Ireland is among a small number of countries where the use of 'last-line' antibiotics to treat serious infection is on the increase.
A European watchdog has expressed concern at the trend, which is linked to the rise of so-called 'super bugs'.
The fear is that the over-use of these hospital-prescribed antibiotics will leave even more patients at life-threatening risk in the longer term.
This is because bacteria are becoming increasingly resistant to the treatments.
The warning comes on European Antibiotic Awareness Day today.
Hospitals are repeatedly seeing patients that cannot be treated with carbapenems, a last-line antibiotic group, said the European Centre for Disease Prevention and Control.
It also showed that Ireland has the ninth-highest rate of antibiotic consumption outside of hospital in 30 countries.
The watchdog's acting director, Dr Andrea Ammon, said the issue was of "major concern".
"The further spread of bacteria resistant to carbapenems, a last-line group of antibiotics, is a cause for major concern in the EU as alternative options for the treatment of infected patients are limited.
"We are encouraged to see that many EU countries have taken action to combat it, with national plans and other measures.
"However, there is more work to be done at all levels, local, national and European," she said.
Dr Ammon added: "Decreasing antibiotic consumption in five countries shows that Europe is moving towards a more prudent use of antibiotics in the community.
"Prudent antibiotic use in both the community and in hospitals is critical to make sure that we are getting the most out of existing drugs."
The first global campaign for the better use of antibiotics will be launched by the World Health Organisation in World Antibiotic Awareness Week, beginning today.
This is intended to remind the world that bacterial resistance to antibiotics is growing and to highlight the importance of reducing the use of antibiotics whenever possible.