Genomic profile of extraintestinal pathogenic Escherichia coli isolates from prosthetic joint infections: The search for molecular fingerprints

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Escherichia coli is a key pathogen in extraintestinal infections, including prosthetic joint infections (PJIs), which account for approximately 9% of all such cases. Despite its clinical relevance, the molecular pathogenesis of E. coli in PJIs remains poorly defined. This study investigated the clinical, phylogenetic, and virulence profiles of E. coli isolates from PJIs and compared them to isolates from bacteremic urinary tract infections (UTIs). A total of 13 isolates from each infection type were analyzed using whole-genome sequencing (WGS) to determine phylogenetic relationships, sequence types, and the presence of virulence genes. PJI isolates exhibited substantial genetic diversity, encompassing 10 sequence types, with ST131 and ST69 being the most frequent. Phylogroup B2 predominated (53.9%) among PJI isolates. Adhesion and biofilm-related genes, such as fimG/H, csg, and epaO, were highly prevalent in PJI isolates, supporting the role of biofilm formation in pathogenesis. Conversely, toxin-associated genes (e.g. pic and senB) were more frequently detected in UTI isolates. Notably, the matA gene, linked to biofilm enhancement, was significantly associated with microbiological failure in PJIs (75% vs. 0%, p = 0.02). Phylogenetic analyses revealed no clustering by infection type, suggesting that ExPEC strains share a versatile genomic background, enabling them to adapt to different infection environments. The study highlights the critical role of biofilm formation in PJIs and underscores the genetic adaptability of ExPEC strains, which lack distinct virulence profiles specific to PJIs. However, the small number of PJI isolates limits the generalizability of these findings and warrants confirmation in larger cohorts.

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