On any given day, some 80 000 patients in Europe are fighting an infection they picked up in hospital, often while in intensive care, the EU's disease monitoring agency said in a survey published on Thursday.
Although some of these infections can be treated easily, others like the superbug MRSA and other drug-resistant bugs can be fatal or affect patients' health very seriously, taking several months of costly hospital care and medication to beat.
A survey by the European Centre for Diseases Prevention and Control (ECDC) found that on any given day, one in 18 patients in European hospitals has at least one hospital-acquired infection amounting to around 3.2 million patients per year.
"Healthcare-associated infections pose a major public health problem and a threat to European patients," said Marc Sprenger, director of the Stockholm-based ECDC.
He said many of these infections could be prevented by well thought-out, sustained and multi-pronged prevention and control programmes and he urged hospitals to step up the fight.
"Such programmes, as well as prudent use of antibiotics, will help all actors involved to protect the patients of European hospitals," he said in a statement.
The ECDC warned last year that doctors are increasingly having to turn to last-ditch antibiotics due to growing drug-resistant superbug infections in Europe, many of them acquired in hospitals.
The latest survey, which covered 1 000 hospitals in 30 European countries, found the highest rates of hospital-acquired infections were among patients admitted to intensive care units, where 19.5% of patients had at least one bug they had picked up from the hospital.
The most common types of infection are respiratory tract infections such as pneumonia and infections of the bloodstream. These are often caused by Klebsiella pneumoniae and E. coli bacteria, both of which have shown an ability to develop resistance to some of the most powerful antibiotics.
Among a total 15 000 reported healthcare-associated infections, surgical site infections and urinary tract infections are also common. Many of the infections are also found to be drug-resistant "superbugs", the survey showed.
Among all infections with Staphylococcus aureus bacteria in which full testing was carried out, more than 40% were reported as resistant to methicillin , in other words they were MRSA infections, the ECDC said.
Worldwide, MRSA infects an estimated 53 million people annually and costs more than $20 billion a year to treat. It kills around 20 000 people a year in the United States and a similar number in Europe.
EU health and consumer affairs commissioner Paola Testori Coggi said the findings of the European survey were "worrying" and urged health authorities to do more to protect patients in hospital and to step up the fight against antibiotic resistance.
Drug resistance is driven by the misuse and overuse of antibiotics, which encourages bacteria to develop new ways of overcoming them.
Experts say hospitals are often guilty of overusing antibiotics, giving them as "blanket" treatments before full testing has established which drugs are really needed.