Cases of Clostridium difficile have fallen, but it is too soon to say whether the corner has been turned on tackling the hospital superbug, according to the Health Protection Agency (HPA).
The number of people over 65 reported to have the potentially deadly intestinal infection in England fell 13 percent in the three months to June compared to the previous quarter.
But the level had jumped 22 percent three months previously and an agency spokeswoman said it was not possible to determine a trend on just a quarterly basis.
The agency released annual figures for 2006 showing that incidents of the bug were still rising, up 7 percent at 55,620 cases, but at a slower rate than the previous year.
The government is under pressure to show success in reducing the level of superbug infections in NHS hospitals.
It has announced a 50 million pound ward-by-ward deep clean of hospitals and ordered medics to wear short-sleeved tunics to prevent accidental spread of infection.
Last month the chairman of the Maidstone and Tunbridge Wells Hospital Trust in Kent resigned after C. difficile outbreaks contributed to the deaths of 90 patients in its care.
The HPA said there had been a 10 percent annual fall in the number of bloodstream infections with the antibiotic-resistant bacterium MRSA, down to 6,381 cases in the 12 months to March 2007.
"These latest figures show a continuing downward trend in MRSA blood poisoning infections," said Pete Borriello, director of the HPA'S Centre for Infections.
"However, more work needs to be done to see the same level of decrease with C. difficile and we are encouraging (NHS) Trusts to use the figures to raise the profile of local infection control practices and make changes where the results indicate this may be necessary."
Health Secretary Alan Johnson said the figures were encouraging.
"Healthcare-associated infections pose a significant challenge for health services around the world, including the NHS, and we are determined to tackle them," he said.
"We are the only country in the world to impose mandatory, universal surveillance of MRSA and C. difficile, including for the first time gathering information on C. difficile in those under 65."
