Genomic Features and Phylogenetic Analysis of Antimicrobial-Resistant Salmonella Mbandaka ST413 Strains

In recent years, Salmonella enterica subsp. enterica serovar Mbandaka (S. Mbandaka) has beenincreasingly isolated fromlaying hens and shell eggs around theworld. Moreover, this serovar has beenidentified as the causative agent of several salmonellosis outbreaks in humans. Surprisingly, little is knownabout the characteristics of this emerging serovar, and therefore, we investigated antimicrobial resistance,virulence, and prophage genes of six selected Brazilian strains of SalmonellaMbandaka usingWholeGenomeSequencing (WGS).Multi-locus sequence typing revealed that the tested strains belong to Sequence Type413 (ST413), which has been linked to recent multi-country salmonellosis outbreaks in Europe. A totalof nine resistance genes were detected, and themost frequent oneswere aac(6′)-Iaa, sul1, qacE, blaOXA-129,tet(B), and aadA1. A point mutation in ParC at the 57th position (threonine → serine) associated withquinolone resistance was present in all investigated genomes. A 112,960 bp IncHI2A plasmid wasmappedin 4/6 strains. This plasmid harboured tetracycline (tetACDR) andmercury (mer) resistance genes, genescontributing to conjugative transfer, and genes involved in plasmidmaintenance. Most strains (four/six)carried Salmonella genomic island 1 (SGI1). All S.Mbandaka genomes carried seven pathogenicity islands(SPIs) involved in intracellular survival and virulence: SPIs 1-5, 9, and C63PI. The virulence genes csgC, fimY,tcfA, sscA, (two/six), and ssaS (one/six) were absent in some of the genomes; conversely, fimA, prgH, andmgtC were present in all of them. Five Salmonella bacteriophage sequences (with homology to Escherichiaphage phiV10, Enterobacteria phage Fels-2, Enterobacteria phageHK542, Enterobacteria phage ST64T, Salmonellaphage SW9) were identified, with protein counts between 31 and 54, genome lengths of 24.7 bp and 47.7 bp,and averageGCcontent of 51.25%. In the phylogenetic analysis, the genomes of strains isolated frompoultryin Brazil clustered into well-supp
In recent years, Salmonella enterica subsp. enterica serovar Mbandaka (S. Mbandaka) has been increasingly isolated from laying hens and shell eggs around the world. Moreover, this serovar has been identified as the causative agent of several salmonellosis outbreaks in humans. Surprisingly, little is known about the characteristics of this emerging serovar, and therefore, we investigated antimicrobial resistance, virulence, and prophage genes of six selected Brazilian strains of Salmonella Mbandaka using Whole Genome Sequencing (WGS). Multi-locus sequence typing revealed that the tested strains belong to Sequence Type 413 (ST413), which has been linked to recent multi-country salmonellosis outbreaks in Europe. A total of nine resistance genes were detected, and the most frequent ones were aac(6′)-Iaa, sul1, qacE, blaOXA-129, tet(B), and aadA1. A point mutation in ParC at the 57th position (threonine → serine) associated with quinolone resistance was present in all investigated genomes. A 112,960 bp IncHI2A plasmid was mapped in 4/6 strains. This plasmid harboured tetracycline (tetACDR) and mercury (mer) resistance genes, genes contributing to conjugative transfer, and genes involved in plasmid maintenance. Most strains (four/six) carried Salmonella genomic island 1 (SGI1). All S. Mbandaka genomes carried seven pathogenicity islands (SPIs) involved in intracellular survival and virulence: SPIs 1-5, 9, and C63PI. The virulence genes csgC, fimY, tcfA, sscA, (two/six), and ssaS (one/six) were absent in some of the genomes; conversely, fimA, prgH, and mgtC were present in all of them. Five Salmonella bacteriophage sequences (with homology to Escherichia phage phiV10, Enterobacteria phage Fels-2, Enterobacteria phage HK542, Enterobacteria phage ST64T, Salmonella phage SW9) were identified, with protein counts between 31 and 54, genome lengths of 24.7 bp and 47.7 bp, and average GC content of 51.25%. In the phylogenetic analysis, the genomes of strains isolate