Phenotypic and Genotypic Characterization of Virulence Factors and Susceptibility to Antibiotics in Salmonella Infantis Strains Isolated from Chicken Meat: First Findings in Chile

Simple Summary SalmonellaInfantis (S.Infantis) is a zoonotic pathogen that causes gastroenteritis in humans and animals, with poultry being its main reservoir. This pathogen has emerged over the last few decades in different countries, causing outbreaks in humans subsequent to foodborne transmission. It is important to be able to characterize this pathogen in order to establish control measures in the poultry industry. In this study, we investigated the presence of virulence genes, biofilm formation abilities, antibiotic resistance genes, and antibiotic susceptibility inS.Infantis. The results showed that theS.Infantis strains isolated from chicken meat for sale in supermarkets in Santiago, Chile are multidrug-resistant (MDR) and contain virulence genes, making them pathogenic. Thus,SalmonellaInfantis should be under surveillance in the poultry food production chain with the aim of protecting public health. SalmonellaInfantis is a zoonotic pathogen that causes gastroenteritis in humans and animals, with poultry being its main reservoir. In Chile, there are no data to characterizeS.Infantis strains in poultry production. In this study, 87S.Infantis strains were isolated from chicken meat for sale in supermarkets in Santiago, Chile, and characterized according to their virulence genes, biofilm formation abilities, antibiotic susceptibility, and resistance genes. Through polymerase chain reaction or PCR, the strains were analyzed to detect the presence of 11 virulence genes, 12 antibiotic resistance genes, and integrase genes. Moreover, disc diffusion susceptibility to 18 antimicrobials and the ability to form biofilm in vitro were evaluated. Results demonstrated six different virulence gene profiles. Ninety-four percent of the strains were multi-resistant to antibiotics with weak biofilm formation abilities, 63.2% of the strains were broad spectrum beta- lactam resistant, and thebla(CTX-M-65)gene was amplified in 13 strains. Only 3.4% of the strains were fluoroquinolone resistant, and theqnrBgene was amplified in two strains. Colistin resistance was exhibited in 28.7% of the strains, butmrcgenes were not amplified in any strain under study. The isolatedS.Infantis strains are pathogenic and antibiotic multi-resistant, and thus, thisSalmonellaserotype should be under surveillance in the poultry food production chain with the aim of protecting public health.