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Investigating possible transmission of diseases from farm animals

Catherine Ludden talks about her research into possible links between bacteria from farm animals and humans.
This is Catherine, and we are going to be talking to her about her research on the transmission of E. coli between animals and humans. So Catherine, what’s your research involves? So during my research here I use a One Health approach to investigate the origin and transmission of antibiotic-resistant E. coli. This involves use of whole genome sequencing to determine the genetic relatedness of the strains but also the associated resistance genes that’s commonly carried on mobile elements. You mentioned One Health. What does this mean? One Health refers to the health of humans, animals, but also bacteria in the environment.
So really, we encourage collaboration efforts to be performed with veterinarians, connections, environmental scientist, so we could all come together to really understand the transmission of bacteria between different reservoirs. And the real aim of this is that we can potentially introduce effective interventions to minimise the spread of resistant bacteria between these reservoirs. So these transmission of bacteria between these reservoirs you’ve mentioned, is it common in the UK? Well this is one of the reasons why I prefer performing this research is because we don’t actually really know what’s happening. We know that for certain pathogens such as Salmonella and Campylobacter that there is transmission between animals and humans. And this happens sometimes through indirect contact, through food consumption. But really for E.
coli, we’re not too sure. E. coli commonly causes infections in humans, such as urinary tract infections, and bloodstream infections, but it also decolonizes the gut in animals and humans. So really what we don’t know is if the E. coli decolonizes the gut of animals, if this contributes to disease in humans. And this is why we’re looking at these transmission studies from one health approach to learn more about this. So by using genomics rather than the traditional molecular typing techniques. So previously in the literature, a lot of people have used a typing technique called Multilocus Sequence Typing. This is the abbreviation as MLST. And MLST uses typing based on seven housekeeping genes.
So it’s giving a unique allele profile, and therefore this is the ST type. So currently, the thinking is that there is transmission between animals and humans based on Multilocus Sequence Typing. However, with genomic sequencing, we have a lot more discriminatory power. So instead of using seven genes, now we can use thousands of genes than in the core gene in E. coli to compare the genetic relations of strains. And actually using the genome sequencing, we can dig deeper to learn more about how close the relation strains are.
And as a result I’ve seen, for example, one strain that could be Multilocus Sequence Type 10 in animals and could have the same ST in humans could actually be over 100 snips apart and even sometimes well over 1,000 snips. So really this is the great advantage of genomic sequencing is to dig deeper into the transmission. And what have you found from your research? So currently from the research that I’ve been doing, I’ve seen very little transmission between animals and humans. So I looked at E. coli strains that colonise the gut in animals. I’ve looked at E. coli in meat, and I’ve also looked at E. coli that causes invasive disease in humans.
And I’ve actually seen no evidence of recent transmission between animals and humans. So the findings of your research, what does this mean practically? Is it useful ? Well learning about the reservoirs of resistant bacteria is extremely important. It means that we can tailor interventions to what our research outputs have shown us. So for example, I’ve seen that acquisition of resistant E. coli in humans is mainly associated with human-to-human transmission. This result shows that if we want to put in an effective intervention, that really they should be focused in either in a hospital or in the community where we have human-to-human transmission.
But we also want to bring back the animal side, because we’ve seen that animal-to-animal transmission in farms, which means that if we want to reduce antimicrobial-resistant bacteria in farms, then really the intervention should be based at the farm level. But actually, bringing the data together is really important, because we need to know more about where these resistant bacteria are coming from. Thank you very much, Catherine.

In this video we hear from Catherine Ludden about her research into possible links between bacteria from farm animals and humans.

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Bacterial Genomes: Disease Outbreaks and Antimicrobial Resistance

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