By Nick Triggle
BBC News health reporter
Hospital bosses have rounded on Tory leader Michael Howard after he leafleted thousands of homes quoting misleading figures about MRSA rates.
Mr Howard was trying to draw attention to his party's plan to tackle MRSA
In North Yorkshire, leaflets from Mr Howard claimed there had been 247 MRSA cases at the local hospital in the last year when there had only been six.
Several other trusts have told the NHS Confederation similar misleading claims have been made about their MRSA rates.
The Tories said they should have made clear these were regional figures.
Leaflets have gone out to areas across the country which the Tories are targeting.
A spokeswoman for the party said it was not possible to say how many areas had been affected.
And she added: "The leaflets should have made it clear that they were referring to hospitals across the region, and not just in the local [constituency].
"We do not want it [the mistake] to detract from the greater issue. Nationally 5,000 people die every year from hospital acquired infections."
About 10,000 leaflets went to residents in Harrogate and Knaresborough, saying there were 247 MRSA cases in the last year in the local NHS trust.
But the figure actually refers to the regional total for Leeds, York and Harrogate.
In the letter, Mr Howard said he was wanting to draw attention to his party's plans to tackle the hospital superbug.
A spokeswoman for the Harrogate and District NHS Foundation Trust, which runs one hospital, said the trust had written to the local paper to allay people's concerns as the figure may have caused alarm.
"We are a foundation trust and work very hard to tackle MRSA. Six people have contracted MRSA in the last 12 months.
"They seem to have added up the figure for the region, but the letter implies it is just one hospital."
Residents in Twickenham, Surrey, received letters saying there had been 166 MRSA cases, but the two local hospitals only had 60 in 12 months.
Dr Gill Morgan, chief executive of the NHS Confederation, which represents hospital bosses, said several other trusts had come forward with similar disparities.
"We are extremely concerned about the public fears that may have been raised by the Conservative Party letter about MRSA rates at voters' local hospitals.
"We fear it could create a misleading picture and damage the reputation of local hospitals up and down the country where frontline staff and their managerial and support staff colleagues are working so hard to tackle MRSA."
She said the confederation agreed that tackling MRSA was a top priority and a legitimate subject for debate during the general election.
But she added: "That debate needs to based on accurate facts that aren't open to being wrongly interpreted by voters."
Liberal Democrat health spokesman Paul Burstow said: "This is fighting the election by frightening elderly people for no good reason.
"It is running down the NHS and hardworking staff and playing on people's fears."