Hospitals have been put on alert about a group of new superbugs brought into the UK by patients returning home after surgery abroad, including cosmetic treatments and organ transplants.

The virulent new strains of drug resistant bacteria, which are much harder for doctors to tackle than MRSA or Clostridium difficile, have killed two people and left 18 others seriously ill in 12 months.

At least 17 hospitals in England and Scotland have seen cases, prompting the Health Protection Agency to issue a warning about what it calls “a notable public health risk”. The bacteria can cause wound infections, septicaemia, pneumonia and gastroenteritis and are posing real problems for the NHS because they are proving resistant to all the usual antibiotics.

This year hospitals have reported seeing the infections in at least nine UK nationals who appear to have acquired them while staying in hospitals in India and Pakistan after having “tummy tuck” surgery, liver and kidney transplants or surgery following a car crash. Previous cases have emerged in holidaymakers who picked up the bacteria while hospitalised in Greece and Turkey after a moped accident.

But doctors are worried because the latest strains, known as enterobacteriaceae, produce enzymes that attack and counteract powerful antibiotics called carbapenems which the NHS relies on as its last line of defence against particularly damaging infections.

The HPA admits that tackling the threat posed by the bacteria “presents major challenges, [as most of them] are resistant to all standard intravenous antibiotics for treatment of severe infections”.

John McConnell, editor of the medical journal the Lancet Infectious Diseases, said: “There’s the potential for this to become a substantial problem of antibiotic resistance within UK hospitals, and there’s not much we can do at the moment.

MRSA

“Compared to MRSA or C difficile or a regular pneumonia-type infection this is pretty small beer, purely in terms of the number of cases so far. But small beer is the way that things like MRSA started. These cases could be the start of what could go on to be a major cause of healthcare-acquired infections.”

The situation is so serious that the HPA is urging pharmaceutical companies to urgently start producing drugs that are effective against these types of bacteria. McConnell said the government should offer financial incentives.

Dr David Livermore, the HPA’s director of antimicrobial research, said doctors had been forced to fall back on two drugs which had previously been abandoned. However, one of them, Polymyxin is very toxic, which means doctors have to be very careful about the doses they give.

The bugs are four categories of carbapenem-destroying enzymes known as carbapenemases. The HPA’s antibiotic resistance monitoring and reference laboratory (ARMRL) “urges hospitals to be vigilant to multiresistant gram-negative bacteria in patients with recent hospital contact in the Indian subcontinent as well as the eastern Mediterranean”. Samples from any patients testing positive should be sent to the lab for further investigation. Israel and the US are also classed as countries which have been “a repeated source of introduction to the UK”, says the HPA.

Scientists at the ARMRL are alarmed by the recent emergence of the New Delhi Metallo-1 enzyme, which has been found in patients who have been operated on in New Delhi in India and Karachi in Pakistan. However, while they warn that that strain has “been repeatedly imported into the UK from the Indian subcontinent” they are also concerned that “there may now also be UK circulation since some affected patients have no immediately identifiable overseas links”.

In 2007 two unconnected patients at an unnamed Scottish hospital tested positive for enterobacteriaceae, prompting speculation that a local reservoir was the source of the infection.

Livermore said the NDM-1 variant had proved resistant to all usual antibiotics used in severe infections. “We are getting to our last line of antibiotics. Over the past one and a half years we have seen more and more cases. There have been two fatalities [this year], but we can’t say if [carbapenem resistance] was the direct cause as they were people who were very unwell.”

Some 77,000 Britons travelled abroad for surgery or cosmetic or dental treatment in 2006 and it is estimated 150,000 will do so this year.