Genetic Diversity ofsubsp.Serovar Enteritidis from Human and Non-Human Sources in Portugal.

Abstract

subsp.serovar Enteritidis (Enteritidis) is one of the leading causes of foodborne infections associated with broilers and laying hens. Portugal has had the lowest notification rates of salmonellosis in recent years, due to the vaccinations of layer and breeder flocks and strict compliance with biosecurity measures. However, data about the genetic diversity ofEnteritidis in Portugal are scarce. In this study, 102Enteritidis isolates selected from human (= 63) and non-human sources (= 39) were characterized by serotyping, antimicrobial susceptibility, and whole genome sequencing. TheEnteritidis population was mainly resistant to fluoroquinolones, and a sole isolate showed resistance to extended-spectrum cephalosporins. ST11 was the most frequent sequence type, and three novel STs from human isolates (ST9236, ST4457, and ST9995) were assigned. Severalpathogenic islands (SPI) and Putative SPI were present in the genomes, namely SPI-1, 2, 3, 4, 5, 9, 10, 12, 13, and 14, C63PI, CS54_island, and 170 virulence genes were identified. The phylogenetic analysis revealed that strains from Portugal are genetically heterogeneous regarding sample type, collection date, and genetic content. This study increases the available data, essential to a better characterization of strains in a global context.