Implications of Foraging and Interspecies Interactions of Birds for Carriage of Escherichia coli Strains Resistant to Critically Important Antimicrobials

• Published in: Applied and environmental microbiology Vol. 86; no. 20
• Main Authors: Mukerji, Shewli, Gunasekera, Samantha, Dunlop, James Nicholas, Stegger, Marc, Jordan, David, Laird, Tanya, Abraham, Rebecca Jane, Barton, Mary, O'Dea, Mark, Abraham, Sam
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01-10-2020
• Subjects: Animals; Antimicrobial agents; Birds; Cephalosporins; Charadriiformes - microbiology; Coastal environments; Columbidae - microbiology; Disease Reservoirs - microbiology; Disease Reservoirs - veterinary; E coli; Environmental Microbiology; Escherichia coli; Escherichia coli - isolation & purification; Escherichia coli Infections - microbiology; Humans; Laridae; Pigeons; Species; Spheniscidae - microbiology; Western Australia; Western Australia; CTX-M; Escherichia coli; ST131; bird; gulls; penguins; mobile genetic elements; Antimicrobial resistance; pigeons
• DOI: 10.1128/AEM.01610-20
• EISSN: 1098-5336
• ISSN: 0099-2240

Globally, gulls have been associated with carriage of high levels of
strains resistant to critically important antimicrobials (CIAs), a major concern, as these antimicrobials are the sole alternative or one among only a few alternatives available to treat severe life-threatening infections in humans. Previous studies of Australian silver gulls demonstrated high levels of resistance to CIAs, particularly fluoroquinolone and extended-spectrum cephalosporins, among
strains (carriage at 24% and 22%, respectively). This study aimed to identify and characterize strains from four distinct bird species inhabiting a common coastal environment, determine the frequency of carriage of CIA-resistant
strains, and examine if these resistant clones and their resistance-encoding mobile genetic elements (MGEs) could be transmitted between species. CIA-resistant
was detected in silver gulls (53%), little penguins (11%), and feral pigeons (10%), but not in bridled terns. In total, 37 different sequence types (STs) were identified, including clinically significant human-associated lineages, such as ST131, ST95, ST648, ST69, ST540, ST93, ST450, and ST10. Five main mobile genetic elements associated with
-positive
strains isolated from three bird species were detected. Examination of clonal lineages and MGEs provided indirect evidence of transfer of resistance between bird species. The carriage of CIA-resistant
by gulls and pigeons with proximity to humans, and in some instances food-producing animals, increases the likelihood of further bidirectional dissemination.
It has been shown that 20% of Australian silver gulls carry drug-resistant
strains of anthropogenic origin associated with severe diseases, such as sepsis and urinary tract infections, in humans. To further characterize the dynamics of drug-resistant
in wildlife populations, we investigated the carriage of critically important antimicrobial (CIA) drug-resistant
in four bird species in a common environment. Our results indicated that gulls, pigeons, and penguins carried drug-resistant
strains, and analysis of mobile genetic elements associated with resistance genes indicated interspecies resistance transfer. Terns, representing a bird species that forages on natural food sources at sea and distant from humans, did not test positive for drug-resistant
This study demonstrates carriage of CIA-resistant bacteria in multiple bird species living in areas commonly inhabited by humans and provides further evidence for a leapfrog effect of resistance in wildlife, facilitated by feeding habits.