"John Hunter is a referral site for more complicated cases, so quite often we see very difficult to treat infections that are resistant to most and occasionally all antibiotics," Professor Davis said.
He said the Hunter was in a similar predicament to most of Australia, although the problem is "seen a lot more in bigger city hospitals".
It is the bacteria, not humans or animals, that become antibiotic-resistant and make the drugs ineffective.
Antibiotic resistance occurs naturally, but misuse of the drugs in humans and animals is accelerating the process, the World Health Organisation says.
"Antibiotic resistance can affect anyone, of any age, in any country. It is one of the biggest threats to global health, food security and development today."
Professor Davis said the most common antibiotic resistance problems in the Hunter were for E. coli bacteria [which cause bladder and urine infections] and golden staph [which cause skin infections with boils].
He said severe illnesses such as pneumonia, sepsis, septicaemia and meningitis were "obviously more of a concern".
These invasive infections were also showing antibiotics resistance in some people.
"In the Hunter, people do sometimes die of it. We haven't crunched the numbers on attributable deaths."
However, he cited a report the UK government commissioned that estimated about 10 million deaths a year globally by 2050 due to the rise of drug-resistant superbugs.
Professor Davis said the key message to the public was "the more we use antibiotics inappropriately, the more resistance we'll get".
"The main thing people can do is not ask their doctor for antibiotics when they have a cold," he said.
"If you have pneumonia you need antibiotics, but not if you have an upper respiratory infection."
He said data showed almost half of Australian adults have a prescription for antibiotics each year.
"We do know from lots of data that more than half of people that get antibiotics in the community from GPs don't need them.
"It's hard for doctors because patients come and say they want antibiotics. It's much easier for them to just write a script than explain everything and think about all the pros and cons."
A national report on antimicrobial use and resistance, released last week, said antimicrobial prescriptions under the PBS fell by 25 per cent from 2019 to 2021, but rose by 10 per cent the following year.
The report noted an "increasing proportion of private prescriptions for antimicrobials".
The Royal Australian College of GPs [RACGP] said the fall in Australia's antimicrobial use "highlighted efforts by GPs" to tackle the problem.
"GPs and other health professionals in general practice know we need to be prudent in our use of antimicrobials," RACGP president Dr Nicole Higgins said.
"The days of providing a prescription for antibiotics as a matter of course are long in the past."
Professor Davis said "we just want people to appreciate how valuable antibiotics are".
"In the first half of the 20th century, a lot of simple operations ended in death because of severe infection. There were no antibiotics.
"If we didn't have antibiotics, our life expectancy would be way shorter. If we waste them, we might end up in a world without effective antibiotics."