An Australian tradition of sharing fish and chips with seagulls may need a rethink after researchers found the birds carry a drug-resistant E. coli superbug.

Sharing your fish and chips with seagulls at the beach may harm your health, with researchers revealing the birds carry drug-resistant superbugs.

A study found Australian silver gulls were infected with antimicrobial-resistant bacteria that could cause illnesses in humans such as urinary tract infections and sepsis.

"Seagulls act as ecological sponges and we have earmarked them as a potential reservoir for agents that may cause human disease," Murdoch University antimicrobial researcher Sam Abraham said.

"This is the first comprehensive study establishing that seagulls across Australia are carriers of drug-resistant disease-causing E. coli that could affect humans."

More than 20 per cent of seagulls tested carried bacteria resistant to two commonly used antimicrobial drugs in humans.

Birds found in NSW and Victoria were also resistant to carbapanem drugs, used to combat antimicrobial-resistant infection in hospitals if other drugs fail.

A seagull at the popular Cottesloe Beach in Perth also carried resistance to colistin, which is a last resort drug to fight antimicrobial-resistant infection.

Researcher Mark O'Dea said it was the first time resistance to the drug had been recorded in an Australian wild animal.

"Seagulls could be acquiring this pathogen through their opportunistic feeding habits, where they scavenge from leftover human waste and may then be subsequently spreading these resistant bacteria over vast distances," he said.