically dormant “persister cells” in driving high relapse rates and analyze the epidemiological shift toward Candida parapsilosis, a pathogen with a unique affinity for foreign bodies and parenteral nutrition lines. Diagnostically, we scrutinize the limitations of traditional blood cultures and the “Differential Time to Positivity” (DTP) criteria, arguing that the slower growth kinetics of fungi render DTP unreliable compared to bacterial infections. The core of this review evaluates the efficacy and safety of Antifungal Lock Therapy (ALT) as a bridging strategy. We provide a comparative analysis of lock agents, contrasting the broad lytic potential of ethanol (the “nuclear option”) with the safety profile of taurolidine and the pharmacological nuances of amphotericin B and echinocandins. Ultimately, we propose that while catheter removal remains the gold standard, a nuanced mastery of biofilm biology and lock therapy protocols is essential for managing complex, access-challenged patients where immediate removal is not feasible.