Cases of superbug MRSA in English hospitals have fallen by more than a third over the past year, according to official figures released today.

Prime Minister Gordon Brown hailed the reduction as "dramatic" in a letter to all NHS staff congratulating them on exceeding their target of halving the cases of the potentially fatal hospital-acquired infection since 2004.

Figures from the Health Protection Agency for April to June showed a 14% decrease in hospital-acquired MRSA infections in England compared to the previous quarter, and a 36% reduction on the corresponding quarter of 2007.

Prime Minister Gordon Brown hailed the fall as "dramatic" in a letter to NHS staff released by Downing Street.

Official figures from the Health Protection Agency for April to June showed a 14 per cent decrease in hospital-acquired MRSA infections in England compared to the previous quarter - and a 36 per cent reduction against the corresponding quarter of 2007.

The fall in MRSA infections follows a drive to "deep clean" all NHS hospitals.

The HPA's quarterly report, released today, found that 836 cases of MRSA were reported in England from April to June this year, compared to 969 in the previous quarter and 1,306 in the same period of 2007.

The total fall since 2004 is 57%, said Mr Brown, adding that the latest figures show a 32% decline in another hospital-acquired infection, C difficile, over the past year.

The director of the HPA's Centre for Infections, Professor Peter Borriello, said: "The reduction of healthcare associated infections is a big challenge throughout the world and the falls we are seeing in cases of MRSA bloodstream infections demonstrate the huge efforts being made by NHS staff to tackle these infections.

"The next challenge for the NHS will be to ensure that the downward trend continues and that we move to a position of zero tolerance.

"Of course, not all cases are preventable but if the fight against healthcare associated infections is to be won, it is vital that the measures which have achieved this significant success remain in place and that both the public and healthcare workers recognise the importance of these measures."

In a letter to all NHS staff, released by 10 Downing Street, Mr Brown wrote: "This tremendous achievement is down to you, the staff of the NHS, and I wanted to write to thank you on behalf of everyone who relies on the NHS for your efforts over the course of the last year.

"These improvements come on top of significant falls in waiting times and they show that when you, the staff, are supported in the right ways you can achieve great things for the people of this country."

Anna Walker, chief executive of the Healthcare Commission hailed the figures as "a big success in the war against MRSA".

Ms Walker added: "Infections like this are not easy to control and they have had a real hold on hospitals in this country. The personal cost has in too many cases been terrible."

However, she warned that there was still a variation in performance between different trusts, and that some still do not have the necessary systems in place to fight outbreaks.

"Some are falling far short of targets to reduce rates of MRSA," she said. "Our message to those trusts is that reductions can be achieved and you must strengthen your approach.

The Government's "deep clean" programme for hospitals was announced last September and completed in March this year.

Health Secretary Alan Johnson issued orders for every NHS hospital in England to be scrubbed in a bid to tackle bugs like MRSA and C diff, backed by £50 million additional funding from the Department of Health.

The hygiene blitz followed the reintroduction of matrons to keep a close eye on the cleanliness of wards across the NHS, as well as a new "bare below the elbows" dress code for hospital staff to encourage regular hand-washing.

The scheme came in for repeated criticism from contract cleaners, the NHS Confederation and opposition parties, but ministers will be hoping that today's figures convince voters that it has been a success.

Mr Johnson said he was "absolutely delighted" that the targets had been achieved.

"This is a tribute to NHS staff. They have focused remorselessly on this, whether it is clean hands, whether it is isolation of patients that acquire infections, which is very important, or whether it's responsibly prescribing antibiotics, a big issue with C Difficile.

"There has been a total focus and the fact that we have not just met the target but exceeded it is brilliant news."

Mr Johnson acknowledged that public concern over MRSA had put pressure on the Government to take action, and praised the Prime Minister for his role in tackling the superbug.

"I think patients recognised this as their number one concern and I think the fact that the NHS is politically accountable meant that eventually politicians felt the hot breath of the public saying 'that is our priority'.

"And I think there is a certain feeling that it wasn't the priority that it should have been," he said.

"These things have developed all around the world and we're the Government that actually made it transparent and made it open.

"But I think if you look at what Gordon Brown did when he came into government last year, he decided that this was an absolute priority and so we had the introduction of the bare-below-the-elbows pre-screening that's been introduced in every hospital around the country, a whole series of measures, none of which on their own led to this reduction but all together meant they were a really big focus.

"So I think that the Prime Minister should take credit for actually deciding this shouldn't just be a public priority, it should be our priority."

Mr Johnson admitted that there was still work to be done to keep MRSA rates down.

"It's going to be sustained. It's obviously not a fluke because we have seen the reductions every quarter," he said.

"We have got everything in place now to maintain these levels of over 50% and drive them down to the lowest level we can get."

The Health Secretary was speaking during a visit to Imperial College Healthcare NHS Trust in London, one of seven "showcase hospitals" that will try new products to help reduce healthcare-associated infections.

The hospital's director of infection prevention and control, Dr Alison Holmes, said: "I think the figures are great news. Here we have reduced our MRSA numbers by over 60% over the same period.

"I think the main message is that this needs to be sustained, it really is deeply impressive that the country has done this but it is very important that locally we keep our eye on all infections and don't lose sight of all our patient needs."