The prime minister's delivery unit is due to report this month on what more could be done to deliver the 2008 MRSA target.

A memo on healthcare-associated infections, which was sent to ministers in October last year, shows the extent of Number 10's concerns over the bug. It states: 'We have started a detailed piece of work with PMDU to analyse the impact of the current interventions and what more could be done to deliver the target in the time frame. This will include the potential impact of the system reform levers. Initial conclusions will be available in early January, when the effect of targeted support and recovery planning will be clearer.'

The PMDU is also mentioned when the document considers how to 'handle' the target, which the memo says the NHS is not on track to meet. It states: 'The MRSA target is regarded as one of our highest priorities by the PMDU. 'The document shows that of six options discussed - five of which assume dropping, changing or failing to hit the target - the PMDU only supports the option to 'keep the target and drive as hard as we can to meet it'.In the option to 'drop the target altogether' it states it would be 'difficult to get Number 10 to agree'.

The document discusses advice from its infection control experts that the target may never be deliverable. But it also notes more optimistic advice from 'others' who say it is too early to see the full impact of several measures. 'It could be that once they begin to bite we will see a sharper fall in the infection rate, but this will not be clear until January 2007.'