Draft Genome and Phenotypic Characterization of an Adherent, Biofilm-Forming Uropathogenic Escherichia coli Strain (HU5) Isolated from Urinary Tract Infection in Mexico

Abstract

Uropathogenic Escherichia coli (UPEC) is the main cause of urinary tract infections (UTIs), and its clinical success depends on adherence and colonization of the urothelium. Most publicly deposited UPEC genomes lack accompanying phenotypic validation of adherence or biofilm capacity, limiting genotype–phenotype linkage. Here, we report the draft genome sequence and phenotypic characterization of HU5, a clinical UPEC isolate that displayed a strong adherent phenotype, with rugose, dry colonies, strong biofilm formation (crystal violet OD570 = 0.675 ± 0.132), and marked aggregative adherence to T24 bladder epithelial cells. Hybrid Illumina/Nanopore sequencing yielded a four-contig, 4,875,467 bp draft assembly (99.6% BUSCO completeness) comprising a fragmented chromosome (ST1434, phylogroup A, serotype O18ab:H14) and two plasmids. No acquired resistance genes were detected, though CARD analysis identified a MarR substitution as a candidate correlate for the intermediate β-lactam results; a co-occurring GlpT substitution was classified as functionally neutral and did not correlate with any resistance phenotype, consistent with the fully susceptible fosfomycin phenotype. The strain carried a complete curli operon (csgBAC/csgDEFG), two distinct cellulose biosynthesis loci (a complete chromosomal operon and a plasmid-borne, horizontally acquired copy), an apparently complete type VI secretion system, and a serum-resistance determinant (traT), alongside a heat-resistance genomic island, dual antiphage defense systems (CRISPR-Cas and BREX), and four candidate prophage regions. Pairing this genomic profile with the strain’s documented strong adherent and biofilm-forming phenotype provides a reference dataset for identifying candidate genetic determinants of UPEC adherence beyond the classical chaperone–usher pilus repertoire.