The chairman of the hospital trust that was hit by an outbreak of a killer bug, claiming the lives of at least 21 patients has resigned.

James Lee stood down after Alan Johnson, the Health Secretary, announced a Department of Health review of his role leading the Maidstone and Tunbridge Wells Hospitals NHS Trust in Kent.

The trust faced withering criticism from the Healthcare Commission in a report into outbreaks of the C. difficile infection between 2004 and 2006.

Describing its findings as a "truly shocking document", Mr Johnson told MPs he wanted to apologise on behalf of the Government and the NHS.

Mr Lee faced criticism when it emerged that the trust's former chief executive Rose Gibb, who resigned days before the report's publication, was offered a severance package worth a reported £250,000.

Mr Johnson ordered the trust to withhold the payment, pending legal advice.

The Commission found that 1,176 patients were infected with C. difficile during two outbreaks of the bug at the Maidstone and Tunbridge Wells Hospitals NHS Trust between April 2004 and September 2006, of whom at least 345 later died. Its report concluded that C. difficile was probably or definitely the main cause of death in 90 cases and that there was no doubt it was to blame in at least 21 of the deaths.

Mr Johnson said: "We must all shoulder our share of the blame. But I hope the House will recognise the awful failures in Maidstone and Tunbridge are entirely unrepresentative of the standards of care that patients and the public rightly expect and is delivered across the country, day after day."

Andrew Lansley, the shadow Health Secretary, said the outbreak was not an isolated occurrence.

He said: "We have had other cases and the common link is that managers in the NHS have been more focused on the Government's targets ... than they have on patient safety."