The number of patients contracting the hospital bug Clostridium difficile (C diff) is falling, figures showed today.

There were 6,257 cases in patients aged 65 and over between October and December 2008, data from the Health Protection Agency (HPA) revealed.

This represents an 11% drop on the previous quarter, when there were 7,062 cases, and a 38% fall on the same quarter in 2007, when there were 10,012 cases.

Today's figures also show there were 1,649 cases of C diff in people aged two to 64 between October and December 2008. Another 7,906 infections were found in babies aged under two. Both sets of figures represent a slight drop on the previous quarter.

C diff is linked to the use of antibiotics and can occur when normal, healthy intestinal bacteria is being killed off by the drugs. It causes diarrhoea and particularly affects the weak or elderly.

An HPA spokeswoman said: "Cases of C difficile have fallen again this quarter, demonstrating how hard NHS staff are working to fight healthcare-associated infections.

"However, to see ongoing reductions and to win the fight against C difficile we cannot afford to take our eyes off the ball; winning the fight will only happen with continued dedication and hard work.

"Healthcare-associated infections are a global problem and remain a challenge for all of us. Robust infection control and appropriate use of antibiotics remain key to tackling infections such as C difficile.

"It is important to remember that some healthcare associated infections can arise as the result of the treatment of other life-threatening infections, and as such, can be difficult to avoid."

She added: "However, this shouldn't lead to complacency around tackling the infections that are preventable and engaging in the battle to continually drive down rates of healthcare-associated infections."

Nigel Ellis, head of national assessment and inspection at the Care Quality Commission, said: "Last month it was reported that rates of MRSA fell again and now we are seeing the same trend with C difficile.

"Overall, NHS trusts are continuing to strengthen their grip on infection control, which is good news for service users. They must remain vigilant to ensure that all healthcare-associated infections are kept down.

"We are monitoring NHS providers to check they are maintaining tight practices for infection control, including good antibiotic prescribing, cleaning and decontamination."

The shadow health secretary, Andrew Lansley, said: "Despite the welcome decrease in the last quarter, there are still an appalling number of people catching hospital infections in this country.

"And it's shameful evidence of Labour's failure that deaths from Clostridium difficile every year are now more than eight times higher than they were when Labour came to power.

"Far too many patients are catching infections like Clostridium difficile as a result of having to share overcrowded wards."

But the care services minister, Phil Hope, said: "This data shows that the NHS is continuing to make excellent progress in reducing the number of C difficile infections and is on track to achieving its target of reducing the number by 30% by 2010-11.

"This, together with the ongoing progress that is also been made in reducing the number of MRSA cases by more than half, is a tribute to the hard work of staff working throughout the NHS.

"However, one avoidable infection is one too many and we will continue to battle infections on every front to reduce them still further."