The deaths of six patients at Dublin's Mater Hospital last year have now been linked to a powerful superbug.
The six were among 71 found to have the clostridium difficile or C. difficile bug at the Mater between July and December last year.
According to the results of a study presented at a recent conference, the bug "appears to be endemic" at the Mater.
At least 10 patients (all with toxin-variant C. difficile) developed severe pseudomembranous colitis, six of whom died, it said.
Details of the study were published in yesterday's Irish Medical Times.
The C. difficile bacterium is commonly found in the intestinal tract during or after a course of antibiotics, and causes several million cases of diarrhoea and colitis around the world each year.
Patients can pick up the bug in hospital, and the primary treatment is to stop using the antibiotic.
A spokesman for the Mater said: "The figures in 2003 and 2004 have been the lowest they have been for some time due to better infection control methods and also reduced use of cephalosporins [antibiotics], particularly among the elderly."
The results of this study come within a week of reports that 189 patients in the main Dublin teaching hospitals were last year identified as having methicillin-resistant staphylococcus aureus (MRSA), another hospital-acquired infection.