City birds such as ducks and crows are carriers of potentially deadly antibiotic resistant bacteria, study finds
City birds such as ducks and crows living close to humans are 'reservoirs' of bacteria that are resistant to human antibiotics, scientists have discovered.
Antimicrobial resistance (AMR) is largely caused by the overuse of drugs such as antibiotics among humans and livestock.
It occurs when disease-causing microbes such as bacteria become resistant to antibiotics that would otherwise kill them.
The study found that wild birds living close to humans, such as crows and ducks, contained a wider range of bacterial strains, and up to three times more AMR genes than birds living in more isolated environments such as mountains.
It's thought this is because animals living in urban areas are exposed to contaminated rivers that could be a source of antimicrobial resistant bacteria.
The study, published in the Current Biology journal, found that wild birds living close to humans, such as crows and ducks, contained a wider range of bacterial strains, and up to three times more AMR genes than birds living in more isolated environments such as mountains
Antimicrobial resistance (AMR) is largely caused by the overuse of drugs such as antibiotics (pictured) among humans and livestock. It occurs when disease-causing microbes such as bacteria become resistant to antibiotics that would otherwise kill them
Researchers say this creates an urgent need for policy makers and health services to consider how antibiotic resistant bacteria AMR can spread outside hospital settings.
The issue is of serious concern, it is estimated that in England 58,224 people had a severe antibiotic-resistant infection in 2022, and 2,202 died.
In the study, published in the Current Biology journal, researchers analysed 700 samples of bacteria taken from the guts of 30 species of wild birds across eight countries, including the UK.
They looked at Campylobactor jejuni, a common diarrhoea-causing bacteria found in birds’ gut microbiomes — the bacteria, viruses and fungi that live inside us and on our skin.
Genetic signals associated with AMR were found across all the bird species studied.
This graph shows the combined direct and associated deaths from antibiotic-resistant bacteria per global region measured in the new research. Africa and South Asia had the greatest number of deaths per 100,000 people, however Western European countries like, the UK, still recorded a significantly high number of fatalities
Figures showed a recent sharp increase in the number of prescriptions for antibiotics following years of decline. According to the UKHSA, 58,224 people in England had an antibiotic-resistant infection in 2022, up four per cent on 2021
'Antimicrobial resistance is a complex problem that affects not only human health but also animals and the environment,' said Professor Samuel Sheppard, co-author of the research from the Ineos Oxford Institute.
'Wild birds have potential to transfer AMR over long distances to livestock raised for meat consumption and companion animals such as pets.
'This can have economic implications for agriculture, animal welfare, and food security.'
'Our study is the first to demonstrate that wild bird populations in cities are reservoirs of bacteria resistant to many important human antibiotics,' he added.
'There is an urgent need to understand how human activity is influencing the spread of zoonotic diseases and AMR.'
Birds can travel large distances, and many species identified in the study, such as crows and thrushes, are prevalent in urban environments, in close contact with humans.
Animals living in urban areas are exposed to various sources of antimicrobial resistant bacteria, such as wastewater-contaminated rivers, and could play a role in spreading these to humans.
As human populations continue to grow, urbanisation disrupts the existing environment as well as the animals that live there, potentially leading to increased contact between humans and wild animals.
The experts suggest the data provided by their research will be invaluable for future studies to understand the full impact of human expansion on the spread of zoonotic disease and AMR.
Professor Sheppard said: 'Our study highlights the need for co-ordinated global action that considers wildlife conservation, public health, and agriculture, to limit far-reaching impacts of AMR.'
