Pressure on hospital beds led to the superbug outbreak in Wales last year that claimed three lives, an inquiry says.
The Healthcare Inspectorate Wales review of a Clostridium difficile 027 outbreak at the former North Glamorgan NHS Trust, found that wards, which had been closed because of the infection, were opened in a bid to relieve pressures.
And the report said the trust had over-prescribed antibiotics, increasing the risk of vulnerable patients catching the bug, which causes severe diarrhoea.
A total of 37 patients at Prince Charles and St Tydfil hospitals in Merthyr Tydfil and at Aberdare and Mountain Ash hospitals, became ill during the outbreak in March and April last year.
Three patients died after catching the more virulent 027 strain of C.diff.
The report said the decision to open closed wards early at Prince Charles Hospital prolonged the outbreak.
"It is clear that at the time of the outbreak the trust was experiencing significant bed pressures, due to high bed occupancy rates and long lengths of stay associated with patients with chronic conditions, which are exacerbated during the winter months," the report said.
It also found that there was a shortage of infection control staff at the time in the trust, which was in the process of a merger to become part of the larger Cwm Taf NHS Trust.
Tina Donnelly, director of the Royal College of Nursing in Wales, said: "All trusts should ensure nurses and other healthcare professionals receive adequate training in infection control and sufficient funding is ring-fenced to provide the training."
The former North Glamorgan NHS Trust also ignored its own infection control plans, which stated that patient transfers to community hospitals should be kept to a minimum.
Before the outbreak was declared on March 28, a number of patients with diarrhoea and vomiting were transferred out of Prince Charles Hospital for rehabilitation.
A final factor in the outbreak was a simultaneous Norovirus outbreak, which HIW contributed to the cases of C.diff, Wales Online reported.
"Norovirus is also highly contagious and patients with this virus may also be colonised with Clostridium difficile spores and hence the need for the careful management of any patient with symptoms of diarrhoea is of paramount importance," the report said.
But Peter Higson, HIW's chief executive, added: "North Glamorgan NHS Trust. now part of Cwm Taf NHS Trust, must be commended for recognising the seriousness of their situation in the spring of last year and for taking urgent steps to manage the Clostridium difficile outbreak.
"However, it is a tragedy when patients die as a result of an infection outbreak and it is entirely right that HIW should be asked to review the management of infection outbreaks to check whether improvements can be made and lessons need to be learned."
Dr Tony Jewell, Wales' chief medical officer, said: "We welcome the publication of the HIW report, which assures us that the trust takes the issue of infection control and management seriously and responded appropriately to last year's outbreak.
"However, it does recognise it has more to do to reduce infection further and we expect them to address concerns swiftly."