Caracterización genómica de factores de virulencia, mecanismos de resistencia y plásmidos en cepas de Salmonella enterica serovar Infantis aisladas de urocultivos en el periodo 2022-2024 en Ecuador

Abstract

Salmonella enterica serovar Infantis has become an established emerging pathogen and a leading cause of human salmonellosis. This pathogen is notable for its association with poultry and the high prevalence of multidrug resistance, making it a major cause of gastrointestinal infections. Its infectious capacity has also led to extraintestinal infections, such as urinary tract infections. This research aimed to characterize the genomic profile of Salmonella enterica serovar Infantis isolates from urine cultures in order to understand their pathogenicity and transmission dynamics, also to establish a phylogenetic relationship with strains from the country's poultry industry. A cross-sectional observational study was conducted with 12 Salmonella infantis strains isolated from urine cultures in Ecuador during the period 2022–2024. Through whole-genome sequencing using Oxford Nanopore technology and bioinformatics tools, resistance factors, virulence, and plasmids were characterized in the isolates. Analyses showed that all strains belong to the ST32 clonal lineage and harbor the IncFIB replicon characteristic of the pESI megaplasmid. 91.6% of the isolates exhibited an MDR genotype against various antibiotic families, along with a highly conserved virulence profile mediated by genes such as shdA, sipA, and sifA. Phylogenetic analysis demonstrated that the strains in this study are closely related to isolates from the national poultry industry. Thus, it was concluded that a wellestablished clonal lineage of Salmonella enterica serovar Infantis is circulating in Ecuador, both in the poultry industry and in clinical settings. These clones exhibit a high prevalence of multidrug resistance and virulence driven by the presence of pESIlike plasmids. These findings provide further evidence of zoonotic transmission from the poultry industry to humans with strains whose genotypic characteristics can cause extraintestinal infections, highlighting the need for surveillance and control of this pathogen through a One Health approach.