New strains of the MRSA infection have been detected in two patients at the Royal Glasgow Infirmary.

MRSA is resistant to many common antibiotics, but the new strains also show signs of resisting Vancomycin, one of the key remaining antibiotics which is effective.

BBC Scotland's Asad Ahmed has been speaking to the doctors

MRSA, which stands for Methycillin Resistant Staphylococcus Aureus, is carried by many people, and can easily spread in a hospital environment.

It generally only becomes dangerous to patients who are already in a weakened state through illness or injury.

Dr John Hood, consultant bacteriologist at the hospital's Infection Control Unit, said that while this strain showed increased resistance to traditional antibiotics, it was not yet immune to them and newer drugs were also available to combat it.

Hugh Pennington: "Very worrying"

"This is not an outbreak," he stressed. "We have two separate organisms and they are not linked and the patients are not linked.

"It is colonising patients - it is not, as far as we know, infecting them - and it is not spreading."

The two patients found to be carrying the new strains have not become ill from the rare VISA strain of the bug.

But Professor Hugh Pennington, who conducted the inquiry into the 1996 Lanarkshire E.coli infection, described the development as "worrying".

"If it turns out to be the case that this strain proves resistant to Vancomycin, that really is quite bad news and would confirm our fears that these bugs are developing a full house of resistance," he said.

Traditional drugs

"There is a fear that we might be left in the situation that we might want to treat the infection but will be unable to do so with traditional drugs."

He said that if a patient did become ill with the new strain, the hospital would try a new antibiotic which was being made available early.

A spokesman for the Public Health Laboratory Service said that although Vancomycin-resistant strains had previously been discovered in the US and Japan, Glasgow's were the first to be detected in Europe.

But Dr Ahilya Noon, a consultant in public health at the Scottish Centre for Infection and Environmental Health in Glasgow, said that Vancomycin-resistance had been found in strains in France and Bristol.

She said that although new antibiotics were constantly under development, Vancomycin currently represented a "last line of defence".

A microscope image of bacteria

She said hospitals were now working hard to prevent the spread of MRSA by instituting strict hand-washing and hygeine regulations, and screening patients for the bug before allowing them into areas filled with vulnerable patients.

"The incidences of MRSA are increasing in numbers in both England and Scotland.

"In Scotland, we had around 400 reports last year, compared to around 200 the year before. Hospitals are working very hard to contain it," she said.

Micro-organisms exposed to antibiotics can become resistant as a natural form of defence against them, in the same way as a human becomes immune after suffering certain infections.

The rise in resistance has been blamed on the overuse of antibiotics by doctors, which, particularly if patients do not complete the full course and eradicate the infection, allow new strains to develop.

The widespread use of antibiotics in farming has also been criticised.