Infection by methicillin-resistant Staphylococcus aureus (MRSA) bacteria is increasingly common in hospitals, and there have been cases of bugs which show resistance even to vancomycin, an antibiotic traditionally regarded as "the last line of defence".

The news comes as doctors battle another MRSA outbreak in a Hampshire hospital.

While not dangerous, and often symptomless in more healthy patients, in the elderly, weak or immuno-suppressed, MRSA can cause fever and pneumonia.

Two-pronged attack

The new drug, Synercid, which could be available in the UK at the end of this year, contains two ingredients which work together to kill bacteria.

Because of this, researchers believe it will be far more difficult for bacteria to develop resistance to it.

It is the first new class of antibiotic to be introduced in the UK for a decade, and is given by injection.

Its manufacturer, Rhone-Poulenc Rorer is currently applying for a UK licence for the drug.

Foreign trials found that of 432 patients, half of whom had life-threatening bacterial blood infections, almost three-quarters were successfully treated.

Patient screening

The arrival of a new weapon against MRSA will be welcomed by infection control specialists at hospitals throughout the UK, many of whom have introduced complex procedures to limit the spread of the bug.

A large proportion of the healthy population are thought to carry MRSA strains without ever feeling ill, and many hospitals screen new patients with blood tests before they come into contact with other, more vulnerable patients.

Figures released the Public Health Laboratory Service show that the proportion of Staphylococcus aureus strains sent to them which are resistant to antibiotics has increased from 1.5% in 1991 to more than 31% in 1997.

Professor Gary French, Head of Clinical Microbiology and Infection Control at the Guys and St Thomas' Hospitals Trust in London said: "The emergence of intermediate-resistant strains to vancomycin in a number of countries is extremely worrying.

"If we get widespread resistance or tolerance to vancomycin, we will be back to the pre-penicillin era.

"That's why it's so important new treatment alternatives, such as Synercid, are developed and made available to hospital clinicians."

Vancomycin-resistant bacteria strains are still very rare in the UK, with two cases reported in Glasgow last month, and one previously in Bristol.

But there have been several cases in Japan, the US and France.

A major outbreak of the antibiotic-resistant MRSA bug this week forced a hospital to cancel operations for a week and place patients in isolation.

The bacteria was discovered at the Queen Alexandra Hospital in Cosham, Hampshire.

A clean-up operation is underway, with 13 patients placed in isolation, and 31 operations cancelled.

The rapid reproduction of bacteria means that genetic mutations which cause antibiotic resistance happen quickly and then spread swiftly.