Biology subjects

Alastruey-Izquierdo, A.

Publications and source records attributed to Alastruey-Izquierdo, A..

6 recordsLinked to original sources

bioRxiv2026

Spatiotemporal dynamics and stability of multi-kingdom microbial communities in hospital sinks acting as persistent pathogen reservoirs

Hospital sink drains act as persistent reservoirs for nosocomial pathogens, yet the structure and long-term stability of their associated microbial communities remain poorly known. Here, we present an extensive characterization integrating multi-kingdom meta-taxonomic profiling (16S rRNA, ITS, and 18S rRNA, n=93 samples) with culturomics (n>4000 isolates) and phenotypic resistance testing across 14 sinks from a former intensive care unit (ICU). Over a 17-month study period, we tracked community assembly and stability through the renovation and transition from an unpopulated baseline to active clinical use, encompassing both structural remodeling and functional conversion. We showed that former-ICU drains harbor a highly conserved multi-kingdom core that remains resilient despite significant structural changes and periods of inactivity. While a persistent core baseline exists, community composition changes along a continuous temporal gradient driven by structural and anthropogenic shifts. Furthermore, individual sinks assemble as unique microecosystems shaped by local environmental factors. Topological network modeling shows these communities are not random assemblages but integrated ecological units, with clinically relevant, multidrug-resistant WHO-priority pathogens deeply embedded in the network alongside often-overlooked fungi and protozoa. Together, these findings identify hospital sink drains as persistent and structured multi-kingdom microbial reservoirs that harbor clinically relevant multidrug-resistant organisms (MDROs). Their temporal stability and strong sink-specific signatures highlight the need to consider the broader microbial community when monitoring hospital environmental reservoirs and developing infection-control strategies.

microbiology↗

bioRxiv2025

Establishing thresholds for azole tolerance and persistence in Aspergillus fumigatus to study their impact on voriconazole treatment in vivo

Antimicrobial tolerance and persistence are phenomena that enable pathogenic microbes to survive for extended periods in the presence of high concentrations of cidal drugs. Current evidence suggests that these phenomena may contribute to treatment failure and could even lead to the development of resistance. However, our understanding of antifungal tolerance and persistence in Aspergillus fumigatus, as well as their potential role in therapeutic failure, remains limited. In this study, we present an optimized, easy-to-perform method for detecting A. fumigatus tolerance and persistence to azole antifungals, based on a single colony-forming unit (CFU) measurement. Additionally, we developed a microscopic approach to investigate the dynamics of conidial killing in medium-throughput assays. Using these methods, we established epidemiological threshold values to classify strains as tolerant or persister and applied them to screen and categorize a collection of clinical isolates. Furthermore, we demonstrate that tolerance--but not persistence--negatively impacts the efficacy of voriconazole treatment in a Galleria mellonella infection model. Based on these findings, we propose that tolerance and persistence should be monitored in clinical isolates and potentially considered when determining therapeutic strategies.

microbiology↗

bioRxiv2024

Pathogenicity is associated with population structure in a fungal pathogen of humans

Aspergillus flavus is a clinically and agriculturally important saprotrophic fungus responsible for severe human infections and extensive crop losses. We analyzed genomic data from 250 (95 clinical and 155 environmental) A. flavus isolates from 9 countries, including 70 newly sequenced clinical isolates, to examine population and pan-genome structure and their relationship to pathogenicity. We identified five A. flavus populations, including a new population, D, corresponding to distinct clades in the genome-wide phylogeny. Strikingly, > 75% of clinical isolates were from population D. Accessory genes, including genes within biosynthetic gene clusters, were significantly more common in some populations but rare in others. Population D was enriched for genes associated with zinc ion binding, lipid metabolism, and certain types of hydrolase activity. In contrast to the major human pathogen Aspergillus fumigatus, A. flavus pathogenicity in humans is strongly associated with population structure, making it a great system for investigating how population-specific genes contribute to pathogenicity.

evolutionary biology↗

bioRxiv2020

Genomic and phenotypic heterogeneity of clinical isolates of the human pathogens Aspergillus fumigatus, Aspergillus lentulus and Aspergillus fumigatiaffinis

Fungal pathogens are a global threat to human health. For example, fungi from the genus Aspergillus cause a spectrum of diseases collectively known as aspergillosis. Most of the >200,000 life-threatening aspergillosis infections per year worldwide are caused by Aspergillus fumigatus. Recently, molecular typing techniques have revealed that aspergillosis can also be caused by organisms that are phenotypically similar to A. fumigatus but genetically distinct, such as Aspergillus lentulus and Aspergillus fumigatiaffinis. Importantly, some of these so-called cryptic species exhibit different virulence and drug susceptibility profiles than A. fumigatus, however, our understanding of their biology and pathogenic potential has been stymied by the lack of genome sequences and phenotypic profiling. To fill this gap, we phenotypically characterized the virulence and drug susceptibility of 15 clinical strains of A. fumigatus, A. lentulus, and A. fumigatiaffinis from Spain and sequenced their genomes. We found heterogeneity in virulence and drug susceptibility across species and strains. Genes known to influence drug susceptibility (cyp51A and fks1) vary in paralog number and sequence among these species and strains and correlate with differences in drug susceptibility. Similarly, genes known to be important for virulence in A. fumigatus showed variability in number of paralogs across strains and across species. Characterization of the genomic similarities and differences of clinical strains of A. lentulus, A. fumigatiaffinis, and A. fumigatus that vary in disease-relevant traits will advance our understanding of the variance in pathogenicity between Aspergillus species and strains that are collectively responsible for the vast majority of aspergillosis infections in humans.

microbiology↗

bioRxiv2020

Tracing the evolutionary history and global expansion of Candida auris using population genomic analyses

Candida auris has emerged globally as a multidrug-resistant yeast that can spread via nosocomial transmission. An initial phylogenetic study of isolates from Japan, India, Pakistan, South Africa, and Venezuela revealed four populations (Clades I, II, III, and IV) corresponding to these geographic regions. Since this description, C. auris has been reported in over 30 additional countries. To trace this global emergence, we compared the genomes of 304 C. auris isolates from 19 countries on six continents. We found that four predominant clades persist across wide geographic locations. We observed phylogeographic mixing in most clades; Clade IV, with isolates mainly from South America, demonstrated the strongest phylogeographic substructure. C. auris isolates from two clades with opposite mating types were detected contemporaneously in a single healthcare facility in Kenya. We estimated a Bayesian molecular clock phylogeny and dated the origin of each clade within the last 339 years; outbreak-causing clusters from Clades I, III, and IV originated 34-35 years ago. We observed high rates of antifungal resistance in Clade I, including four isolates resistant to all three major classes of antifungals. Mutations that contribute to resistance varied between the clades, with Y132F in ERG11 as the most widespread mutation associated with azole resistance and S639P in FKS1 for echinocandin resistance. Copy number variants in ERG11 predominantly appeared in Clade III and were associated with fluconazole resistance. These results provide a global context for the phylogeography, population structure, and mechanisms associated with antifungal resistance in C. auris. ImportanceIn less than a decade, C. auris has emerged in healthcare settings worldwide; this species is capable of colonizing skin and causing outbreaks of invasive candidiasis. In contrast to other Candida species, C. auris is unique in its ability to spread via nosocomial transmission and its high rates of drug resistance. As part of the public health response, whole-genome sequencing has played a major role in characterizing transmission dynamics and detecting new C. auris introductions. Through a global collaboration, we assessed genome evolution of isolates of C. auris from 19 countries. Here, we described estimated timing of the expansion of each C. auris clade and of fluconazole resistance, characterized discrete phylogeographic population structure of each clade, and compared genome data to sensitivity measurements to describe how antifungal resistance mechanisms vary across the population. These efforts are critical for a sustained, robust public health response that effectively utilizes molecular epidemiology.

genomics↗

bioRxiv2018

Diversity of coelomycetous fungi in human infections: a 10-year experience of two European reference centres

The coelomycetous fungi are difficult to properly identify from their phenotypic characterization and their role as etiologic agents of human infections is not clear. We studied the species distribution of these fungi among clinical isolates that had been collected and stored over a ten-year period in two European reference laboratories (France and Spain). We identified phenotypically and molecularly 97 isolates by sequencing the D1-D2 fragment of the 28S nrRNA (LSU) gene. Species of the orders Pleosporales and Glomerellales were present in both collections, and Botryosphaeriales and Diaporthales only in the French one. The most prevalent species were Medicopsis romeroi, Neocucurbitaria keratinophila, Neocucurbitaria unguis-hominis and Paraconiothyrium cyclothyrioides, which had been recovered primarily from superficial tissues. The Didymellaceae was the most common family represented, with 27 isolates distributed into five genera.

microbiology↗