Researchers at NUI Galway’s School of Medicine and University Hospital Galway have discovered a form of superbug which is thought to be resistant to even the most powerful antibiotics.
The discovery of the NDM enzyme is thought to be the first of its kind in European seawaters.
According to the Irish Examiner, the two beaches in question are adjacent to each other and are located in Co. Galway.
Human sewage has been identified as the likely source of the bug which has been discovered in samples taken since last July.
Martin Cormican, one of the lead researchers, said:
"We have known for more than 100 years that proper control of sewage is a foundation stone for protection of public health, but in 2017 we are still allowing sewage to flow into the sea and rivers because we have not organised ourselves to build the treatment systems we need."