Biology subjects

La Bella, A. A.

Publications and source records attributed to La Bella, A. A..

6 recordsLinked to original sources

bioRxiv2026

Liquid-Infused Silicone Catheters Reduce Fungal Burden and Inflammation in Candidozyma auris Bladder Infections.

Candidozyma auris is a high-priority, emerging fungal pathogen frequently isolated from urine in healthcare settings. These isolates are often associated with indwelling urinary catheters, a primary risk factor for catheter-associated urinary tract infections (CAUTIs). Despite its clinical prevalence, the mechanisms of C. auris colonization and pathogenesis within the bladder remain poorly understood. In this study, we screened C. auris isolates from diverse clades using an in vitro biofilm model and in vivo murine models of uncomplicated UTI and CAUTI. While in vitro biofilm formation varied among isolates, the presence of a catheter in vivo significantly enhanced fungal burden in the bladder. Notably, one strain (B11103) caused rapid systemic dissemination and mortality. To address this, we evaluated a liquid-infused silicone (LIS)-catheter coating, which has previously shown efficacy against other uropathogens. The LIS-coating significantly reduced C. auris attachment in vitro and, crucially, mitigated fungal burden on both the catheter and bladder tissue in vivo across all tested strains. For the hyper-virulent B11103 strain, LIS-catheters also significantly reduced dissemination to the kidneys and bloodstream. Furthermore, cytokine analysis revealed that C. auris CAUTI upregulates IL-6, CSF3, and CXCL1; notably, this damaging inflammatory response was dampened by the LIS-catheter. These findings demonstrate that catheterization potentiates C. auris pathogenicity and identify LIS-catheters as a promising, antimicrobial-sparing strategy to prevent colonization, systemic spread, and inflammation during C. auris CAUTI. IMPORTANCEThis research addresses the critical public health challenge posed by the emergence of Candidozyma auris, elucidating its pathogenesis in the urinary tract, the second most common yet understudied reservoir. Here, we find that C. auris exhibits plasticity in its ability to form biofilms in urine and cause uncomplicated UTIs and catheter-associated UTIs. Importantly, we show that our liquid-infused silicone (LIS)-catheters effectively disrupt this cycle by reducing fungal burden, preventing systemic spread, and dampening the damaging host inflammatory response. This work establishes the urinary tract as a critical niche for systemic entry and provides a validated strategy for infection prevention.

microbiology↗

bioRxiv2025

Emergence and spread of outbreak-adapted Candidozyma auris harboring mutations in RBA1

Candidozyma auris is an emerging healthcare-associated fungal pathogen, increasingly isolated from clinical outbreaks, with a high propensity to colonize patients and the medical environment. Here, we leveraged C. auris isolates from multi-facility clinical outbreaks to identify genomic patho-adaptations promoting persistence and dissemination in the healthcare environment. Genomic and phylogenetic analyses revealed loss-of-function mutations in the uncharacterized C. auris transcription factor gene RBA1 to have independently emerged multiple times within these outbreaks. We demonstrate loss of RBA1 increases C. auris adhesion to plastic and human keratinocytes, enhances biofilm formation, and exacerbates fungal burden in a mouse model of catheter-associated urinary tract infection. Finally, we uncover mutations in RBA1 have emerged during multiple C. auris outbreaks across the globe, and that RBA1 mutant lineages are present among large ongoing clinical outbreaks. These results reveal loss-of-function mutations in C. auris RBA1 as a novel and clinically relevant genetic determinant of enhanced outbreak characteristics.

microbiology↗

bioRxiv2025

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. SIGNIFICANCECatheter-associated urinary tract infections (CAUTIs) are common hospital-acquired infections that can lead to severe complications and death. Although most are caused by bacteria, the fungus Candida albicans is an increasingly prevalent cause, yet the pathogenesis of fungal CAUTIs is poorly understood. Previous research identified Efg1 as necessary for CAUTI, and now this study defines the urine-specific Efg1 regulon, validating its clinical relevance in catheter samples from infected patients. We further assessed how key downstream factors, Ece1 and Eed1, contribute to bladder infection. This first report of the urine-specific EFG1 network provides new targets for diagnosing and treating these life-threatening infections.

microbiology↗

bioRxiv2024

The catheterized bladder environment induces dysregulation of macrophage polarization exacerbating bacterial UTI

Urinary catheterization causes bladder damage, predisposing hosts to catheter-associated urinary tract infections (CAUTIs). CAUTI pathogenesis is mediated by bladder damage-induced inflammation, resulting in accumulation and deposition of the blood-clotting protein fibrinogen (Fg) and its matrix form fibrin, which are exploited by uropathogens as biofilm platforms to establish infection. Catheter-induced inflammation also results in robust immune cell recruitment, including macrophages (M{phi}s). A fundamental knowledge gap is understanding the mechanisms by which the catheterized-bladder environment suppresses the M{phi} antimicrobial response, allowing uropathogen persistence. Here, we found that Fg and fibrin differentially modulate M1 and M2 M{phi} polarization, respectively. We unveiled that fibrin accumulation in catheterized mice induced an anti-inflammatory M2-like M{phi} phenotype, correlating with pathogen persistence. Even GM-CSF treatment of wildtype mice to promote M1 polarization was not sufficient to reduce bacterial burden and dissemination, indicating that the catheterized-bladder environment provides mixed signals, dysregulating M{phi} polarization, hindering its antimicrobial response against uropathogens.

immunology↗

bioRxiv2022

Development and applications of a CRISPR activation system for facile genetic overexpression in Candida albicans

For the fungal pathogen Candida albicans, genetic overexpression readily occurs via a diversity of genomic alterations, such as aneuploidy and gain-of-function mutations, with important consequences for host adaptation, virulence, and evolution of antifungal drug resistance. Given the important role of overexpression on C. albicans biology, it is critical to develop and harness tools that enable the analysis of genes expressed at high levels in the fungal cell. Here, we describe the development, optimization, and application of a novel, single-plasmid-based CRISPR activation (CRISPRa) platform for targeted genetic overexpression in C. albicans, which employs a guide RNA to target an activator complex to the promoter region of a gene of interest, thus driving transcriptional expression of that gene. Using this system, we demonstrate the ability of CRISPRa to drive high levels of gene expression in C. albicans, and we assess optimal guide RNA targeting for robust and constitutive overexpression. We further demonstrate the specificity of the system via RNA sequencing. We highlight the application of CRISPRa to overexpress genes involved in pathogenesis and drug resistance and contribute towards the identification of novel phenotypes. Together, this tool will facilitate a broad range of applications for the study of C. albicans genetic overexpression.

microbiology↗

bioRxiv2021

Catheterized-bladder environment induces hyphal Candida albicans formation, promoting fungal colonization and persistence.

Catheter-associated urinary tract infections (CAUTIs) account for 40% of all hospital-acquired infections. Given that 20-50% of all hospitalized patients receive a catheter, CAUTIs are one of the most common hospital-acquired infections and a significant medical complication as they result in increased morbidity, mortality, and an estimated annual cost of $340-370 million. Candida spp. - specifically Candida albicans - are a major causative agent of CAUTIs (17.8%), making it the second most common CAUTI uropathogen. Despite this frequent occurrence, the cellular and molecular details of C. albicans infection in the CAUTI microenvironment are poorly understood. Here, we characterize fungal virulence mechanisms and fungal biofilm formation during CAUTI for the first time. We found that the catheterized bladder environment triggers Candida virulence programs and robust biofilm formation through Efg1-dependent hyphal morphogenesis and Als1, an Efg1-downstream effector. Additionally, we show that the adhesin Als1 is necessary for in vitro and in vivo C. albicans biofilm formation dependent on the presence of fibrinogen (Fg), a coagulation factor released in the bladder due to the mechanical damage caused by urinary catheterization. Furthermore, in the presence of Fg, overexpression of ALS1 in C. albicans led to enhanced colonization and dissemination, while deletion of ALS1 reduced both outcomes during CAUTIs. Our study ultimately unveils the mechanism that contributes to fungal CAUTI, which may provide more effective targets for future therapies to prevent these infections.

microbiology↗