A new report shows the most common bacterial cause of bloodstream infections in Australia is becoming increasingly resistant to antibiotics.

The widespread and unnecessary use of antibiotics has put Australians at risk of life-threatening sepsis infections caused by superbug E.coli, a report warns.

Analysis of surveillance data, released by the Australian Commission on Safety and Quality in Health Care, shows the bacterium Escherichia coli (E.coli) is the most common bacterial cause of bloodstream infections, otherwise known as sepsis, in Australia and has become more resistant to the antibiotics doctors rely on to treat it.

The Australian Group on Antimicrobial Resistance Sepsis Outcomes Programs: 2016 report states E.coli accounted for 37 per cent of the total 11,163 cases of bacterial sepsis reported over the year.

Of those, an increasing number had become less susceptible to the antibiotics used to treat them, with nearly one in eight (12.7 per cent) susceptible to cefriaxone and ciprofloxacin.

Alarmingly, resistance to 'last resort' antibiotics fluoroquinolones had also increased.

The "potentially excessive" use of other types of antibiotics within the community, namely cephalosporins and penicillins may be to blame, the authors suggest.

One thing is clear: Australia is losing the battle against E.coli, says Professor John Turnidge, Senior Medical Advisor for the Commission's AURA Surveillance System.

"We are on the verge of losing a class of drugs, fluoroquinolones, that Australia has put a lot of effort into protecting over the past 25 years," Professor Turnidge said.

"If these drugs lose their effectiveness, then many more people will end up being hospitalised because only injectable drugs given intravenously will be effective."

E.coli is a bug that lives in the gut and most of the time is harmless.

Most commonly it is responsible for a urinary tract infection but can also cause kidney infection and this is when patients are at high risk of it reaching the bloodstream, Professor Turnidge said.

"That's when you are seriously ill, you need to be in hospital - probably in intensive care to make sure you recover quickly and that's where we really need the antibiotics to work," he said.

Professor Turnidge, the commission's senior medical advisor, said this drug-resistant E.coli is a growing threat and the overuse of antibiotics needs to be taken seriously by everyone.

"The surveillance in this and other reports has identified that the very high use of antibiotics in the community is helping to drive this problem, and reducing the unnecessary use of antibiotics in the community is a national priority," he said.