The decision not to launch a criminal investigation into deaths at Maidstone and Tunbridge Wells trust will not set a precedent, NHS managers have been warned.

Kent Police and the Health and Safety Executive reviewed information from the Healthcare Commission before announcing they would not investigate further and no charges would be brought.

NHS Confederation policy director Nigel Edwards said the new Corporate Manslaughter and Corporate Homicide Act, which took effect this year, was intended to make it easier to bring cases but required a "very high" level of proof.

But he warned: "NHS trusts will be under no illusion that successful prosecutions are perfectly possible."

The decision not to prosecute anyone in connection with the deaths from C difficile was greeted with dismay by patients' relatives. But Kent Police said there was no information to indicate "grossly negligent acts" occurred.

HSE deputy chief executive Sandra Caldwell said: "We concluded that there was insufficient information to link the actions of any individual with the spread of infection or to show that any senior manager within the trust was personally responsible for any direct failure that led to infection."

The Healthcare Commission report last October said C difficile was definitely or probably the cause of deaths of 90 patients over a two-and-a-half year period. It described a catalogue of errors at the trust.

Chief executive Rose Gibb left the trust the week before the report was released. Her partner Mark Rees - a former trust chief executive - welcomed the announcement that no charges would be brought.

"I would suggest any further questions should be put to the leadership of the NHS and secretary of state as they are better placed to explain the real underlying causes and issues then existing throughout the NHS," he said.

Ms Gibb is pursuing the trust for full payment of a£150,000 payoff agreed before her departure.

Managers in Partnership, which is representing her, said: "Senior managers must be able to account for their actions, especially around patient and staff safety [and] this includes criminal investigation. All staff are responsible for safety but managers shoulder the greatest burden. What's important is that managers get a fair hearing and investigators consider the full background to managerial decisions."

The trust's new chief executive Glenn Douglas said: "We cannot change the past, but we can learn from it and that is what we have done. We are determined to ensure our hospitals continue to be as safe as possible for patients."