London School of Hygiene & Tropical Medicine

Leading researchers from around the world gathered in France, for the International Symposium on Salmonella and Salmonellosis (I3S 2025). 

Assistant Professor Dr Zoe Dyson, who the AMR Centre funded to attend, presented her work on the genomic epidemiology of Salmonella enterica serovar Paratyphi A, a leading cause of enteric fever, at the event held from 23-25 June in the coastal town of Saint-Malo, France. Dyson was joined by other members of the Global Typhoid Genomics Consortium (GTGC), a group working to encourage genomic data sharing and reuse for reporting on AMR data of enteric fever pathogens.  The GTGC is coordinated by LSHTM researchers Dr Dyson, Dr Carey, Prof Holt, and colleagues from the University of Cambridge and University of Oxford.

I3S is an intimate and highly collaborative meeting held every three years in Saint-Malo, that brings together researchers from academia, industry, and public health laboratories. This year’s conference held sessions on identification methods, source attribution, host-pathogen interactions, epidemiology, ecology, and evolution.

For Dr Dyson, the highlight of the meeting was the discussion of what future integrated surveillance leveraging data from food, clinical, animal, and environmental sources, and a variety of techniques from genomic, laboratory, and epidemiological sciences might look like, and how this could inform on different drug-resistant Salmonella enterica serotypes that differ in their biology and epidemiology.

Zoe presented her poster titled “Diversity and antimicrobial resistance of Salmonella Paratyphi A: a collaborative global typhoid genomics consortium initiative”. The study, led by Dr Dyson, analysed ~3000 Paratyphi A genomes. The study highlighted high levels of ciprofloxacin non-susceptibility observed in multiple pathogen genotypes circulating throughout South Asia and Southeast Asia, and co-resistance to both ciprofloxacin and azithromycin is emerging in pathogen genotypes 2.4.4 and 2.3.3.

Dyson also demonstrated that travel-associated Paratyphi A genomes sequenced routinely by public health laboratories in high-income countries are a suitable means of sentinel surveillance for Paratyphi A pathogen populations circulating locally throughout Bangladesh, Cambodia, India, and Pakistan. These data can help fill gaps in formal surveillance programmes and provide insights where there are not yet established genomics surveillance programmes for enteric fever pathogens.

Dr Dyson said: “It was a privilege to attend the I3S conference, and have the opportunity to connect with a wide range of researchers working to combat drug-resistant infections driven by this important WHO priority pathogen. Connections made during this meeting have highlighted important opportunities for future collaborations.”