Medical tourists travelling from the UK to destinations in Pakistan and India may have contracted a superbug resistant to virtually all known antibiotics, experts warn.

A study in The Lancet finds bacteria that make an enzyme called NDM-1 have travelled back with NHS patients who went abroad for treatments such as cosmetic surgery.

To date some 50 cases have been recorded in the UK, with scientists warning it could spread further.

“The potential of NDM-1 to be a worldwide public health problem is great, and co-ordinated international surveillance is needed,” Timothy Walsh of Cardiff University and his international colleagues wrote.

Scientists explained NDM-1 can exist inside different bacteria, like E.coli, making them resistant to one of the most powerful groups of antibiotics - carbapenems.

This creates “an alarming potential to spread and diversify among bacterial populations”.

Study co-author Dr David Livermore, director of antibiotic resistance monitoring at the Health Protection Agency (HPA), said: “The findings of this paper show resistance to one of the major groups of antibiotics, the carbapenems, is widespread in India.

“This is important because carbapenems were often the last ‘good’ antibiotics active against bacteria that already were resistant to more standard drugs.

“International travel gives a great potential for spread of resistant bacteria between countries.

“Few antibiotics remain active against these bacteria.”

National Health

The department of health (DoH) confirmed an alert had already been issued.

The National Resistance Alert came in 2009 after the HPA noted an increasing number of cases - some fatal - emerging in the UK.

A statement also said normal infection control measures, such as disinfecting hospital equipment and doctors and nurses washing their hands with antibacterial soap, can stop the spread.

Currently, most of the bacteria carrying NDM-1 have been treatable using a combination of different antibiotics, the DoH added.