Salmonella from imported Brazilian poultry doesn’t cause a lot of illnesses in UK consumers, according to a study.
Long-term surveillance data collected in the United Kingdom showed no rise in two types of Salmonella following the increase of these serovars in Brazilian poultry.
Scientists from the Quadram Institute, University of East Anglia, UK Health Security Agency (UKHSA), Animal and Plant Health Agency (APHA) in the UK and the University of São Paulo tracked how changes in chicken rearing in Brazil impacted the profile of Salmonella circulating within the poultry industry.
Brazil produces almost 14 million tons of chicken meat each year and is the largest exporter. Previous studies have shown the presence of Salmonella on meat imported into the UK and EU. Scientists wanted to know if the strains of Salmonella in Brazil were causing food poisoning in countries that import the products.
Focus on two Salmonella types
Researchers compared 183 Salmonella genomes collected from chickens in Brazil from 2012 to 2018 and 357 genomes from humans, domestic poultry, and imported Brazilian poultry in the UK. They also looked at more than 1,200 genomes of the two main types of Salmonella found in Brazil. Findings were published in the journal PLOS Genetics.
A survey of Brazilian poultry found dozens of different types of Salmonella, with Heidelberg and Minnesota, the most dominant. Of 318 samples from meat sent to the UK, 91 percent were either Heidelberg or Minnesota with most being the former.
The team looked at the types of Salmonella behind infections from samples going back 15 years. About one in 200 were attributed to Heidelberg or Minnesota, and some could be linked to recent foreign travel.
There was no official data on Salmonella infections in Brazil to assess the scale of the impact of these serovars on Brazilian public health.
By comparing the Brazilian Heidelberg and Minnesota genomes with others collected around the world, it was clear they formed a distinct subgroup separate from human cases. Work with the Animal and Plant Health Agency showed the Brazilian-associated Salmonella were not found in UK chickens.
Role of vaccine and antibiotic usage
Introduction of a Salmonella vaccine and increased antibiotic usage by Brazilian farmers led to the rise of strains that are more antibiotic-resistant, but less likely to cause disease in humans.
Intensive farming techniques used in Brazil to produce large amounts of chicken meat involves the use of antimicrobials. Salmonella Heidelberg and Minnesota had a combination of genes conferring resistance to different classes of antimicrobials: sulphonamides, tetracyclines and beta lactams. This likely gave them a competitive advantage in the poultry production environment in Brazil.
The team found that the two main Salmonella types developed in Brazil around 2006, a few years after the country introduced a Salmonella Enteritidis vaccine for poultry. Despite the rise, these antibiotic-resistant bacteria have caused very few cases of Salmonella in the UK and have not spread to domestic chickens.
Alison Mather, from the Quadram Institute, said they looked at how changes in chicken rearing in Brazil affected the profile of Salmonella in the poultry sector.
“Whilst this poses no immediate health risk to importing countries like the UK, the bacteria were resistant to antimicrobial drugs, and this highlights the importance of taking a One Health approach that sees the connections between the health of people, animals and the environment, especially when assessing global food supply chains,” Mather said.