The number of deaths linked to hospital bug Clostridium difficile has soared in England and Wales, figures from the Office for National Statistics show.
Tackling hospital infections is a top government priority
Between 2005 and 2006 the number of death certificates which mentioned the infection rose by 72% to 6,480, most of which were elderly people.
In over half of cases, it was listed as the underlying cause of death.
It is thought that some of the increase may be due to more complete reporting on death certificates.
Deaths involving C. difficile increased by 77% in men, and 66% in women between 2005 and 2006.
Rates in both sexes have gone up dramatically since 2001, when there were only 1,200 mentions of the infection on death certificates.
The ONS figures also showed deaths involving MRSA remained roughly the same between 2005 and 2006 - at around 1,650.
C. difficile usually affects the elderly, and can prove fatal if antibiotic treatment fails to kill all the spores in the gut, and they take hold again before the patient's own gut bacteria have had chance to mount a resistance.
It is also very difficult to eradicate from the ward environment, which means it is easy for other patients to become infected.
Professor Brian Duerden, chief microbiologist at the Department of Health, said in July 2005 they called for more accurate reporting of infections such as MRSA and C. difficile on death certificates.
"These statistics from 2006 show that this move has worked and our figures are now in line with other developed countries.
"Since 2006 we have taken significant steps to tackle infections.
"These include stringent hand-washing guidance for the NHS, a bare below the elbows dress code, putting matrons back in charge of cleanliness on their wards and an ongoing deep clean of every ward."
And he added hospital infection rates were now falling.
The Health Protection Agency reported in November 2007 that rates of C. difficile infection may be levelling off with the number of new cases down 7% to 13,660, while MRSA cases are falling.
Liberal Democrat health spokesman Norman Lamb said: "These figures beg the question of why it took so long for the government to realise the seriousness of deadly infections such as C. difficile.
"Recent successes in keeping infection rates down are down to the hard work of NHS staff, who are up against enormous pressure to hit targets while keeping their wards infection-free."
Shadow health secretary, Andrew Lansley, said: "Almost three times as many people are now killed by hospital infections as are killed on the roads each year.
"The overall scale of infection is unacceptable and the need for a comprehensive infection control strategy, including improved antibiotic prescribing and access to isolation facilities, hand hygiene and cleanliness is paramount."
He added: "An expert told the Department of Health last week that it was the government's failure to implement guidelines since as far back as 1994 that has contributed to the recent rise."