Genome divergence and increased virulence of outbreak associated Salmonella enterica subspecies enterica serovar Heidelberg

Abstract

Salmonella enterica serotype Heidelberg is primarily a poultry adapted serotype of Salmonella that can also colonize other hosts and cause human disease. In this study, we compared the genomes of outbreak associated non-outbreak causing Salmonella ser. Heidelberg strains from diverse hosts and geographical regions. Human outbreak associated strains in this study were from a 2015 multistate outbreak of Salmonella ser. Heidelberg involving 15 states in the United States which originated from bull calves. Our clinicopathologic examination revealed that cases involving Salmonella ser. Heidelberg strains were predominantly young, less than weeks-old, dairy calves. Pre-existing or concurrent disease was found in the majority of the calves. Detection of Salmonella ser. Heidelberg correlated with markedly increased death losses clinically comparable to those seen in herds infected with S. Dublin, a known serious pathogen of cattle. Whole genome based single nucleotide polymorphism based analysis revealed that these calf isolates formed a distinct cluster along with outbreak associated human isolates. The defining feature of the outbreak associated strains, when compared to older isolates of S. Heidelberg, is that all isolates in this cluster contained Saf fimbrial genes which are generally absent in S. Heidelberg. The acquisition of several single nucleotide polymorphisms and the gain of Saf fimbrial genes may have contributed to the increased disease severity of these Salmonella ser. Heidelberg strains.Electronic supplementary materialThe online version of this article (10.1186/s13099-018-0279-0) contains supplementary material, which is available to authorized users.

Detection of virulence genes in Salmonella Heidelberg isolated from chicken carcasses

“…However, Antony et al . 14 detected the operon safABCD in strains isolated in USA between 2009 and 2017. This operon has been previously described as absent in this serotype 14 .…”

“…14 detected the operon safABCD in strains isolated in USA between 2009 and 2017. This operon has been previously described as absent in this serotype 14 . These results support the theory that modification in genetic profile of circulating SH strains are a possible reason for the increased detection of this particular serotype.…”

“…The increase in the occurrence of SH in food products and in SH-related infections is of concern to Brazilian authorities, since SH control and elimination from poultry farms is a major problem (data not shown). Changes in the acquisition of genes by SH strains have been reported in other animal species and have been considered as important factors that may have contributed to the increase of virulence 14 . In this context, the present study aimed to screen the 24 genes associated with virulence of SH isolates by polymerase chain reaction (PCR).…”

Genomic Evidence of Environmental and ResidentSalmonellaSenftenberg and Montevideo Contamination in the Pistachio Supply-chain

“…Next-Generation sequencing (NGS) now regularly allows for further investigation into the genomes of Salmonella enterica that are responsible for illnesses, outbreaks, (17)(18)(19) and other contamination events, including a determination of whether a resident strain may be causing contamination (20). Additionally, NGS techniques provide an abundance of data regarding virulence genes, phages, and antimicrobial resistance gene patterns.…”

“…Although these are different methods, the results are very comparable. WGS data are essential to fully characterize a bacterial pathogen of interest and can often assist in finding ways to prevent future contamination (17)(18)(19).…”