The really big resistance problem is in hospitals

Professor David Livermore

But Professor David Livermore, director of the Antibiotic Resistance Monitoring and Reference Laboratory, London, UK, says new drugs do offer hope.

Speaking at the Public Health Laboratory Service Annual Scientific Conference in Warwick on Monday, he said it was important to keep ahead of the bacteria - which mutate to take account of new drugs developed to fight them.

It is in hospitals that the key fight to develop new antibiotics is being fought - and to some extent won.

'Fatal infections'

At any one time, 9% of patients in NHS hospitals are suffering from an infection acquired while on wards or in surgery, according to the National Audit Office.

It has estimated around 5,000 patients die every year, because of these infections, costing the NHS �1 billion annually.

Urinary tract infections are particularly common, but surgical wounds, skin and the bloodstream can all be infected with potentially deadly bacteria.

Scientists have to find antibiotics to treat two families of bacteria.

Gram positive bacteria include methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci - two notorious superbugs.

In development

Drugs are available, or in development, which can treat these. At the forefront are antibiotics called Synercid and Linezolid. Two more, Daptomycin and Oritacancin, are in development.

But the other "family" of bacteria - gram negative, particularly a type called Pseudomonas, are proving harder to treat.

Professor Livermore told BBC News Online: "We have got treatment options available for these particular, gram positive, forms of bacteria."

But he said: "Against gram negative, there are very few antibiotics."

There have also been fears that too much of prescribing of antibiotics by GPs has meant the drugs will be less effective for patients.

Professor Livermore said "less and better" prescribing of antibiotics would slow the development of resistance against the drugs.

But he said scientists had to keep "one step ahead" as bacteria became resistant to new antibiotics.

Professor Livermore added: "The really big resistance problem is in hospitals rather than in the community."