The first two Irish cases of MRSA which displayed resistance to the main antibiotics used to treat serious cases of the infection over the past few decades have now been documented.
The cases were detected in August and have been confirmed by the Centers for Disease Control in the United States.
One was in a male patient (67), who had undergone heart surgery, and the other was in a female patient (58), on renal dialysis. They were being treated in different hospitals.
Their MRSA showed "some resistance" to glycopeptide antibiotics, such as vancomycin and teicoplanin, which have been the mainstay treatments of serious MRSA infections over the last 20 to 30 years.
Dr Brian O'Connell, director of the National MRSA Reference Laboratory, said the first cases of this kind worldwide had been documented in Japan in 1997.
"Since then a small number of other cases have been described around the world but they are not too common. We have now described the first cases in Ireland."
He said the development wasn't surprising as it was almost inevitable with antibiotic use that one got antibiotic resistance.
The good news was, he said, that there were newer antibiotics that could be used to treat patients with serious MRSA infection if they showed resistance to the mainstay drugs of the past.
The Irish cases have just been reported in EPI-Insight, a monthly publication.