More than 6,000 deaths a year could be caused by a 30% fall in the effectiveness of antibiotics in the US, a report in The Lancet suggests.
It said most of the extra deaths would happen in patients having colorectal surgery, blood cancer chemotherapy and hip replacements.
UK experts said the study confirmed their fears that antibiotic resistance would affect routine surgery.
England's chief medical officer has called the issue a "ticking time bomb".
In this report, a team of scientists from a number of different American institutions estimated that as many as half of all bacteria that cause infections after surgery are resistant to antibiotics in the US.
They also estimated that one in four infections treated with antibiotics after chemotherapy treatment was now drug-resistant.
For the report, the researchers looked at what could happen to people having common operations and being treated for cancer with chemotherapy if antibiotic resistance increased by a third - in line with current trends.
They calculated that in the US there would be 120,000 more infections and 6,300 more deaths each year.
Lead study author Prof Ramanan Laxminarayan, director of the Centre for Disease Dynamics, Economics and Policy in Washington DC, said antibiotics were the bedrock of modern medicine but their reduced effectiveness was a "significant challenge".
He explained: "The danger is that antibiotic resistance is squeezing the value out of modern medicine."
He said antibiotic resistance was already killing newborns in the developing world and mostly elderly people in the developed world.
And as the elderly population increased, they would have more operations and be more at risk of infections, he said.
He urged public health experts to come up with "new strategies for the prevention and control of antibiotic resistance at national and international levels".
Prof Laura Piddock, director of Antibiotic Action and professor of microbiology at the University of Birmingham, has previously warned of the potential effects of antibiotic resistance on routine operations.
"It is good to see evidence from the US that supports these serious concerns that antibiotic resistance will impact upon many areas of medicine, including that it is undermining the treatment of cancer patients."
She said she hoped the report would be "a loud 'wake-up call' to pharmaceutical companies" to research and develop new treatment for bacterial infections.
"Without them, patients will be less likely to survive cancer and so unable to take advantage of new life-extending cancer therapies," she said.
However, in the UK at present, there are no major signs of antibiotics failing to control infections after routine surgery.
In fact, data shows that UK infection rates are falling slightly, according to a Public Health England report.
But Prof Nigel Brown, President of the Microbiology Society, said the study was relevant to the UK.
"Antibiotic resistance is a global problem and it is likely that routine surgery such as hip replacement and elective caesarean sections will become much rarer in the UK, unless steps are taken to prevent its spread."
Humans vs superbugs
- Superbugs are now a major global health threat with multi-drug resistant bacteria causing around 400,000 infections and 25,000 deaths in Europe every year.
- Our actions speed up antibiotic resistance in bacteria, especially in the areas of farming and healthcare. Nearly 50% of antibiotic prescriptions are inappropriate.
- Are we are facing a future where a cough or cut could kill once again?