Kristin Weber (Wernigerode / DE), Michael Pietsch (Wernigerode / DE), Sandra Simon (Wernigerode / DE), Denise Dekker (Hamburg / DE), Antje Flieger (Wernigerode / DE)
Introduction: In Germany S. Enteritidis and S. Typhimurium are the most common serovars of the genus Salmonella enterica associated with foodborne illness. Typically, infection leads to gastrointestinal symptoms like diarrhoea, light fever and vomiting. However, also invasive non-typhoidal Salmonella (iNTS) infections especially in Sub Saharan Africa are known. Importantly, in recent years, an increase in the numbers of iNTS in Germany, among these infections due to S. Typhimurium and S. Enteritidis, has been observed at the National Reference Centre for Salmonella (NRC). Salmonellae of specific MLST sequence types (ST), such as ST 313, ST19 (S. Typhimurium) and ST11 (S. Enteritidis), are primarily responsible for iNTS cases in Sub-Saharan Africa, particularly in children under 5 years (case fatality rate of 20-25%). Additionally, these pathogens exhibit special resistance patterns, including resistance towards the antibiotic ceftriaxone, which belongs to the 3rd generation of cephalosporines.
Goals: We aimed to compare iNTS isolates from Germany with those from Sub-Saharan Africa to identify genomic signatures and infection phenotypes associated with invasive disease.
Materials and Methods: Selected S. Typhimurium strains isolated from blood and stool samples of Sub Saharan African and German patients were analysed for their virulence potential and genomic differences. Specifically, they were tested in cell culture infection assays to assess invasiveness and intracellular replication capacity. Further, bioinformatic analyses like creating a Gene presence/absence table (tools: PROKKA, Roary and Scoary) were performed to identify possible underlying genetic factors accounting for a difference in virulence.
Results: Within phylogeny of S. Typhimurium ST 19 strains, we identified a clade in which strains from Germany and Africa show higher invasiveness and intracellular replication in comparison to other strains tested. Genome comparisons are currently ongoing.
Summary: Invasive Salmonella strains occur in Africa as well as in Germany. Here, we would like to identify genetic factors (genes, pseudogenization, host factors) that contribute to higher invasiveness.