Rising resistance to antibiotics is an alarming health trend around the world, and now new research on infections stemming from otherwise successful medical procedures highlights how serious the risks are for patients.

Up to half of infections after surgery and more than a quarter of infections after chemotherapy are caused by microbes that are already resistant to standard prophylactic antibiotics in the US, according to the study.

"This is the first study to estimate the impact of antibiotic resistance on broader medical care in the United States," said Ramanan Laxminarayan, director of the Centre for Disease Dynamics, Economics & Policy in Washington. "A lot of common surgical procedures and cancer chemotherapy will be virtually impossible if antibiotic resistance is not tackled urgently."

The researchers reviewed studies on the success of antibiotic trials between 1968 and 2011 to examine the efficacy of antibiotics in preventing infections and infection-related deaths after the 10 most common surgical procedures in the US, and also after immunosuppressing cancer chemotherapy.

They then calculated the number of additional infections and infection-related deaths that could result under a range of projected scenarios in which antibiotics resistance becomes slightly, moderately, significantly, or unimaginably worse (according to a respective 10 percent, 30 percent, 70 percent, and 100 percent reduction in efficacy).

In the most optimistic scenario, with just a 10 percent reduction in antibiotics efficacy, the researchers found 40,000 additional infections would occur in the US every year, and up to 280,000 with a 70 percent drop in efficacy. Infection-related deaths for 30 and 70 percent reductions in efficacy would respectively increase to 2,100 or 15,000 additional deaths a year – with about 20,000 additional deaths occurring every year if a 100 percent reduction in efficacy eventuated.

Dire statistics in the face of the decreasing efficacy of antibiotics, and a call to arms for more research to be conducted to find ways of fighting antimicrobial resistance.

"Not only is there an immediate need for up-to-date information to establish how antibiotic prophylaxis recommendations should be modified in the face of increasing resistance," said Laxminarayan, "but we also need new strategies for the prevention and control of antibiotic resistance at national and international levels."

The findings are published in The Lancet Infectious Diseases.