First report on whole genome sequencing and comparative genomics of Salmonella enterica serovar Abortusequi isolated from Donkey in India

Salmonella enterica subspecies enterica serovar Abortusequi (S. Abortusequi) is a leading cause of abortion in equines that hinders the rapid growth of equine industry. S. Abortusequi infection in equids has re-emerged over last ten years. In the present study, S. Abortusequi was isolated and characterized from donkeys during an abortion storm in the southern peninsular region of India. Further, whole genome sequencing and phylogenomic analysis revealed that the present isolate was clustered among S. Abortusequi clade. The core genome MLST (cgMLST) analysis based on hierarchical clustering and single nucleotide polymorphism (SNP) core-genome dendrogram of the present isolate against 10 S. Abortusequi isolates revealed that the present isolate established a distinct clade compared to all previously reported isolates. A comparison of cgMLST and SNP analyses revealed the same clustering concordance between isolates. In addition, comparative genomics and phylogenetic analysis was carried out with six S. Abortusequi serovars showed a higher number of core genes than accessory genes. Further, comparative analysis of phenotype and genotype antimicrobial resistance revealed a concordance of 32% and discordance of 68% respectively.

Virulence genes and antimicrobial susceptibility in Salmonellaenterica serotypes isolated from swine production in Argentina

Salmonella is a worldwide-distributed pathogen that affects both humans and animals and is usually associated with intensive animal production such as poultry and swine. This bacterium carries different virulence genes, whose expression favors its interaction with the host and may influence the course of the infection. Extended usage of antibiotics for metaphylaxis or prophylaxis and as growth promoters favors the emergence of multiresistant Salmonella strains. The aim of this work was to assess the association between the presence of virulence-associated genes and the antimicrobial resistance phenotype in Salmonella isolates obtained from swine intensive and backyard farms in Argentina during 2012-2018. A total of 59 Salmonella strains belonging to several serotypes were studied. All the strains carried the sopB and ssaQ genes, whereas more than 90% of the isolates carried the mgtC, avrA, and siiD genes. Some isolates also carried the bcfC, sodC1, gipA, sopE1 and spvC genes; however, their presence varied among them. Susceptibility to the antibiotics tested was diverse. Isolates from intensive farms were resistant to a larger number of antimicrobials than those from backyard farms and some of the strains showed high virulence potential and extensive antimicrobial resistance profiles. Continuous surveillance is essential to detect the emergence of strains that may represent a significant risk not only for animal production but also for the human population.