Salmonella vaccine for poultry contributed to rise of antibiotic-resistant bacteria

An investigation into the evolution of Salmonella bacteria infecting Brazilian poultry showed that the introduction of a Salmonella vaccine, combined with increasing antibiotic usage, led to the rise of strains that are more antibiotic-resistant, but less likely to cause disease in humans. These findings are published in the open access journal PLOS Genetics.

The researchers compared the genomes of 183 Salmonella collected from chickens in Brazil and 357 Salmonella genomes collected from humans, domestic poultry, and imported Brazilian poultry products.

They found that distinct lineages of the two main Salmonella types. These bacteria possess genes that make them resistant to three types of antibiotics. But despite their rise, these antibiotic-resistant bacteria have caused very few cases of Salmonella in humans and have not spread to domestic chickens.

Overall, these findings suggest that the use of the Salmonella vaccine, along with greater antibiotic usage, enabled the rise of drug-resistant forms of Salmonella, but that these bacteria have not led to greater numbers of food poisoning cases. Hence, it is important to evaluate theSalmonellagenomes from a range of sources.