Sequencing tracks zoonotic transmission of pathogens

Sequencing tracks zoonotic transmission of pathogens

RESEARCHERS used whole-genome sequencing to reveal if drug-resistant bacteria were transmitted from animals to people in two disease outbreaks that occurred on different farms in Denmark.

The results, published March 25 in EMBO Molecular Medicine, confirmed animal-to-human transmission of methicillin-resistant Staphylococcus aureus (MRSA), a disease-causing bacterium that carries the recently described mecC gene that is responsible for resistance to the antibiotic methicillin.

Drug-resistant bacterial infections pose a significant challenge to public health and may have severe and sometimes fatal consequences. As the costs of whole-genome sequencing methods decline and the speed of analysis increases, it increases scientists' ability to use whole-genome sequencing to answer disease-related questions, an announcement said.

"We used whole-genome sequencing to see if we could determine if the two disease outbreaks were caused by the same bacterium and to investigate if the pathogens were transmitted from animal to humans or the other way around," senior author Mark Holmes from the University of Cambridge said.

"At first glance, it seems reasonable to expect the same pathogen to be the source of the two outbreaks at the two geographically close locations. By looking at the single differences in nucleotides or SNPs (single nucleotide polymorphisms) in the DNA sequences of each isolate, it became obvious that two different strains of bacteria were responsible for the two disease outbreaks," Holmes added. "In one case, the results also clearly showed that the most likely direction of transmission was from animal to human."

By comparing single differences in nucleotides in the two SNP sequences, the researchers were able to reach conclusions about the identity of the pathogens and the routes of infection.

The researchers emphasized that while whole-genome sequencing cannot replace traditional types of disease analysis, it can greatly increase the ability to distinguish between different pathogens as the cause of a disease.

Volume:85 Issue:13

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