The Growing Threat of Antibiotic-Resistant Bacteria in Urban Birds
Urban ducks and crows may seem like charming fixtures of city life, offering a connection to nature amidst the concrete jungle. However, recent research has shed light on a concerning issue: wild birds that live in close proximity to humans are more likely to harbor bacteria that are resistant to important antibiotics. This poses a serious threat not only to the birds themselves but also potentially to humans who come into contact with them.
Antimicrobial resistance (AMR) is a major global health concern, primarily driven by the overuse and misuse of antibiotics in human and animal populations. The consequences of AMR are dire, with approximately 4.95 million deaths worldwide in 2019 attributed to bacterial infections that were resistant to antibiotics. Among these deaths, 1.27 million were directly caused by antimicrobial resistance.
Researchers have found that certain species of wild birds commonly found in urban environments serve as reservoirs for bacteria with the hallmarks of antibiotic resistance. Samuel Sheppard, a coauthor of the research conducted at the Ineos Oxford Institute for Antimicrobial Research, explains, “Basically what we’re seeing are genes that confer resistance to antimicrobials that would be used to treat human infections.” This discovery raises concerns about the potential for these birds to transfer antimicrobial-resistant bacteria to other species, including captive birds intended for consumption by humans, such as those raised on poultry farms.
Research and Findings
In a study published in the journal Current Biology, Sheppard and his colleagues analyzed the genomes of bacteria present in 700 samples of bird feces collected from 30 different wild bird species across various countries, including Canada, Finland, Italy, Lithuania, Japan, Sweden, the UK, and the US. The focus of their investigation was on the prevalence of different strains of Campylobacter jejuni, a type of bacteria commonly found in birds as a natural part of their gut microbiome. While these bacteria are a leading cause of human gastroenteritis, antibiotics are typically only used in severe cases.
Normally, each wild bird species would be expected to harbor a single strain of C. jejuni specific to that species. However, the researchers discovered that wild birds inhabiting urban areas contained a significantly higher number of different C. jejuni strains compared to those living in more rural settings. Furthermore, the strains found in urban-dwelling bird species exhibited approximately three times as many genes associated with antimicrobial resistance, with these genes conferring resistance to a broader spectrum of antimicrobials.
The authors propose that wild birds may acquire antimicrobial-resistant bacteria through various means, such as scavenging for food at landfill sites (e.g., gulls and crows) or coming into contact with contaminated water sources polluted with human wastewater (e.g., ducks and geese). These findings highlight the potential for urban birds to serve as vectors for the spread of antibiotic-resistant bacteria to other wildlife and potentially to humans.
Implications for Human Health
The implications of antimicrobial-resistant bacteria in urban birds extend beyond avian populations and raise concerns about public health. Danna Gifford from the University of Manchester emphasizes, “While alarming, the risk of direct transmission of resistance from urban birds to humans is unclear. Poultry-to-human transmission, however, is well documented.” With increasing urban development encroaching on agricultural land, the proximity between urban birds and poultry raises significant concerns about indirect transmission of antimicrobial resistance through the food chain.
Andrew Singer, a researcher at the UK Centre for Ecology & Hydrology, underscores the need for further research to validate the findings and suggests precautionary measures to mitigate the spread of antibiotic-resistant bacteria. He advocates for preventing birds from congregating in areas with high pathogen and antimicrobial resistance levels, such as landfills, wastewater treatment plants, and animal waste sites. Additionally, he highlights the importance of eliminating the discharge of untreated sewage into rivers, which poses a risk of exposing wildlife and humans to human-associated pathogens and antimicrobial resistance.
Addressing the Issue
To address the growing threat of antibiotic-resistant bacteria in urban birds, collaborative efforts are needed among researchers, policymakers, and the public. Monitoring and surveillance programs should be established to track the prevalence and spread of antimicrobial resistance in wildlife populations, including urban birds. Public awareness campaigns can educate communities about the risks associated with antibiotic overuse and improper disposal of pharmaceuticals, as well as the importance of responsible waste management practices.
Furthermore, interdisciplinary research initiatives can explore innovative strategies for mitigating antimicrobial resistance in urban bird populations, such as the development of alternative treatment options for bacterial infections in birds. By fostering a holistic approach to combating antimicrobial resistance, we can safeguard both wildlife and human populations from the potentially devastating consequences of antibiotic-resistant bacteria.
In conclusion, the threat of antibiotic-resistant bacteria in urban birds underscores the interconnectedness of human, animal, and environmental health. By recognizing and addressing this pressing issue, we can work towards a sustainable future where antimicrobial resistance is effectively managed, protecting both wildlife and human populations from the devastating impacts of drug-resistant infections.
