Genomic Epidemiology of Salmonella Infantis in Ecuador: From Poultry Farms to Human Infections

Abstract

<i>Salmonella enterica</i> is one of the most important foodborne pathogens around the world. In the last years, <i>S</i>. <i>enterica</i> serovar Infantis has become an important emerging pathogen in many countries, often as multidrug resistant clones. To understand the importance of <i>S. enterica</i> in the broiler industry in Ecuador, we performed a study based on phenotypic and WGS data of isolates from poultry farms, chicken carcasses and humans. We showed a high prevalence of <i>S. enterica</i> in poultry farms (41.4%) and chicken carcasses (55.5%), but a low prevalence (1.98%) in human samples. <i>S</i>. Infantis was shown to be the most prevalent serovar with a 98.2, 97.8, and 50% in farms, foods, and humans, respectively, presenting multidrug resistant patterns. All sequenced <i>S</i>. Infantis isolates belonged to ST32. For the first time, a pESI-related megaplasmid was identified in Ecuadorian samples. This plasmid contains genes of antimicrobial resistance, virulence factors, and environmental stress tolerance. Genomic analysis showed a low divergence of <i>S</i>. Infantis strains in the three analyzed components. The results from this study provide important information about genetic elements that may help understand the molecular epidemiology of <i>S</i>. Infantis in Ecuador.