A health trust in Northern Ireland has said it may have to put new practices in place to better monitor the hospital bug Clostridium difficile.
C. difficile is largely recognised as a hospital-acquired infection
The South Eastern Trust said six people had died of the bug last year.
However, it still does not know the number of cases where C difficile was a contributory cause, as that information is not recorded on death certificates.
Trust microbiologist Dr Hugh Webb said the trust does not yet use these to compile its figures.
The South Eastern Trust was the second trust to publicly state the number of deaths from the bug last year but had to revise the number from 48 to six when it checked its records.
The figure of six relates to the number of people who died where C difficile was the primary cause of death.
Dr Webb said: "The death certificates are held at ward level and, of course, death certificates are available to families and relatives.
"We don't have a mechanism to readily collate death certificates from all the wards at present. It may be that we will have to develop systems to do that."
SDLP assembly member Carmel Hanna, of the assembly's health committee, said a new system should be put in place quickly.
"It may have been practice in clinical terms to have primary and secondary causes of death and, quite often, a death certificate might only have the major cause," she said.
"But the more detail, especially of infection, may help pinpoint the source and it is a very important part of research and reduction in the prevalence."
On Wednesday, the Northern Health Trust said there had been three more deaths in its current outbreak of C difficile.
It brings to 23 the total number of deaths linked to the bug in the trust's area since last summer.
The bacterium causes diarrhoea and can even lead to a rupturing of the bowel. It tends to affect the over 65s.
The Northern Health Trust recently identified a virulent strain called ribotype 027.
It is believed to be the first time this strain has emerged in Northern Ireland.