An investigation has begun at a Kent hospital where six people died from the diarrhoea bug clostridium difficile.
Eileen Wilson died at Maidstone Hospital from the bug in May
The deaths at Maidstone Hospital happened earlier this year, causing another 136 infections.
Maidstone and Tunbridge Wells NHS Trust and the strategic health authority requested an investigation by the Healthcare Commission.
Trust chief executive Rose Gibb said the inquiry would scrutinise the hospital's handling of the outbreak.
In a statement, she said: "The trust takes the care and safety of its patients extremely seriously."
She added that the trust would be working to bring in "any additional measures that can be made to further improve patient care and safety".
A review by the trust found that clostridium difficile was the definite cause of six deaths.
Another 14 patients who died were found to have the bug - the trust said it was a contributory factor in their death, but not the main cause of death.
It added that a further four patients who died also had the bug, but that it was unlikely to have led to their deaths.
The Healthcare Commission said it would be interviewing patients, staff and others.
Nigel Ellis, head of investigations, said: "We recognise that outbreaks of infection such as clostridium difficile are not always easy to control, but when they do happen they pose a very serious risk to patient safety.
"We need to find out what happened."
The bug primarily affects elderly people or those who are already ill
Meeting dates have been set for 11 and 12 October in Maidstone and Tonbridge.
Paul Wilson, whose mother Eileen, 83, died in May, said: "I hope the investigation will mean that fewer people are going to die, that you can bring your parents and children to the hospital and be able to come out and not catch a bug that's going to kill."
After the outbreak in April, the trust said infection control measures were being taken.
Measures included stricter hand washing controls, additional hospital cleaning and dedicated wards for those infected.
It said that powerful antibiotics could kill the bug, but some patients were resistant to the treatment.
The bug primarily affects elderly people or those who are already ill.