Picking up an infection is the public's main concern about hospital care, a UK-wide BBC poll shows.
Of the 1,040 people quizzed, 40% listed the risk of potentially deadly infections such as MRSA and Clostridium difficile as their top NHS concern.
In a separate finding, 31% said they would consider avoiding NHS surgery for fear of getting an infection.
The government said it had introduced a raft of measures which were already having an impact in reducing infection.
Despite the concerns raised by the survey, 82% of respondents said they were proud of the health service, with half claiming it was still the envy of the world.
The most widely-cited concern after infections was the wait people face for treatment.
Despite the NHS in England, Scotland, Wales and Northern Ireland making shorter waits a priority, one in four people still cited this as a concern.
In England, which is the furthest ahead in reducing waits, no-one should be waiting longer than 18 weeks by the end of the year.
By comparison, a decade ago, waits of two years were not uncommon.
One in 10 polled also said that both the lack of staff and mixed-sex accommodation was their biggest concern.
However, it is superbugs which dominate people's thoughts in the poll carried out by ICM Research for the BBC.
Lack of confidence
Just 33% of respondents said they were confident that the NHS would protect them from picking up an infection in hospital.
In contrast, 94% were confident that the NHS would provide good care in an emergency such as a car crash, and 86% were confident it would deliver a baby safely.
Ministers have made tackling bugs a priority, launching initiatives such as this year's £50m deep clean of wards.
MRSA rates have been falling almost consistently for the last two years - although they have recently shown signs of stalling at just above 4,000 cases per quarter in England.
Nonetheless, the government is confident it will meet its target to halve rates this year based on a 2004 baseline.
The number of cases of C.difficile, which can cause severe diarrhoea and inflammation of the bowel and is more common but less deadly than MRSA, has also shown signs of falling.
Infection rates are even higher in Scotland, while in Wales and Northern Ireland they are slightly lower.
Dr Hamish Meldrum, chairman of the British Medical Association, said the findings on infection were of "huge concern".
He said: "We understand why people are so concerned about hospital-acquired infections and although infection rates are coming down, no-one can be happy with the levels that still exist.
"We owe it to patients to be able to prove to them that hospitals are a safe place to go to benefit from the help modern medicine can provide."
Professor John Appleby, chief economist of the independent think thank The King's Fund, said media coverage had fuelled fears about hospital infections.
"The good news from the NHS to the public is that in the last four years it has reduced the numbers of MRSA infections to a risk that is half the chance of getting four correct numbers in the lottery."
A Department of Health spokeswoman said it had "come a long way in tackling infections, but any avoidable infection is one too many".
"We have introduced a raft of measures that we know will reduce infection and are already having an impact," she said.
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"We have implemented 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."
Health Secretary Alan Johnson said hospital-acquired infections had always been a problem, but attention on the subject had become more intense.
"The latest statistics show that MRSA is down by 30% on this time last year, and C.diff is down by 23%.
"We have got a grip of this problem, but I am not surprised that people feel concerned."