Galway University Hospital is to revamp its plumbing system over the next six weeks after the bacteria that cause Legionnaires' disease were found in its paediatric wing.

However, officials from the Republic's Health Services Executive (HSE) last night stressed that none of its patients has tested positive for the potentially fatal infection that can trigger pneumonia in vulnerable patients.

The bacteria legionella was found in a sink in the children's ward last week. It has also been detected at six other locations at the hospital over the past year, including St Teresa's ward, St Pius's ward, St Anthony's ward as well as the psychiatric wing and the nurses' home during routine monthly testing.

An HSE spokeswoman said hospital officials moved immediately to correct the problem. "When a high level was detected, the sink was taken out immediately and the water supply was shut off," she said.

"We've minimised any potential risk," she said, adding "we are fully satisfied that the measures taken provide protection against legionella infection for patients and staff in the paediatric department.

The bacteria can occur naturally in many water supplies but in order to minimise the chance of infection, routine tests are performed at the hospital on a monthly basis, she said.

"Many major hospitals throughout the world regularly test the water for legionella so that there is an opportunity to take action to reduce legionella in water before anyone develops infection. Once the risk is removed, it poses no further risk to patients or staff members," she said.

The hospital has put in place an infection prevention program in which old water tanks are replaced while anti-bacterial agents are added to the water. The hospital has carried out 360 water tests for the bacteria at the main hospital so far this year along with 100 tests at its Merlin Park facility.

Even though the bacteria have been detected six times at the hospital so far this year, no-one has ever come down with Legionnaires' disease, the spokeswoman added.

"The lab regularly tests patients with pneumonia for this organism and no cases of infection have ever been identified. Legionellosis is a notifiable disease and should patients be found positive, the Public Health Department would be notified. Legionella infection is not a common disease in Ireland and some cases diagnosed here have been in people who have returned from travel outside of Ireland," she added.