Seagulls from a species that feeds on human rubbish are harbouring highly-drug-resistant superbugs, a study has found.
Researchers analysed 57 samples of droppings from the yellow-legged gull Larus cachinnans. They found that one in 10 carried superbug bacteria resistant to the “last-resort” antibiotic vancomycin, which is used when most others have failed. The white and grey birds, recognisable by their bright yellow legs, can often be seen flocking on rubbish tips, and are common in many southern parts of the UK.
Scientists collected the samples from an island off the Portuguese coast.
Lead researcher Dr Gilberto Igrejas, from the University of Tras-os-Montes and Alto Douro in Portugal, said: “We used a novel technique called proteomics to detect the maximum number of bacterial proteins which are thought to be connected in some, as yet unknown, way to antibiotic resistance. “Our comprehensive description of the proteins that we found may provide new targets for development of antimicrobial agents. This knowledge may also help to identify new biomarkers of antibiotic resistance and virulence factors.”
Yellow-legged gulls are scavenging omnivores and opportunistic marine feeders. They will readily eat from food sources provided by humans, especially garbage.
It is thought the gulls might be one explanation for how antibiotic resistance is spread from place to place.
“Migrating birds that fly and travel long distances can act as transporters, or as reservoirs, of antibiotic-resistant bacteria and may consequently have a significant epidemiological role in the dissemination of resistance,” said Dr Igrejas.
The research was published yesterday in the online journal Proteome Science. The yellow-legged gull has only recently been recognised as a species in its own right, having previously been classified as a type of herring gull. Adults have darker grey backs and wings than herring gulls but are paler than lesser black-backed gulls.
The scientists identified several strains of enterococcus bacteria in the seagull samples. Enterococcal bugs often live harmlessly in the human gut but can cause serious infections in vulnerable people, including hospital patients.
Experts fear the bacteria may transfer genes for antibiotic resistance to other microbes such as Staphylococcus aureus, giving rise to more dangerous strains.
The MRSA superbug is a variant of Staphylococcus aureus.