The number of cases of an "almost untreatable" superbug are on the rise, according to NHS data.
CPE, or carbapenemase-producing Enterobacteriaceae, has proved immune to even the most powerful antibiotics, including the so-called last-line drugs.
Figures from the US-based Centers for Disease Control and Prevention show that 40 to 50% of patients with CPE bloodstream infection die.
Since 2009, at least 81 people infected with CPE have died at 66 NHS Trusts in England, Public Health England (PHE) said.
The number of cases is now running at around 2,000 a year, compared to just three cases 15 years ago.
Professor Nigel Brown, from the Society for General Microbiology, said the CPE bacteria is carried "everywhere".
He told Sky News: "We have them in our guts and some of them produce this enzyme which destroys the antibiotic carbapenem.
"These can then transmit from your gut, into your bloodstream and go on to hospital beds and re-infect other people.
"They spread in all sorts of ways like that. They're quite resilient and quite hard to get rid of."
He is also joining calls from doctors for the mandatory reporting of cases in hospitals.
"At the moment the way in which the data are collected is a little bit unsatisfactory," he said.
"Some health authorities are very good, with good sound data. Others can't actually untangle their data or don't have the data at all."
Emily Morris, 24, has lived with a superbug, or antibiotic-resistant bacteria, for a decade.
She said more "almost untreatable" superbugs are "inevitable".
"It does affect the way I look at life," she said.
"I appreciate life every day because, for example, at the moment I'm currently waiting on results to know if I have got a bug again.
"I'm currently on antibiotics and we don't know; we think they are working but we don't know if they are working until three days later."
Public Health England said most hospitals and laboratories do report cases of CPE.
Professor Alan Johnson, head of the Department of Healthcare Associated Infection and Antibiotic Resistance at PHE, said: "Our national surveillance programme collects robust data on rates of antibiotic resistance.
"It shows that fewer than 2% of E. coli or Klebsiella bloodstream infections are resistant to carbapenems.
"Patients should be reassured that infections caused by carbapenemase-producing Enterobacteriaceae (CPE) can usually be treated with other antibiotics.
"We carry out enhanced surveillance on carbapenem-resistant bacteria to determine the numbers and different types of CPE.
"Although reports of CPE have increased recently, part of this may reflect increased laboratory testing of many sample types other than blood stream infections, as awareness of CPE has grown.
"We are working closely with the NHS to further improve data collection and surveillance and have also published advice to help hospitals in detecting, managing and controlling infections caused by CPE.
"This is part of wider work in tackling antimicrobial resistance, which is a priority for both PHE and the NHS."
Hospitals in London, Manchester, Birmingham, Edinburgh, Belfast, Nottingham and other cities in the UK have had confirmed outbreaks.
It is an issue that is already costing the NHS millions of pounds to deal with.
Medical experts have warned that antibiotic resistance poses a serious threat worldwide and could reverse advances in medical history by making some surgery, such as heart transplants, impossible.