The number of superbug infections at St George's Hospital fell in the last quarter of 2007 but the council's health chief has warned infection rates still need careful monitoring.

While MRSA rates at the hospital remained constant C Difficile rates jumped in November before falling again in December.

A St George's Healthcare Trust spokesman said: "The number of cases of C difficile will vary month by month, partly because of a seasonal variation - rates usually peak during winter - but also because the number and type of patients we are seeing.

"However, we are on target to reduce our rates of C difficile by 10 per cent by March 2008.

Overall during the last quarter of 2007, our rates have dropped more than a third compared to the same quarter in 2006.

"We have not have had a case of hospital-acquired MRSA bloodstream infection in the last three months. The few cases we have seen already had the infection when they were admitted to St George's, although diagnosed here, these were therefore classified as having acquired the infection elsewhere."

Ian Hart, chairman of Wandsworth Council's health and overview committee, said the hospital was now providing it with superbug figures on a regular basis but sounded a note of caution. He said: "The C-difficile figures were worryingly high for November, which indicates an underlying problem there.

"The lower figures in December are explained by the Christmas break.

"We need to continue to monitor the figures over a longer period to ascertain if the long term trend is downwards."

The hospital made national headlines last October when it was discovered 116 people in three years had died of superbug related deaths at the hospital.