Pets in a British animal hospital have been found to be harbouring potentially lethal drug-resistant bugs that could be transferred to owners.

Tests by Public Health England (PHE) revealed three cats a dog were colonised by bacteria able to fend off Linezolid, a “last-resort” antibiotic used to treat superbugs such as MRSA (methicillin-resistant Staphylococcus aureus).

No staff or owners are known to have been taken ill as a result, however the agency last night warned veterinary surgeries to enforce proper cleaning practices after this first discovery of its kind.

Experts said it implies that resistance to one of a shrinking number of last-resort antibiotics can spread between different bacterial populations in animals and humans.

Dr Katie Hopkins, from PHE, who led the research, said: "This is concerning as transmission of this organism to owners carries the potential for spread to other bacteria, including Staphylococcus aureus.

"This may lead to difficult-to-treat infections. In order to minimise transmission of resistant bacteria between companion animals and people, veterinary surgeries need to ensure adequate cleaning takes place and pet owners should wash their hands after handling pets."

The gene that enables bacterial resistance to linezolid is known as optrA.

Dr Hopkins said it was thought to be the first time optrA-positive enterococci had been identified in pets in the UK.